Basic l. iii refresher corse HELLIER NDT, Study Guides, Projects, Research of Materials science

Download Basic l. iii refresher corse HELLIER NDT and more Study Guides, Projects, Research Materials science in PDF only on Docsity! HELLIER DHNICAL TRAINING © CERTIFICATION © CONSULTING BASIC REFRESHER LEVEL fil Q77 » NIANTIC, CT 9357-1018 © (860) 739-2950 * PAX (860) 739-6732 ¢ gmaillnioNiantic@HelliceN Teo, NOT MEASUlcERIENT / SENSITII'E 25 Januarv 1991 SUPERSEDING . MILSI7D-410D 23 JULY 1974 MILITARY STANDARD NONDESTRUClTVi? TESTING PERSONNEL QUALIFICATION AND CERTIFICATION AMSC N/A AREA NDTI DISTRJBUnON STATEMENT A. Approved for public release distribution is unlimited. MILSTD-310E CONTENTS PARAGRAPH PAGE 4 . GENERAL F?EQUlREMENTS . . . . . . . . . . . . . . . . . . . . 5 4.1 Certification procedure . . . . . . . . . . . . . . . . . . . . . . . . 5 4.1.1 Levels of qualification . . . . . . . . . . . . . . . . . . . . . . . . 5 4.1.2 Perso'nnel duties and responsibilities . . . . . . . . . . . . . . . 5 . . 4.1.3 Tralnrng program . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4.1.4 Experience requirements . . . . . . . . . . . . . . . . . . . . . . . . 5 4.1.5 Examination practices . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4.1.6 Records and documentation administrative practices ..... 5 4.1.7 Recertification requirements . . . . . . . . . . . . . . . . . . . . . 5 4.2 Personnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4.3 Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4.4 Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4.5 Outside agency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5 . DETAILED REQtJIREMENTS . . . . . . . . . . . . . . . . . . . . . 6 5.1 Levels of qualification . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.1.1 Trainee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.1.2 Level I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.1.3 Level I1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5.1.4 Jnstructor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5.1.5 Level ID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5.2 . . Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5.2.1 Specialist personnel . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5.2.2 Exams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5.2.3 Minimum required training hours . . . . . . . . . . . . . . . . . 7 5.2.4 Previous training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5.3 Experience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 5.3.1 Previous experience . . . . . . . . . . . . . . . . . . . . . . . . . . 10 5.3.2 Equivalent experience . . . . . . . . . . . . . . . . . . . . . . . . 10 5.4 . . Exam~natlons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 5.4.1 Physical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 5.4.2 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 5.4.3 Specific . . . . . . . : . . . . . . . . . . . . . . . . . . . . . . . . . . 11 5.4.4 Practical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 5.4.4.1 Level l . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 5.4.4.2 Level I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 5.4.4.3 LevelIII . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 5.4.5 Administxation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 5.4.6 Grading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 5.4.7 Re-examination . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 5.5 Designation of instructors . . . . . . . . . . . . . . . . . . . . . 12 5.6 Certification . . . . . . . . . . . . . . : . . . . . . . . . . . . . . . . 13 5.6.1 Records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 PARAGRAPH MILSTD-410E CONTENTS Loss of certification . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Reinstatement of certification . . . . . . . . . . . . . . . . . . . . 13 Recertification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 NOTES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Level1 Special ..................................... 14 ....................................... Intended Use 14 Subject tenn (key word) listing . . . . . . . . . . . . . . . . 14 Changes from previous issue . . . . . . . . . . . . . . . . . . . . . 15 1. SCOPE 1.1 Pumose. This standard establishes the minimum requirements for the qualification and certification for personnel involved in the application of nondestructive inspection WI) or nondestructive testing (NDT) personnel. These requirements include training, experience and examination. 1.2 ~oplicability. This standard applies to personnel using NDI or NDT methods to accept materials, products, subsystems, components or systems for the Government, prime contractors or subcontractors. It also applies to those individuals directly responsible for the technical adequacy of the NDI and NDT methods used as well as those providing the technical training or supervision for NDI or NDT personnel. This standard is not intended to apply to individuals with administrative authority only over the above identified personnel or to research personnel developing technology for use by qualified and certified NDI or NDT personnel. 1.2.1 Common methods. This standard contains detailed requirements for the applicable training, experience, and examination for the following methods: Liquid penetrant Magnetic particle (pr) 0 Mdy current m) Ultrasonic Radiography m (RT) Acoustic emission (AE) Neutron radiography (NRT) 1.2.2 Other methods. This standard may apply to other NDI or NDT methods such as leak testing. thermography, holography, computed tomography. or any other method that can determine the acceptability or suitability for intended service of a material, part, component, subsystem, or.system without impairment of the intended function. The requirements for personnel training, experience, and examination for these other methods shall be as established by the contracting agency and shall be in accordance with the guidelines established for the methods listed in 1.2.1. 1.3 Levels of The levels of qualification established by this standard are: Trainee Level I Level I1 hstructor Level III 3.19 Practical examination. The examination used to demonstrate an individual's ability in conducting the NDI or NDT methods that will be performed for the employer. Questions and answers need not be written, but observations and results must be documented. 3.20 Prime contractor. The organization having responsibility to the government for a system, component, or materials. 3.21 Procedure. A detailed, written instruction for conducting NDI or NDT or certifying personnel. All procedures shall be approved by a Level ID. 3.22 Product form. Materials, parts, or components having similar NDI or NDT characteristics. Examples of individual product forms are: castings. extrusions, plate, aeldments, pyrotechnics, bonded assemblies, composite materials, and printed circuit boards. 3.23 Oualification. The skills, training, knowledge and experience required for personnel to properly perform to a particular Level. 3.24 Soecific examination. The written examination to determine an individual's understanding of procedures, codes, standards, and specifications for a given method used by the employer. 3.25 Techniaue. A category within a method, for example: ultrasonic immersion testing or fluorescent dye penetrant inspection. 3.26 Test samples. Parts containing known defects and used in the practical examination to demonstrate the candidate's proficiency in using a particular method. Test samples will not be production parts unless the Level ID has previously investigated the parts and documented all abnormal or out of specification conditions within the samples. Alternatively, test samples can refer to images of actual hardware, i.e.. radiographs, when the candidate's required proficiency is in the interpretation of the image rather than the generation of the image. 3.27 Training. An organized and documented program of activities designed to impart the knowledge and skills t o be qualified to this standard. This program may be a mix of classroom, laboratory, programmed self-teaching and on-the-job training as approved by the appropriate Level III. 4. GENERAL REQUIREMENTS 4.1 Certification ~rocedure. All organizations involved in any aspect of NDI or NDT shall develop and maintain a procedure for the qualification and certification of their NDI or NDT personnel. This procedure shall be in accordance with the requirements of this standard. The procedure shall be available for review by the organization's customers. The procedure, as a minimum, shall include: 4 . l . i Levels of aualification. This shall include identification of the levels of qualification covered by the procedure. The organization may add any additional levels that are appropriate; however, in no manner can the organization eliminate or reduce minimum requirements of this standard in its qualification and certification procedure. 4.1.2 Personnel duties and responsibilities. This shall include the identification of the duties and responsibilities for the different levels of qualification. 4.1.3 Trainine Droeram. This shall include-outlines of the instruction provided by the organization as well a s sources of outside training utilized by the organization. 4.1.4 Exoerience reauirements. This shall include the techniques within the method and the minimum amount of time for each technique. 4.1.5 Examination oractices. This shall include the designation of the individuals or organizations that will perform the examinations as well as the number of questions. and the specific types of physical tests to be used. 4.1.6 Records and documentation administrative oractices. This shall include the description of the details to be recorded for each certified individual and identification of the individuals responsible for developing, administering, and maintaining the employer's certification program. 4.1.7 Recertification requirements. This shall include the employer's requirements for recertification of personnel. It shall also include the requirements for the loss and r&nstatement of certification. 4.2 Personnel. Personnel (Government. prime contractor, subcontractor, outside agency, etc.) performing, specifying, reviewing, monitoring, supervising, or evaluating . NDI or NDT functions for the purpose of accepting items for the Government shall be qualified to the appropriate requirements of this standard. Personnel performing specialized NDI or NDT, such a s ultrasonic thickness gauging or e l e d & l conductivity tests, with equipment designed for and limited to such usage and that produces clearly recognizable output for both acceptable and unacceptable conditions, do not require qualification to this standard. 4.3 Methods. For the common methods listed in paragraph 1.2.1 of this standard, the requirements for training, experience and examination are detailed in section 5 of this standard. These requirements, as well as those requirements contained in the two publications referenced in paragraph 2.1, shall serve as guidelines for those methods not listed in paragraph 1.2.1. 4.4 Com~liance. Prime contractors shall be responsible for compliance to this standard by their subcontractors. Those organizations utilizing outside sources for training or examination of their personnel shall be responsible for assuring that the appropriate requirements of this standard are met. The employer'is solely responsible for the certification of its employees and cannot certify for another employer. Individuals cannot certify themselves. 4.5 Outside agency. An employer may utilize an outside agency to develop a certification program, train and examine NDI or NDT personnel and perform any other Level LU function. An outside agency cannot certify personnel. The employer shall document the suitability of any outside source selected to perform any function to meet the requirements of this standard. This documentation shall be sufficient to justify that the outside agency is capable of performing the required Level III functions. 5. DETAILED R E Q W S 5.1 Levels of qualification. There shall be five levels of personnel qualification. 5.1.1 Trainee. A trainee is an individual who is participating in a training program for an NDI or NDT method and is not certified. Trainees shall obtain work experience only under the direct supervision of a Level Il, Level III or Instructor in the same method. Trainees shall not independently conduct tests, make accept or reject decisions, or perform any other NDI or NDT functions. 5.1.2 Level I. Level I is the first certifiable qualification level. The Level 1 certification shall be for a specific technique in a given method. The Level I individual shall have the skills and howledge to perform specific tests, specific calibrations, and, with prior written approval of the appropriate Level III individual, specific interpretations and evaluations for acceptance or rejection, and document the results in accordance with specific procedures. The individual shall be knowledgeable of any necessary preparation of parts before or after inspection. The individual shall be able to follo\r procedures in the techniques for which certified and shall receive the necessaiy guidance or supervision from an Level II or Level El individual. 5.1.3 Level II. Level I1 individuals shall have the skills and knowledge to set up and calibrate equipment, conduct tests, and t o interpret, evaluate, and document results in accordance with procedures approved by the appropriate k v e l LU. The individual shall be thoroughly familiar with the scope and limitations of the method in which he is . , certified and shall be capable of directing the work of trainees and Level I personnel. The individual shall be able to organize and document NDI or NDT results. The individual shall be familiar with the codes, standards, and other contractual documents that control the method as utilized by the employer. 5.3 Ex~erience. Candidates for certification at Levels 1. II or IU shall have sufficient practical experience to assure that they are capable of performing the duties of the level for which certification is sought. The minimum requirements for Levels I, II and Dl are given in Table II. TABLE II. h4NMUvl EXPERIENCE REQUIREh4ENTS , CONDITION METHOD [I1 [21 PI PI [51 , [61 Penetrant 130 hrs 270 hrs 400 hrs 4 yrs 2 yrs Magnetic particle 130 hrs 400 hrs 530 hrs 4 yrs 2 yrs 1 Yr Eddy current 130 hrs 1200 hrs 1330 hrs 4 yrs 2 yrs 1 yr Ultrasonics 400 hrs 1200 hrs 1600 hrs 4 yrs 2 yrs 1 y i Radiography 400 hrs 1200 hrs 1600 hrs 4 yrs 2 yrs 1 Yr Acoustic Emission 400 hrs 1200 hrs 1600 hrs 4 yrs 2 yrs 1 Yr Neutron radiography 800 hrs 2400 hrs 3200 hrs 4 yrs 2 yrs 1 yr [I] Trainee experience for Level I. Experience in method must be at least half this tine. [2] Level I experience for Le\.el II. Experience in method must be at least half this time. [3] Trainee experience for direct certification to Level II. . Evperience in method must be a t least half this time. [4] Level Il experience required for Level III with no college degree. [5] Level II experience required for Level III with technical associate degree. [6] Level II or equivalent work experience required for Level El with technical bachelors degree. Equivalency of the work experience shall be determined and documented by the Level III responsible for the employer's certification program. 5.3.1 Previous ex~eriencc. A candidate's experience with a previous employer may be accepted by the current employer only if that experience is documented and verified by the former employer. 5.3.2 Eauivalent ex~erience. For personnel certified under previous revisions of this document or other qualification/certification programs, the equivalency of their previous experience to the requirements of table TI will be determined and documented by the Level III. 5.4 Examinations. The examinations to verify the physical and technical qualifications of candidate personnel shall consist of a physical examination. a general examination, a specific examination, and a practical examination. The requirements for the physical examinations; the questions utilized for the general and specific examinations and the checklist for the practical examination shall be available for review by the facility's customers. If the actual test questions given during certification examinations are not kept in each certified individual's records, then the listing of questions from which examinations are derived shall be available for review by the facility's customers. The questions shall be made available to certification candidates only during administration of the examinations. 5.4.1 Phvsical. The physical examination shall assure that the applicants near vision and color perception meet the following requirements. Near vision tests shall be administered annually and color perception tests shall be administered prior to certification or recertification. These tests shall be administered by an individual approved by the Level III responsible for the maintenance of the certification program or by the outside agency utilized for the examination of personnel: Near vision - Jaeger #I test chart at not less than 12 inches, or equivalent with one eye, either natural or corrected. Color oerception - Distinguish and differentiate between the colors used in the methad for which certification is sought. 5.4.2 General. The general examination for all levels shall be a closed book examination consisting of questions that cover the cross-section of the applicable method at the appropriate level. The questions, answers, and references in the appliixble SNT-TC-IA supplement and other publications may be used to develop the general examination. A minimum of 40 questions shall be used for the general examination at each level. For Level IlI. the general examination questions will address the general knowledge of other methods as well as the method for which certification is sought. Possession of a current ASNT NDT Level III certificate by the candidate shall be satisfactory evidence that the general examination requirement is satisfied. 5.4.3 Suecific. The specific examination for all levels shall be a closed book examination and shall cover the specifications, codes, equipment, operating procedures, and test techniques the candidate may use in the performance of his duties. A minimum of 30 questions shall be used for the specific examination at each level. 5.4.4 Practical. The practical examination shall consist of a demonstration of proficiency by the candidate in performing tasks that are typical of those to be accomplished in the performance of his duties. Test samples used in the examination may be actual hardware, if the candidate is required to demonstrate proficiency in the application of the process as well as interpretation of results, or may be images, such as radiographs, if the candidate is only required to interpret the results and not perform the process of generating the image. Written checklists covering the topics detailed below shall be developed by the Level IJI to assure adequate coverage and to assist in the administration and grading of the examination. 5.4.4.1 b v e l I. The candidate shall demonstrate proficiency by using the appropriate method to examine at least one test sample for each technique to be used and document the results. The test samples shall be representative of the products to be encountered by the candidate in the performance of his duties. The checklist shall address proficiency in the use of the procedures and equipment or materials, adherence to procedural details and the documentation of the results. If the Level I candidate is to accept products, then the checklist shall also include proficiency in the interpretation and evaluation of indications. 5.4.4.2 Level Il. The candidate shall demonstrate proficiency by using the appropriate method to examine a t least one test sample for each technique. The candidate shall interpret, evaluate and document the results of the examination of the test samples. At least two test samples shall be evaluated for each method. The test samples shall be representative of the products to be encountered by the candidate in the performance of his duties. The checklist shall include proficiency in the use of the procedures and equipment or materials. adherence to procedural details, and the accuracy and completeness of interpretations and evaluations of indications. 5.4.4.3 Level. III. The candidate shall demonstrate proficiency by preparing an NDIMDT procedure appropriate to his employer's requirements. When the candidate's duties will include inspection or evaluation of products, then proficiency in performance of such tasks shall be demonstrated also. The checklist shall address the practical and technical adequacy of the procedures prepared by the candidate, and when applicable, the adequacy of the interpretation and evaluation of indications. In the event that the candidate has already developed satisfactory procedures, then it is not necessary to develop another one for the practical examination. The results of the practical examination shall be documented. Procedures developed for a previous employer can be used to satisfy this requirement if their adequacy can be verified and documented. 5.6.4 Recertification. Level I and I1 personnel shall be recertified ar intervals not to exceed three years. Level lIl personnel shall be recertified at intervals not to exceed 5 years. The physical and practical examinations, equivalent to those required for initial certification, shall be given prior to recertification. The extent to which the individual's knowledge of the general and specific examination subject areas is examined shall be determined by the Level III responsible for the employer's certification program and shall be documented in the individuals certification records. 6. NOTES (This section contains information of a general or explanatory nature that may be helpful, but is not mandatory.) 6.1 Level I Soecial. The Leve! I designation in this revision is equivalenL to the Level I Special designation of MIL-STD-410D. The MIL-STD-4IOD Level I Special was limited to the ultrasonic and eddy current methods. Experience has shown that the Level I Special designation is an effective way of designating the entry level certification for nondestructive inspection and that it should be allowed a for all methods; thus the change was made in this revision. Because of the increased responsibilities assigned to the Level I, minimum required classroom training hours are no? specified (see table 1). ur 6.2 Intended use. When invoked in a Request for Proposal (RFP), lnvitation for Bid m), of other similar document, the contracting agency should request that a copy of the offeror's existing qualification/certification procedure for NDI o r NDT personnel be included with the technical proposal. If the offeror has no existing procedure or if the existing procedure does not comply with this standard, then the contracting agency should request that the offeror's approach for establishing a procedure that complies with this standard be included in the technical proposal. In addition, if the contacting agency intends that personnel using methods other than those listed in paragraph 1.2.1 be qualified and certified to this standard, then details on the offeror's approach to conducting such an effort should be requested as part of the technical proposal. 6.3 Subiect term (key word) listing. Acoustic emission Certification Eddy current Liquid penetrant Magnetic particle Neutron radiography Nondestructive testing Qualification Radiography Ultrasonic 6.4 Chanees from orevious issue. Marginal notations are not used in this revision to identify changes with respect to the previous issue due to the extensiveness of the changes. Custodians: Preparing Activity: Army.- MR Navy - AS Air Force - 11 Reviewer Activities: Army - AR Air Force - I1 (Project No. NDTI-0176) 'TE 2 I1 may be used to determine duralion and level b) The practical test lor levels 1 and 2 is to verify training and experience required prior to ability to set Up and Operate test equipment, and perform the necessary settings to yield satislac- 3.10 NDT training: A process o l instruction in the- lory test results. ory and practice in the NDT methods in which certi- -d" fication is being sought, which may take the form of C 3.19 specific examination: The specific examination training courses to an approved syllabus in addition 4 includes both a written and a practical part for levels to periods of practical work under qualified super- I and 2. and only two written parts for level 3. vision but shall not include the use of specimens used in practical examinations. a) The written test is concerned with components, . systems, equipment, operating procedures and 3.11 experience: The period during which the can- test techniques commonly used in a particular didale performed the specific NDT method as his industry or industrial sector. It involves the dem- main activity under qualified supervision. inciuding onstration of knowledge related to the product personal application ofthe NDT method to materials, being tested and covers the applicable specifi- parts or structures but not including tests performed cations, codes and acceptance criteria. For level during training courses. 3 only, this examination includes the writing of one or more satisfactory procedures. 3.12 NDT method: The application of a physical principle in nondestructive testing (for example: b) The practical test involves, for levels1 and 2. the ultrasonic testing). demonstration of familiarity with and the ability to operate the necessary test equipment on pre- 3.13 NDT technique: A specific way of utilizing an scribed mmponents and the ability to record and NDT method (for example: immersion ultrasonlc analyse the resultant informalion to the degree testing). required. 3.14 NDT procedure: An orderly sequence of ~ l e s which describe in detailed terms where, how and in .fhich sequence an NDT method should be applied ,o a product. 3.15 NDT inshuctions: A written document detailing the.precise steps to be lollowed in testing in ac- cordance with an NDT procedure. 3.16 industrial sector. A particular area in industry or technology where specialized NOT practices are utilized requiring specific skill. knowledge, equip- ment or training to achieve satisfactory perform- ance. An industrial sector may be interpreted to mean a product (welds, castings, elc.) or an Industry (aerospace, steel, etc.). 3.17 qualiIica~lon examlnauon: An examination ad- ministered by the national certifying body or by an authorized qualifying body, which shall include a general examination and a specific examination for each level of competence. 3.20 lob-specific examination: Any additional & examcnation - concerned with the application of an NDT methog to a specialized product not commonly involved in a particular industrial sector. This examination. which supplements this International Standard. is carried out following written guidelines with results recorded to meet quality-assurance or customer-audit requirements. NOTE3 This examination is outside the scope of lhis International Standard. 3.21 bainee: An individual who works under the supervision of certified personnel but who does not conduct any tests independently. does not interpret test results and does not write reports on test re- sults. This individual may be'regislered as being in the process of gaining appropriate experience to establish eligibility for qualilication lo level 1 or for direct access to level 2. 4 Levels of competence 3.18 general examinauon: The general examination 4.1 Classification includes both a written and a Practical part for levels An individual certified in accordance with this 1 and 2. and only a written part for level 3. national Standard shall be classified in one of three levels depending upon the Individual's respective a) The written test Is mncerned with the principles level of whereas one who has not yet Of the method and' at least lor attained certllicallon may be registered as a trainee, level 3, covers basic knowledge of other NDT melhods. of materials and pmcesses. and of discontinuities arising through the use of various 4.2 NDT level 1 materials, manufacturing processes or service conditions. For level 3, the requirements for An individual certified to NDT level 1 is qualified to certification of NDT personnel are also Included. carry out NDT operalions in accordance with written instructions and under the supervision of level 2 or 0) 5.2 National certifying body level 3 personnel. The individual shall be able to set (/ up the equipment. carry out the tests, record the The national certifying body shall be a non-profit resulls obtained, classify the results in accordance organization which has no direct involvement in with written criteria, and report the results. He shall training of NOT personnel and which is recognized not be responsible for the choice of the test method by the IS0 member body of the country Concerned. or technique to be used. nor for the assessment of test results. 5.2.f Composition 4.3 NDT level 2 An individual certified to NDT level 2 is qualified to perform and direct nondestroctive testing in ac- cordance with established or remgnized tech- niques. The individual shall be competent to choose the test techniques to be used; to set up and cali- brate equipment; to interpret and evaluate results in accordance with applicable codes, standards and specifications; to carry out all duties for which a level 1 lndlvldual is qualifed and to check that they are property executed; to develop NDT procedures adapted to problems which are the subject of an NDT specification; and to prepare written in- structions and organlze and report the results of nondestructive tests. The individual shall also be familiar with the scope and limitations of the method for which helshe is qualifed, and be able to exercise assigned responsibility for on-the-job tralnlng and guidance of trainees and NDT level I personnel. 4.4 NDT level 3 An individual certified to NDT level 3 shall be capa- ble of assuming full responsibility for a test facility and stall; establishing techniques and procedures; interpreting codes, standards. specifications and procedures; and designating the particular test methods, techniques and procedures to be used. The individual shall have the competence to inter- pret and evaluate results in anordance with exist- ing codes. standards and specifications: have a sulficient practical background in applicable ma- terials. labrication and product technology to select methods and establish techniques and to assist in establishing acceptance criteria where none are olherwise available: have general familiarity with other NDT methods; and have the ability to train level I and level 2 personnel. 5 General principles of certification 5.1 Administration The certification activity that includes ail procedures adopted to demonstrate the qualification of an indi- vidual to carry out tasks in a specific NDT method and leads to a written testimony of hislher com- petence shall be adminlstered in each country by the national certifying body, with the assistance. where necessary, of duly authorized qualifying bodles. The national certifying body shall be Supported by an adminislrative committee, which shall inc lde eminent representatives of NDT societies, cum- mittees, users, suppliers. government departments and other interested parties as appropriate. The NCB shall establish. In writing. the number of mem- bers of this committee, their qualifications (including education. training and experience), the means and extent of documentation of their qualifications. and their tenure. 5.22 Responsibilities - The national certifying body a) shall initiate, maintain and promote the national certification scheme as specified in this Inter- national Standard; b) shall administer the procedures and operations for certification in accordance with national documents meeting the minimum requirements of this International Standard, and a stringent code of ethics. including sanctions, which shall apply to committee members and certificate holders; c) may delegate, under its direct responsibility. the detailed administration of the certification pm- cedure to other organizations which will act as qualifying bodies and which could represent in- dustrial sectors: d) shall take the ultimate responsibility for the certilication scheme, including technical and ad- minislrative requirements; e) 'shall approve, either directly o r through a quali- fying body, properly stafied and equipped exam- ination centres which it shall monitor on a periodic basis and f) shall keep ail appropriate records and issue, or delegate the issuing of, written testimonies. o r responslble agency --a- The employer or responsible agency shall introduce the candidate to the national certifying body and document the validity of the personal information provided, including the declaration of educatlon. :ng and experience needed to eslablish the el- ,w,lity of (he candidate, but shall not be directly in- iolved in the certification procedure itself. The employer or responsible agency shall be fully responsible for all t11at concerns the authorization to operate and the validity of the results of NDT oper- ations. If the individual is self-employed, or introduces him- self* he shall assume all responsibilites deskribed for the employer or responsible agency. 5.4 Examination centres Examination centres established by the national certifying body o r through authorized qualifying bodies shall, as a minimum requirement. a) have adequate qualified stan; premises and equipment to ensure satisfactory qualification examinations for the levels, methods and . . indus- trial sectors concerned; b) use only those documents and .examination questionnaires established or approved by the national certifying body; use only specimens prepared or approved by the national certifying body for the practical examin- ations conducted at that centre. Whenmore than one authorized examination centre exists, each shall have specimens containing com- parable defects. Under no circumstances shall examination specimens be used for training pur- poses. 6 Eligibility for examination 6.1 General Candidates shall have a combination o f education. training and experience adequate to ensure that they have the polential to understand the principles and procedures of the applicable NDT method. 6.2 Education fvldence of education may be required to establish the eligibility o f a candidate. 6.3 Training j.3.1 Levels 1 and 2 To be eligible to apply for certification in any NDT method. the candidate shall provide evidence of successful completion of a training programme ap- proved by the national certifying body in that method. Table 1 and annex 8 are provided for guid- ance; however national certifying bodies shall lake into consideration education. certification in other methods, training facilities and other factors. Table 1 - Minimum duration of trainina Training hours NDT method 1 Eddy-current testing 1 40 +._ 80 ( 1 Liquid-penetrant testing 1 l 6 1 40 I 1 Magnetic testing I 1 Training hours include both praclical and lheor- etical lrainlng courses. I Radiographic testing Ultrasonic tesliog 2 Direct access to level 2 implies the total of the. hours shown lor levels 1 and 2 6.3.2 Level 3 40 . 40 Taking into account the scientific and technical po- tential of candidates for level 3 certification. i t i s considered that preparation for qualification could be done in dilierent ways: by taking training courses. attending conrerences o r seminan such as organ- ized by industrial or independent associations, and studying books. periodicals and other specialized printed matter. No training hours have therefore been specified in table 1, although references cited in annex B do suggest course content and duration. 80 80 6.4 Experience 6.4.1 Levels 1 and 2 To be eligible lor certification. the candidale shall have the minimum experience Indicated in table2 for the method in which helshe is seeking certi- Sication. . . period of similar duration, provided the individual meets the following criteria: a) helshe provides evidence at least every second year of satisfactory visual examination and b) heishe provides evidence of continued satisfac- tory work activity without significant interruption. NOTE 5 A significant interruption means an absence or a change of activity which prevents h e certified individual from practising the duties corresponding to his/her level in the method and the industrial sector(s) for which helshe is certified, for one or several periods for a total time exceeding one year. If the criteria for renewal are not met. the individual shall apply for recertification. 9.3 Recertification Upon completion of each second period of validity, or at least every ten years. certification shall be re- newed by the national certifying body. directly o r through an authorized qualifying body, for a similar period, provided the individual meets the two cri- teria for renewal and successfully completes a slm- plified examination to assess hislher current knowledge. This simplified examination shall consist of: a) Level I and level 2: a practical examination or- . ganized in accordance with a simplified pro- cedure: b) Level 3: a written examination which includes 20 questions on the application of the test method in the industrial sector concerned and 5 questions on this International Standard (the national certifying body will have the option of replacing this simplified examination by an alternative. structured credit system under its control). if the individual fails to achieve a grade of 80 % or better in the simplified examination, helshe shall apply for new certification. 10 Files The national certifying body or its authorized quati- wing bodies shall keep a) an updated list of all Individuals certified. classi- fied amrding to level. test melhod and industrial sector; b) an individual file for each lndividual certified and for each individual whose certification has been withdrawn, containing I) application forms. 2) examination documents, including question- naires, answers. descriptions of specimens, records, results of tests. written procedures and/or techniques, and grade sheets, 3) renewal documents, including evidence of physical condition and continuous activity. 4) reasons for any withdrawal of certification and details of any further penalty inflicted. Individual liles shall be kept under suitable con- ditions of safely and discretion for a period at least equal to the total of the initial period of validity plus the renewal period. Annex A (normative) Administration of examinations A.l Examinations for leve l 1 and level 2 A.l.l Qualification examination The qualification examination administered under this International Standard shall include a general examination and a specific examination for each level of competence. Each examination shall mnsist of a written parl and a pradlcal part The pradlcal parl shall be of sullicient duration, complexity and smpe to verify adequately the candidate's ability to apply the NDT method to real test situations. A.1.2 Examination content 1.21 General exarnlna~on A.1.22 Specific examlnation Table A.l - Required number of questions - General examination In the genera! examlnation, the candidate shall demonstrate proficiency in performing the relevant In .the specilic examlnation, the candidate shall NDT method. demonstrate his ability to use the relevant test method in the industrial sector concerned. NDT method Eddycurrent testing Liquidpenelrant testing Magnetic testing Radiographic testing Ultrasonic testing The written test in the general examination shall in- clude only questions selected from the national cer- The written test in the specific examination shall in- body's collection of basic-knowledge clude only questions selected from the national cer- questions valid at the date of examination. The can- tifying body's current mllection related to all didate shall be required, as a minimum, to give an- industrial sectors or from the mllection of specific questions maintained by an authorized qualifying to the fixed number Of multiple-choice ' body related to the industrial sector concerned. questions shown in tableA.1. During the specific examination. the candidate shall The practical test in the general examinalion is to be required to give to a fixed number of verify the candidate's ability to make the required settings and operate the test equipment properly in questions. as defined in tableA.2. including multiple-choice questions. calculations. written pro- order to obtain satisfactory results and correctly in- cedures and questions on codes, standards and terpret these results. The candidate shall therefore specilications. be required to demonstrate this ability. with mm- Number of questions ments; using the means of verification>vailable for ~ h , practical test in the specific examination is to each test method. such as calibration blocks, verify the ability to perlorm testing of Image-quality, indicators and magnetic-field lndi- prescribed components relating to the industrial Level 1 30 30 30 40 40 f a l O E . sector concerned, and to record and analyse the Level 2 30 30 30 40 40 For the radiographic test method, there shall be an resultant information to the degree required, ac- additional examination on radiation safety. curding to specific testing instructions or specifi- cations. and to the NDT level being sought. The specimens used for the practical test shall be "OTE 6 Examinations on the radiographic test method Selected from a ml~ection of representative speci- .ay indude either X- or garnrna-radiation, or both, de- pending upon the procedure of the national certirying mens chosen b~ the national certifying body or by its MY. authorized qualifying body. For level 2. the candidate shall be required to dem- onstrate the ability to prepare written instructions for level 1 personnel. If the practical test in the specific examination cov- ers two o r more industrial sectors, the number of specimens to be tested shall be increased pro- portionally to examine the candidate's competence in each of the industrial sectors concerned. If the written part o f the specific examination covers two or more industrial sectors. the number of questions shall be increased proportionately to reasonably cover each o f the industrial sectors, and evaluated accordingly. Table A.2 - Required number of questions - Specific examlnation A.1.3 Conduct of examinations NDT method Eddy-current testing Liquid-penetrant testing Magnetic testing Radiographic testing Ultrasonic testing All examinations shall be conducted in examination centres approved and monitored by the national certifying body, either directly or through an author-' ized qualifying body. At the examination. the candidate shall have in his possession a valid proof o f identification and an of- ficial notification o f the examination, which shall be shown to the examiner o r invigilator on request. Number of questions Any candidate who, during the course of the exam- ination, does not abide by the examination rules o r who perpetrates, o r is an accessory to, fraudulent conduct shall be excluded from further participation. Level 1 15 20 20 20 20 The written and practical tests shall be conducted and supervised by an examiner chosen among NDT level 3 personnel and designated by the natlonal certifying body, either directly o r through an author- lzed qualifying body. The examiner may be assisted by one o r more invigilators placed under his re- sponsibility. Level 2 15 15 15 20 20 The examiner shall mark the written tests completed by the candidate; he shall judge and mark the re- sults of the practical tests in accordance with a oro- cedure which includes at least ten check points. 7his procedure shall be developed by the national certi. lying body o r an authorized qualifying body. A candidate for a practical examination may use his own apparatus. The examiner shall investigate the reliability of the test apparatus made available to the candidate. and unreliable apparatus shall be re_ placed. as well as any apparatus that may be ren- dered unserviceable during the course of the examination. Any item of apparatus brought by a candidate that is unreliable o r rendered unservice- able during the examination shall be replaced by the candidate himself. A.1.4 Grading The general examination shall be graded separately from the specific examination so that the candidate may be examined later for certification in another branch of industry without having to take the general examination again; thus a certified operator chang- ing from one industrial sector to another keeps the benefit of the general examination valid for all in- dustrial sectors. To be certified. the candidate shall obtain a grade of at least 70 % in each of tfi&ur tests I - examination ana a cumnosite arade of at least The composite grade for.the respeclive level shall be determined by adding the weighted marks ob- tained from multiplying each of the four test marks by a weighting factor to be selected from tableA.3. The total of the selected weighting factors shall equal 1.00. /( Table A.3 - Weighting factors for gradlng - Levels /c, 1 and 2 I Weighting factor I Level General A candidate failing for reasons of unethical behav- iour shall wait at least 12 months before reapplying. Speciflc 1 2 A candidate who fails to obtain the pass grade for the whole examination may take one. and only one. retest in a maximum of two parts. provided the minimum percentage (70%) was obtained in each 1 Written 0.2 to 0.4 0.2 to 0.4 Written 0.2 to 0.4 0.2 to 0.4 Practical 0.2 to 0.4 0.2 lo 0,4 Practical 0.2 to 0.4 0.2 to 0.4 Annex B (informative) 6.1 General Technical knowledge of NDT personnel [2] The cdrnpiete Recommendations on inter- .' national harmonization offraining qualification This annex provides a bibliography of international and cerfilication or nondestructive testing per- publications detailing course content. The minimum sonnel. Prepared by the lnternational Corn- hours of training recommended to confirm eligibility rnittee on Non-Destructive Testing. adopted for examination are detailed in the main text of this November 1985. Available from tlie Foundation International Standard. lor the Qualification of NDT Personnel. P.O. Box 190. 27M1- AD Zoetermeer. The 8.2 References [3] ASNT recommended praclice SNTITC-IA. 1988 C13 Technical Document IAEA-TECDOC-407 (1987). Edition. Tables I-A l o I-H (recommended Training guidelines in nondestructive testing training courses). Published by the American techniques, International Atomic Energy Society for Non-destructive Testing. 1711 Agency, WagramrnerstraCe 5. P.O. Box 100. Arlingate Lane, P.O. Box 28518. Columbus. A-1400 Vienna. Austria. Ohio 43228-0518. USA. LIQUID PENETRANT TESTING JpJ")' At.( GENERAL DESCRIPTION A.5 L& ,& st-\< CD-, &Cc&o,:f.. c ~ p a,e\&";,::..; s.\. - Liquid Penetrant testing is a quick and reliable nondestructive test method used for detecting various types of discontinuities which are opened to the surface of a material or part. During normal operation, critical components of aircraft engines, airframes, missiles, space vehicles, nuclear reactors, and other modern machinery, are often subjected to extreme loads and vibrations. In time, these extreme loads and vibrations may cause a component to develop an intemption in its normal physical structure or configuration. This is called a DISCONTINUITY.. Although the discontinuity may not affect the usefulness of a part when it occurs, or even alter the parts appearance to the naked eye (since the discontinuity may be minute) repeated stresses or overloading may eventually cause that part to fail. It can be seen therefore, that detection of small discontinuities before they progress into a DEFECT, which is detrimental to part serviceability, is of vital importance to prevent loss of equipment and personnel. , Failure of the part may cause one of the following: $-~)s&~ 2 P-0 \ 1 ._Maior Repair: "Down %me" for major repair caused by part failure is expensive inc_;u) &&& ,A \ , (2 terms %st time. 2. Lpss of Eclui~meG: Total loss of equipment due to part failure is expensive in terms of "7% \o\\, '." 2. 7 lost time and equipment. ' * b' -' 3. Loss of Personnel: Total loss of the equipment may result in the loss of operating d s .$, @-' personnel. -3 t a';, PENETRANT INSPECTION CAPABILITIES Penetrant inspection can detect open to the surface discontinuities, such as: I- p +6+.r.~ 23 f ~ r a c k s Laps . yo Porosity " ' Leaks (hole through a wall) -'*, <& &.X, Seams --:I Pits +, ,') bD ~ n d e r c u t . ~ /" Note: This is only a partial listing. A listing of all discontinuities caused by metal and non-metallic material preparation, material forming, and material processing would be too unwieldy for this study guide. Penetrant inspection can be used w$h reliable accuracy on the following nonabsorbent materials: 1. Aluminum 2. Magnesium 3. Brass 4. Copper 5. Titanium 6. Bronze 7. Cast lmn 8. Stainless Steel 9. Non-Magnetic Alloys 10. Ceramics .. 11. Hard Rubber 12. Plastic Caution: As some plastics, rubber, and synthetic products may be affected by oil, tests should be made before penetrant inspecting such materials to avoid damaging the part under test. BASIC PRINCIPLES OF PENETRANT INSPECTION xv*\ -* u \ The basic principle of penetrant inspection is capillary action. Capillary action is the action by which the surface of a liquid, where it is in contact with a solid, is elevated or depressa The materials, processes, and procedures used in liquid penetrant testing are all designed to facilitate capillarity and to make the results of such action visible and capable of interpretation. The forces of capillarity, or capillary action, may be obsewed when a plastic straw is inserted into a glass of water. When the straw is inserted, the water molecules enter the straw and begin to attract other nearby molecules, pulling them up the straw by cohesion. This process continues as the water rises higher and higher. The water continues to rise until the pull of the surface tension is equalized. Cohesive forces prevent the water from falling back down the straw. Capillary action as applied in nOndeSt~~ t i~e testing is somewhat more complex, since various surface conditions hindering or assisting the action are encountered. Liquid penetrants in nondestructive testing have low tension and high capillarity. Capillary action is illustrated in Figure 1-1. WATER LEV€! $6 WATER LEVEL IN STRAW .IN GLASS (_I* t \ Figure 1-1 CAPILIARY ACTION 8. Inspection Interpretation: The part shall be inspected and the discontinuity interpreted and evaluated to the applicable acceptance standard. Figure 1-5. Fgure 1-5 lNSPECTlON AND INTERPRETATION OF INDICATIONS t 9. Post-Cleaning: The developer shall be removed after inspection interpretation and prior to returning the part to service. PENETRANT SELECTION FACTORS The proper selection of a penetrant to be used for penetrant inspection is dependent on many factors such as penetrabilu visibility, particular type of discontinuity sought, configuration of part, surface conditions, facilities and equipment available, etc. Selection of the proper penetrant, therefore, should be based on penetrant sensitivity. PENETRANT SENSITIVIPI: Penetrant Sensitivity is herein defined as the ability of the penetrant, along with compatible family items in its group, to effectively find discontinuities of the type sought under the. penetrant inspection circumstances involved. Using this definition, the penetrant most adaptable to the majority of penetrant inspection conditions that will exist, is the proper penetrant. COMPATIBILITY: Penetrant materials supplied by qualified producers are not compatible or interchangeable for the purposes of penetrant inspection. Use only one manufactureCs group of materials in an inspection line or portable inspection operation. This is known as a farnilygroup, and intermixing of families is not permitted unless the "mixed family" has been previously qualified. + - PENETRANT MATERIALS Penetrants: Penetrants are classified by Method and Type as follows: Method A Fluorescent dye c+&+$\a Method B Visible dye TYPe 1 Water-washable Type 2 Post emulsifiable, lipophilic, or , , Post emulsifiable, hydrophilic Type 3 Solvent removable Emulsifier: Emulsifiers are classified as either: Hydrophilic An emulsifier that is water-soluble Lipophilic An emulsifier that is oil-soluble and not water-soluble Solvent Remover: Solvent removers are classified as follows: Halogenated Non-halogenated Developers: Developers are classified by form as follows: / Dry powder I ;./ Water soluble Water suspendible Nonaqueous Specific application (i.e.Plastic film) All penetrant materials are supplied in either bulk form or in small pressurized canisters. ,-' r / Y SELECTION OF LIQUID PENETRANTTEST METHOD F When a specific liquid penetrant test method is not specified by the contract, the selection of a suitable penetrant inspection process is made by the Level Ill who makes this decision based on seven basic factors. 1. Requirements previously established by component drawings applicable documents on material or Darts to be laced under examination. 2. Type and siie of disc&tinuity to bGetected. 3. Suriace c~ndi t ig i of part to be examined. - - jw;bc4, 'mih) 4. Configuration of part to be examined. %Y . 5. The number of parts lo be examined. -+ f .i.i 3 6. Facilities and equipment available. i 7. Effect of the penetrant chemicals on material being examined. PT Ill BASIC TABLE 1 ASME CODE CLASSIFICATION OF LIQUID PENETRANT METHODS AND TYPES METHOD A -FLUORESCENT PENETRANTS Type 1 Water Washable Penetrant (Procedure A-1) Dry, Wet, or Nonaqueous Developer Type 2 Post-emulsifiable Penetrant (Procedure A-2) Lipophilic or Hydrophilic Emu!sifier Dry, Wet, or Nonaqueous Developer Type 3 Solvent Removable Penetrant (Procedure A-3) Solvent Rernover/Cleaner Dry. Wet, or Nonaqueous Developer METHOD 8--VISIBLE PENETRANTS Type 1 Water Washable Penetrant (Procedure B-1) Wet or Nonaqueous Developer Type 2 Post-emulsifiable Penetrant (Procedure B-2) Lipophilic or Hydrophilic Emulsifier Wet or Nonaqueous Developer Type 3 Solvent Removable Penetrant (Procedure 8-3) Solvent RemoverICleaner Wet or Nonaqueous Developer PT Ill BASIC METHOD A TYPE 2 INSPECTION PROCESS The Method A Type 2 Penetrant Inspection process uses a post-emulsifiable fluorescent penetrant, a lipophilic emulsifier, and a dry, wet, or non-aqueous wet developer. The materials used in this process are very similar to that described for Method A Type 1 process, except that these penetrants are not self- emulsifiable. A lipophilic or hydrophilic emulsifier is used to make the penetrant water washable. METHOD A TYPE 2 INSPECTION PROCESSES ARE GENERALLY USED WHEN: 1. Examining large volume of parts. 1- 2. A higher sensitivity than Method A. Type 1 is required or 'desired. 3. The part is contaminated with acid or other chemicals that will harm'water-washable ?j ,I/ 1 penetrants. y7 4. Discontinuities are wider than their depth. 5. Variable, but controlled, sensitivities are necessary so that nondetrimental discon- tinuities can be disregarded while harmful or detrimental discontinuities are detected. 6. Examining parts which may have discontinuities contaminated with in-sewice soils. 7. Examining for stress, cracks or intergranular corrosion. 8. Examining for grinding cracks. 9. High visibility is required. TABLE 3 ADVANTAGES AND DISADVANTAGES OF P d@+4{ 'IJ METHOD A TYPE 2 INSPECTION PROCESS,/" - h--- / ADVANTAGES I DISADVANTAGES -- 1. Fluorescence used in this p w s s is more 1. Process is a two-step process, and brilliant, thus ensuring greater visibility of flaw indications. 2. High sensitivity for very fine discontinuities. 3. Good on wide shallow discontinuities. (width greater than depth) 4. Process good for high volume production. 5. Process normally not affected by acids. 6. Process not as susceptible to over-washing. PT Ill BASIC therefore requires more time. 2. Additional equipment is required for application of the emulsifier. 3. Not as good on parts with complex shapes (i.e. threads) as Type 1. 4. Additional material increases cost. 5. Emulsifier dwell time very critical. METHOD A TYPE 3 INSPECTION PROCESS The Method A Type 3 Penetrant lnspection process uses a solvent-removable fluorescent penetrant, a penetrant remover (solvent) and non-aqueous developer. The penetrant is not water-washable but is removed instead with the solvent remover. Method A Type 3 lnspection Process is generally used when: 1. Spot examination is required. 2. Water-rinsing method is not feasible because of part size, weight, surface condition, no water available, no heat for drying, or field use. TABLE 4 ADVANTAGES AND DISADVANTAGES OF METHOD A TYPE 3 INSPECTION PROCESS ADVANTAGES DISADVANTAGES 1. Process can be used for spot inspection 1. Use of solvent to remove penetrant on large parts. prohibits inspecting large areas. 2. Process can be used when water-rinsing 2. Sensitivity can be reduced by the methods are not feasible. +- application of excessive amounts of remover. METHOD B TYPE 1 INSPECTION PROCESS Method B Type 1 Penetrant lnspection process uses a water-washable visible dye penetrant and wet or non-aqueous developer. The penetrant has self-emulsifying properties to make it water removable and is of a brilliant red color. Method B Type 1 Process is generally used when: 1. The lowest sensitivity is sufficient to detect the discontinuities inherent to the part. 2. Examining large volume of parts. 3. Discontinuities are not wider than their depth. 4. Surfaces are very rough (i.e., sand castings, rough weldments, pitted areas). 5. Examining large areas. 6. Examining threads and keyways. 7. Removal of excess penetrant may be difficult due to rough surfaces. PT Ill BASIC TABLE 5. ADVANTAGES AND DISADVANTAGES OF METHOD B TYPE 1 PROCESS ADVANTAGES DISADVANTAGES 1. No blacklight or darkened area required. 1. Process is not reliable in finding scratches. 2. Process can be considered as a one-step 2. Process is less sensitivity for fine process and, therefore, fast and economical. discontinuities. 3. Process can be used for detecting a wide 3. Penetrant can be affected by acids and range of discontinuities. ch-omtes. 4. Penetrant used can be easily washed off 4. Process is not reliable on anodized surfaces. with water. 5. Process is susceptible to over-washing. 5. Process is easily adaptable to a large 6. Water contamination may destroy usefulness volume of small parts. of penetrant. 6. Process is excellent for rough surfaces, 7. Not good for wide shallow discontinuities keyways, and threads. (widlh greater than depth). 7. Process is relatively inexpensive. METHOD B, TYPE 2 INSPECTION PROCESS Method B, Type 2 Penetrant lnspection process uses a post-emulsifiable visible dye penetrant, an . emulsifier, and a dry, wet or non-aqueous developer. The materials used in this process are very similar to that described for Method A, Type II process, however, the eenetrants are not self-emulsifiable. An emulsifier is applied over the penetrant to make it water washable. Method 8, Type 2 lnspection process is generally used when: 1. Examining large volume of parts. 2. A higher sensitivity than Method B, Type 1 is required or desired. 3. The part is contaminated with acid or other chemicals that will harm water- washable penetrants. 4. Discontinuities are wider than their depth. 5. Examining parts which may have discontinuities that are contaminated with in- service soils. 6. Examining finished suiiaces and other general purpose examinations. PENETRANT INSPECTION KITS. Penetrant inspection is practical for field use, because these materials are supplied in the form of portable kits. Both Fluorescent and Visible Dye Penetrant inspection kits are available, but it is essenlial that only the complete family of penetrant inspection materials be employed for these field kit inspection operations. PORTABLE VISIBLE DYE PENETRANT KITS. Portable Visible Dye Penetrant Kits are available for field inspection. A typical Visible Dye Penetrant Kit is illustrated in Figure 2. A VlSlBLE DYE PENETRANT KIT usually contains: 1. Spray cans of cleaning or removal fluid 2. Spray cans of visible dye penetrant. 3. Spray cans of nonaqueous developer. 4. Wiping cloths and brushes. CLEAN BRUSH A N D WIPES PENETRANT Figure 2 Portable Visible Dye Penetrant Kit PORTABLE FLUORESCENT DYE PENETRANT KITS. Portable Fluorescent Dye Penetrant Kits are available for field inspection. A typical Fluorescent Dye Penetrant Inspection Kit is illustrated in Figure 3. A FLUORESCENT DYE PENETRANT KIT usually contains: 1. A portable black light and transformer. 2. Spray cans of cleaning or removal fluid. 3. Spray cans of fluorescent dye penetrant. 4. Spray cans of nonaqueous developer. 5. Wiping cloths and brushes. PENETRANT DEVELOPEfi \ PORTABLE BLACK LIGHT Figure 3 Portable Fluorescent Dye Penetrant Kit PT Ill BASIC In summary, let's consider the advantages and limitations of the liquid penetrant test method ADVANTAGES OF PENETRANT TESTING Materials are relatively inexpensive Some methods are relatively fast Sensitive: can detect discontinuities .001" or greater. Versatile: can be used on any non-porous, non-absorbent material. LIMITATIONS OF PENETRANTTESTING Some methods are time consuming and therefore expensive. Can only detect discontinuities open to the surface. / Surface of part should be 60 to 125 degrees F. Cannot be used on very rough surfaces..-----+ Procedure can be messy. May require good ventilation. No easy pemlanent record. A properly cleaned part would show only a very faint, or no pink background if visible penetrants were used, or only very faint, or no areas of background fluorescence when fluorescent penetrants are used. False indications due to incomplete washing are usually easy to identify, since the penetrant will be in broad areas rather than in the sharp patterns found in the true indications. The danger of poorly cleaned parts, which produce the false indications, lies in the fact that there may be actual discontinuities in the improperly cleaned areas which would be masked by the false indications. If false indications interfere with interpretation of true indications found on the parts complete reprocessing of the parts would be required. NON-RELEVANT INDICATIONS Non-relevant indications are true indications produced by uncontrolled test conditions. However, the conditions causing them are present by design or accident, or other features of the part having no relation to the damaging flaws being sought. The term signifies that such an indication has no relation to discontinuities that might constitute defects. NON-RELEVANT INDICATIONS DUET0 FILLETS, THREADS, AND KEYWAYS: Sharpfillets, threads, and keyways will often retain penetrant at their base and produce indications despite a good removal f'- technique. This is particularly tiue when post emulsified penetrants are employed. Because heat-treating or fatigue cracks often do m r at such locations it is essential that the inspector check these locations very carefully. NON-RELEVANT INDIGATTONS DUE TO PRESS-FIT: Anotherwndition which may create nokrelevant indications is when parts are press-fitted into each other. if a wheel is press-fitted onto a shaft, penetrant will show an indication at the fit line. This is perfectly normal since the two parts are not welded together. The only problem with such indications is that penetrant from the press fit may bleed out and mask a true . . dis~ontinuity. CWUliUOW: Where penetrant bleed out may mask discontinuities on press-fit parts, the time between application of developer and inspection should be held to a minimum to prevent excessive bleed out. Hellier Associates, Inc. PTMod 4 Q 1989 TRUE INDICATIONS The last classification of indications is the group of which we are most interested and is called the true indication which is caused by a discontinuity. True indications can be further classified into four major groups. They are: inherent, primary processing, secondary processing, and service discontinuities. These are covered in detail in another module. Three basic questions must be answered to facilitate proper interpretation of the flaw indications: 1. What type of discontinuity would cause the indications? 2. What is the extent of this discontinuity? 3. What effect will this discontinuity have on the anticipated service of the part? NOTE: The answers to the first two questions are the prime responsibility of the inspector. The answer to the third question, unless specific acceptance criteria are specified, usually requires special assistance. SPECIFIC TYPES OF DlSCONTlNUrflES Generally speaking, we can divide discontinuities into five basic types. These are: f 1 Fine, Tight Surface Cracks. Such cracks may be shallow or deep, but their most signifmnt characteristics is their very small and tigM surface opening. Deep cracks of this type, once well penetrated, may provide a reservoir of penetrant, and therefore, may be easier to show than shallow cracks. 2. Broad, Open Surface Discontinuities. Discontinuities of this type may be shallow or relatively deep. Their significant characteristic is their width which tends to permit penetrants to be removed from the discontinuity, especially when water spray removal techniques are employed. Care must be taken to ensure this does not occur. 3. Porosity. Generally speaking, porosity is a discontinuity having a cavity below the surface which is connected to the surface by a very small channel. Porosity is typically found in castings and welds and is sometimes referred to as gas holes. 4. Shrinkage: Micro or sponge shrinkage in castings which is opened to the surface by machining and etching may be hard to differentiate from cracks. Much care must be used in evaluating this type of indication. 5. Leaks or Through Cracks. Discontinuities of this type are cracks or openings which pass from one surface to another. Hellier Associates, lnc. PTMcd4 63 1989 FLAW INDICATION CATEGORIES There are five basic types of indications which may be seen by the inspector. These indication types caused by the discontinuities listed in the above paragraph are as follows: 1. Continuous linear indications 2. Intermittent linear indications 3. Rounded indications 4. Small dot indications 5. Diffuse or weak indications It is possible to examine an indication of a discontinuity and determine its cause as well as its extent. such an appraisal can be made if something is known about the manufacturing processes or the operational use to which the part has been subjected. The extent of the indications, or acurmulation of penetrant, will show the extent of the discontinuity. The vividness of the visible dye penetrant on the contrasting white developer or the brilliance of the fluorescent dye penetrant will give some indication of the discontinuity's depth. Deekdiscontinuities will hold penetrant and therefore, will be broader and more brilliant. Very fine discontinufies can hold only small amounts of penetrant and will therefore appear as fine lines. f - In many instances, more accurate flaw evaluation may be obtained by removing the indications and ! reapplying nonaqueous wet developer so that the rate and amount of penetrant bleed out can be closely observed to facilitate the interpretation of the flaw discontinuity. CON'NUOUS LINEAR INDICATIONS Cracks, cold shuts, and forging laps usually show as a continuous line indication. A crack will appear as a sharp or faint-jagged line, straight line or intermittent line, while cold shuts will usually appear as smooth, straight, narrow lines. Scratches and die marks will also appear as straight lines, but the bottom of the . ,di.s.continuity is usually visible. f \ \ / a, \ CONTINUOUS LINEAR INDICATIONS \ / Hellier Associates. Inc P T M w ' 4 @ 1989 FATIGUE OR SERVICE CRACKS Fatigue cracks or sharp shallow cracks developed while the part is in service are extremely dangerous and represent an eventual part failure. Care must be taken to detect these discontinuities. / \ FATIGUE OR SERVICE CRACKS \ / Hellier Associates. Inc. PTMod4 8 1989 LEARNING MODULE 1 MAGNETIC PARTICLE TESTING PRlNClPLES OF MAGNETISM In order to understand how and why a magnetic particle test works it is necessary to understand the principles of magnetism. HORSESHOE MAGNET The most familiar type of magnet is the horsehoe magnet shown in figure 1-1. It will attract magnetic materials to its ends where a leakage field occurs. These ends are commonly called "north" and "south" poles, indicated by N and S on the diagram. There will be no attraction except at these poles. Magnetic flux lines, or lines of force flow from the north to the south pole . as long as they are external to the magnet. Since these lines of force always form a complete circuit, they also pass through the iron or steel of which the magnet is made. Note thatwithin the magnet the lines are Figure 1-1. Horseshoe hfqnet If the ends of the horseshoe magnet are bent so that they are close together, as shown in figure 1-2, the ends will sti!l attract magnetic materials. However, if the ends of the magnet zre benl closer together, and the two poles completely fused or welded into a ring as shown in figure 1-3, the magnet will no longer attract or hold magnetic materials because there is no longer a leakage field. The magnetic field remains as shown by the arrows, but without poles there is no attraction. Such a piece is said to have a circular field, or to be circularly magnetized, because the magnetic lines of force are circular. Fiwre 1-2. H o m s h a e hiagnel w i th Polci CloseTocclher MT MOD 1 Any crack in the fused magnet or cicularly magnetized part which crosses the magnetic flux lines will immediately create noflh and south poles on either side of the crack. (see figure 1-4). This will lorce some 01 the rnagnetic flux (lines ol force) out of the metal path and is referred to as lluxleakage. Magnetic materials or particles will be attracted by the pole created by the crack, forming an indication of the discontinuity in the metal part. This is the principle whereby rnagnetic particle indications are formed by means of circular magnetization. Figure 1-4. Cnck in Fused Horjeshoe Magnet BAR MAGNET If a horseshoe magnet is straightened, a bar magnet is created as shown in figure 1-5. The bar magnet has poles at either end and magnetic lines of force flowing through the length of it. Magnetic particles will be attracted only to the poles. Such a piece is said to have a longitudinal field, or to - - be longitudinally magnetized. MT M O D 1 Figure 1-5. f f o n e s h o e Magnet Straightened to Form 831 Magnet MAGNETIC PROPERTIES OF MATERIALS Low Carbon Content Sleel Vs. High Carbon Content steel Low Large grain with a very simple structure High Smaller grain size; the structure is more complex for added strenth Example of each before a magnetizing force is applied: Low Carbon Hiah Carbon Figure 1-8 ATOM ARRANGEMENT Figure 1-9 When a magnetizing lorce is applied to low carbon content steel, the aloms align easily. F i g u r e 1-10 More magnetizing force is required to align the atoms of high carbon steel into magnetic domains. As illustrated in figure 1- 9, the atom directions are more disarranged than low carbon content in figurel-8 I Figu re 1-11 magnetizing force When the magnetizing force is removed from low carbon content steel, most of the atoms return to their normal orientation (figure 1-8), leaving little magnetism. High carbon content steel is different. Because it is much harder to align the atoms; when the magnetizing force is removed many atoms will stay aligned and the material will retain a greater amount of magnetism as shown in figure 1-12. Figure 1-12 You will notice thal a malerial of high reluctance has: 1. Low permeability .. . 2. High retentivity 3. High coercive force 4. High residual magnetism And material with low reluctance is easy lo magnethe. It has: 1. High permeability 2. Low retentivity /- 3. Low residual magnetism 4. Low coercive force PROPERTY Permeability Reluctance Relentivily Residual Field Coercive Force LOW CARBON High Low Low Low Low HIGH CARBON Low High High High High Since a magnetic part is in eHect a large conductor, electric current passing through this part creates a magnetic field in the same manner as with a small conductor (see figure 2-2). The magnetic lines of force are at right angles to the direction of the current as before. This type of mangetization is called circular mangetization because the lines of force, which represent the direction of the magnetic field, are circular within the part. The strength of the magnetic field is dependent upon the current passing through the conductor. Magnetic Field in Part Used as a Conductor F i g u r e 2- 2 CIRCULAR MAGNETIZATION WITH INSPECTION EQUIPMENT. To create or induce a circularfield in a part with stationary magnetic particle inspection equipment, the part is clamped between the contact plates and current is passed through the part as indicated in figure 2-3. This sets up acircuiar magnetic field in the part which creates poles on either side of any cradc or discontinuity which wns parallel to the length of the part. The poles will attract magnetic particles, forming an indication of the discontinuity. T CONTACT PLATE CONTACT PLATE 7 . Cteating n Circular Magnetic Field in a Part On parts that are hollow or tubelike, the inside surfaces are as important to inspect as the outside. When such parts are circularly magnetized by passing the magnetizing current through the part, the magnetic field on the inside surface is negligible. Since there is a magnetic field surrounding the conductor of an electric current it is possible to induce a satisfactory magnetic field by placing the part on a copper bar or other conductor. This situation is illustrated in figures 2-4 and 2-5. Passing current through the bar induces a magnetic field on both the inside and outside surfaces. CRACKS O.D. OR 1.0. MAGNETIZING CURRENT Figure 2- 4 Circular Magnetization of a Cyclinder Using a Central Conductor Figure 2- 5 Circular Magnetization of Ring-Type Parts Using a Central Conductor LONGITUDINAL MAGNETIZATION. Electric current can also be used to create a longitudinal magnetic field in a piece of magnetic material. The nature and direction of this field is the result of the field around the conductor which forms the turns of the coil. Application of the rule of the thumb to the conductor at any point in the coil illustrated in figure 2-6 will show that the field within the coil is lengthwise as indicated. F A G N E T I C FIELD W I R E COIL 7 Figure 2- 6 Magnetic Lines of Force in a Coil When a part made of magnetic material is placed inside a coil as shown in figure 2-7, the magnetic lines of force created by the magnetizing current concentrate themselves in the part and induce a longitudinal mangetic field. Inspection of a cylindrical part with longitudinal magnetization is shown in figure2-18. If there is a transverse discontinuity in the part, such as that in the illustration, small magnetic poles are formed on either side of the crack. These poles will attract magnetic particles, forming an indication of the discontinuity. Compare figure 2-8 with figure 2-3 and note that in both cases a magnetic field has been induced in the part which is at right angles to the defect. This is the most desirable condition for reliable inspection. The strength of the magnetic field within a coil is dependent upon the current flowing through the coil, the number of turns in the coil, and the diameter of the coil. ,-WIRE COIL LM,*GNETIZING CURRENT Figure 2-17 Longiludinal Magnetic Field in a Fart Placed in a Coil WET METHOD ADVANTAGES AND LIMITATIONS. As is true of every process, the wet method has both good points as well as less favorable characterisitics. The more important good points of the wet method, which constilute the reason for its extensive use, as well as the less attractive characteristics are tabulated as follows: a It is the most sensitive method for very fine surface cracks. b. It is the most sensitive method for very shallow surface cracks. c. It quickly and thoroughly covers all surfaces of irregularly-shaped parts, large or small, with magnetic particles. d. It is the fastest and most thorough method for testing large numbers of small parts. e. The magnetic particles have excellent mobiliy in liquid suspension. f. It is easy to measure and control the concentration of particles in the bath, which makes for uniformity and accurate reproducibility of resuls. 9. It is easy to recover and reuse the bath. h. It is well adapted to the short, timed shot technique of magnetization for the continuous method. i. It is readily adaptable to automatic unit operation. j. It is not usually capable of finding defects lying wholly below the surface if more than a few thousandthsof an inch deep. k. It is messy to work with, especially when used for the expendable technique, and in field testing. I. A recirculating system is required to keep the particles in suspension. rn it sometimes presents a post-inspection cleaning problem to remove magnetic particles linging to the surface Fluorescent magnetic particles used in suspension in liquids have the same unfavorable characteristics which go with the usual wet visible method techniques. There is the additional requirement for a source of black-light, and an inspection area from which the white light can be excluded. Experience has shown that these added special requirements are more than justified by the gains in reliability and sensitivity. - GENERAL. The dry powder method is primarily used for the inspection of welds and castings where the detection of defects lying at or very close to the surface is considered important. The particles used in the dry method are provided in the form of a powder. They are available in red, black, yellow and gray colors. The magnetic properties, particle size and shape, and coating method are similar in all colors making the particles equally efficient. The choice of powder is then determined primarily by which powder will give the best contrast and visibility on the parts being inspected and the degree of sensitivity desired. ADVANTAGES AND LIMITATIONS. The dry powder method has good points and less favorable characteristics. These advantages and disadvantages which may influence its use for a specific application are summarized in the following list: Excellent for locating defects wholly below the surface and deeper than a few thousandths of an inch. Easy to use for large objects with portable equipment. Easy to use for field inspection with portable equipment. Good mobility when used with alternating current (AC) or half-wave direct current (HWDC). Not as messy as the wet method. Equipment may be less expensive. Not as sensitive as the wet method for very fine and shallow cracks. Not easy to cover all surfaces properly, especially of irregularly-shaped or large parts. Slower than the wet method for large numbers of small parts. Not readily usable for the short, timed shot technique of the continuous method. Difficult to adapt to a mechanized test system. MAGNETIC PARTICLE TESTING EQUIPMENT GENERAL. Considerations involved in the selection of magnetic particle inspection equipment include the type of magnetizing current and the location and nature of inspection. Magnetic particle inspection equipment serves two basic purposes, which dictate requirements for the size, shape and functions. These two purposes are to provide convenient means for accomplishing proper magnetization and to make possible, rapid inspection of parts, with assurance that the inspection results will be reliable and reproducible. STATIONARY EQUIPMENT. A typical stationary horizontal wet magnetic particle inspection unit of intermediate size is shown below. The unit has two contact heads for either direct contact or central conductor, circular magnetization using a copper rod between the heads or a cable connected to a contact block between the heads. Units contain a coil used for longitudinal magnetization. The coil and one contact head are movable on rails. The other contact head is iiied; the contact plate on it, being air cylinder operated, provides a means for clamping the part. The unit has a self-contained power supply with all the necessary electrical controls. Magnetiuing currents are usually three phase full-wave DC or AC depending upon usage requirements. The units are made in several different sizesto accomodate different length parts and with various maximum output currents. A full length tank with pump, agitation and circulating system for wet inspection media is located beneath the head and coil mounting rails. A hand hose with nozzle is provided for applying the bath. On special units automatic bath application facilities are provided. Typical Wet Horizontal Magnetic Particle Test Unit INTERPRETATION AND EVALUATION OF INDICATIONS DEFINITIONS in order to properly and accurately intrepret and evaluate magnetic particle indications the magnetic particle inspector should understand certain definitions which are used in connection with this inspection i method. Since these terms are used frequently in this learning module, the inspector must fully understand the meaning of each of the following. INDICATION. in magnetic particle inspection an indication is an accumulation of magnetic particles being held by a magnetic leakage field to the surface of a part. The indication may be caused by a discontinuity (an actual void or break in the metal) or it may be caused by some other condition that produces a leakage field. DISCONTINUIN. A discontinuity is an interruption in the normal physical structure or configuration of a part. These discontinuities may be cracks, laps in the metal, folds, seams, inclusions, porosity, and similar conditions. A discontinuity may be very fine or it may be quite large; it will generally be a definite separation or void in the metal. DEFECT. A defect is a discontinuity which exceeds the limits of the acceptance criteria and, therefore, interferes with the usefulness of a part. BASIC STEPS OF INSPECTION. Magnetic particle inspection can be divided into these three basic steps: a. Producing an indications on a part. b. Interpreting the indication c. Evaluating the indication. PRODUCING AN INDICATION. In order to produce a proper indication on a part it is necessary to magnetize the part using the proper magnetizing force necessaryto produce the desired magnetic flux oriented in the proper direction (i.e. circular or longitudinal). INTERPRETING THE INDICATION. After the indication is created, il is necessary to interpret that indication. Interpretation is the deciding of what caused that indication, what magnetic disturbance has attracted the particles in the particular pattern found on the part. If the operator knows something about metal processing, it is possible to determine from the appearance and location of an indication the cause of the indication. NON-RELEVANT INDICATIONS NATURE AND TYPE. It is possible to magnetize parts of certain shapes in such a way that magnetic leakage fields are created even though there is no discontinuity in the metal at the point. Such indications are sometimes called erroneous indictions or false indications. They should be called "non-relevant indications" since they are actually caused by distortion of the magnetic field. They are real indications but .. since there is no interruption in the metal they do not affect the usefulness of the part. It is important that the operator know how and why these non-relevant indications are formed and where to look for them on the parts being inspected. EXAMPLES OF NON-RELEVANT INDICATIONS MAGNETIC WRITING. This is a condition caused by a piece of steel wbbing against another piece of steel which has been magnetized. Since either or both pieces contains some residual magnetism the rubbing or touching creates magnetic poles at the points of contact. These local magnetic poles are usually in the form of a line or scrawl and for this reason the effect is referred to as magnetic writing. COLD WORKING. Cold working consists of changing the size or shape of a metal part without raising its temperature before working. When a bent nail is straightened by a carpenterwith a hammer the nail is being cold worked. Cold working usually causes a change in the permeability of the metal where the change in size or shape occurs. The boundary of the area of changed permeability may attract magnetic particles when the part is magnetized. HARD OR SOFT SPOTS. If there are areas of the part which have a different degree of hardness than the remainder of the part these areas will usually have a different pemteabirQ. When a part w l h such areas of different permeability is inspected with magnetic particle inspection, the boundaries of the areas may create local leakage fields and altract magnetic particles to form indications. BOUNDARIES OF HEATTREATED SECTIONS. Heat treating a part mnsists of heating it to a high temperalure and then cooling it under controlled conditions. The cooling may be relativity rapid or it may be done quite slowly, depending upon the characteristics of the metal which are desired. It is possible to increase or decrease the hardness or the grain size of the metal by varying the temperature and the rate of cooling. On a cold chisel the point is hardened to cut better and to hold an edge. The head of the chisel, which is the end struck by the hammer, is kept softer than the cutting edge solhat il won't shatter and break. The edge of the hardened zone frequently creates a leakage field when the chisel is inspected with magnetic particle inspection. MOD 2 ABRUPT CHANGES OF SECTION. Where there are abrupt changes in section thickness of a magnetized part, the magnetic field may be said to expand from the smaller section to the larger. Frequently thiscreates local poles due to magnetic field leakage or distortion. These leakage fields will attract magnetic particles thereby creating an indication. The non-relevant indication will usually be "fuzzy" like an indication which is produced by a discontinuity beneath the surface. INTERPRETATION AND ELIMINATION OF NON-RELEVANT INDICATIONS, INTERPRETATION. It may at first appear to the operator that some types of non-relevant indications discussed and illustrated in the preceeding material would be difficult to recognize and interpret. For example, the non-relevant indications shown in figures 9-5 and 9-6 may look like indications of subsurface discontinuities. However, there are several characteristics of non-relevant indications which will enable the operator to recognize them in the example cited and under most other conditions. These charac- terisitics of non-relevant indications are: a. On all similar parts, given the same magnetizing technique, the indications will occur in the same location and will have identical patterns. This condition is not usually en- countered when dealing with real subsurface defects. b. The indications are usually uniform in direction and size. c. The indications are usually "fuzzy" ratherthan sharp and well defined. d. Non-relevant indications can always be related to some feature of construction or cross section which accounts for the leakage field creating the indication. ELIMINATION OF NON-RELEVANT INDICATIONS. Although non-relevant indications can be recognized in most cases, they do tend to increase the inspection time, and under certain condiiions may mask or cover up indications of actual discontinuities. Therefore it is desirable to eliminate them whenever possible. In most cases non-relevant indications occur when the magnetizing current is higher than necessary for a given part. consequently, these indications will disappear if the part is demagnetized and reinspected using a sufficiently low magnetizing current. TRUE OR VALID INDICATIONS. If the indication is caused by a discontinuity it is termed a true indication or a valid indication. If the indication is caused by a discontinuity at the surface of the part the particles are usually tightly held to the surface by a realtively strong magnetic leakage field. The line of particles is sharper and well defined and there is a noticeable "build-up" of the particles. This build-up consists of a slight mound or pile of MOD 2 1 5 PRODUCING AN INDICATION In order to produce a proper indication on a part it is necessary to have some knowledge of the principles of magnetism, the materials used in inspection, and the technique employed. Since these subjects have been covered in previous learning modules observance of the procedural steps outlined should insure that a proper indication is produced. INTERPRETING M E INDICATION Aiter the indication is created, it is necessary to interpret that indication. Interpretation is the deciding of what caused that indication, what magnetic disturbance has attracted the particles in the particular pattern found on the part. If the operator knows something about metal processing, it is possible to determine from the appearance and location of an indication the cause of the indication. NON-RELEVANT INDICATIONS NATURE AND TYPE It is possible to magnetize parts of certain shapes in such a way that magnetic leakage fields are created even though there is no discontinuity in the metal at the point. Such indications are sometimes called erroneous indications or false indications. They should be called "non-relevant indications" since they are actually caused by distortion of the magnetic field. They are real indications but since there is no interruption in the metal they do not affect the usefulness of the part. It is important that the operator know how and why these non-relevant indications are formed and where to look for them on the parts being inspected. NOTFF The use of fluorescent magnetic particles on parts with non-relevant indications is recommended since they emphasize the contrast between the particle build-up at a relevant discontinuity and that due to the non-relevant field. . . .-... Non-relevant indications are divided into the following five classes depending upon their cause: a. Magnetic writing. b. Cold working. c. Hard or soft spots. d. Boundaries of heat treated sections. e. Abrupt changes of section. Hellier Associales. Inc. MTMod 9 C3 1989 MAGNmC WRITING This is a condition caused by a piece of steel Nbbing against another piece of steel which has been magnetized. Since either or both pieces contains some residual magnetism the ~ b b i n g or touching creates magnelic poles at the points of contact. These local magnetic poles are usually in the form of a line or scrawl and for this reason the effect is referred to as magnelic writing. In figure 9-1 the part in the top view is magnetized wilh a circular field. If another part made of magnetic material is ~ b b e d against or. comes into contact with the magnetized part, as in the second view, a weak field will be induced into the smaller part. Afler the smaller part has been removed the circular field in the original part will be altered or distorted to some extent as shown in the bottom view. Since there is no force to change the direction of the altered field, there will be some leakage at the point of distortion which will attract magnetic particles. Hellier Associates. Inc. MTMod9 G3 1989 FEURE 9-1 CREATION OF MAGNETIC WAITING COLD WORKING. Cold working consists of changing the size or shape of a metal part without raising its temperature before working. When a bent nail is straightened by a carpenterwith a hammer the nail is being cold worked. Cold working usually causes a change in the permeability of the metal where the change in size or shape occurs. The boundary of the area of changed permeability may attract magnetic particles when the part is magnetized. HARD OR SOFT SPOTS If there are areas of the part which have a different degree of hardness than the remainder of the part these areas will usually have a different permeability. When a part with such areas of different permeability is inspected with magnetic particle inspection, the boundaries of the areas may create local leakage fields and attract magnetic particles to form indications. BOUNDARIES OF HEATTREATED SECTIONS Heat treating a part consists of heating it to a high temperature and then cooling it under controlled conditions. The cooling may be relativity rapid or it may be done quite slowly, depending upon the characteristics of the metal which are desired. It is possible to increase or decrease the hardness or the grain size of the metal by varying the temperature and the rate of cooling. On a cold chisel the point is hardened to cut better and to hold an edge. The head of the chisel, which is the end struck by the hammer, is kept softer than the cutting edge so that it won't shatter and break. The edge of the hardened zone frequently creates a leakage field when the chisel is inspected with magnetic particle inspection. ABRUPT CHANGES OF SECTION Where there are abrupt changes in section thickness of a magnetized part, the magnetic field may be said to expand from the smaller section to the larger. Frequently this creates local poles due to magnetic field leakage or distortion. If a part as shown in figure 4 2 is magnetized in a coil, poles are set up at each end and some leakage occurs at A and B. also, the change of section at C is quite abrupt and there may be a leakage across this angle as shown. These leakage fields will attract magnetic particles thereby creating an .-- indication. The indications formed at A and B are usually very easily interpreted; that at C may be more difficult to recognize as being non-relevant. If the indication is continuous around the shaft it should be suspected as being caused by the shape of the part ratherthan by a discontinuity. The non-relevant indication at C will usually be "fuzzy" like an indication which is produced by a discontinuity beneath the surface. If there is a crack ordiscontinuity in that area it will usually produce an indication which is sharper and it probably will not run completely around the part. Hellier Associates, Inc. MTMod 9 0 1 9 8 9 INTERPRETATION AND ELIMINATION OF NON-RELEVANT INDICATIONS. INTERPRETATION It may at first appear that some types of non-relevant indications discussed and illustrated in the preceeding material would be difficult to recognize and interpret. For example, the non-relevant indications shown in figures 9-5 and 9-6 may look like indications of subsurface discontinuities. However, there are several characteristics of non-relevant indications which will enable the operator to recognize them in the example cited and under most other condiiions. These characteristics of non-relevant indications are: a On all similar parts, given the same rnagnefiing technique, the indications will occur in the same location and will have identical patterns. b. The indications are usually uniform in direction and size. c. The indications are usually "fuzzy" rather than sharp and well defined. d. Non-relevant indications can always be related to some feature of condruction or cross section which accounts for the leakage field creating the indication. ELIMINATION OF NON-RELEVANT INDICATIONS Although non-relevant indications can be recognized in most cases, they do tend to increase the inspection time, and under certain conditions may mask or cover up indications of actual discontinuities. It is-therefore, desirable to eliminate them whenever possible. In most cases non-relevant indications occur when the magnetizing current is higher than necessary for a given part. consequently, these indications will disappear if the part is demagnetized and reinspected using a sufficiently low magnetizing current. Under most conditions the value of magnetizing current which is low enough to eliminate non-relevant indications will still be sufficient to produce indications at actual discontinuities. This will be true where the non-relevant indication is magnetic writing, and for . sewml other types, but may not hold where there are abrupt changes of section. It is therefore desirable to determine whether the non-relevant indication was caused by an abrupt change of section before reinspecting. The proper procedure is to demagnetize and reinspect using a lower value of magnetizing current, repeating the operation with still lower current if necessary until the non-relevant indications disappear. Care must be taken not to reduce the current below the value required to produce indications of all actual discontinuities. Where there are abrupt changes of section two inspections may be required: one at a fairly low amperage to inspect only the areas at the change in section, the other at a higher current value to inspect the remainder of the part. Hellier Associates, lnc. MTModS 0 1 9 8 9 TRUE OR VALID INDICATIONS If the indication is caused by a discontinuity it is termed a true orvalid indication. If the indication is caused by a discontinuity at the surface of the part the particles are usually tightly held to the surface by a relatively strong magnetic leakage field. The line of particles is sharper and well defined and there is a noticeable "build-up" of the particles. This build-up consists of a slight mound or pile of particles which on deep surface cracks is sometimes high enough above the surface of the part to cast a shadow. If such an indication is wiped off the discontinuity can usually be seen. If the indication is caused by a discontinuity below the surface it will be a broad fuzzy looking accumulation of particles rather than being sharp and well defined. The particles in such an indication are less tightly held to the surface because the leakage field is weaker. The difference in appearance between indications of surface and subsurface discontinuities is clearly shown in figures 9-7 and 9-8. Notice the sharpness and definition of the line of magnetic particles in figure 9-7. The pattern in figure 9-8 is much broader than that in figure 9-7 and is quite typical of the indications formed over subsurface discontinuities. Figure 9-7 indication of surface discontinuity Helliar Associates, lnc. MTMcd9 0 1989 Figure 9-8 Indication of subsurface dismntinuS 8 EVALUATING THE INDICATION Lastly, after the indication has been formed and has been interpreted, it must be evaluated. It is necessary for the operator to decide whether that indication in that particular location on that particular part will affect the usefulness of the part. Evaluation is the determination of whether the part can be used in spite of the indication, whether the cause of the indication can be removed without affecting the strength of the part, or whether the part must be scrapped. As a guide, the following basic considerations may be used in conjunction with the operator's knowledge and experience to help in the evaluation of indications. a. A discontinuity of any kind lying at the surface is more likely to be harmful than a discontinuity of the same size and shape which lies below the surface. b. Any discontinuity having a principal dimension or a principal plane which lies at right .. angles or at a considerable angle to the direction of principal stress, whether the discontinuity is surface or sub-surface is more likely to be harmful than a discontinuity of the same size, location and shape lying parallel to the stress. c. Any discontinuity which occurs in an area of high stress must be more carefully considered than a discontinuity of the same sue and shape in an area where the stress is low. d. Discontinuities which are sharp, such as grinding cracks or fatigue cracks, are severe stress-raisers and are more harmful in any location than munded discontinuities such as scratches. e. Any discontinuity which occurs in a location close to a keyway or fillet must be considered to be more harmful than a discontinuity of the same size and shape which occurs away form such a location. Hellier Associates, Inc. MTModQ @3 1989 Radiopphy uses X or &&on to produce an image on a f i l m A radiograph records the radiation that has passed through a component so that flaws can be derectcd A comwnent of uniform seaion without flaws or defects allows the radiafion to pass through the film and produce a uniform A defect in a component such as a bIow hole is deteaed by producing a darker image on the film. image. MAKING A RADIOGRAPH Beam of radiation Film in a caswttc . . I ~ h t component to be tested orinpxted is placed between aliadiation s o m and a speiAIY prepared film Precautions are taken to wure that unauthorized persons are kept away from the area to.prevent U n I l M a r y exposnre to radiation. When the equipment is operated some radiation penetrates the component and is recorded on the film. After cxposnre the film is p e in a darkmom m M o p the image. RT LESSON 101 .,- - . INTRODU&'~ON TO IONIZING RADIATION T H E STRUCTURE OF MATTER AU matter whether solid, liquid or gas consists of elements, or combiinations of elements. . ' :.' An element is a substance which cannot be broken down into simpler substances by chemical m a s . . - Two or more dements can combine chemically to form compounds as follows: 1) at room temperature, sodium and combine chemically to form the solid sodium chloride (NaCI). 2) !hydrogen and oxygen combine to form water (HzO). 3) carbon and hydrogen combine toform the gas methane (m). There are 92 mmally d g dements. If an element is qeatedly divided a stage wilI b e d e d where i t can no longer be subdivided and still possess its chemical form. These individual particles of matter, whose existence was suggested by the Greeks, are called 'atoms'. THE STRUCTURE OF THE ATOM The atdm is the basic building block of all matter. The atom. is the d e s t particle that possesses all the chamcteristics of an element ~ ~ ~ i s ~ ~ & ~ ~ l ~ ~ ~ ~ ~ ; ~ ~ h : ' . ' . ;.'' '. Atd.l&-of&atomisthe-'Z'.Y planets orii~ting-the sun. bulk or 'nude& which is positively . . , .,.. . . charged Whirling around . . the . . . . - ........... ,.: '. - n u c l e u s i n p ~ ~ i m ~ ~ ... . . .. . . . . . . .. . . . . , ... . . . . . . . . . . ::" .:.-.4d&&&*.*& are & & ~ Y Y . "-;i>:... . . . I . . . . .., . . . . , ;:jr;.; 'charged !'> -.: .. ;;. . ': .: , , . .. s! . . . . a . : . . . . . . . . ,, -. . - .?, . ->c. -.. . . . . . . . . . . . \ ..