Tube to Tubesheet Welds-Boilers and Welding-Article, Essays (high school) of Boilers and Welding

Download Tube to Tubesheet Welds-Boilers and Welding-Article and more Essays (high school) Boilers and Welding in PDF only on Docsity! ARTICLE F-3 SPECIAL REQUIREMENTS FOR TUBE-TO-TUBESHEET WELDS AF-300 MATERIAL REQUIREMENTS Tubes may be attached to tubesheets by welding provided the tubes and tubesheets or tubesheet facings are of weldable materials covered by this Division. AF-301 Preparing Holes in Tubesheets Tube holes in tubesheets shall be drilled full size or they may be punched to three-quarters size and then drilled, reamed, or finished full size with a rotating cutter. AF-301.1 Clearance Between Tubes and Tube Holes. The clearance between the outside surface of the tubes and the inside surfaces of the tube holes shall not exceed clearance used in the welding procedure qualification tests. AF-301.2 Finish of Holes. The edges of the tubesheet at the tube holes on the side to be welded shall be free of burrs, and the edges of the tubesheet at the tube hole on the side opposite the weld shall have sharp corners removed. The surfaces of tube holes in tubesheets shall have a workmanship-like finish. AF-310 WELD DESIGN AND JOINT PREPARATION The weld dimensions and weld detail, and joint preparation, if used, shall comply with the details included in the Welding Procedure Specification. AF-320 QUALIFICATION OF WELDING PROCEDURE AND OF WELDER OR WELDING OPERATOR The welding procedure qualification and welder or welding operator qualification shall be in accordance with the rules in AF-321. 191 AF-321 Essential Variables The welding procedure shall be set up as a new procedure specification and shall be completely requali- fied when any of the changes listed below are made in the procedure. Changes other than those given below may be made in a procedure without the necessity for requalification, provided the procedure specification is amended to show these changes. AF-321.1 For All Welding Processes (a) A change from one welding process to any other welding process or combination of welding processes. (b) A change in P-Number classification of tube material in QW-422 of Section IX. A separate qualifica- tion is required for each tube material which is not included under any P-Number. (c) A change in the P-Number of the tubesheet material. The tubesheet may be of homogeneous material or have a cladding of wrought material or weld overlay. If welding is performed between the tube and cladding, the cladding shall be considered the base material. A separate qualification is required for welding tubes to base material or cladding material which is not included under any P-Number. (d) Any of the following changes in the analysis of the weld metal to be deposited: (1) a change from any A-Number in QW-422 of Section IX to any other A-Number or to any F-Number in QW-432 or to any analysis not listed in the tables; except that each AISI type of A-No. 7 or A-No. 8 of QW-422 shall require separate qualification; (2) a change from any F-Number in QW-432 to any other F-Number or to any A-Number in QW-422 or to any analysis not listed in the tables. docsity.com