Piping Flanges, Bolts, and Gaskets 2024-2025. Questions and Correct Answers. Graded A+, Exams of Engineering

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Piping Flanges, Bolts, and Gaskets 2024-

2025. Questions and Correct Answers.

Graded A+

Blind Flanges - ANS* A Blind flange is used to blank off the end of pipe, valve, or pressure vessel openings.

• Compared to other flanges, a blind flange has no opening to allow fluid to pass through.
• Often, a blind flange is inserted into a pipeline when a repair is required further up the line. Bolts - ANSThere are two different types of bolts that are used with flanged connections.

• Machine Bolts
• Stud Bolts Cap Screws - ANS* The are particular instances when cap screws are used in lieu of bolts. For example, a turbine or compressor might have no flange connections but just a machined surface with tapped holes to accommodate cap screws.

• Another instance is for certain types of butterfly valves.

Flange Face - ANS* Different types of flange faces are used as the contact surfaces to seat the sealing gasket material.

• ASME B16.5 and B16.47 define various types of flange facings :

1. Raised Face (RF)
2. Flat Face (FF)
3. Ring Joint (RTJ)
4. Male and Female (seldom used in our industry)
5. Tongue and Groove (seldom used in our industry) Flange Face Finish - ANS Flange Types - ANSThe most common used flange types are:
6. Weld-Neck
7. Slip-on
8. Socket-weld
9. Screwed or Threaded
10. Blind flange
11. Lap-joint
12. Orifice Flange Flanges General - ANSA flange is a method of connecting pipes, valves, pumps and other equipment to form a piping system. It also provides easy access for cleaning, inspection or modification. Flanges are usually welded or screwed. Flanged joints

are made by bolting together two flanges with a gasket between them to provide a seal. Flanges General Standards - ANSASME B16.5 : Flanges with rating class designations 150, 300, 400, 600, 900, and 1500 in sizes NPS 1⁄2 through NPS 24 and flanges with rating class designation 2500 in sizes NPS 1⁄2 through NPS 12 ASME B16.47 : Flanges with rating class designations 150, 300, 400, 600, and 900 in sizes NPS 26 through NPS 60. Flat Face - ANShas a gasket surface in the same plane as the bolting circle face. Applications using flat face flanges are frequently those in which the mating flange or flanged fitting is made from cast iron or a non-metallic material. Flat Ring - ANSIt is used on flanges with raised faces. Its outside diameter is manufactured so as to align itself within the bolts. Full face - ANSThey are used for flat faced flanges and the O.D. extends to the outer edge of the flange face with holes provided for the bolts. Gaskets - ANS* A gasket forms the seal necessary between flange connections to prevent leaks.

• The type of gasket is dependent upon three things:

• Pressure and Temperature of the line;
• Commodity of the line;
• Facing of the flanges they are placed between.

Lap-Joint Flanges - ANS* This flange exists of 2 parts, the flange and the pipe stub.

• Lap-joint flanges are used in expensive (stainless steel) pipe classes. The pipe stub is of the expensive material and the flange which slides over the stub is made of carbon steel. Machine Bolts - ANSMachine bolts a hexagonal forged head and requires only one nut. A commonly used machine bolt is the carbon steel, ASTM-A307 Grade-A. Male and Female - ANSOne flange face has an area that extends beyond the normal flange face (Male). The other flange or mating flange has a matching depression (Female) machined into it's face. The female face is 3/16-inch deep, the male face is 1/4-inch high, and both are smooth finished. The outer diameter of the female face acts to locate and retain the gasket. Custom male and female facings are commonly found on the heat exchanger shell to channel and cover flanges. Materials for gaskets - ANS* Non-metallic types
• Semi-metallic types
• Metallic types Metallic gaskets - ANSare fabricated from one or a combination of metals to the desired shape and size. Often used metallic gaskets are ring-type-joint gaskets (RTJ). ASME B16.20 covers materials, dimensions, dimensional tolerances, and markings for metallic gaskets.

Non-metallic Gasket - ANSare usually composite sheet materials are used with flat-face and raised-face flanges in low Pressure Class applications. Non-metallic gaskets are manufactured from arimid fiber, glass fiber, elastomer, Teflon (PTFE), graphite etc. ASME B16.21 covers types, sizes, materials, dimensions, dimensional tolerances, and markings for non-metallic flat gaskets. Orifice Flanges - ANS* Orifice Flanges are intended for use instead of standard pipe flanges when an orifice plate or flow nozzle must be installed.

• Pairs of pressure "Tappings", typically on 2 sides, directly opposite each other, are machined into the orifice flange. Pressure Ratings - ANSFlanges, according to ASME B16.5, are made in seven primary pressure ratings:

• Class 150
• Class 300
• Class 400 (not used in our industry)
• Class 600
• Class 900
• Class 1500
• Class 2500 Raised Face - ANSis the most common type used in process plant applications, and is easy to identify. It is referred to as a raised face because the gasket surfaces are

raised above the bolting circle face. The purpose of a RF flange is to concentrate more pressure on a smaller gasket area and thereby increase the pressure containment capability of the joint Ring Type Joint - ANS* The cross section of the ring is either oval or octagonal. It fits into machined groves in the flange faces, namely ring joint.

• This type of gasket is made of solid metal and is used in high pressure or high temperature service. Ring-Type Joint - ANSare typically used in high pressure (Class 600 and higher rating) and/or high temperature services above 800°F (427°C). They have grooves cut into their faces with steel ring gaskets. The flanges seal when tightened bolts compress the gasket between the flanges into the grooves, deforming (or Coining) the gasket to make intimate contact inside the grooves, creating a metal to metal seal. Screwed or Threaded Flanges - ANS* Threaded flanges, which depend on threads to seal, are unsuited under cyclic conditions where leakage through threads may occur.
• Seal welding is sometimes employed to overcome this difficulty. Semi-metallic gasket - ANSare composites of metal and non-metallic materials. The metal is intended to offer strength and resiliency, while the non-metallic portion provides conformability and sealability. Frequently used semi-metallic gaskets are spiral wound and Kammprofile, and a variety of metal-reinforced graphite gaskets. Semi-metallic gaskets are used on raised face, male-and-female, and tongue-and-groove flanges.

ASME B16.20 covers materials, dimensions, dimensional tolerances, and markings for metallic and semi-metallic gaskets. Slip-On Flanges - ANS* The slip-on flange is much cheaper than the weld-neck, however there are two welds required for welding this flange to pipe.

• An advantage of this flange is that it is easier to line up and match to the counter flange. This flange can also be supplied as a reducer flange Socket-weld Flanges - ANS* In attaching these flanges, the pipe end is inserted into the socket and welded at the flange hub.
• Socket-weld flanges were initially developed for use on small-size high pressure piping. Stud bolts - ANS* Stud bolts do not have heads. They are completely threaded from end to end and require two hex nuts to install.
• The two types that we generally use are the alloy steel, ASTM-A193 Grade "B7" and "B16". Tongue and Groove - ANSOne flange face has a raised ring (Tongue) machined onto the flange face while the mating flange has a matching depression (Groove) machined into it's face. They differ from male-and-female in that the inside diameters of the tongue-and- groove do not extend into the flange base, thus retaining the gasket on its inner and outer diameter. Types of Gaskets - ANS1. Flat Ring (for raised face flanges)

2. Full face (for flat face flanges)
3. "Ring Type Joint" (ring joint flanges) Weld-Neck Flanges - ANSWeld-Neck Flanges are easy to recognize due to the long tapered hub that goes gradually over to the wall thickness from a pipe or fitting. It has the advantage of requiring only one weld to attach it to the pipe.