Standards

Flange dimensions are determined by the pipe size and the pressure class required for the application. Flanges are standardized according publications from organizations like ASME, MSS, API and others.

Each flange according to ASME B16.5 has a number of standard dimensions. If a draftsman in Japan or a work preparer in Canada or a pipefitter in Australia is speaking about a Welding Neck flange NPS 6, Class 150, Schedule 40 ASME B16.5, then it goes over the flange which in the image here below is shown.

If the flange is ordered, the supplier want to know the material quality. For example ASTM A105 is a forged carbon steel flange, while A182 is a forged stainless steel flange.

So, in a correct order to a supplier two standards must be specified:

WELDING NECK FLANGE NPS 6, CLASS 150, SCHEDULE 40, ASME B16.5 / ASTM A105

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The flange above has 8 bolt holes, and a welding bevel of 37.5 degrees (red circle). All given dimensions are in millimeters. The raised face (RF) does not need to be specified, because according to ASME B16.5, each flange is standard delivered with a raised face. Only a different design (Ring Type Joint (RTJ), Flat Face (FF) etc.), should be specified.

Highlights of the Flanges

Specification

• ASME B16.5, ASME B16.47 (Serie A and Serie B),API 6A, ASME B16.36, ASME B16.48 and MSS SP44 are the key specifications covering the dimensions and the manufacturing tolerances of Flanges. ASME B16.25 covers the preparation of butt weld connections between pipes and Weld Neck Flange. MSS SP25 covers the marking system.

• ASTM A961 is standard specification for common requirements for steel flanges and parts for piping applications.

• The weld neck and socket weld flanges has the same SCH as the mating pipe.

Hydrostatic Test

• Parts manufactured under ASTM A961 shall be capable of passing hydrostatic test compatible with the rating of the finished part. Such test shall be conducted by the supplier only when the hydrostatic test supplementary requirement in the product specification is invoked by the purchaser.

Disadvantage

• Flanged pipe systems need much more space (just think of a pipe rack).

• Each flange connection can leak (some people claim that a flange connection is never 100 percent leak proof).

• Insulation of flanged pipe systems is more expensive (special flange caps).

Cost

• Material costs are low, but labor costs are moderate to high due to the need for specialized welders and ﬁtters.

Size

• FROM 0.5'' TO 60'‘

• conformity with the customers drawing

Other Properties

• 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, including the Flat face, raised face and the large male and female facings which have identical dimensions to provide a relatively large contact area.

Standard

ASME B16.5, ASME B16.47 (Serie A and Serie B), API 6A ASME B16.36, ASME B16.48 and MSS SP44 are the key specifications covering the dimensions and the manufacturing tolerances of Flanges. ASME B16.25 covers the preparation of butt weld connections between pipes and Weld Neck Flange. MSS SP25 covers the marking system.

ASME B16.5

ASME B16.5 Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard covers pressure-temperature ratings, materials, dimensions, tolerances, marking, testing, and methods of designating openings for pipe flanges and flanged fittings. Included are: 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 (Serie A and Serie B), MSS-SP44

Large Diameter Steel Flanges, NPS 26 through NPS 60 Metric/Inch Standard, Weld Neck, Slip-On, Blind. Class 150 to Class 900

API 6A

Today API Spec 6A and MSS SP-44 specify all flanges commonly used in surface drilling and production. These flanges have a long history and many flanges used in the past have been discontinued, or obsoleted and replaced by more modern configurations. Originally, all flanges related to pipe and became standard as weld neck, threaded and blind configurations. As equipment with integral flanges came to the oilfield, standardization became necessary for functional interchangeability.

ASME B16.36

This Standard covers flanges (similar to those covered in ASME B16.5) that have orifice pressure differential connections. Coverage is limited to the following: (a) welding neck flanges Classes 300, 400, 600, 900, 1500, and 2500 (b) slip-on and threaded Class 300.

ASME B16.48

This Standard covers pressure-temperature ratings, materials, dimensions, tolerances, marking, and testing for operational line blanks in sizes NPS 1/2 through NPS 24 for installation between ASME B16.5 flanges in the 150, 300, 600, 900, 1500, and 2500 pressure classes.

Material Standard

ASTM A105/ A105 M-98, This specification covers standards for forged carbon steel piping components, that is, flanges, fittings, valves, and similar parts, for use in pressure systems at ambient and higher-temperature service conditions. Materials shall be subjected to heat treatment (annealing, normalizing, tempering, or quenching). Material shall conform to carbon, manganese, phosphorus, sulfur, silicon, copper, nickel, chromium, molybdenum and vanadium contents. The forgings shall be subjected to tension, hardness and hydrostatic tests, with the latter applicable when required. Material shall adhere to tensile strength, yield strength, elongation, reduction of area, and hardness requirements. Guidelines for retreatment, repair by welding, and product marking are given.

ASTM A181 M-95 b Class 60, ASTM A181 M-95 b Class 70, his specification covers nonstandard as-forged fittings, valve components, and parts for general service. Forgings made to this specification are limited to a maximum weight of 10 000 lb [4540 kg]. Larger forgings may be ordered to Specification A266/A266M.

ASTM A694/ A694M (F42, F46, F48, F50, F52, F56, F60, F65, F70), This specification covers carbon and alloy steel forgings for pipe flanges, fittings, valves, and parts for high-pressure transmission service. A chemical heat analysis of the steel shall be made, and the steel shall conform to specified chemical composition requirements. Materials adhere to testing and tensile property requirements as well.

ASTM A515/ A515M (Gr.55, 60, 65, 70), This specification covers carbon-silicon steel plates primarily for intermediate- and higher-temperature service in welded boilers and other pressure vessels. Plates are available in three grades having different strength levels: Grade 60; Grade 65; and Grade 70. The steel shall be killed and made to a coarse austenitic grain size practice. The steel shall conform to the chemical requirements specified. Tension test shall be made to conform to the requirements specified.

ASTM A350/ A350M-99(LF1, LF2, LF3, LF5, LF6, LF9, LF787), This specification covers several grades of carbon and low alloy steel forged or ring-rolled flanges, forged fittings and valves for low-temperature service. The steel specimens shall be melt processed using open-hearth, basic oxygen, electric furnace or vacuum-induction melting. A sufficient discard shall be made to secure freedom from injurious piping and undue segregation. The materials shall be forged and shall undergo heat treatment such as normalizing, tempering, quenching and precipitation heat treatment. Heat analysis and product analysis shall be performed wherein the steel materials shall conform to the required chemical compositions of carbon, manganese, phosphorus, sulfur, silicon, nickel, chromium, molybdenum, copper, columbium, vanadium, and nitrogen. The materials shall also undergo tension tests and shall conform to the required values of tensile strength, yield strength and elongation. Impact tests shall also be performed and the steel materials shall conform to the required values of minimum impact energy, temperature, and minimum equivalent absorbed energy. Hardness and hydrostatic tests shall also be performed.

ASTM A707/ A707M(L1, L2, L3, L4, L5, L5, L6, L7, L8), This specification covers forged carbon and alloy steel flanges intended primarily for petroleum and gas pipelines in areas subject to low ambient temperatures. Eight grades, four yield-strength classes, and three different notch toughness levels are included. All material shall be heat treated by annealing, normalizing, precipitation hardening, quenching-and-tempering, normalizing-and-tempering, normalizing-and-precipitation hardening, or quenching-and-precipitation hardening. A chemical heat analysis shall be made and conform to the requirements as to chemical composition specified. The material in the weld neck shall conform to the mechanical property requirements specified. Hardness test, impact test, ultrasonic test, tension test, and hydrostatic test shall be made to conform to the specified requirements.

ASTM A516/ A516M (Gr. 60, 65, 70), This specification covers carbon steel plates intended primarily for service in welded pressure vessels where improved notch toughness is important. According to different strength levels, the plates are available in four grades: Grades 55, 60, 65, and 70. The maximum thickness of plates is limited only by the capacity of the composition to meet the specified mechanical property requirements. The steel shall be killed and shall conform to fine austenitic grain size requirements. The mechanical properties such as tensile strength, yield strength, and elongation shall be determined by a tension test for the plates.

ASTM A182/ A182 M-98ª(F 304, F 304H, F 304L, F 304N, F304 LN, F 309H, F310, F 310H, F 310 MoLN, F 316, F 316H, F 316L, F 316N, F 316LN, F 317, F 317L, F 347, F 347 H, F 348, F 348 H, F 321, F321 H), This specification covers forged or rolled alloy and stainless steel pipe flanges, forged fittings, and valves and parts for high-temperature service. After hot working, forgings shall be cooled to a specific temperature prior to heat treatment, which shall be performed in accordance with certain requirements such as heat treatment type, austenitizing/solution temperature, cooling media, and quenching. The materials shall conform to the required chemical composition for carbon, manganese, phosphorus, silicon, nickel, chromium, molybdenum, columbium, titanium. The material shall conform to the requirements as to mechanical properties for the grade ordered such as tensile strength, yield strength, elongation, Brinell hardness. All H grades and grade F 63 shall be tested for average grain size.

ASTM A240/ A240M( 304,310, 316), This specification covers chromium, chromium-nickel, and chromium-manganese-nickel stainless steel plate, sheet, and strip for pressure vessels and for general applications. The steel shall conform to the requirements as to chemical composition specified. The material shall conform to the mechanical properties specified.

ASTM A182/ A182 M-98a( F 1, F 2, F 5, F 5a, F 9, F 91, F 92, F911, F11 Class 1, F11 Class 2, F11 Class 2, F12 Class 1, F12 Class 2,F 21 F3V, F21 3VCb, F22 Class 1, F22 Class 3, F 23, F 24, F R) ASTM A387/ A387M(Gr.2, 12, 11, 22, 22L, 21, 21L, 5, 9, 91), This specification covers forged or rolled alloy and stainless steel pipe flanges, forged fittings, and valves and parts for high-temperature service. After hot working, forgings shall be cooled to a specific temperature prior to heat treatment, which shall be performed in accordance with certain requirements such as heat treatment type, austenitizing/solution temperature, cooling media, and quenching. The materials shall conform to the required chemical composition for carbon, manganese, phosphorus, silicon, nickel, chromium, molybdenum, columbium, titanium. The material shall conform to the requirements as to mechanical properties for the grade ordered such as tensile strength, yield strength, elongation, Brinell hardness. All H grades and grade F 63 shall be tested for average grain size.

ASTM A182 (F 50, F 51, F 52, F 53M F 54, F 55, F 57, F 59, F 60, F 61, F 904L), This specification covers forged or rolled alloy and stainless steel pipe flanges, forged fittings, and valves and parts for high-temperature service. After hot working, forgings shall be cooled to a specific temperature prior to heat treatment, which shall be performed in accordance with certain requirements such as heat treatment type, austenitizing/solution temperature, cooling media, and quenching. The materials shall conform to the required chemical composition for carbon, manganese, phosphorus, silicon, nickel, chromium, molybdenum, columbium, titanium. The material shall conform to the requirements as to mechanical properties for the grade ordered such as tensile strength, yield strength, elongation, Brinell hardness. All H grades and grade F 63 shall be tested for average grain size.

SB 564(UNS N02200, UNS N04400, UNS N06022, UNS N06025, UNS N06035, UNS N06045, UNS N06058, UNS N06059, UNS N06110), specification for nickel alloy forgings