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ASME/ANSI Pipe Flanges

Pipe flanges are used to joint pipes.

Pipe flanges that are made to standards called out by ASME/ANSI B!." or

 ASME/ANSI B!.#$ are typically made from forged materials and ha%e machinedsurfaces.

&hey are typically in 'Pressure (lasses' such as ")*+ ,))*+ !))*+ -))*"))*+"))* ho0e%er+ ASME B!.#$ still recogni1es the $"* or '(lass $"'flange for certain lo0 pressure and lo0 temperature applications. &hese'Pressure (lasses' ha%e both pressure and temperature ratings for specificmaterials.

&he flange faces are made to standardi1ed dimensions and are typically 'flatface' 'raised face' 'tongue and gro%e' or 'ring joint' styles+ although other

obscure styles may be permitted.

2lange designs are a%ailable as '0elding nec3' 'slip4on' 'lap joint' 'soc3et 0eld''threaded' and also 'blind flange'.

&he gas3et type and bolt type are generally specified by the standard5s6ho0e%er+ sometimes the standards refer to the ASME Boiler and Pressure 7essel(ode 5B8P7(6 for details 5 see ASME (ode Section 7III 9i%ision 4 Appendi: 6. &hese flanges are recogni1ed by ASME Pipe (odes such as ASME B,.Po0er Piping+ and ASME B,., Process Piping.

Materials for flanges are usually under ASME designation; SA4)" 5Specificationfor (arbon Steel 2orgings for Piping Applications6+ SA4!! 5Specification for(arbon Steel 2orgings for Pressure 7essel (omponents6 or SA4igh4&emperature Ser%ice6.

Weld neck flange

 A%ailable 0eld nec3 flanges are designed for most high pressure industrialapplications. &he 0eld nec3 pipe flanges are ideal for use in hea%y dutyapplications in%ol%ing high pressure+ sub41ero and/or ele%ated temperatures.

Slip-on flange

&he slip4on pipe flanges are designed to easily slide o%er the outside diameterof the pipe and be attached by fillet 0elding. &hese flanges are ideal for lo0erpressure applications.

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Blind pipe flange

&he superior design of the blind flanges enables deployment in high pressureapplications. &he blind flanges can also be used to pro%ide access co%ers forpressure %essels.

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Flange Rating Class

• Based on ASME B!.".

•  Acceptable pressure/temperature combinations.

• Se%en classes 5")+ ,))+ #))+ !))+ -))++"))+ +"))6

• 2lange strength increases 0ith class number.

• Material and design temperature combinations 0ithout pressure indicated not

acceptable

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Sample Problem; 2lange =ating

Ne0 piping system to be installed at e:isting plant. 9etermine re?uired flangeclass for;

@ Pipe Material; (r 4 Mo@ 9esign &emperature; $))C2@ 9esign Pressure; ")) psig

Solution;

9etermine Material Droup Number;Droup Number .-

2ind allo0able design pressure at intersection of design temperature and group

2or class ").4 Allo0able pressure ) psig F design pressure.4 Mo%e to ne:t higher class and repeat steps.

2or class ,));4 Allo0able pressure "$) psig.4 =e?uired flange (lass; ,))

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GASKE

 A gasket is a mechanical seal that fills the space bet0een t0o objects+ generallyto pre%ent lea3age bet0een the t0o objects 0hile under compression. Das3et isinserted bet0een flanges and compressed by bolts to create seal.

(ommonly used type of gas3ets are;

i6 Sheetii6 Spiral 0ound.iii6 Solid metal ring.i%6 9ouble jac3eted .

S!eet Gaskets

Sheet Das3ets are by the far the cheapest option for gas3ets. &he gas3et shapeis 'punched out' of a sheet of fibrous materials. &his leads to a %ery crude+ fastand cheap gas3et. &hese gas3ets can fill many chemical re?uirements based onthe inertness of the material used and fit many budgetary restraints.

Spi"al Wo#nd Gaskets

Spiral 0ound gas3ets and 9ouble Gac3eted gas3ets are t0o of the most usedgas3ets in industry. Spiral 0ound gas3et utili1es a mi: of metallic material and'filler material' generally the gas3et has a chosen metal+ normally a carbon richor stainless steel+ 0ound 5hence the name6 out0ards in a circle 5although othershapes are possible this is the primary6 0ith the filler material+ generally a fle:iblegraphite+ starting at the opposite side of the circle and 0inding in the samedirection.

Spiral Hound Das3ets can be used to seal fluid pressure up to ") bar+cryogenic temperature as lo0 as 4)))( and up to ele%ated temperature of

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)))o( Products are 0idely used in the oil+ gas+ petrochemical process andengineering industries.

Solid Metal =ing

Is used for high temperatures and pressure applications 0ith =&G type flanges.&he 3ey do0nside is that a solid metal must be greatly compressed in order tobecome flush 0ith the flange head and pre%ent lea3age.

9ouble Gac3eted Das3et

Metal Gac3eted gas3ets is made from graphite+ ceramic+ non4asbestos etc. fillerco%ered 0ith thin metal jac3eted+ such as stainless steel+ carbon steel+ copperetc.+ special used in sealing spots of heat e:changer+ pressure %essel etc. thisgas3ets highly resistance against blo04out +suitable for high assembly stress

2iller material Gac3et material &emperature (

Draphite+ Asbestos

Non4asbestos(eramic/P&2E

(arbon steel ,))(opper #))

,)#/,! ",)

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$t!e" Info"%ation

Deneral gas3et material pressure/temperature ratings.

&pes $f Gasket

&pe 'E' Gaskets ha%e the same outside diameter as the flanges+ and aremade 0ith precision4located bolt holes. &hey are easy to center and 0ill pre%entforeign material from becoming lodged bet0een the flange faces and 'shortingout' the flange insulation.

&pe 'F' Gaskets are made to fit 0ithin the bolt hole circle of the flange faces.&he outside diameter of the gas3et is slightly larger than the inside diameter ofthe bolt hole circle. &hey are a%ailable in any of the materials described this 0ebsite.

Ins#lating Slee(es and Was!e"s are a%ailable in complete 3its+ 0ith or 0ithouta gas3et. Slee%es and 0ashers are a%ailable as separate parts or as a one4piecemolded unit.

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&pe ')' Gaskets are made specifically to fit into the ring groo%e of =&G flanges.&hey are a%ailable in reinforced phenolic and other materials.

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