The most used flange types in Petro and chemical industry are:

• 
  Blind pipe flanges
• 
  Lap Joint Flanges
• 
  Slip-On flanges
• 
  Socket weld flanges
• 
  Threaded Flanges
• 
  Weld Neck Flanges

Except the most used standard flanges, there are still a number of specialty flange such as:

• 
  Anchor flange
• 
  Expander Flange
• 
  Large Diameter Flanges
• 
  Long Neck Welding flange
• 
  Nipo flange
• 
  NW Long Weld Neck Flanges
• 
  Orifice flanges
• 
  Reducing Flanges
• 
  Screwed Flanges

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The choice of the material largely depends on the purpose of the flange. For example, stainless steel is more durable and is necessary for heavy use.

On the other hand, plastic is more feasible for use in the home because of its reasonable price and easy installation. The materials used for flanges are under the designation of the American Society of Mechanical Engineers.

Requirements are valid for normal situation, in special you have to contact us to introduce.

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• 

Material	Test basis / Requirements	Delivery Condition
C 22.8 (1.0460)	DIN 17243: 01.87 + VdTUEV – WB 350/3: 2009   DIN 17243: 01.87   VdTÜV – WB 350/3: 2009	+N
P250GH (1.0460)	DIN EN 10222-2: 04.2000   National Annex	+N
P245GH (1.0352)	EN 10222-2:1999-12 + AC : 2000-02	+N
A105N / C21	ASTM A105/A105M-05/ ASME BPVC Sec.2 Part.A:04   + VdTUEV399/3: 1996-09   + NACE MR 0175: 2000	+N
A105N	ASTM A105/A105M-05/ ASME BPVC Sec.2 Part.A:04   + NACE MR 0175: 2000	+N
C21 (1.0432)	VdTUEV – WB 399/3: 1996-09	+N
RSt 37-2 (1.0038)	DIN 17100: 1980-01	+N
S235JR (1.0038)	DIN EN10025-2: 2005-04	+N
16Mo3 (1.5415)	DIN EN10222-2:1999-12 + AC:2000-02	+N
WStE355 / TStE355   (1.0565 / 1.0566)	DIN EN17103 :1989-10, + VdTUEV-WB 354/3 : 2001-06	+N or QT
P355NH  (1.0565)	DIN EN10222-4: 1998 + A1: 2002-12	+N
WStE355 / P355NH    (1.0565)	DIN EN17103 :1989-10, + VdTUEV-WB 354/3 : 2001-06   + DIN EN10222-4: 1998 + A1: 2002-12   + DIN EN17103 :1989-10   + DIN EN10222-4: 1998 + A1: 2002-12	+N or QT
1.4301 (X5CrNi17-10)	DIN EN10222-5: 2000-02	+AT
1.4306 (X2CrNi19-11)	DIN 17440:1996-09	+AT
1.4401 (X5CrNiMo17-12-2)	DIN EN10222-5: 2000-02	+AT
1.4404 (X2CrNiMo17-12-2)	DIN EN10222-5: 2000-02	+AT
1.4432 (X2CrNiMo17-12-3)	DIN EN10222-5: 2000-02	+AT
1.4541 (X6CrNiTi18-10)	DIN EN10222-5: 2000-02	+AT
1.4571 (X6CrNiMoTi17-12-2)	DIN EN10222-5: 2000-02	+AT
1.4541 / F321	DIN EN10222-5: 2000-02 / +ASTM A 182/A 182M :2005	+AT
1.4571 / F316Ti	DIN EN10222-5: 2000-02 / +ASTM A 240	+AT
1.4404 / F316L	DIN EN10222-5: 2000-02 / +ASTM A 182/A 182M :2005	+AT
1.4306 / F304L	DIN 17440.1996-09 / +ASTM A 182/A 182M : 2005	+AT
1.4307 / F304L	DIN EN10222-5: 2000-02 / +ASTM A 182/A 182M :2005	+AT

Basic requirements for Material and Fitting

Material	Test basis / Requirements	Delivery Condition
1.4541 (X6CrNiTi18-10)	DIN 17458:1996-09	+AT
1.4571 (X6CrNiMoTi17-12-2)	DIN 17458:1996-09	+AT

Flange	Test basis / Requirements
DIN, Carbon Steel	DIN2519:1991-06 + AD2000-W9: 02.04; -W13/ TRD107;TRB100; + Directive 97/23/EG Annex I, Chap. 4.3: 1998-02
DIN, corrosion-resistant Steel	DIN2519:1991-06 + AD2000-W9: 02.04; -W2; -W10 / TRD107; TRB100; + Directive 97/23/EG Annex I, Chap. 4.3: 1998-02
DIN EN 1092-1, Carbon Steel	DIN EN 1092-1: 2008-09 + AD2000-W9; -W13/TRD107;TRB100 + Directive 97/23/EG Annex I, Chap. 4.3: 1998-02
DIN EN 1092-1, Stainless Steel	DIN EN 1092-1: 2008-09 + AD2000-W9; -W2; -W10/ TRD107; TRB100 + Directive 97/23/EG Annex I, Chap. 4.3: 1998-02
ANSI	ASME B16.5:2003 ASME B16.47:2006

Fittings	Test basis / Requirements
DIN2609 Stainless Steel	VdTUEV –MB 1252/ AD2000- W2; W10/TRD107;TRB100
T-Piece	Directive 97/23/EG Annex I, Chap. 4.3:1998-02
Bow	DIN2615-1
Reducer	DIN2605-1 DIN2616-1

Requirements are valid for normal case, in special case you have to contact the technical department.

• 
  DIN flanges
• 
  AWWA Standard flange
• 
  Alloy steel flanges
• 
  Carbon steel flanges
• 
  Forged steel flanges
• 
  Stainless Steel Flanges

Outside Diameter	When O.D. is 24″ or less	±1.6mm﹡
Inside Diameter	10″ and smaller	±0.8mm
	12″ thru 18″	±1.6mm
	20″ and larger	+3.2mm, -1.6mm
Outside Diameter of hub	5″ and smaller	+2.4mm, -0.8mm﹡
	6″ and larger	+4.0mm, -0.8mm
Diameter of contact face	1/16″ rasied face tongue and groove male, female	±0.8mm
	1/4″ rasied face tongue and groove male, female	±0.4mm
Diameter of hub at base	when hub base is 24″ or smaller	±1.6mm﹡
Diameter of hub at point of welding	5″ and smaller	+2.4mm, -0.8mm
	6″ and larger	+4.0mm, -0.8mm
Drilling	Bolt circle	±1.6mm
	Bolt hole spacing	±0.8mm
	Eccentricity of bolt circle with respect to facing	2 1/2″ and smaller: 0.8mm, max﹡
	Eccentricity of bolt circle with respect to bore	3″ and larger: 1.6mm, max﹡
Thickness	18″ and smaller	+3.2mm, -0mm
	20″ and larger	+4.8mm, -0mm
Length of thru hub	10″ and smaller	±1.6mm
	12″ and larger	±3.2mm

Tolerance of Threaded Flanges, Socket Welding Flanges, Slip-On Flanges
Lap Joint Flanges and Blind Flanges

Outside Diameter	When O.D. is 24″ or less	±1.6mm﹡
Inside Diameter	Threaded	Within limits on boring gauge
	Socket welding, Slip-on and Lap joint, 10″ and smaller	+0.8mm, -0mm
	Socket welding, Slip-on and Lap joint, 12″ and larger	+1.6mm, -0mm
Outside Diameter of hub	5″ and smaller	+2.4mm, -0.8mm﹡
	6″ and larger	+4.0mm, -0.8mm
Diameter of contact face	1/16″ rasied face tongue and groove male, female	±0.8mm
	1/4″ rasied face tongue and groove male, female	±0.4mm
Diameter of counterbore	same as for inside diameter
Drilling	Bolt circle	±1.6mm
	Bolt hole spacing	±0.8mm
	Eccentricity of bolt circle with respect to facing	2 1/2″ and smaller: 0.8mm, max﹡
	Eccentricity of bolt circle with respect to bore	3″ and larger: 1.6mm, max﹡
Thickness	18″ and smaller	+3.2mm, -0mm
	20″ and larger	+4.8mm, -0mm
Length of thru hub	10″ and smaller	±1.6mm
	12″ and larger	±3.2mm

Dimensional tolerances for AWWA pipe flanges

Listed below are the Dimensional Tolerances to which flanges are manufactured. 

Ring type Slip-on and Blind flanges			HUB type slip-on
O.D.	<=24"	+/- 0.6"(1.6mm)	O.D.	<=24"	+/- 0.6"(1.6mm)
	>24"	+/- .12"(3.2mm)		>24"	+/- .12"(3.2mm)
I.D.	Socket-Welding	10" and Samller +.03"(0.8mm),-0"	I.D.	10" and Samller	+.03"(0.8mm)
	Slip-on and Lap Joint	12" and Larger +.06"(1.6mm),-0"		12"-18"	+/-.06"(1.6mm)
				20"-42"	+.12"(3.2mm) +.06"(1.6mm)
O.D. of Hub	<=12"	+.09"(2.4mm), -.06"(1.6mm)	Diameter of Contact Face	0.06" Raised Face	+/-.03"(0.8mm)
	14"-42"	+/-.12"(3.2mm)
Diameter of Contact face	0.06" Raised Face	+/- .03"(0.8mm)	Diameter of Hub at base	X<=24"	+/-.06"(1.6mm)
				X>24"	+/-.12"(3.2mm)
Deameter of Contact face	<=10"	+.03"(0.8mm), -0"	Diameter of Hub at point of Welding	<=5"	+.09"(2.4mm), -.03"(0.8mm)
	12"-42"	+.06"(1.6mm), -0"		>=6"	+.16"(4.0mm), -.03"(0.8mm)
Drilling	Bolt Circle	1/2"-24" /26"-42"	Drilling	Bolt Circle	1/2"-24" /26"-42"
		+/-.06"(1.6mm) +/-.06"			+/-.06"(1.6mm) +/-.06"
	Bolt hole spacing	+/-.03"(0.8mm)		Bolt hole spacing	+/-.03"(0.8mm)
	Eccentricity of Bolt circle with respect to bore	.03" Max. (0.8mm)		Eccentricity of Bolt circle with respect to bore	.03" Max. (0.8mm)
Thickness	18"& Small	+.12"(3.2mm),-0"	Thickness	18"& Small	+.12"(3.2mm),-0"
	20"-42"	+.19"(1.6mm)		20"-42"	+.19"(1.6mm)
Length Thru Hub	<=10"	+/-.06"(1.6mm)	Length Thru Hub	<=10"	+/-.06"(1.6mm)
	12"-42"	+/1.12"(3.2mm)		12"-42"	+/1.12"(3.2mm)

These tolerances are a part of ANSI B16.5 and AWWA C207-01 Sec. 4.2 except where noted otherwise. 

The limits given are maximum.  Rigid inspection procedure assures the maintenance of high standards of accuracy in regular day to day production.

Dimensional tolerances for AWWA pipe flanges

Ring type Slip-on and Blind flanges			HUB type slip-on
O.D.	<=24"	+/- 0.6"(1.6mm)	O.D.	<=24"	+/- 0.6"(1.6mm)
	>24"	+/- .12"(3.2mm)		>24"	+/- .12"(3.2mm)
I.D.	Socket-Welding	10" and Samller +.03"(0.8mm),-0"	I.D.	10" and Samller	+.03"(0.8mm)
	Slip-on and Lap Joint	12" and Larger +.06"(1.6mm),-0"		12"-18"	+/-.06"(1.6mm)
				20"-42"	+.12"(3.2mm) +.06"(1.6mm)
O.D. of Hub	<=12"	+.09"(2.4mm), -.06"(1.6mm)	Diameter of Contact Face	0.06" Raised Face	+/-.03"(0.8mm)
	14"-42"	+/-.12"(3.2mm)
Diameter of Contact face	0.06" Raised Face	+/- .03"(0.8mm)	Diameter of Hub at base	X<=24"	+/-.06"(1.6mm)
				X>24"	+/-.12"(3.2mm)
Deameter of Contact face	<=10"	+.03"(0.8mm), -0"	Diameter of Hub at point of Welding	<=5"	+.09"(2.4mm), -.03"(0.8mm)
	12"-42"	+.06"(1.6mm), -0"		>=6"	+.16"(4.0mm), -.03"(0.8mm)
Drilling	Bolt Circle	1/2"-24" /26"-42"	Drilling	Bolt Circle	1/2"-24" /26"-42"
		+/-.06"(1.6mm) +/-.06"			+/-.06"(1.6mm) +/-.06"
	Bolt hole spacing	+/-.03"(0.8mm)		Bolt hole spacing	+/-.03"(0.8mm)
	Eccentricity of Bolt circle with respect to bore	.03" Max. (0.8mm)		Eccentricity of Bolt circle with respect to bore	.03" Max. (0.8mm)
Thickness	18"& Small	+.12"(3.2mm),-0"	Thickness	18"& Small	+.12"(3.2mm),-0"
	20"-42"	+.19"(1.6mm)		20"-42"	+.19"(1.6mm)
Length Thru Hub	<=10"	+/-.06"(1.6mm)	Length Thru Hub	<=10"	+/-.06"(1.6mm)
	12"-42"	+/1.12"(3.2mm)		12"-42"	+/1.12"(3.2mm)

These tolerances are a part of ANSI B16.5 and AWWA C207-01 Sec. 4.2 except where noted otherwise.  The limits given are maximum.  Rigid inspection procedure assures the maintenance of high standards of accuracy in regular day to day production.

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Industry Specification for Pipe Flange

Before we dive in to the different types of flange, it is important to understand the industry specification it conforms to. So what is ANSI Flange, AWWA Flange and ASME Flange? What is the difference between ANSI Flange and ASME Flange? What is the difference between Series A and Series B Flange. We will answer all these questions.

There are four types of industry standards covering different flange types;

1. ANSI Flange, also called ASME B16.5 Flange
2. ASME Flange, also called ASME B16.47 Flange (Series A and Series B)
3. Industry Standard Flange (ASME B16.1 Flange)
4. AWWA Flange

ANSI 16.5 / ASME B16.5 Flange Specification

ASME B16.5 pipe flange and flanged fittings cover sizes from 1/2″ nominal to 24″ nominal. The standard covers pressure, temperature, material, tolerance, dimension, testing and marking of flange. The pressure classed included in ASME B16.5 are 150#, 300#, 600#, 900# and 1500# for sizes up to 10″ nominal and 2500# for sizes 12″ through 24″.

ASME B16.5 standard is limited to flanges made from cast or forged material.

ASME B16.47 Series A and Series B Flange Specification

ASME B16.47 covers large diameter steel flanges from 26″ nominal to 60″ nominal pipe sizes. There are two types of B16.47 flanes, Series A and Series B. Both have slightly different dimensions such as thickness, bolt circle diameter and number of bolt holes. Pressure class covered by B16.47 is Class 75, 150, 300, 400, 600 and 900#. Standard covers flanges made of cast, forged or plate material (for blind flange only).

What is the difference between ASME B16.47 Series A and Series B (API605) flanges?

ASME B16.5 standard covers Steel Pipe Flanges and Flanged Fittings from NPS 1/2 through NPS 24 Metric/Inch in pressure class 150 to class 2500. It covers pressure-temperature ratings, materials, dimensions, tolerances, marking, testing, and methods of designating openings for pipe flanges and flanged fittings. Two very important flanges such as weld neck flange and blind flanges are very commonly used in piping systems. The term “B16.5” or “B16 5” is used interchangeability and refers to same standard. However, the standard ASME B16 5 (ANSI B16 5) only covers size up to 24 inches. For bigger sizes, ASME B16.47 standard covers pressure-temperature ratings, materials, dimensions, tolerances, marking, and testing for pipe flanges in sizes NPS 26 through NPS 60 and in ratings Classes 75, 150, 300, 400, 600, and 900.

However, the standard ASME B16.47 is further divided into ASME B16.47 series A and ASME B16.47 series B flange for Blind flange and Weldneck flange. Series B flange was also formerly known as API 605 flange. Term B16.47 or B 16 47 or ANSI B 16 47 are all used interchangeabily and refers to the same standard.

The ASME B16.47 standard incorporate MSS SP-44: Steel Pipe Flanges and API 605: Large Diameter Flanges for Carbon Steel. Hence MSS SP44 flanges are equivalent to Series A flange where as API 605 flanges are equivalent to Series B flange. Materials covered in this standard are as that in ASME / ANSI B16.5 except for nickel alloys. They also share the same pressure temperature rating as B16.5 flanges.

So what is the difference between ASME B16.47 Series A and Series B (API605) flanges?

ASME B16 47 Series A flanges are much thicker, heavier and stronger than Series B flanges for the same pressure ans size. Series A flange can withstand more external loading than Series B flange. ASME B16.47 Series B flanges need smaller fasteners, in larger quantity, than Series A flanges. They also have a smaller bolt circle diameter than that of Series A flanges. The smaller bolt circle diameter results in less flange movement after installation. Both Series A and Series B standards define weld neck flanges and blind flanges in raised face type (RF) but only Series A defines ring type joint (RTJ) flanges from Class 300 through Class 900 within this standard. Price wise, ASME B16.47 Series A flanges are more expensive than ASME B16 47 Series B flanges.

Most piping users or designers may choose Series A flanges for the new pipeline or equipment. But if you are doing some refurbishment, replacement job or non-critical piping design, Series B flanges are more popular.

See documents below for comparison of flange sizes in two main standards (B16.5 and B16.47)

Flange Dimensions as per ASME B 16 5 standard for 150# Welding Neck Flange, Blind Flange, Slipon, Socketweld & Lapjoint flange is here

Flange Dimensions as per ASME B16 47 series A standard for 150# weldneck and blind flange is here

Flange Dimensions as per ASME B 16.47 series B standard for 150# weld neck and blind flange is here

Conclusions: Standard weld neck, slip on, blind etc. flanges are covered by standard B16.5 for sizes up to 24″ nominal pipe. Sizes 26″ and bigger are covered by B16.47 series A or series B for weldneck and blind flanges. Series A flange is heavier, thicker and cost more whereas series B flange has more bolt holes and is lighter cheaper than series A. API605 flange and series B flanges are same thing.

Industry Standard Flange (ASME B16.1 Flange)
No national standard or governing body controls the Industry Standard Flange. The dimension and material of Industry Standard Flange has been adopted after years of “common” industry practice. It is important to note that size and material of industry standard flange are covered by standard ASME B16.1 whic his a standard for Class 25, 125 and 250 Cast Iron Pipe Flange and Flanged Fittings. Pressure rating of industry flange matches the AWWA table 4 class E standard. In sizes smaller than 24″, Industry Standard Flange also matches B16.5 flanges.

AWWA Flange

This standard covers slip-on and blind flanges for waterworks service in sizes 4″ through 144″ nominal (100mm through 3600 mm).

Difference between ANSI and AWWA flange

We have already covered that ANSI flange means ASME B16.5 flange. ANSI and AWWA standard for flanges differ in several ways. The AWWA standard is intended for potable water use. Where as ANSI/ASME standard is aimed at industrial application. AWWA flange rating are applicable only at atmospheric temperature whereas ANSI rating covers from -20°F to 1500°F.

The two standards also differ in the scope of application. ANSI standard includes information for welding auxiliar connections while AWWA does not cover the installations. The AWWA standard only covers hub-type, ring, blind and threaded flange whereas ANSI standard has more types such as weld neck, lap joint, socket weld flange etc.

Standards covering AWWA and ANSI flanges are;

• ANSI/AWWA C115/A21.15-99: “American National Standard for Flanged Ductile-Iron Pipe with Ductile-Iron or Gray-Iron Threaded Flanges”
• ANSI/AWWA C207-94: “AWWA Standard for Steel Pipe Flanges for Waterworks Service-Sizes 4 In. Through 144 In.”
• ANSI / ASME B16.5-1981: “Pipe Flanges and Flanged Fittings”.

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Flange gaskets are used to create a static seal between two flanges faces, at various operating conditions, with varied pressure and temperature ratings. A gaskets fills the microscopic spaces and irregularities of the flange faces, and then it forms a seal that is designed to keep liquids and gases. Correct installation of damage-free gaskets and demage-free flange faces is a requirement for a leak-free flange connection.

Steel pipe flange gaskets are used to create seal between two flange faces. The flange face acts at the seal seat and the flange gasket compresses between two flanges, with the bolt compression, to fill all irregularities in the flange face and create a seal. The gasket is selected based on the operating condition such as pressure, temperature and chemical exposure.

Gaskets are available in following three types;

• Full Face Gasket: covers the full face of the flange. Generally used on flat face flanges
• Flat ring Gasket: covers only the sealing surface or the raised face of the flange.
• Metallic Ring Gakset: designed to be fitted in RTJ Flanges.

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Some of pipe fittings and equipment have been built-flange, also falls within the flange connection. Has flanged pipe and fittings, also belongs to the flange. Flange connections are an important connection for pipeline construction. Flange connections easy to use, able to withstand greater pressure.

Sub-threaded flange connection (wiretapping) flange and welding flange. Low-pressure small-diameter wire access flange, high pressure and low pressure are the use of large-diameter welded flange, different pressure, flange thickness and bolt diameter and the number of connections are different.

Within the family, pipe diameter, and are low-voltage, see flange connection. If produced in a boiler room or scene is full of flanged pipes and fittings.

As iron welded flange, a lot of customers have doubts is the quality is better than the forging of iron welding flange welding flange. Actually iron welding flange of quality and forged of welding flange of quality is as of, but iron welding flange what place cannot has guarantees does, is iron welding flange of material most no guarantees has, because General of process among, iron welding flange of density is no problem of, but in for production of process among, iron welding flange of rough rarely for detection, so for, by production out yahoo, not after detection of iron welding flange of material cannot guarantee.

The different grades based on the pressure, flange pad also has a variety of materials, from the low-pressure asbestos pad, high-pressure pads to the metal pads are asbestos.

Within the family, pipe diameter is small, but also ow-voltage, see flange connection. If a boiler room or a production site, full of flanged pipes and equipment. Flange connection is to two pipes, fittings or equipment before each fixed at a flange on the flange between the two, together with flange pad, fastened together with bolts to complete the connection. Some of pipe fittings and equipment have been built-flange, also falls within the flange connection.

How to select the gasket for Flange Connections?

One of the best all-around seals, the spiral wound gasket offers a low-cost solution that has the ability to handle temperature and pressure fluctuations. Multiple plies of metal and filler in the spiral create a barrier that reduces the possibility of leaks.

Temperature and Chemical Considerations

Be certain that the gasket you order is as resistant as possible to the media and temperature involved. Check the chemical compatibility of the metal as well as the filler material for the media to be sealed. As a general rule, the metal used in either the spiral winding or double-jacketed gasket should be similar to the flange material.

The compressibility of flexible graphite makes it an excellent filler material for metallic gaskets. Flexible graphite may be used in services with temperatures up to 950ºF (485ºC), though it should not be used with strong oxidizers such as nitric or sulfuric acid.

PTFE filler material provides excellent chemical resistance at temperatures below 500ºF (260ºC). In accordance with ASME B16.20, an inner ring is required when using conventional PTFE filler materials, in order to protect the winding from radial buckling.

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Pressure Classes of Flanges

The Pressure Class or Rating for flanges will be given in pounds. Different names are used to indicate a Pressure Class.

Forged steel flanges, according to ASME B16.5, are made in seven primary Pressure Classes:

150 300 400 600 900 1500 2500

The concept of flange ratings likes clearly. A Class 300 flange can handle more pressure than a Class 150 flange, because a Class 300 flange are constructed with more metal and can withstand more pressure. However, there are a number of factors that can impact the pressure capability of a flange.

The Pressure Class or Rating for flanges will be given in pounds. Different names are used to indicate a Pressure Class.
For example: 150 Lb or 150 Lbs or 150# or Class 150, all are means the same.

The concept of flange ratings likes clearly. A Class 300 flange can handle more pressure than a Class 150 flange, because a Class 300 flange are constructed with more metal and can withstand more pressure. However, there are a number of factors that can impact the pressure capability of a flange.
The Pressure Class or Rating for flanges will be given in pounds. Different names are used to indicate a Pressure Class.
For example: 150 Lb or 150 Lbs or 150# or Class 150, all are means the same.

Example of Pressure Rating

Flanges can withstand different pressures at different temperatures. As temperature increases, the pressure rating of the flange decreases. For example, a Class 150 flange is rated to approximately 270 PSIG at ambient conditions, 180 PSIG at approximately 400°F, 150 PSIG at approximately 600°F, and 75 PSIG at approximately 800°F.
In other words, when the pressure goes down, the temperature goes up and vice versa. Additional factors are that flanges can be constructed from different materials, such as stainless steel, cast and ductile iron, carbon steel etc.. Each material have different pressure ratings.
Below an example of a flange NPS 12 with the several pressure classes. As you can see, inner diameter and diameter of the raised face at all the same; but outside diameter, bolt circle and diameter of bolt holes become larger in each higher pressure class.

The number and diameters (mm) of the bolt holes are:

CL 150 – 12 x 25.4 CL 300 – 16 x 28.6 CL 400 – 16 x 34.9 CL 600 – 20 x 34.9
CL 900 – 20 x 38.1 CL 1500 – 16 x 54 CL 2500 – 12 x 73

Pressure-temperature ratings are maximum allowable working gage pressures in bar units at the temperatures in degrees celsius. For intermediate temperatures, linear interpolation is permitted. Interpolation between class designations is not permitted.
Pressure-temperature ratings apply to flanged joints that conform to the limitations on bolting and on gaskets, which are made up in accordance with good practice for alignment and assembly. Use of these ratings for flanged joints not conforming to these limitations is the responsibility of the user.
The temperature shown for a corresponding pressure rating is the temperature of the pressure-containing shell of the component. In general, this temperature is the same as that of the contained fluid. Use of a pressure rating corresponding to a temperature other than that of the contained fluid is the responsibility of the user, subject to the requirements of applicable codes and regulations. For any temperature below -29°C, the rating shall be no greater than the rating shown for -29°C.

ASTM GROUP 2-1.1 MATERIALS

Nominal Designation	Forgings	Castings	Plates
C-Si	A105(1)	A216 Gr.WCB (1)	A515 Gr.70 (1)
C Mn Si	A350 Gr.LF2 (1)	…	A516 Gr.70 (1), (2)
C Mn Si V	A350 Gr.LF6 Cl 1 (3)	…	A537 Cl.1 (4)
3.1/2Ni	A350 Gr.LF3	…	…

Notes:

• (1) Upon prolonged exposure to temperatures above 425°C, the carbide phase of steel may be converted to graphite. Permissible but not recommended for prolonged use above 425°C.
• (2) Do not use over 455°C.
• (3) Do not use over 260°C.
• (4) Do not use over 370°C.

ASTM GROUP 2-2.3 MATERIALS

Nominal Designation	Forgings	Cast	Plates
16Cr 12Ni 2Mo	A182 Gr.F316L	…	A240 Gr.316L
18Cr 13Ni 3Mo	A182 Gr.F317L	…	…
18Cr 8Ni	A182 Gr.F304L (1)	…	A240 Gr.304L (1)

Note: Do not use over 425°C.

PRESSURE-TEMPERATURE RATINGS FOR ASTM GROUP 2-1.1 MATERIALS

Working pressure by Classes, BAR

TEMP(°C)	150	300	400	600	900	1500	2500
-29 TO 38	19.6	51.1	68.1	102.1	153.2	255.3	425.5
50	19.2	50.1	66.8	100.2	150.4	250.6	417.7
100	17.7	46.6	62.1	93.2	139.8	233	388.3
150	15.8	45.1	60.1	90.2	135.2	225.4	375.6
200	13.8	43.8	58.4	87.6	131.4	219	365
250	12.1	41.9	55.9	83.9	125.8	209.7	349.5
300	10.2	39.8	53.1	79.6	119.5	199.1	331.8
325	9.3	38.7	51.6	77.4	116.1	193.6	322.6
350	8.4	37.6	50.1	75.1	112.7	187.8	313
375	7.4	36.4	48.5	72.7	109.1	181.8	303.1
400	6.5	34.7	46.3	69.4	104.2	173.6	289.3
425	5.5	28.8	38.4	57.5	86.3	143.8	239.7
450	4.6	23	30.7	46	69	115	191.7
475	3.7	17.4	23.2	34.9	52.3	87.2	145.3
500	2.8	11.8	15.7	23.5	35.3	58.8	97.9
538	1.4	5.9	7.9	11.8	17.7	29.5	49.2
TEMP (°C)	150	300	400	600	900	1500	2500

PRESSURE-TEMPERATURE RATINGS FOR ASTM GROUP 2-2.3 MATERIALS

Working pressure by Classes, BAR

TEMP(°C)	150	300	400	600	900	1500	2500
-29 TO 38	15.9	41.4	55.2	82.7	124.1	206.8	344.7
50	15.3	40	53.4	80	120.1	200.1	333.5
100	13.3	34.8	46.4	69.6	104.4	173.9	289.9
150	12	31.4	41.9	62.8	94.2	157	261.6
200	11.2	29.2	38.9	58.3	87.5	145.8	243
250	10.5	27.5	36.6	54.9	82.4	137.3	228.9
300	10	26.1	34.8	52.1	78.2	130.3	217.2
325	9.3	25.5	34	51	76.4	127.4	212.3
350	8.4	25.1	33.4	50.1	75.2	125.4	208.9
375	7.4	24.8	33	49.5	74.3	123.8	206.3
400	6.5	24.3	32.4	48.6	72.9	121.5	202.5
425	5.5	23.9	31.8	47.7	71.6	119.3	198.8
450	4.6	23.4	31.2	46.8	70.2	117.1	195.1
TEMP(°C)	150	300	400	600	900	1500	2500

As an example, below you will find two tables with material groups acc. to ASTM, and two other tables
with flange pressure-temperature ratings for those ASTM materials acc. to ASME B16.5.

Requirements are valid for normal situation, in special you have to contact us to introduce.

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Flange facing types according to DIN EN 1092-1

Flanges and their joints – Circular flanges for pipes, valves, fittings and accessories, PN designated – Part 1: Steel flanges

This European standard specifies requirements for circular steel flanges in PN designations PN 2,5 to PN 400 and nominal sizes from DN 10 to DN 4000. This standard specifies the flange types and their facings, dimensions, tolerances, threading, bolt sizes, flange face surface finish, marking, materials, pressure/ temperature ratings and flange masses.

Flange faces have to be smooth enough to ensure a tight, leak-free seal for bolted flanges.

Flange facing dimensions (units [mm])

DN	PN												f1	f2	f3	f4	w	x	y	z	α	R
	2.5	6	10	16	25	40	63	100	160	250	320	400
	d1
10	35	35	40	40	40	40	40	40	40	40	40	40	2	4.5	4	2	24	34	35	23	–	2.5
15	40	40	45	45	45	45	45	45	45	45	45	45					29	39	40	28	–
20	50	50	58	58	58	58	58	58	58	58	58	58					36	50	51	35	41º
25	60	60	68	68	68	68	68	68	68	68	68	68					43	57	58	42
32	70	70	78	78	78	78	78	78	78	78	78	78					51	65	66	50
40	80	80	88	88	88	88	88	88	88	88	88	88	3				61	75	76	60
50	90	90	102	102	102	102	102	102	102	102	102	102					73	87	88	72
65	110	110	122	122	122	122	122	122	122	122	122	122					95	109	110	94
80	128	128	138	138	138	138	138	138	138	138	138	138					106	120	121	105
100	148	148	158	158	162	162	162	162	162	162	162	162		5	4.5	2.5	129	149	150	128	32º	3
125	178	178	188	188	188	188	188	188	188	188	188	188					155	175	176	154
150	202	202	212	212	218	218	218	218	218	218	218	218					183	203	204	182
200	258	258	268	268	278	285	285	285	285	285	285	285					239	259	260	238
250	312	312	320	320	335	345	345	345	345	345	345	–					292	312	313	291
300	365	365	370	378	395	410	410	410	410	–	–	–	4				343	363	364	342
350	415	415	430	438	450	465	465	465	–	–	–	–		5.5	5	3	395	421	422	394	27º	3.5
400	465	465	482	490	505	535	535	535	–	–	–	–					447	473	474	446
450	520	520	532	550	555	560	560	560	–	–	–	–					497	523	524	496
500	570	570	585	610	615	615	615	615	–	–	–	–					349	375	376	548
600	670	670	685	725	720	735	735	–	–	–	–	–	5				649	675	676	648
700	775	775	800	795	820	840	840	–	–	–	–	–					751	777	778	750
800	880	880	905	900	930	960	960	–	–	–	–	–					856	882	883	855
900	980	980	1005	1000	1030	1070	1070	–	–	–	–	–					961	987	988	960
1000	1080	1080	1110	115	1140	1180	1180	–	–	–	–	–		6.5	6	4	1062	1092	1094	1060	28º	4
1200	1280	1295	1330	1330	1350	1380	1380	–	–	–	–	–					1262	1292	1294	1260
1400	1480	1510	1535	1530	1560	1600	–	–	–	–	–	–					1462	1492	1494	1460
1600	1690	1710	1760	1750	1780	1815	–	–	–	–	–	–					1662	1692	1694	1660
1800	1890	1920	1960	1950	1985	–	–	–	–	–	–	–					1862	1892	1894	1860
2000	2090	2125	2170	2150	–	–	–	–	–	–	–	–					2062	2092	2094	2060
2200	2295	2335	2370	–	–	–	–	–	–	–	–	–		–	–	–	–	–	–	–	–	–
2400	2495	2545	2570	–	–	–	–	–	–	–	–	–		–	–	–	–	–	–	–	–	–
2600	2695	2750	2780	–	–	–	–	–	–	–	–	–		–	–	–	–	–	–	–	–	–
2800	2910	2960	2000	–	–	–	–	–	–	–	–	–		–	–		–	–	–	–	–	–
3000	3110	3160	3210	–	–	–	–	–	–	–	–	–		–	–	–	–	–	–	–	–	–
3200	3310	3370	–	–	–	–	–	–	–	–	–	–		–	–	–	–	–	–	–	–	–
3400	3510	3580	–	–	–	–	–	–	–	–	–	–		–	–	–	–	–	–	–	–	–
3600	3720	3790	–	–	–	–	–	–	–	–	–	–		–	–	–	–	–	–	–	–	–
3800	3920	–	–	–	–	–	–	–	–	–	–	–		–	–	–	–	–	–	–	–	–
4000	4120	–	–	–	–	–	–	–	–	–	–	–		–	–	–	–	–	–	–	–	–

Flange facing types C, D, E, F, G and H are not used for PN 2,5 and PN 6.

Flange facing types G and H are only used for PN 10 to PN 40.

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The type of forged flange and sealing face for flange

Flanges provide the necessary connections to link pipelines. Faces are the mating surface of a flange.

Different types of flange faces are used as the contact surfaces to seat the sealing gasket material.

The type of flange	The type of sealing face	Pressure Class(PN,MPA)
Plate flange(PL)	Raise Face(RF)	0.25-2.5
	Flat Face( FF)	0.25-1.6
Slip on flange(SO)	Raise Face(RF)	0.6-4.0
	Flat Face( FF)	0.6-1.6
	male and female face (MFM)	1.0-4.0
	Tongue and groove face (TG)	1.0-4.0
Welding Neck Flange(WN)	Raise Face(RF)	1.0-25.0
	male and female face (MFM)	1.0-16.0
	Tongue and groove face (TG)	1.0-16.0
	Ring Joint Face(RTJ)	6.3-25.0
	Flat Face( FF)	1.0-1.6
Integral type flange(IF)	Raise Face(RF)	0.6-25.0
	male and female face (MFM)	1.0-16.0
	Tongue and groove face (TG)	1.0-16.0
	Ring Joint Face(RTJ)	6.3-25.0
	Flat Face( FF)	0.6-1.6
Socket Weld Flange(SW)	Raise Face(RF)	1.0-10.0
	male and female face (MFM)	1.0-10.0
	Tongue and groove face (TG)	1.0-10.0
Thread Flange(Th)	Raise Face(RF)	0.6-4.0
	Flat Face( FF)	0.6-1.6
Lap joint Flange(LP)	Raise Face(RF)	0.6-1.6
	male and female face (MFM)	1.0-1.6
	Tongue and groove face (TG)	1.0-1.6
Blind flange(BL)	Raise Face(RF)	0.25-25.0
	male and female face (MFM)	1.0-16.0
	Tongue and groove face (TG)	1.0-16.0
	Ring Joint Face(RTJ)	6.3-25.0
	Flat Face( FF)	0.25-1.6

Other flange facings covered by these standards include the large and small tongue-and-groove facings, and the ring joint facing specifically for ring joint type metal gaskets.

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WHAT IS ANSI?

ANSI-approved flanges are used for the industrial market which handles gas, air and steam process systems. Originally formed in 1918, the American National Standards Institute is headquartered in Washington, DC, and is widely recognized as the American organization responsible for overseeing the national standards and conformity assessment system for products, services, processes, systems, and personnel.

ANSI works domestically with American government agencies and organizations, as well as with international entities, to make ANSI standards useful around the world.

Prior to the creation of ANSI, standards for engineering and equipment such as flanges were developed by the American Institute of Electrical Engineers (AIEE or IEEE), the American Society of Mechanical Engineers (ASME), the American Institute of Mining, Metallurgical, and Petroleum Engineers (AIME), the American Society of Civil Engineers (ASCE), and the American Society for Testing and Materials (ASTM International) as members of the United Engineering Society, or UES.

Types of ANSI Flanges

The types of ANSI flanges are: slip on flange, welding neck flange, lap joint flange, plate flange, threaded flange on forge steel, carbon steel, stainless steel, alloy steel and blind flange. The classes of the flanges are the pressure ratings, which is between Class 150 and Class 2500. The dimensions of the flange are determined by the size of the pipe and the class of the pressure, which are required for the flange to be able to withstand water pressure and heat. Temperatures and materials of the flange can withstand pressures from -20 (degrees, Celsius) to 200 (degrees, Celsius).

Purpose

Flanges are used to attach a series of pipes or other flanges together. Some flanges, such as in the oil and gas sector, are required to sustain under high amounts of pressure. ASNI provides standards to flange manufactures to test flanges before they can be marketed to a particular sector.

Significance

ANSI provides standards on flanges depending upon pressure in pounds per second per inch (PSI), according to size in inches of the flange. Pressure and size are dependent upon whether the flange is welded to the pipe, threaded or bolted.

Considerations

Depending on the material the flange is made from, such as cast iron or steel, and the type of threaded material used for fittings, every flange is designated to a particular class. From these class ratings, several requirements, such as pressure-temperature rating, bolt and nut dimensions, coating material and several other factors, make up the standards according to the flange characteristics.

Standards of ANSI Flanges

The classes for flat face flanges are Class 125 and Class 250. The classes for ring joint flanges, tongue and groove flanges and raised flanges are: Class 150, Class 300 (Class 400 – rarely), Class 600, Class 900, Class 1500 and Class 2500. ANSI flanges are divided into classes, depending on pressure, temperature and the type of material used.