Flange materials acc. to ASTM

Dimensions from carbon steel and stainless steel flanges are defined in the ASME B16.5 standard.

The most common materials for pipe flanges (forged grades) are: ASTM A105 (carbon steel high temperature to match A53/A106/API 5L pipes), A350 Grades LF1/2/3 (carbon steel low temperature to match A333 pipes), A694 Grades F42 to F80 (high yield carbon steel to match API 5L pipe grades), ASTM A182 Grades F5 to F91 (alloy steel flanges to match A335 pipes), A182 Grade F304/316 (stainless steel flanges to match A312 SS pipes), A182 Gr. F44/F51/F53/F55 (duplex and super duplex to match A790/A928 pipes) and various nickel alloy grades (Inconel, Incoloy, Hastelloy, Monel).

The material qualities for these flanges are defined in the ASTM standards.

What are ASTM Grades?
For example, a carbon steel pipe can be identified with Grade A or B, a stainless-steel pipe with Grade TP304 or Grade TP321, a carbon steel fitting with Grade WPB etc.

Stainless Steel

As you may be have noted, in the table below, ASTM A105 has no Grade. Sometimes ASTM A105N is described;
“N” stands not for Grade, but for normalized. Normalizing is a type of heat treatment, applicable to ferrous metals only. The purpose of normalizing is to remove the internal stresses induced by heat treating, casting, forming etc.

Chemical requirements composition, %
Chemical elements Grade F304 (A) Grade F304L (A) Grade F316L (A-B)
Carbon, max 0.08 0.035 0.035
Manganese, max 2.00 2.00 2.00
Phosphorus, max 0.045 0.045 0.045
Sulfur, max 0.03 0.03 0.03
Silicon, max 1.00 1.00 1.00
Nickel 8-11 8-13 10-15
Chrome 18 – 20 18 – 20 16 – 18
Molybdenum - - 2.00-3.00

(A) Carbon 0.040% max. is necessary where many drawing passes are required, as with outside diameter <0.5 inch (12.7 mm), or nominal wall thickness <0.049 inch (1.2 mm).

(B) On pierced tube, Nickel may be 11 – 16.00%.

FREQUENTLY USED ASTM GRADES

Material Fittings Flanges Valves Bolts & Nuts
Carbon Steel A234 Gr WPA A105 A216 Gr WCB A193 Gr B7
A194 Gr 2H
A234 Gr WPB A105 A216 Gr WCB
A234 Gr WPC A105 A216 Gr WCB
Carbon Steel
Alloy
High-Temp
A234 Gr WP1 A182 Gr F1 A217 Gr WC1 A193 Gr B7
A194 Gr 2H
A234 Gr WP11 A182 Gr F11 A217 Gr WC6
A234 Gr WP12 A182 Gr F12 A217 Gr WC6
A234 Gr WP22 A182 Gr F22 A217 Gr WC9
A234 Gr WP5 A182 Gr F5 A217 Gr C5
A234 Gr WP9 A182 Gr F9 A217 Gr C12
Carbon Steel
Alloy Low-Temp
A420 Gr WPL6 A350 Gr LF2 A352 Gr LCB A320 Gr L7
A194 Gr 7
A420 Gr WPL3 A350 Gr LF3 A352 Gr LC3
Austenitic
Stainless
Steel
A403 Gr WP304 A182 Gr F304 A182 Gr F304 A193 Gr B8
A194 Gr 8
A403 Gr WP316 A182 Gr F316 A182 Gr F316
A403 Gr WP321 A182 Gr F321 A182 Gr F321
A403 Gr WP347 A182 Gr F347 A182 Gr F347

ASTM standards define the specific manufacturing process of the material and determine the exact chemical composition of pipes, fittings and flanges, through percentages of the permitted quantities of carbon, magnesium, nickel, etc., and are indicated by "Grade".

Carbon steel flanges

The chemical composition and the mechanical properties of the three main carbon steel flanges material grades:

  • ASTM A105 (high-temperature carbon steel) to match A53, A106, API 5L carbon steel pipes
  • ASTM A350 LF1, LF2, LF3 (low-temperature carbon steel) to match ASTM A333 pipes
  • ASTM A694 F42, F52, F60, F65 (high-yield carbon steel to match API 5L X42, X52, X60, and X65 steel pipes
Chemical composition ASTM A105 105, A350, A694

ASTM A105 (High-temperature carbon steel flange material)

Grade C Mn P S Si Cu Ni Cr Mo V
A105 0.6 0.1    
0.35 1.05 0.035 0.04 0.35 0.4 0.4 0.3 0.12 0.08

ASTM A350 (Low-Temperature carbon steel flange material)

Grade
C% Mn% Si% S% P% Cr% Ni%
A350 LF1 0.30 max 0.6/1.35 .15/.30 .040 max .035 max 0.30 max 0.40 max
A350 LF2 0.30 max 0.6/1.35 .15/.30 .040 max .035 max 0.30 max 0.40 max
A350 LF3 0.20 max 0.9 .20/.35 .040 max .035 max 0.30 max 3.3/3.7

ASTM A694 (High-yield carbon steel flanges)

Grade C Mn P S Si
ASTM A694 F42 0.26-0.265 1.60-1.64 0.025-0.030 0.025-0.030 0.15-0.35
ASTM A694 F52 0.26-0.265 1.60-1.64 0.025-0.030 0.025-0.030 0.15-0.35
ASTM A694 F60 0.26-0.265 1.60-1.64 0.025-0.030 0.025-0.030 0.15-0.35
ASTM A694 F65 0.26-0.265 1.60-1.64 0.025-0.030 0.025-0.030 0.15-0.35
Mechanical properties A105, A350, A694

ASTM A105 (High-temperature carbon steel flange material)

Property ASTM A105 ASTM A350-LF2
Tensile Strength Min, psi 70,000 70,000-95,000
Tensile Strength Min, N/mm² 485 485-655
Yield Strength Min, psi 36,000 36,000
Yield Strength Min, N/mm² 250 250
Elongation (%) 22 22
Reduction of Area (%) 30 30
Hardness, maximum 187 15/12 ft-lbs
CVN at -50℉ 20/16 joules

ASTM A694 (High-yield carbon steel flanges)

ASTM A694 Flange Material Grade Min Yield Strength (0.2 % Offset), in ksi [MPa] MinTensile Strength Elongation in 2 in. or 50 mm, min %
in ksi [MPa]
A694 F42 42 [290] 60 [415] 20
A694 F46 46 [315] 60 [415] 20
A694 F48 48 [330] 62 [425] 20
A694 F50 50 [345] 64 [440] 20
A694 F52 52 [360] 66 [455] 20
A694 F56 56 [385] 68 [470] 20
A694 F60 60 [415] 75 [515] 20
A694 F65 65 [450] 77 [530] 20
A694 F70 70 [485] 82 [565] 18

 

Alloy steel flanges

Alloy flange materials (chrome-moly) have higher chrome and molybdenum content than carbon steel flanges. Alloy steel flange materials suit high temperature and high-pressure applications and improved resistance to corrosion when compared to regular carbon steel flanges grades.

  • ASTM A182 alloy flanges are extremely ductile, strong and tough and easy to weld and offer oxidation and scaling resistance.
Chemical composition ASTM A182 F5, F9, F11, F22
ELEMENT & PROPERTIES LOW ALLOY STEEL MEDIUM ALLOY STEEL
F11 CL2 F22 CL3 F5 F9
CARBON 0.10-0.20 0.05-0.15 0.15 MAX 0.15 MAX
MANGANESE 0.30-0.80 0.30-0.60 0.30-0.60 0.30-0.60
PHOSPHORUS MAX 0.04 0.04 0.03 0.03
SULFUR MAX 0.04 0.04 0.03 0.03
SILICON 0.50-1.00 0.50 MAX 0.50 MAX 0.50-1.00
NICKEL MAX 0.5
CHROMIUM 1.00-1.50 2.00-2.50 4.00-6.00 8.0-10.0
MOLYBDENUM 0.44-0.65 0.87-1.13 0.44-0.65 0.90-1.10
OPPER MA
COLUMBIUM MAX
VANADIUM MAX
Mechanical A182
Element & properties Low alloy steel Medium alloy steel
F11 CL2 F22 CL3 F5 F9
TENSILE STRENGTH PSI (MPA) 70,000 (485) 75,000 (515) 70,000 (485) 85,000 (585)
YIELD STRENGTH PSI MIN 40,000 (275) 45,000 (310) 40,000 (275) 55,000 (380)
ELONGATION 2” % MIN 20 20 20 20
REDUCTION AREA % MIN 30 30 35 40
HARDNESS (HB) MAX* 143 ~ 207 156 ~ 207 143 ~ 217 179 ~ 217

Recommended service for alloy steel flange material grades ASTM A182:

ASTM A182 Alloy steel flange TRADE DESIGNATION RECOMMENDED SERVICE
A182 F1 C-1/2 Mo Low Alloy Steel Non-corrosive applications Including water, oil, and gases at temperatures between -29 ~ 593ºC* (Not prolonged use > 470ºC).
A182 F2 0.75% Ni; Mo; 0.75% Cr Low Alloy Steel Non-corrosive applications including water, oil, and gases at temperatures F2:-29ºC ~ 538ºC, WC5: -29ºC ~ 575ºC
A182 F11 1 1/4% Chrome; 1/2% Moly Low Alloy Steel Non-corrosive applications including water, oil, and gases at temperatures between -30ºC (-20ºF) and +593ºC (+1100ºF).
A182 F22 2 1/4% Chrome Low Alloy Steel Non-corrosive applications including water, oil, and gases at temperatures between -30ºC (-20ºF) and +593ºC (+1100ºF).
A182 F5/F5a 5% Chrome; 1/2% Moly, Medium Alloy Steel Mild corrosive or erosive applications as well as non-corrosive applications at temperatures between -30ºC (-20ºF) and +650ºC (+1200ºF).
A182 F9 9% Chrome; 1% Moly, Medium Alloy Steel Mild corrosive or erosive applications as well as non-corrosive applications at temperatures between -30ºC (-20ºF) and +650ºC (+1200ºF).
A182 F91 9% Chrome; 1% Moly; V-N, Medium Alloy Steel Mild corrosive or erosive applications as well as non-corrosive applications at temperatures between -30ºC (-20ºF) and +650ºC (+1200ºF).

Stainless steel flanges

The key elements that differentiate stainless steel materials for flanges, compared to other grades, are the Nickel (Ni), Chrome (Cr), and Molybdenum content (Mo).

Stainless steel flange simplified as SS flange, it refers to the flanges that made of stainless steel. Common material standards and Grades are ASTM A182 Grade F304/L and F316/L, with pressure ratings from Class 150, 300, 600 etc and to 2500. It used in more industries than carbon steel as stainless steel has better resistant performances on corrosion environment and always provides with a good appearance.

These ASTM standards, define the specific manufacturing process of the material and determine the exact chemical composition of pipes, fittings and flanges, through percentages of the permitted quantities of carbon, magnesium, nickel, etc., and are indicated by “Grade”.
For example, a carbon steel flange can be identified with Grade F9 or F11, a stainless-steel flange with Grade F316 or Grade F321 etc..
Below you will find as an example a table with chemical requirements for fittings ASTM A403 Grade WP304, WP304L, WP316L and a table with frequent Grades, arranged on pipe and pipe-components, which belong together as a group.

About Stainless Steel

In metallurgy, stainless steel also called as inox steel or inoxidizable steel. It is a steel material alloyed with high content of chromium and nickel, where

  • Minimum Cr at 10.5% 
  • Minimum Ni at 8% 
  • Maximum Carbon at 1.5%

As we know, stainless steel flange is impressed by it's great corrosion resistance, which because of the elements of Chromium, and as Cr increased, better resistant performances will be gained. 

On the other hand, additions of Molybdenum will increase corrosion resistance in reducing acids and against pitting attack in chloride solutions. So there are different grades of stainless steel with varying Cr and Mo compositions to suit the environment with required to be alloyed. 

Chemical composition ASTM A182 F304/F316/F321
ASTM A182 GRADE C Mn P S Si Ni Cr Mo Nb Ti Others
F304(1) 0.08 2 0.045 0.03 1 8.0-11.0 18.0-20.0        
F304H 0.04-0.10 2 0.045 0.03 1 8.0-11.0 18.0-20.0        
F304L(1) 0.03 2 0.045 0.03 1 8.0-13.0 18.0-20.0        
F304N(2) 0.08 2 0.045 0.03 1 8.0-10.5 18.0-20.0        
F304LN(2) 0.03 2 0.045 0.03 1 8.0-10.5 18.0-20.0        
F309H 0.04-0.10 2 0.045 0.03 1 12.0-15.0 22.0-24.0        
F310 0.25 2 0.045 0.03 1 19.0-22.0 24.0-26.0        
F310H 0.04-0.10 2 0.045 0.03 1 19.0-22.0 24.0-26.0        
F310MoLN 0.03 2 0.03 0.015 0.4 21.0-23.0 24.0-26.0 2.0-3.0     N 0.10-0.16
F316 0.08 2 0.045 0.03 1 10.0-14.0 16.0-18.0 2.0-3.0      
F316H 0.04-0.10 2 0.045 0.03 1 10.0-14.0 16.0-18.0 2.0-3.0      
F316L(1) 0.03 2 0.045 0.03 1 10.0-15.0 16.0-18.0 2.0-3.0      
F316N(2) 0.08 2 0.045 0.03 1 11.0-14.0 16.0-18.0 2.0-3.0      
F316LN(2) 0.03 2 0.045 0.03 1 11.0-14.0 16.0-18.0 2.0-3.0      
F316Ti 0.08 2 0.045 0.03 1 10.0-14.0 16.0-18.0 2.0-3.0   -3 N 0.10 max
F317 0.08 2 0.045 0.03 1 11.0-15.0 18.0-20.0 3.0-4.0      
F317L 0.03 2 0.045 0.03 1 11.0-15.0 18.0-20.0 3.0-4.0      
F321 0.08 2 0.045 0.03 1 9.0-12.0 17.0-19.0     -4  
F321H 0.04-0.10 2 0.045 0.03 1 9.0-12.0 17.0-19.0     -5  
F347 0.08 2 0.045 0.03 1 9.0-13.0 17.0-20.0   -6    
F347H 0.04-0.10 2 0.045 0.03 1 9.0-13.0 17.0-20.0   -7    
F348 0.08 2 0.045 0.03 1 9.0-13.0 17.0-20.0   -6   Co 0.20
Ta 0.10
F348H 0.04-0.10 2 0.045 0.03 1 9.0-13.0 17.0-20.0   -7   Co 0.20
Ta 0.10

Notes:

  1. Grades F304, F304L, F316, and F316L shall have a maximum Nitrogen of 0.10%.
  2. Grades F304N, F316N, F304LN, and F316LN shall have a Nitrogen of 0.10 to 0.16%.
  3. Grade F316Ti shall have a Titanium content five times above the Carbon plus Nitrogen and not more than 0.70%.
  4. Grade F321 shall have a Titanium content five times above the Carbon and not more than 0.70%.
  5. Grade F321H shall have a Titanium content four times above the Carbon and not more than 0.70%.
  6. Grades F347 and F348 shall have a Niobium content ten times above the Carbon and not more than 1.10%.
  7. Grades F347H and F348H shall have a Niobium content above than eight times the Carbon and not more than 1.10%.
Mechanical properties A182 F304/F316/F321
ASTM A182 Grade Minimum Tensile Strength Minimum Yield point Minimum Elongation Minimum Reduction of in
in MPa in Mpa in % min, %
ASTM A182 F304 515 205 30 50
ASTM A182 F304L 485 170 30 50
ASTM A182 F316 515 205 30 50
ASTM A182 F316L 485 170 30 50
ASTM A182 F321 515 205 30 50

Recommended service for stainless steel flange materials:

Material MATERIAL GROUP RECOMMENDED SERVICE
A182-F304 18% Cr, 8% Ni Stainless Steel Corrosive services and atmospheres from -450°F to 1000°F (-268°C to 537°C)
A182-F316 18% Cr, 8% Ni, 2% Mo Stainless Steel High resistance to corrosion from -450°F to 1000°F (-268°C to 537°C).

Flanges Material Grades: Comparison European and American Standards

Material number EN ASTM
1.4541 X 6 CrNiTi 18 10 X6CrNiTi18-10 A 182 Grade F321
1.4571 X 6 CrNiMoTi 17 12 2 X6CrNiMoTi17-12-2 A 182 Grade F316Ti
1.4301 X 5 CrNi 18 10 X5CrNi18-10 A 182 Grade F304
1.4306 X 2 CrNi 19 11 A 182 Grade F304L
1.4307 – X2CrNi18-9 A 182 Grade F304L
1.4401 X 5 CrNiMo 17 12 2 X5CrNiMo17-12-2 A 182 Grade F316
1.4404 X 2 CrNiMo 17 13 2 X2CrNiMo17-12-2 A 182 Grade F316L
1.4462 X 2 CrNiMoN 22 5 3 X2CrNiMoN22-5-3 A 182 Grade F51 (Duplex)
1.4529 X 1 NiCrMoCuN 25 20 6 X1NiCrMoCuN25-20-7 UNS N 08926
1.4539 X 1 NiCrMoCuN 25 20 5 X1NiCrMoCu25-20-5 A 182 Grade F904L
1.4547 – X1CrNiMoCuN20-18-7 UNS S 3125
Duplex steel flanges

Duplex steel flanges

Duplex steel (ASTM A182 2205) is an extremely corrosion resistant, work hardenable stainless steel, whose microstructure consists of a mixture of austenite and ferrite phases.

Duplex stainless has increased in popularity over the years due to its excellent chemical and mechanical properties versus their basic stainless counterparts, given especially that the cost differences are minimal now as the availability has increased.

Due to this particular chemical and physical composition, duplex stainless steel UNS S31803 features the properties characteristic of both types of stainless steel materials (ferritic and austenitic).

Generally speaking, duplex stainless steel is way tougher than ferritic stainless steels, has a superior strength than austenitic steels (series 300 and 400) and has superior resistance to corrosion when compared to SS304 and SS316 (high intragranular corrosion, also in chloride and sulfide environments).

Whilst austenitic stainless steels are non-magnetic, duplex stainless steel shows magnetic properties.

Duplex and super duplex flanges match with ASTM A790 seamless pipes (or A928 welded duplex pipes).

Chemical composition of ASTM A182 Duplex and super duplex
% Duplex 2205(ASTM A182 UNS S31803 – UNS S32205) Super DuplexASTM A182 UNS S32750 – 32760)
C 0-0.03 0.03 max
Mn 2 1.5
Si 1 0.8
P 0-0.03 0.035
S 0-0.02 0.02
Cr 21-23 24-26
Mo 2.5-3.5 3.0-5.0
Ni 4.5-6.5 5.5-8.0
N 0.08-0.2 0.2-0.35
Cu 0.5-3.0

The most widely used grade for Duplex flange is 2205, due to its superior resistance to corrosion and mechanical strength.

The designation “2205” is related to the chemical composition of this material, which features 22% of chromium and 5% of nickel.

Super Duplex flange show an even superior strength and a higher corrosion resistance than standard duplex steel (and austenitic grades, of course).

The main difference between a duplex and a super duplex grade is the addition of copper to the alloy (in addition to increased amounts of Chromium, Moly, and Nickel).

The addition of copper gives Super Duplex Stainless Steel an improved resistance to hot chlorides and strong reducing acids, like sulphuric acid, compared to a standard Duplex grade.

Whilst UNS S31803, UNS 32205 (duplex) and UNS S32750, UNS S32760 are standard designations, most manufacturers of superalloys attribute proprietary names to these steels (example UR52N+ is a Usinor/Arcelor Super Duplex steel, Ferralium, Zeron, Sandvik SAF 2205 22Cr, etc).

Mechanical properties A182 duplex and super duplex
Mechanical Properties Duplex 2205 Super Duplex
(ASTM A182 UNS S31803 – UNS S32205) ASTM A182 UNS S32750 – 32760)
Tensile Strength (in MPa) 620 770
Proof Stress 0.2% (in MPa) 450 550
A5 Elongation (in %) 25 25
Physical Attribute Duplex 2205 Super Duplex
(ASTM A182 UNS S31803 – UNS S32205) ASTM A182 UNS S32750 – 32760)
Density (g.cm3) 7.805 7.81
Modulus of Elasticity (GPa) 200 205
Electrical Resistivity (Ω.m) 0.085×10-6 0.085×10-6
Thermal Conductivity (W/m.K) 19 at 100°C 17 at 100°C
Thermal Expansion (m/m.K) 13.7×10-6 to 100°C 13.5×10-6 to 200°C

The significant addition of Chromium in Duplex Steel grades, that protects the alloy against corrosion, is a source of steel embrittlement at temperatures over about 300°C. However, at lower temperatures duplex steels show better ductility properties than ferritic and martensitic stainless steels (they can easily be used at a temperature below -50 C°).

ASTM Materials for flanges & fittings

ASTM International, known until 2001 as the American Society for Testing and Materials (ASTM), is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services.

FITTINGS

Pipe fittings are used to connect pipes. There are different varieties of pipe fittings made of various materials and available in various shapes and sizes.

  • ASTM A234 = This specification covers wrought carbon steel and alloy steel fittings of seamless and welded construction.
  • ASTM A420 = Standard specification for piping fittings of wrought carbon steel and alloy steel for low-temperature service.
FLANGES

A flange is a method of connecting pipes, valves, pumps and other equipment to form a piping system.

  • ASTM A105 = 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.
  • ASTM A182 = This specification covers forged or rolled alloy and stainless steel pipe flanges, forged fittings, and Valves and parts for high-temperature service.
  • ASTM A350 = This specification covers several grades of carbon and low alloy steel forged or ring-rolled flanges, forged fittings and Valves for low-temperature service.
VALVES

A valve is a device that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways.

  • ASTM A216 = This specification covers carbon steel castings for Valves, flanges, fittings, or other pressure-containing parts for high-temperature service and of quality suitable for assembly with other castings or wrought-steel parts by fusion welding.
  • ASTM A217 = This specification covers steel castings, martensitic stainless steel and alloys steel castings for Valves, flanges, fittings, and other pressure-containing parts intended primarily for high-temperature and corrosive service.
  • ASTM A352 = This specification covers steel castings for Valves, flanges, fittings, and other pressure-containing parts intended primarily for low-temperature service.
  • ASTM A182 = This specification covers forged or rolled alloy and stainless steel pipe flanges, forged fittings, and Valves and parts for high-temperature service.
Flange bolts
BOLDS & NUTS

Flange bolts are those type of bolts having a ridge or skirt around the bolt head. They are also know as frame bolts and are designed to provide the holding power as if a washer was installed.

  • ASTM A193 = This specification covers alloy and stainless steel bolting material for pressure vessels, Valves, flanges, and fittings for high temperature or high pressure service, or other special purpose applications.
  • ASTM A320 = Standard Specification for Alloy-Steel and Stainless Steel Bolting Materials for Low-Temperature Service.
  • ASTM A194 = Standard specification for nuts in many different material types.

Read your tape measure, in inches. The distance you have found is the diameter of your flange.