Stainless Steel Flange

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.

Connections Types for Stainless Steel Flanges

Stainless steel flanges also ranged with slip on flange, weld neck flange, blind flange, socket weld flange and threaded pipe flange.

Weld Neck Flange

Slip On Flange

Blind Pipe Flange

Socket Weld Flange

Lap Joint Flange

Threaded Pipe Flange

Generally they could be called stainless steel pipe flange, or stainless steel plate flange.

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. 


  • Resistant to corrosion and staining
  • Low maintenance
  • Bright familiar luster
  • Steel Strength

ASTM A182 - Popular Standard for Stainless Steel Pipe Flange

For stainless steel pipe flange, common use material is ASTM A182 F304/L and F316/L.

ASTM A182: It refers to forged and rolled alloy and stainless steel pipe flanges, fittings, valves and parts for high temperature service. And it includes several grades of austenitic and ferritic-austenitic stainless steels. 

Dimensions: 1/2'' to 2'', 3'', 4'', 6'' and up to 48''.
Wall thickness schedule: SCH 10S, SCH 40S, SCH STD, SCH 80S
Pressure ratings: 150#, 300#, 600#, 900#, 1500#, 2500#
Material Grade: F304, F316, F321 and more

Chemical Composition for F304 and F316 SS Flange

Mechanical Properties

Heat Treatment for SS Flange 

Welding Repair Requirements for Stainless Flange

304 Stainless Steel Flange Features

304 is a relatively versatile stainless steel that is widely used to make equipment and parts that require good overall performance (corrosion resistance and formability). In China, 304 steel is called 0Cr19Ni9 or 0Cr18Ni9 stainless steel, as 304 contains 19% Cr and 9% Nickel. 


As 304 stainless steel is a widely used chromium-nickel stainless steel with good corrosion resistance, heat resistance, low temperature strength and mechanical properties. It has corrosion resistant in the atmosphere, if it is an industrial atmosphere or heavily polluted areas, it needs to be cleaned in time to avoid corrosion. Suitable for processing, storage and transportation of food. Has good processing properties and weldability. Used in plate heat exchangers, bellows, household goods, building materials, chemicals, food industry, etc.

316 SS Pipe Flange Features

Compared to 304 stainless steel, 316 stainless steel material have additionally of Nickel and Molybdenum, which in China called 18Cr-12Ni-2.5Mo steel. So normally it has extra Mo 2.0 to 3.0 percent than 304 steel. And this Mo is an element to offer better resistance for high temperature. 

Therefore, It is particularly good in corrosion resistance, atmospheric corrosion resistance and high temperature strength. It can be used under severe conditions which it has excellent work hardening property (non-magnetic).

Sulfuric acid is one of the largest tonnage industrial chemical manufactured. At room temperature Type 304 is only resistant to 3% acid while Type 316 is resistant to 3% acid up to 50 °C and 20% acid at room temperature. So Type 304 is rarely used in contact with sulfuric acid. Type 904L and Alloy 20 are resistant to sulfuric acid at even higher concentrations above room temperature.


316L stainless steel flange has good anti-corrosion effect, better than 304 in seawater and other various media. So it is also regarded as ''marine grade'' stainless steel, but it is not resistant to warm sea water.

316 SS flange used for equipment resistant to sulfuric acid, phosphoric acid, formic acid and acetic acid. Applications include marine, pumping, chemical production, food industry, irrigation, and other stainless steel pipeline systems.

Manufacturing Types

Ranged with forged type and cast type. But in most of the cases forged type is adopted.

Referred Standards:

  • B16.5 Dimensional standard for steel pipe flanges and flanges fittings
  • B16.34 Valves connect by flanges, threaded and welding end
  • B16.47 Large diameter steel flanges

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Slip On Flange

Weld Neck Flange

Blind Flange

Lap Joint Flange

Socket Weld Flange

Threaded Flange