Stainless Steel Tradename UNS no. Werkstoff No. Density (g/cm3)
321 321 Stainless S32100 1.4541 7.92
321H 321H Stainless S32109 1.4878 7.92


METLINE Industries is a leading manufacturer and supplier of stainless steel 321 (1.4541) and 321H (1.4878) grade buttweld pipe fittings and flanges. METLINE offers a complete range of stainless steel 321/321H pipe fittings such as SS 321 reducer, SS 321 elbow, SS 321 tee, SS 321 cross, SS 321 end caps, SS 321 stub ends and SS 321 pipe bends. Stainless steel 321 and 321H pipe fittings are manufactured in compliance with ASTM A-403 and ANSI B16.9 / 16.28/ MSS SP-43 / Welding Bevel Standards ANSI B 16.25.

We specialise in the manufacture and supply of SS 321 pipe bends in both standard and non standard sizes, with bending radius of 1D to 10D or any other custom bending radius. We offer ex-stock delivery of various standard size and type SS 321 pipe fittings, SS 321 flanges and SS 321 pipe bends. Our specialty is to manufacture and supply large size fabricated 100% radiography tested SS 321 elbows, SS 321 reducers, SS 321 tees and SS 321 large diameter fabricated pipes.

Grade 321 is a common austenitic 18/8 stainless steel alloy, with the addition of titanium. Type 321 stainless steel is similar to Type 304 stainless steel but with a titanium addition of at least five times the carbon content. The major difference between them is that the titanium addition reduces carbide precipitation during welding.

Stainless steel 321 grade is widely used in high temperature environments of up to 900° C. 321 stainless steel has good welding and forming capabilities and is widely used in operating temperature environments in excess of 500° C. Stainless steel 321H, commonly referred as UNS S32109, is the higher carbon version of the 321 grade, to provide higher temperature strength.

METLINE also stocks and supplies a complete range of SS 321 pipes to complement our existing production range of SS 321 buttweld fittings and SS 321 flanges. Stainless steel 321 seamless pipes can be supplied in cut to length sizes and also machined or fabricated to meet your custom piping requirements.

SS 321/321H Flanges Manufacturer/Supplier

SS 321/321H Flanges Manufacturer/Supplier

SS 321/321H Pipe Fittings Manufacturer/Supplier

SS 321/321H Pipe Fittings Manufacturer/Supplier

SS 321/321H Pipes Supplier/Stockholder

SS 321/321H Pipes Supplier/Stockholder

Key Properties of Stainless Steel 321 Pipe Fittings, SS 321 Flanges

  • Excellent resistance to oxidation
  • High resistance to corrosion
  • Good creep strength
  • Can be readily formed and drawn
  • High resistance to organic chemicals and inorganic chemicals
  • Strong resistance to nitric acids and moderate resistance sulfur acids
  • Improved resistance to intergranular corrosion

Common Applications – SS 321 Pipe Fittings and 321 Flanges

  • Oil refinery equipment
  • Pressure Vessels
  • Industrial Boilers
  • Chemical and pharmaceutical equipment
  • Chemical process heat exchangers
  • Petrochemical refineries

SS 321 Pipe Fittings Production Range

Specification ASTM A182 / A403 & ASME SA182 / SA403
Type Seamless / Welded / Fabricated
Variants 321, 321H
Bending Radius R=1D, 2D, 3D, 5D, 6D, 8D, 10D or Custom
Range ½”NB to 48”NB in Sch 10s, 40s, 80s, 160s, XXS.
Dimensions ANSI/ASME B16.9, B16.28, MSS-SP-43.

Buttweld Stainless Steel 321 Pipe Fittings

Seamless/ Welded 100% Radiography Tested

Products Size
SS 321 Elbows – Long Radius SS 321 Stub Ends

Sizes 1/2″ – 48″

SS 321Elbows – Short Radius SS 321 Crosses
SS 321 Reducing Elbows SS 321 Reducing Crosses
SS 321 45° Elbows SS 321 180° LR Return Bends
SS 321 Tees SS 321 180° SR Return Bends
SS 321 Fabricated Tees SS 321 Pipe Bends / Piggable Bends
SS 321 Reducers SS 321 Couplings
SS 321 Concentric Reducers SS 321 Pipe Nipples
SS 321 Eccentric Reducers SS 321 Forged/Plate Cut Rings
SS 321 3D Elbow SS 321 End Caps
SS 321 5D Elbow SS 321 Forged / Plate Circles

High Pressure Forged 321 Pipe Fittings

Threaded and Socket Weld Pipe Fittings

Products Size
SS 321 90° Elbows SS 321 Couplings

Sizes 1/8″ – 4″

Pressure Ratings –
2000 LBS, 3000 LBS, 6000 LBS, 9000 LBS

SS 321 45° Elbows SS 321 Reducers
SS 321 Street Elbows SS 321 Inserts
SS 321 Tees SS 321 Caps
SS 321 Crosses SS 321 Unions

Stainless Steel 321/321H Flanges

Forged and Plate Flanges

Specification ASTM A182 / A240 & ASME SA182 / SA240
Grade 321, 321H
Standard ANSI Flanges, ASME Flanges, BS Flanges, DIN Flanges, EN Flanges, etc.
Size 1/8” to 36″
Dimensions ANSI/ASME B16.5, B 16.47 Series A & B, B16.48, BS4504, BS 10, EN-1092, DIN, etc.
Class / Pressure 150#, 300#, 600#, 900#, 1500#, 2500#, PN6, PN10, PN16, PN25, PN40, PN64 etc.


Product Size
SS 321 Slip-On Flanges SS 321 Threaded Flanges

1/8″ – 36″

Raised Face or Flat Face

SS 321 Weld Neck Flanges SS 321 Socket Weld Flanges
SS 321 Blind Flanges SS 321 Reducing Flanges
SS 321 Lap Joint Flanges SS 321 Plate Flanges

Marking & Packing

Products are packaged to ensure that there is no damage during transit. In case of exports, standard export packaging is done in wooden cases. All fittings and flanges are marked with Grade, Lot No, Size, Degree and our trade mark. On special requests we can also, make custom marking on our products.

Quality Assurance

At METLINE, all fittings and flanges are subject to strict inspection at each stage of the production process, from starting material purchasing to product dispatch. They are visually examined for conformity to ASTM, ASME, MSS, DIN, EN, and JIS codes and standards. Upon request, official certified Inspection Agencies can be called in to witness the material reports, dimensions and quality conformity of products.

Test Certificates: Manufacturer Test Certificate as per EN 10204 / 3.1B, Raw Materials Certificate, 100% Radiography Test Report, Third Party Inspection Report