Stainless Steel 321 Flanges, SS 321H Flanges Supplier

SS 321 and SS 321H flanges are precision-engineered components made from titanium-stabilized austenitic stainless steel, specifically developed to deliver superior corrosion resistance and high-temperature performance. These flanges are designed to ensure secure pipe connections in critical systems, offering long-term durability in corrosive and thermally active environments. SS 321 is ideal for continuous service temperatures up to 870°C, while SS 321H, with a higher carbon content, provides enhanced strength and creep resistance in high-pressure applications. Available in a wide range of types—including weld neck, slip-on, socket weld, blind, and threaded variants—these flanges conform to global standards like ANSI, ASTM, DIN, and JIS, ensuring compatibility across diverse industrial systems.

Technical Overview

The core advantage of SS 321/321H lies in their metallurgical stability under high thermal stress. The titanium content in both grades stabilizes the material against chromium carbide precipitation, which commonly occurs during welding or exposure to elevated temperatures. This property enhances the flanges’ resistance to intergranular corrosion—a critical factor in welded assemblies. Stainless steel flanges SS 321H, characterized by its increased carbon content (0.04–0.10%), is specifically tailored for service where greater mechanical strength and prolonged exposure to elevated temperatures are involved.

Mechanically, these flanges offer a balanced combination of tensile strength, ductility, and oxidation resistance. Their fabrication compatibility with standard welding and machining methods allows for easy integration into custom pipeline systems. Both grades exhibit excellent dimensional stability under load, withstanding thermal cycling without degradation. This makes them suitable for pressure-rated systems and pipelines transporting aggressive fluids or gases.

Applications & Industry Use

SS 321/321H flanges are widely deployed in industries where temperature extremes and corrosive media are routine. Key sectors include oil and gas, petrochemicals, thermal and nuclear power, chemical processing, pharmaceuticals, food and beverage, and aerospace. Their use is prominent in heat exchangers, high-temperature exhaust manifolds, furnace components, pressure vessels, and reactors. The thermal resistance and strength retention of these flanges make them essential in piping systems where failure is not an option.

Kvn Steels is the leading manufacturer and supplier of these flanges to major industrial regions, including India, the United Arab Emirates (UAE), the Kingdom of Saudi Arabia (KSA), Kuwait, Qatar, the Sultanate of Oman, Iran, and Iraq. Their proven performance in high-demand environments, particularly across the Middle East and South Asia, has made them a trusted choice for engineering firms, EPC contractors, and end-users seeking resilient, long-life piping solutions.

321/321H Stainless Steel Flanges Equivalent Grades

STANDARD	UNS	WNR.	JIS	EN
SS 321	S32100	1.4541	SUS 321	X6CrNiTi18-10
SS 321H	S32109	1.4878	SUS 321H	X12CrNiTi18-9

SS 321 Slip On FlangesSS 321/321H Slip On Flanges

ASME SA213 SS 304L /304H Seamless Tube, ASTM A213 Stainless Steel 304 Seamless Tubing, DIN 1.4301 / 1.4307 Seamless Tubes, UNS S30403 / S30409 Seamless TubeStainless Steel 321 SORF Flanges, UNS S32100 / S32109 Slip On Flanges, DIN 1.4541 SORF Flanges, ASME SA 182 SS F321H Slip-on Raised Face Flanges

SS 321/321H Weld Neck Flanges

ASME SA182 SS 321H WNRF Flanges, ASTM A182 Stainless Steel 321 Weld Neck Flanges, DIN 1.4541 Weld Neck Flanges, UNS S32100 Weld Neck Raised Face Flanges

SS 321/321H Blind Flanges

Stainless Steel ASTM A182 F321 Blind Flanges, UNS S32100 / DIN 1.4541 Blind Flanges, ASME SA182 SS 321H BLRF Flanges, SS 321/321H Blind Raised Face Flanges Supplier

SS 321/321H Threaded Flanges

DIN 1.4541 Threaded Flanges, UNS S32100 Screwed Flanges, ASME SA 182 Stainless Steel 321H Threaded Flanges, ASTM A182 321/321H SS Threaded Flanges

SS 321/321H Socket Weld Flanges

ASTM A182 F321H Stainless Steel Socket Weld Flanges, SS UNS S32100/ S32109 Socket Weld Flanges, SS DIN 1.4878 Socket Weld Flanges

SS 321/321H Lap Joint Flanges

UNS S32100 Lap Joint Flanges, Stainless Steel 321 Lap Joint Flanges, ASTM A182 F321H Stainless Steel Lap Joint Flanges, ASME SA 182 SS 321/321H Lap Joint Flanges

SS 321/321H Ring Type Joint Flange

Stainless Steel 321/321H Orifice FlangesSS 321/321H Orifice Flanges

SS 321/321H Long Weld Neck Flanges

UNS S32109 Long Weld Neck Flanges, Stainless Steel 1.4878 Long Weld Neck Flanges, ASTM A182 F321H Stainless Steel Long Weld Neck Flanges, ASME SA 182 SS 321/321H Long Weld Neck Flanges

SS 321/321H Spectacle Blind Flanges

ASTM A182 F321H Stainless Steel Socket Weld Flanges, SS UNS S32100/ S32109 Socket Weld Flanges, SS DIN 1.4878 Socket Weld Flanges

SS 321/321H Forged Flanges

UNS S32109 Forged Flanges, B16.5 Stainless Steel 321 Forged Flanges, ASTM A182 F321H Stainless Steel Forged Flanges, ASME SA 182 SS 321/321H Forged Flanges

SS 321/321H Ring Type Joint Flange

Stainless Steel 321/321H Orifice FlangesSS 321/321H Orifice Flanges

Stainless Steel 321/321H Plate FlangesSS 321/321H Plate Flanges

UNS S32100 Plate Flanges, ANSI B16.5 Stainless Steel 321 Plate Flanges, ASTM A182 F321H Stainless Steel Plate Flanges, ASME SA 182 SS 321/321H Plate Flanges

Stainless Steel Flanges Specification :

ASTM A182 / ASME SA182

Dimension Standard :

ANSI/ASME B16.5, B 16.47 Series A & B, B16.48, BS4504, BS 10, EN-1092, DIN, etc.

Standard :

ANSI Flanges, ASME Flanges, BS Flanges, DIN Flanges, EN Flanges, etc.

Size :

1/2" (15 NB) to 48" (1200NB)

Class / Pressure :

150#, 300#, 600#, 900#, 1500#, 2500#, PN6, PN10, PN16, PN25, PN40, PN64 etc.

Flange Face Type :

Flate Face (FF), Raised Face (RF), Ring Type Joint (RTJ)

DIN Flanges :

DIN 2527, 2566, 2573, 2576, 2641,2642, 2655, 2656, 2627, 2628, 2629, 2631, 2632, 2633, 2634, 2635, 2636, 2637,2638, 2673.

JIS Flanges :

JIS B2220 5K, JIS B2220 10K, JIS B2220 16K, JIS B2220 20K

BS Flanges :

BS4504 PN 6, BS 4504 PN 10, BS4504 PN 16, BS4504 PN 25, BS4504 PN 40, BS 4504 PN 64, BS 4504 PN 100, BS 4504 PN 160, BS 4504 PN 250, BS 10, BS Table D, BS Table E, BS Table F, BS Table H.

Chemical Composition of Stainless Steel 321/321H Flanges

%	Cr	Ni	C	Si	Mn	P	S	N	Ti	Fe
321	min:17.0 max:19.0	min: 9.0 max:12.0	max:0.08	max:0.75	max:2.0	max:0.045	max:0.03	max:0.10	min:5*(C+N) max:0.70	Balance
321H	min:17.0 max:19.0	min: 9.0 max:12.0	min:0.04 max:0.10	min:18.0 max:20.0	max:2.0	max:0.045	max:0.03	max:0.10	min:5*(C+N) max:0.70	Balance