SS 321 Fittings | Stainless Steel 321 & 321H Pipe Fittings Manufacturer

SS 321 Fittings & SS 321H Pipe Fittings Manufacturer, Supplier & Exporter

Amardeep Steel Center is a premier manufacturer, supplier, and exporter of high-performance Stainless Steel 321 Pipe Fittings and Stainless Steel 321H Pipe Fittings engineered for continuous high-temperature service, produced in compliance with ASTM A403 WP321 / WP321H. Our titanium-stabilized austenitic stainless steel fittings are specifically designed for the 425°C–900°C range where un-stabilized grades suffer catastrophic intergranular corrosion through sensitization.

Why Titanium Stabilization Matters: At 425–850°C, carbon in standard austenitic steels migrates to grain boundaries, forming chromium carbides and depleting local corrosion resistance (“sensitization”). The titanium in Grade 321 bonds to carbon first — acting as a sacrificial stabilizer and keeping the chromium in solution where it belongs. For WP321, titanium content is minimum 5× carbon; for WP321H, minimum 4× carbon — this distinction matters for dual-certification eligibility.

SS 321 & 321H Pipe Fittings Specifications
Equivalent Material Grades
Chemical Composition
Mechanical Properties
SS 321/321H vs SS 316 Comparison
Heat Treatment Requirements
Dimensional Tolerances
Types & Forms of SS 321 & 321H Pipe Fittings
Weight Chart
Capacity & Availability
Applications & Industries
Quality Testing & Packaging
Related Products

SS 321 & 321H Pipe Fittings Specifications

Every SS 321 Pipe Fitting and SS 321H Pipe Fitting from Amardeep Steel is manufactured to precise specifications, ensuring complete interchangeability, compliance with global engineering codes, and a perfect fit for high-temperature systems.

Parameter	Details
Material Standard	ASTM A403 / ASME SA403
Grades	WP321 (UNS S32100) \| WP321H (UNS S32109)
Dimensional Standard	ASME B16.9, ASME B16.28, MSS-SP-43, MSS SP-75
Buttweld Size Range	½″ NB to 48″ NB (Seamless & Welded/Fabricated)
Forged Fittings Size	¼″ to 4″ NB
Wall Thickness / Schedule	Sch 5s, 10s, 40s, STD, 80s, XS, 100, 120, 140, 160, XXS
Pressure Class (Forged)	2000 LBS, 3000 LBS, 6000 LBS, 9000 LBS
Bending Radius	R = 1D, 2D, 3D, 5D, 6D, 8D, 10D or Custom
Heat Treatment	Stabilizing Anneal at 870–900°C (321) \| Solution Anneal 1040–1121°C (321H)
Forms Available	Elbow, Tee, Reducer, Cap, Stub End, Bend, Cross, Nipple, Coupling
Test Certificates	EN 10204 / 3.1 Mill TC, PMI, IGC (ASTM A262), Hydro, UT

Equivalent Material Grades of SS 321 Fittings & SS 321H Pipe Fittings

Grade	UNS No.	Werkstoff No.	DIN Name	BS (Old)	JIS
SS 321 (WP321)	S32100	1.4541	X6CrNiTi18-10	321S31	SUS 321
SS 321H (WP321H)	S32109	1.4878	X12CrNiTi18-9	321S51	SUS 321H

Chemical Composition of SS 321 & 321H Pipe Fittings

The addition of titanium is the key to this alloy’s stability at high temperatures. For WP321, titanium content is minimum 5× carbon; for WP321H, minimum 4× carbon — this distinction matters for dual-certification eligibility.

Grade	C	Mn	Si	P	S	Cr	Ni	Ti
SS 321 (WP321)	0.08 max	2.00 max	0.75 max	0.045 max	0.030 max	17.0–19.0	9.0–12.0	5×C min
SS 321H (WP321H)	0.04–0.10	2.00 max	0.75 max	0.045 max	0.030 max	17.0–19.0	9.0–12.0	4×C min

321H has a controlled carbon range (not just a maximum) to ensure sufficient high-temperature creep strength while still maintaining stabilization against sensitization.

Mechanical Properties of SS 321 & SS 321H Pipe Fittings

Grade	Tensile Strength (min)	Yield Strength 0.2% (min)	Elongation in 2″ (min)	Hardness, Rockwell B (max)
WP321	515 MPa (75 ksi)	205 MPa (30 ksi)	40%	95 HRB
WP321H	515 MPa (75 ksi)	205 MPa (30 ksi)	40%	95 HRB

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SS 321 / 321H vs SS 316 — Temperature Resistance Comparison

SS 321 / 321H Pipe Fittings

Titanium-stabilized austenitic grade
Service range: up to 900°C continuous
No sensitization at 425–850°C range
321H: superior creep strength above 538°C
Preferred for: refinery furnaces, power plant superheaters, aerospace exhaust

ASTM A403 WP321 / WP321H

SS 316 / 316L Pipe Fittings

Molybdenum-enhanced austenitic grade
Service range: up to ~550°C continuous
316L avoids sensitization via low carbon
Better chloride / acid corrosion resistance
Preferred for: marine, pharma, chemical plants

ASTM A403 WP316 / WP316L

Heat Treatment Requirements for SS 321 & 321H Pipe Fittings

All Stainless Steel 321 and 321H Pipe Fittings from Amardeep Steel are supplied in a stabilized, heat-treated condition.

SS 321 (WP321): Stabilizing anneal at 870–900°C (1600–1650°F). Relieves manufacturing stresses and causes titanium carbides to precipitate, stabilizing the material and preventing chromium carbide formation during subsequent high-temperature service.
SS 321H (WP321H): Solution anneal at 1040–1121°C (1900–2050°F) followed by rapid quench. The higher anneal temperature ensures full dissolution of carbides and optimises the grain structure for maximum creep resistance at elevated temperatures above 538°C.

Dimensional Tolerances of SS 321 & 321H Pipe Fittings

Amardeep Steel manufactures all SS 321 and SS 321H Pipe Fittings to the strict dimensional standards of ASME B16.9 (buttweld) and ASME B16.11 (forged fittings), guaranteeing accurate angles, diameters, and face-to-centre dimensions for a smooth, leak-free installation.

ASME B16.9 Dimensional Tolerances

DN / NPS	OD Bevel End	Wall Thickness	Elbow C-E	Tee C-E	Reducer (K)	180° Return
15–65 / ½″–2½″	+1.6 / −0.8 mm	−12.5%	±1.6 mm	±1.6 mm	±1.6 mm	±6.4 mm
80–100 / 3″–4″	±1.6 mm	−12.5%	±1.6 mm	±1.6 mm	±1.6 mm	±6.4 mm
125–200 / 5″–8″	+2.4 / −1.6 mm	−12.5%	±2.4 mm	±2.4 mm	±2.4 mm	±9.6 mm
250–450 / 10″–18″	+4.0 / −3.2 mm	−12.5%	±2.4 mm	±2.4 mm	±2.4 mm	±9.6 mm
500–600 / 20″–24″	+6.4 / −4.8 mm	−12.5%	±3.2 mm	±3.2 mm	±4.8 mm	±9.6 mm

ASME B16.9 Angularity Tolerances

NPS Range	Off-Angle Q (°)	Off-Plain P (mm)
½″ – 4″	1°	2
5″ – 8″	2°	4
10″ – 12″	3°	5
14″ – 16″	3°	6
18″ – 24″	4°	10
26″ – 42″	5°	13
44″ – 48″	5°	19

Types & Forms of SS 321 & 321H Pipe Fittings

As a leading manufacturer, Amardeep Steel Center produces a comprehensive range of high-temperature SS 321 Pipe Fittings and SS 321H Pipe Fittings to meet any project specification.

SS 321 / 321H Elbows (45°, 90°, 180°)

Long Radius (LR) and Short Radius (SR) in seamless (up to 24″ NB) and welded execution per ASTM A403 WP321 / WP321H. Widely specified as SS 321 90 Degree Elbow and SS 321H 45 Degree Elbow in furnace, boiler and superheater circuits. Available in Sch 5S through XXS.

SS 321 / 321H Equal & Reducing Tees

Branch connections in heat-exchanger manifolds and process headers operating continuously in the sensitization temperature range. Seamless up to 24″ NB; welded/fabricated to 48″ NB.

SS 321 / 321H Concentric & Eccentric Reducers

Connecting different-diameter lines in high-temperature process systems. Eccentric type prevents air and sediment trapping in horizontal runs.

SS 321 / 321H Pipe Caps

High-temperature end closures for boiler and reformer piping. Available Sch 5S through Sch 160.

SS 321 / 321H Stub Ends

Long and Short Stub Ends for lap joint flanged assemblies in high-temperature service, enabling easy disassembly and bolt-hole alignment.

SS 321 / 321H Forged Fittings

Socket weld and threaded couplings, elbows, tees for ¼″–4″ NB; Class 2000/3000/6000 LB per ASME B16.11.

SS 321 / 321H Pipe Bends (3D–10D)

3D–10D bending radius for superheater and reformer tube circuits where gradual directional changes minimise pressure loss and flow turbulence.

SS 321 / 321H Crosses (Equal & Reducing)

For four-way piping intersections in complex high-temperature layouts. Available per ASME B16.9 in seamless and welded execution.

SS 321 / 321H Swage Nipples

Barrel and swage nipples for connecting pipes of different end types in confined high-temperature installations.

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SS 321 & 321H Pipe Fittings Weight Chart (kg)

Indicative weights for standard elbows and equal tees. Actual weights subject to manufacturing tolerance.

DN	Sch 10S – 90° Elbow	Sch 10S – 45° Elbow	Sch 10S – Equal Tee	Sch 40S – 90° Elbow	Sch 40S – Equal Tee	Sch 80S – 90° Elbow	Sch 80S – Equal Tee
15	0.06	0.03	0.09	0.08	0.10	0.10	0.14
25	0.14	0.08	0.28	0.15	0.29	0.22	0.38
50	0.50	0.25	0.85	0.70	1.28	0.91	1.59
80	1.25	0.63	1.77	2.20	3.31	2.97	4.45
100	2.10	1.08	3.46	4.47	5.27	6.18	7.71
150	5.45	2.72	8.07	10.89	10.99	16.32	13.61
200	10.20	5.33	15.65	21.54	20.91	33.11	28.12
300	25.80	13.62	39.46	59.42	62.14	79.38	83.91

SS 321 & 321H Pipe Fittings – Capacity & Availability

Product	Seamless — Size Range	Seamless — Schedule	Welded — Size Range	Welded — Schedule
Elbow (90°, 45°, 180°)	½″ – 24″	Sch 10S – XXS	8″ – 48″	Sch 5S – 80S/XS
Equal & Reducing Tee	½″ – 24″	Sch 10S – XXS	8″ – 48″	Sch 5S – 80S/XS
Concentric & Eccentric Reducer	½″ – 24″	Sch 10S – XXS	8″ – 48″	Sch 5S – 80S/XS
Cap	½″ – 80″	Sch 5S – 160	—	—
Lap Joint Stub End	½″ – 24″	Sch 5S – 80S/XS	8″ – 80″	Sch 5S – 80S/XS
Long Radius Bend (3D/5D/10D)	½″ – 24″	Sch 10S – 80S	8″ – 48″	Sch 5S – 80S
Cross (Equal & Reducing)	½″ – 12″	Sch 10S – XXS	6″ – 24″	Sch 5S – 80S
Forged Fittings (SW & Threaded)	¼″ – 4″	Class 2000–9000 LB	—	—

Applications for SS 321 and SS 321H Pipe Fittings

The unique high-temperature stability of SS 321H Pipe Fittings makes them essential across these critical industries:

Petroleum Refineries: Catalytic reformers, hydrotreaters, fired heaters and process furnace piping exposed to 500–900°C.
Power Generation: Superheater tubes, economizer headers and steam circuit manifolds in coal and gas-fired boilers.
Aerospace & Defence: Exhaust manifolds, jet engine components and afterburner piping exposed to high cyclic temperatures.
Chemical Processing: Reaction vessels, furnace tubes and transfer lines handling corrosive media at elevated temperatures.
Heat Treatment Equipment: Furnace retorts, radiant tubes and muffle furnace piping systems.
Petrochemical Plants: Ethylene crackers, steam methane reformers and syngas piping systems.
Oil & Gas: Expansion joints, high-temperature headers and offshore platform process lines.
Nuclear Power: Moderator tube supports and auxiliary systems requiring stable corrosion resistance under prolonged heat exposure.
Boiler & Pressure Vessel: Superheaters, reheaters and drum headers where sensitization resistance is mandatory.

Quality Testing & Packaging of SS 321 & 321H Pipe Fittings

All SS 321 and SS 321H Pipe Fittings manufactured by Amardeep Steel undergo the following before despatch: hydrostatic pressure testing, dimensional inspection per ASME B16.9, Positive Material Identification (PMI), intergranular corrosion test (ASTM A262), and 100% visual inspection for surface defects. International shipments are secured in wooden crates with plastic end caps, oil-coated internal surfaces, and stencilled heat/lot marking per customer requirements.

Get Competitive Pricing on SS 321 / 321H Pipe Fittings

Contact our sales team for current pricing: pricing varies with LME nickel/titanium rates and order volume.

Frequently Asked Questions — SS 321 & 321H Pipe Fittings

What is the difference between SS 321 and SS 321H pipe fittings?

SS 321 (C ≤ 0.08%) is for general high-temperature service. SS 321H has a controlled higher carbon range (C 0.04–0.10%) which provides significantly better creep rupture strength above 538°C (1000°F), making it the preferred structural choice for power plant superheaters and refinery furnace tubes.

Can SS 321 fittings be welded without post-weld heat treatment?

Yes. The titanium stabilization in SS 321 / 321H prevents sensitization during welding. No post-weld heat treatment (PWHT) is required to maintain corrosion resistance at the heat-affected zone. However, a stabilizing anneal after welding may be specified for the most demanding applications.

What is the maximum temperature for SS 321H fittings in continuous service?

SS 321H Pipe Fittings are rated for continuous service up to approximately 900°C (1650°F). Above this temperature, scaling and loss of titanium stabilization may occur. For service above 900°C, consider SS 310 or Inconel grades.

What tests are performed on ASTM A403 WP321H fittings?

Standard tests include chemical analysis, tensile/hardness testing, flattening test (for seamless), intergranular corrosion test (ASTM A262 Practice E), and hydrostatic test. PMI, UT, radiography and third-party inspection are available on request.

What are the UNS and DIN equivalents for SS 321 and 321H Pipe Fittings?

SS 321 is UNS S32100, Werkstoff No. 1.4541, DIN X6CrNiTi18-10. SS 321H is UNS S32109, Werkstoff No. 1.4878, DIN X12CrNiTi18-9. These designations are used interchangeably in international procurement specifications for ASTM A403 WP321 and WP321H fittings.

Can SS 321 and SS 321H pipe fittings be dual-certified?

Yes, in many cases. Because the chemical composition requirements of 321 and 321H overlap — the carbon range 0.04–0.08% satisfies both grades — fittings meeting both the 321 and 321H chemistry and mechanical requirements can be dual-certified as ASTM A403 WP321/WP321H. Amardeep Steel can supply dual-certified fittings with MTC documentation confirming compliance with both designations.