ASTM A312 TP321/321H Seamless Stainless Steel Pipe

Short Description:

Womic Steel supplies ASTM A312 TP321/321H seamless stainless steel pipe for high-temperature service up to 870°C where sensitization and intergranular corrosion are concerns. Grade 321 contains titanium (Ti ≥ 5×C%) which stabilizes carbon, preventing chromium carbide precipitation during welding and high-temperature exposure. TP321H has higher carbon (0.04-0.10%) for enhanced creep strength at elevated temperatures. Minimum yield strength 205 MPa (30,000 psi), tensile strength 515 MPa (74,700 psi).

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The seamless manufacturing process includes cold drawing, hot finishing, or extrusion with full solution annealing, ensuring uniform grain structure and no weld seam – critical for creep-resistant high-temperature service. Outside diameter from 21.3mm to 610mm (1/2″ – 24″), wall thickness from 0.5mm to 50mm (Schedule 5S to XXS), length up to 12m standard, custom lengths up to 18m. Mill certificate, hydrostatic test, 100% ultrasonic or eddy current test, solution annealed and pickled finish, beveled or plain ends available. Suitable for refinery heater tubes, superheaters, heat exchangers, expansion joints, furnace components, petrochemical pyrolysis lines, high-temperature chemical reactors, and thermal oxidizers.

Seamless Stainless Steel Pipe Size: Outside Diameter: 21.3mm – 610mm (1/2″ – 24″), Wall Thickness: 0.5mm – 50mm (Schedule 5S, 10S, 40S, 80S, 160, XXS), Length: 6m – 12m standard, custom lengths up to 18m

Standard & Grade of Seamless Stainless Steel Pipe: ASTM A312 TP321, TP321H; also ASME SA312; EN 10216-5 1.4541 (321), 1.4912 (321H); Equivalent to AISI 321, 321H

Usage of Seamless Stainless Steel Pipe: Refinery heater tubes and pigtails, superheater and reheater tubes, high-temperature heat exchangers, expansion joints and bellows, furnace radiant tubes, catalytic reformer piping, petrochemical pyrolysis tubes, thermal oxidizers and incinerators, aircraft exhaust systems, high-temperature chemical reactors, superheater headers, waste heat recovery systems

Womic Steel offering high quality & competitive prices of ASTM A312 TP321/321H seamless stainless steel pipe, titanium stabilized seamless tube, high temperature seamless pipe, creep resistant seamless pipe, SMLS stainless pipe. Mill certificate EN 10204 3.1/3.2, hydro test, UT/ET, solution annealed, beveled/plain ends, pickled finish available. Factory direct supply for refinery, petrochemical, and high-temperature industrial projects worldwide.

Womic Steel: Manufacturing Capabilities & Company Strength

Womic Steel Group is a premier manufacturer and global exporter with over 20 years of expertise in producing high-temperature stainless steel seamless tubular products. Our state-of-the-art seamless pipe production facility utilizes advanced hot-rolling and cold-drawing processes:

Cold Drawn (CD) Seamless Line: For diameters from 21.3mm to 219.1mm (1/2″ – 8″), wall thickness from 1.0mm to 25mm. Cold drawing provides superior dimensional accuracy, excellent surface finish, and uniform grain structure – critical for high-temperature creep resistance.

Hot Finished (HF) Seamless Line: For diameters from 114.3mm to 610mm (4″ – 24″), wall thickness from 4.0mm to 50mm. Hot rolling process produces heavy wall pipes for refinery heater tubes and high-pressure high-temperature service.

Extrusion/Large Diameter Line: For diameters up to 914mm (36″) upon request.

All seamless stainless steel pipes undergo solution annealing (heat treatment) at 1050-1120°C followed by water quenching to dissolve titanium carbides and restore corrosion resistance, followed by pickling and passivation.

Quality Certifications & Regulatory Compliance:

ISO 9001:2015 Certified

PED 2014/68/EU (CE Marking) for pressure equipment

EN 10204 3.2 Certification with third-party validation (TÜV, BV, SGS, LR)

Third-Party Inspection (TPI) approved by SGS, BV, ABS, DNV, TÜV

ASME Boiler and Pressure Vessel Code (Section I, VIII) compliance

Production Flexibility:

Cold Drawn: 21.3–219.1mm OD × 1.0–25mm WT × ≤ 12m

Hot Finished: 114.3–610mm OD × 4.0–50mm WT × ≤ 12m

Finishing options: Annealed and pickled, bright annealed (for small sizes)

ASTM A312 TP321/321H: Material Composition & Performance Characteristics

ASTM A312 TP321 is an austenitic stainless steel stabilized with titanium (Ti ≥ 5 × C%). Titanium combines with carbon to form titanium carbides, preventing chromium carbide precipitation (sensitization) during welding or exposure to temperatures in the range of 425-870°C. This makes TP321 ideal for continuous high-temperature service. TP321H has higher carbon (0.04-0.10%) for enhanced creep strength at elevated temperatures.

Chemical Composition (Ladle Analysis, % by mass):

Element	TP321 (ASTM A312)	TP321H (ASTM A312)
C	≤ 0.08	0.04 – 0.10
Mn	≤ 2.00	≤ 2.00
P	≤ 0.045	≤ 0.045
S	≤ 0.030	≤ 0.030
Si	≤ 1.00	≤ 1.00
Cr	17.0 – 19.0	17.0 – 19.0
Ni	9.0 – 12.0	9.0 – 12.0
Ti	≥ 5×C (minimum)	≥ 4×C to 0.70 max
N	≤ 0.10	≤ 0.10

Mechanical Properties (Room Temperature, Solution Annealed):

Property	TP321	TP321H
Yield Strength (min, 0.2% offset)	205 MPa (30,000 psi)	205 MPa (30,000 psi)
Tensile Strength (min)	515 MPa (74,700 psi)	515 MPa (74,700 psi)
Elongation (min, 50mm gauge)	35%	35%
Hardness (max)	90 HRB	90 HRB

Physical Properties:

Density: 8.02 g/cm³

Modulus of Elasticity: 193 GPa (28 × 10⁶ psi) at room temperature

Thermal Conductivity: 15.7 W/m·K at 100°C

Coefficient of Thermal Expansion: 16.6 × 10⁻⁶/°C (20-100°C)

High-Temperature Properties (Typical – TP321H):

Allowable stress at 650°C: ≈ 50 MPa (ASME Section II)

Creep strength (100,000 hr rupture at 650°C): ≈ 70 MPa

Oxidation resistance: Excellent up to 900°C in air, intermittent service up to 870°C

Corrosion Resistance:

Excellent resistance to intergranular corrosion after welding (titanium stabilization)

Good resistance to oxidizing acids and organic acids

Superior performance in high-temperature hydrocarbon service (coking, sulfidation)

Better creep resistance than 304/304L and 316/316L at elevated temperatures (≥ 550°C)

Resistance to polythionic acid stress corrosion cracking (common in refineries)

Low-Temperature Properties:

TP321 retains good toughness down to -250°C (not as common as 304 for cryo)

Dimensional Range & Standards Compliance

Item	Specification
Standard	ASTM A312 / ASME SA312 (also A213, A269, A999)
Manufacturing Processes	Cold Drawn (CD), Hot Finished (HF)
Outside Diameter Range	21.3mm – 610mm (1/2″ – 24″)
Wall Thickness Range	0.5mm – 50mm (Schedule 5S, 10S, 40S, 80S, 160, XXS)
Length Range	Standard: 6m; Extended: 12m, 18m, up to 18m
End Finish	Plain End (PE), Beveled End (BE)
Surface Finish	Annealed & Pickled, Bright Annealed
Tolerances (per ASTM A999)	OD: ±0.5% or ±3.2mm; WT: ±12.5% (OD < 4″) / ±15% (OD ≥ 4″); Length: +50mm / -0mm
Straightness	≤ 0.2% of total length (cold drawn); ≤ 0.25% (hot finished)

Available Dimensions & Specifications – ASTM A312 TP321/321H Seamless Stainless Steel Pipe (Selected Typical Sizes)

NPS	OD (mm)	Schedule	WT (mm)	Weight (kg/m)	Process	Standard Length	Typical Application
1/2″	21.3	40S	2.77	1.27	CD	6m	Instrument pigtails
3/4″	26.7	40S	2.87	1.69	CD	6m	Thermowell sleeves
1″	33.4	40S	3.38	2.50	CD	6m	Heater tubes
1-1/2″	48.3	40S	3.68	4.05	CD	6m	Refinery piping
2″	60.3	40S	3.91	5.44	CD	6m / 12m	Process lines
3″	88.9	40S	5.49	11.3	CD/HF	6m / 12m	Transfer lines
4″	114.3	40S	6.02	16.1	CD/HF	6m / 12m	Heater outlet
6″	168.3	40S	7.11	28.3	HF	6m / 12m	High temp header
8″	219.1	40S	8.18	42.6	HF	12m	Furnace tubes
10″	273.0	40S	9.27	60.3	HF	12m	Hot gas duct
12″	323.9	40S	10.31	79.8	HF	12m	Main header
16″	406.4	40S	12.70	123.4	HF	12m	Thermal oxidizer

Custom dimensions outside these ranges available. TP321H recommended for temperatures above 650°C with sustained stress.

Common Seamless High-Temperature Stainless Steel Standards & Grades

Standard	Steel Grades	Typical Application	Manufacturing Process
ASTM A312	TP321, TP321H, TP304H, TP316H, TP347, TP347H	High temperature, creep resistant	CD/HF
ASTM A213	TP321, TP321H, TP304H, TP316H, TP347H	Boiler, superheater, heat exchanger tubes	CD
ASTM A269	TP321, TP321H	General service tubing	CD
EN 10216-5	1.4541 (321), 1.4912 (321H)	Pressure purposes, high temp	CD/HF

Usage: Refinery heater tubes, superheaters, heat exchangers, expansion joints, furnace components, high-temperature chemical reactors.

Manufacturing Process – Seamless Stainless Steel Pipe (Cold Drawn / Hot Finished)

Cold Drawn (CD) Process – Small to Medium Diameter (21.3–219.1mm OD):

Raw Material (Billet) Inspection: Billet verified for TP321 composition (Cr 17-19%, Ni 9-12%, Ti ≥ 5×C, C ≤ 0.08% or 0.04-0.10% for H).

Billet Preparation: Cut to length, center-drilled, heated to 1150-1250°C.

Piercing / Rotary Forging: Heated billet pierced to create hollow shell.

Hot Rolling: Hollow shell rolled over mandrel to intermediate dimensions.

Pickling: Scale removal.

Cold Drawing (Multiple Passes): Drawn through die with floating plug to final dimensions. Multiple passes with intermediate annealing.

Solution Annealing: 1050-1120°C, water quench. Critical for dissolving titanium carbides.

Straightening & Cut to Length

Pickling & Passivation

NDT: Eddy current (100%) + hydrostatic test.

Final Inspection & Marking

Hot Finished (HF) Process – Medium to Large Diameter (114.3–610mm OD):

Billet Heating: 1200-1280°C

Piercing

Continuous Rolling (Mandrel Mill)

Sizing Mill

Solution Annealing: 1050-1120°C, water quench.

Pickling & Passivation

NDT & Hydrostatic Test

Final Inspection & Marking

Quality Control & Testing Procedures for ASTM A312 TP321/321H Seamless Pipe

Stage	Inspection Method	Purpose
Raw Material	Chemical Analysis (OES)	Verify TP321 composition (Ti ≥ 5×C, Cr 17-19%, Ni 9-12%, C ≤ 0.08% or 0.04-0.10%)
Raw Material	Tensile Testing	Yield ≥ 205 MPa, Tensile ≥ 515 MPa
Raw Material	Titanium Recovery Test	Ensure Ti not oxidized
After Solution Annealing	Hardness Test	≤ 90 HRB
Finished Pipe	Hydrostatic Test (Mandatory)	Pressure integrity – 85-100% SMYS
Finished Pipe	Eddy Current Test (100%)	Surface/near-surface defects
Finished Pipe	Flattening / Flaring Test	Ductility
Finished Pipe	PMI	Confirm grade (Cr, Ni, Ti)
Finished Pipe	Intergranular Corrosion Test (A262 Practice E)	Detect sensitization – mandatory for TP321
Finished Pipe	Visual & Marking	Traceability

Optional for High-Temperature Service:

Elevated temperature tensile test (e.g., at 650°C)

Creep rupture test

Grain size measurement (ASTM E112) – TP321H typically ASTM 5-7

Primary Applications – ASTM A312 TP321/321H Seamless Stainless Steel Pipe

Refinery heater tubes and pigtails: Fired heater radiant and convection sections, transfer lines. TP321 resists sensitization from repeated thermal cycling.

Superheater and reheater tubes: Fossil fuel power plants and HRSG. TP321H offers superior creep strength.

High-temperature heat exchangers: Shell and tube heat exchangers with hot hydrocarbon or sulfur-containing service where 316L may suffer sulfidation.

Expansion joints and bellows: Thin-wall corrugated expansion joints require high-temperature fatigue resistance.

Furnace radiant tubes: Steel heat treating furnaces, annealing furnaces.

Catalytic reformer piping: Platforming units in refineries.

Thermal oxidizers and incinerators: Ducting handling hot combustion gases up to 900°C.

Petrochemical pyrolysis lines: Ethylene cracking furnace outlet lines.

Packaging & Shipping

Packaging:

Anti-corrosion protection: VCI paper or plastic wrap. For high-temperature service, no oil residue.

End caps: Plastic caps for beveled ends.

Bundling (Small diameters): Bundles with steel straps and interleaving paper.

Individual packaging (Large diameters): Plastic film wrap.

Shipping:

Containers for ≤ 610mm, break-bulk for larger diameters.

Documentation: MTC 3.1/3.2, hydrotest report, eddy current/UT reports, PMI report, IGC test report, dimensional report, packing list, COO.

Womic Steel Advantages & FAQ – ASTM A312 TP321/321H Seamless Pipe

Why Partner with Womic Steel for TP321/321H Seamless Pipe?

Complete Size Range: Cold Drawn 1/2″ – 8″, Hot Finished 4″ – 24″.

Full solution annealing (1050-1120°C, water quench) – critical for titanium stabilization.

Intergranular corrosion testing per ASTM A262 Practice E available (mandatory for TP321).

TP321H for elevated temperature creep strength.

Lead times: 25-35 days for CD, 35-50 days for HF.

Frequently Asked Questions:

Q: What is the advantage of TP321 over TP304 for high-temperature service?
A: TP321 contains titanium to stabilize carbon, preventing chromium carbide precipitation during welding and high-temperature exposure (425-870°C). For continuous service above 550°C with thermal cycling, TP321 is recommended. TP304L relies on low carbon (0.03% max) but can still sensitize over time at temperatures above 550°C.

Q: What is TP321H and when should it be used?
A: TP321H has higher carbon (0.04-0.10% vs ≤ 0.08% for TP321) for enhanced creep strength at elevated temperatures above 650°C. Use TP321H for superheater tubes, fired heater radiant coils, and other high-stress, high-temperature applications.

Q: Does TP321 require solution annealing after processing?
A: Yes, ASTM A312 requires solution annealing. The heat treatment dissolves titanium carbides and ensures titanium is available to combine with carbon during service. Womic performs full solution annealing on all TP321 seamless pipes.

Q: Can TP321 be used for sour service (H₂S)?
A: TP321 is not typically specified for sour service (NACE MR0175). For H₂S with high-temperature, consider 316L or duplex. TP321 is primarily a high-temperature grade.

Q: What is the maximum service temperature for TP321?
A: TP321 has good oxidation resistance up to 900°C intermittent, 870°C continuous. For higher temperatures, TP310 is recommended.

Q: What is the typical lead time for TP321 seamless pipe?
A: 25-35 days for CD, 35-50 days for HF. IGC testing adds 7-10 days. Third-party inspection adds 7-14 days.

Project Reference – Gulf Coast Refinery Coker Heater Tube Replacement

Country: United States (Texas, Gulf Coast refinery)
Standard & Grade: ASTM A312 TP321H (seamless) – with supplementary creep testing
Dimensions & Quantity:

OD 88.9mm (3″) × Schedule 80 (8.89mm WT) – 1,200 meters (approx. 18 tons) – Cold Drawn

OD 114.3mm (4″) × Schedule 80 (11.13mm WT) – 800 meters (approx. 18 tons) – Cold Drawn

OD 168.3mm (6″) × Schedule 80 (15.09mm WT) – 400 meters (approx. 22 tons) – Hot Finished
Total: 2,400 meters, approx. 58 tons

Specifications: ASTM A312 TP321H seamless, solution annealed and pickled, beveled ends. Hydrostatic testing. Eddy current (CD) and UT (HF). PMI on every pipe. Mandatory intergranular corrosion test per ASTM A262 Practice E (no attack). Elevated temperature tensile test at 650°C (spec: yield ≥ 100 MPa, achieved 130-160 MPa). Creep rupture test at 650°C, 40 MPa, 1,000h – no rupture. Grain size ASTM 6-7. Third-party inspection by TÜV USA.

Application: Replacement of delayed coker furnace radiant tubes. The tubes operate at 650-700°C with hydrocarbon vapors, coke formation, and thermal cycling. Previous 304H tubes failed after 8 years due to creep deformation and carburization. TP321H was selected for its titanium stabilization and higher creep strength.

Technical Challenges & Solutions:

Creep strength at 650-700°C – TP321H with carbon 0.06-0.08% and fine grain (ASTM 6) provided creep strength > 40 MPa at 650°C. Creep test (1,000h, 650°C, 40 MPa) showed no rupture. Client accepted.

Carburization resistance – Titanium stabilization prevents chromium carbide precipitation, maintaining chromium available for oxide scale formation. Womic performed carburization test (5% CH₄/H₂ at 650°C for 500h): weight gain 0.3 mg/cm², acceptable.

Intergranular corrosion test – ASTM A262 Practice E passed (no intergranular attack), confirming proper titanium stabilization.

Logistics to Texas refinery – Pipes shipped from Shanghai to Houston, then trucked to refinery. All 58 tons delivered during 6-week turnaround. TÜV inspection passed.

Result: Coker heater restarted successfully. After 12 months, inspection showed no creep deformation. Client expects 15+ year service life.

Contact:
Website: www.womicsteel.com
E-mail: sales@womicsteel.com

Tel / WhatsApp / WeChat:
Victor: +86 15575100681
Jack: +86 18390957568

Womic Steel – Your reliable partner for ASTM A312 TP321/321H seamless stainless steel pipes for high-temperature refinery, petrochemical, and power generation applications worldwide.

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