UNS S32109|1.4878|TP321H Seamless Stainless Steel Tube

Seamless Stainless Steel TP321H Tubes (UNS S32109 / W.Nr. 1.4878) are high-carbon austenitic solutions specifically engineered for superior creep strength and structural stability in extreme thermal environments. As a premier manufacturer based in Wenzhou, China, XinZhe produces high-integrity seamless tubing that strictly adheres to ASTM A213, ASTM A312, and ASME SA213 international standards.

Distinguished by an optimized carbon content (0.04–0.10%) and strategic Titanium (Ti) stabilization, our TP321H tubing prevents sensitization and intergranular corrosion while maintaining enhanced mechanical properties at temperatures exceeding 538°C (1000°F). These tubes are indispensable for mission-critical applications in superheater coils, heat exchanger tubing, and high-pressure steam systems. Through advanced cold-drawing and precise solution annealing, XinZhe guarantees a uniform grain size and maximum durability for demanding thermal cycling conditions.

"The 'H' in TP321H stands for high carbon, which is specifically controlled to provide higher creep-rupture strength at temperatures above 1000°F (537°C) compared to standard TP321."

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What Is a Seamless Stainless Steel TP321H Tube?

Seamless TP321H (UNS S32109 / W.Nr. 1.4878) tube is the high-carbon variant of the titanium-stabilised 321 grade, specified where improved creep and stress rupture strength are required at temperatures above roughly 540 °C. It retains the excellent intergranular corrosion resistance of the 321 family while adding the elevated-temperature mechanical performance needed for superheater and reformer service.

Seamless TP321H stainless steel tube (UNS S32109 / W.Nr. 1.4878) is a titanium-stabilized, high-carbon austenitic stainless steel designed for elevated temperature and high-stress applications.

Manufactured through a seamless process (hot piercing + precision cold finishing), it provides:

Titanium binds with carbon to form TiC (titanium carbides), preventing:

Ideal for service temperatures in the range of: 427°C – 816°C (800°F – 1500°F)

Key Features and Technical Advantages

Superior Creep & Stress Rupture Strength

Higher carbon content improves high-temperature mechanical stability
Excellent resistance to long-term stress and deformation

Titanium Stabilization (IGC Resistance)

Prevents sensitization in the carbide precipitation temperature range
Excellent resistance to intergranular corrosion (IGC)
No post-weld heat treatment required

High-Temperature Oxidation Resistance

Comparable oxidation resistance to TP304/304L
Stable scaling resistance up to ~816°C continuous service

High Pressure & Structural Integrity

Seamless construction eliminates weld defects
ASTM A213
EN 10216-5

Excellent Fabricability

Good ductility and toughness
Easily welded and cold formed
Suitable for complex fabrication requirements

Product Specifications and Data

Cr	Ni	P	S	Ti	Mn	Si	C
17.00 - 19.00	9.00 - 12.00	≤ 0.045	≤ 0.030	≥ 4×(C+N), ≤0.70	≤ 2.00	≤ 1.00	0.04 - 0.10

Note: The titanium content must be at least four times the carbon content to ensure stabilization.

Stainless Steel 321H is specifically designed to maintain its strength and shape in high-temperature, high-stress environments.

Table 2: Typical Mechanical Properties of Stainless Steel 321H

Tensile Strength	Yield Strength	Elongation	Hardness
≥ 515 MPa	≥ 205 MPa	≥ 35%	≤ 192 HBW

These physical properties highlight the material's ability to perform reliably under a wide range of conditions.

Table 3: Typical Physical Properties of Stainless Steel 321H

Density	Melting Point	Thermal Expansion	Thermal Conductivity	Modulus of Elasticity	Electrical Resistivity
8.0 g/cm³	1398 - 1454 °C	16.6 µm/m·°C (20-100°C)	16.3 W/m·K (20°C)	193 GPa	0.72 x 10⁻⁶ Ω·m (20°C)

ASTM A213
EN 10216-5 (D3/D4)
ASTM A269

Dimensional Standards and Tolerances

TP321H seamless tubes are supplied to the dimensional tolerances of ASTM A213 / A213M T2, with outside diameter and wall thickness tolerances checked against ASTM A1016 / A1016M.

Table 4: The Standard of Stainless Steel Seamless Tube Size Tolerance Size Chart :

Standard	OD(D)	Tolerance（MM)		Thickness(S)	Tolerance(MM)	Length	Tolerance
	MM	Common	High	MM			MM
EN 10216-5 HFD	30≤D≤219.1（D2)	±1.0% or ±0.5mm, whicever is the greater(取较大者)		T1, T≤4	±15% or ±0.6mm, whicever is the greater(取较大者)	L≤6M	+5/0
				T2	±12.5% or ±0.4mm, whicever is the greater(取较大者)
	219.1≤D≤610 (D1)	±1.5% or ±0.75mm, whicever is the greater (取较大者)		T≤0.05D	+22.5%/-15%	6≤12	+10/0
				T1, 0.05D≤0.09D	±15% or ±0.6mm, whicever is the greater(取较大者)
				T2, T>0.09D	±12.5% or ±0.4mm, whicever is the greater(取较大者)	L>12	+by agreement/0
EN 10216-5 CFD	D3(D≤219.1)	±0.75% or ±0.3mm, whicever is the greater(取较大者)		T3	±10% or ±0.2mm, whicever is the greater(取较大者)
	D4(D≤219.1)	±0.5% or ±0.mm, whicever is the greater(取较大者)		T4	±7.5% or ±0.15mm, whicever is the greater(取较大者)
ASTM A213 HFD	D≤100	+0.4/-0.8		D<100,S≤2.4	+40%/0	HFD, all size	+5.0/0
		+0.4/-1.2		D<100,2.4≤3.8	+35%/0
		+0.4/-1.6		D<100,3.8≤4.6	+33%/0
				D<100,S>4.6	+28%/0
	100≤200	+0.4/-1.2		D>100, 2.4≤3.8	+35%/0
	200≤225	+0.4/-1.6		D>100,3.8≤4.6	+33%/0
				D>100,S>4.6	+28%/0
ASTM A213 CFD	D<25	±0.10		D≤38.1	+20%/0	CFD, D<50.8	+3.0/0
	25≤D≤40	±0.15
	40	±0.20
	50≤D<65	±0.25
	65≤D<75	±0.30		D>38.1	+22%/0	CFD, D≥50.8	+5.0/0
	75≤D≤100	±0.38
	100≤200	+0.38/-0.64
	200≤225	+0.38/-1.14
ASTM A269	D≤13	±0.13		D≤13	±15%	D<38	+3.2/0
	13	±0.13		13	±10%
	38≤D<89	±0.25				D>38	+4.8/0
	89≤D<140	±0.38
	140≤D<203	±0.76
	203≤D<305	±1.01
	305≤D<356	±1.26
ASTM A270	D<25	±0.13		For weld pipe all size	±12.5%		+3.0/0
	25-50	±0.20
	50-75	±0.25
	75-100	±0.38		For CD SMLS pipe D≤38.1	+20%/0
	100-140	±0.38					+5.0/0
	140-200	±0.75		For CD SMLS pipe D>38.1	+22%/0
	200-300	±1.25

Manufactured to strict international standards:

OD tolerance: ±0.10 mm to ±0.5%
Wall thickness: ±7.5% to ±20%
Length: per standard or customized

Ensures high precision for heat exchanger and pressure systems

Common Industrial Applications

Power Generation

Superheater, reheater and economiser tubing
Main steam and hot reheat pipework
Boiler tube banks in high-temperature service

Petrochemical and Refining

Reformer and cracking furnace tubing
Hydrotreating and hydrodesulphurisation lines
High-temperature process piping

Aerospace and Defence

High-temperature bleed-air and exhaust tubing
Hydraulic and fuel system lines
Engine component tubing

Heat Treatment and Waste Incineration

Recuperator and radiant tube assemblies
Furnace and kiln support tubing
Waste incineration superheater tubing

Quality Assurance and Manufacturing Process

Certification and Documentation

All TP321H tubes are supplied to ASTM A213 / A213M T2 with EN 10204 3.1 mill test certificates. High-temperature property verification, PMI reports and full heat-number traceability are available on request.

Testing and Inspection

Hydrostatic or eddy-current testing is performed on 100% of tubes, with ultrasonic testing and dye-penetrant inspection available for superheater and pressure-part service.

Advanced Metallurgical Testing

Short-time elevated-temperature tensile, stress rupture and creep testing can be supplied to ASTM A213 T2 requirements. Grain size and stabilisation verification are performed per heat.

Third-Party Inspection

Inspection by SGS, BV, TUV or Lloyd’s is available for project orders, covering witness of mechanical testing, dimensional verification and final visual examination before packing.

TP321H vs TP321 / TP316H – Technical Comparison

TP321H is the high-carbon derivative of TP321, created to deliver creep and stress rupture strength in the temperature range where standard TP321 becomes the limiting material. TP316H is the analogous high-carbon molybdenum-bearing grade.

Chemical Composition

Carbon: TP321H 0.04–0.10 % vs TP321 ≤ 0.080 %
Titanium: TP321H ≥ 4 × C (min 0.20 %) vs TP321 ≥ 5 × C
Molybdenum: TP316H 2.00–3.00 %; none in TP321H
Nickel: TP321H 9.0–12.0 %

Creep and Stress Rupture

TP321H is specified above roughly 540 °C, where creep and stress rupture strength govern design
Higher carbon content raises elevated-temperature strength and rupture life relative to TP321
Both grades remain titanium-stabilised, so intergranular corrosion resistance is retained
TP316H trades some high-temperature strength for chloride pitting resistance

Mechanical Properties

Tensile strength: TP321H ≥ 515 MPa, TP321 ≥ 515 MPa
Yield strength (0.2 %): TP321H ≥ 205 MPa, TP321 ≥ 205 MPa
TP321H requires elevated-temperature tensile testing per ASTM A213 T2
Hardness may be specified; grain size control is applied per heat

Selection Guidance

Choose TP321H for superheater, reheater and economiser tubing, and reformer or cracking furnace service
Choose TP321 for welded assemblies below the creep-governed regime
Choose TP316H where chloride resistance is also needed at temperature
Below roughly 540 °C, TP321 and TP304 are usually more economical

Frequently Asked Questions

What is TP321H stainless steel tube?

TP321H (UNS S32109 / W.Nr. 1.4878) is the high-carbon, titanium-stabilised austenitic stainless steel specified where creep and stress rupture strength govern design above roughly 540 °C. It retains the intergranular corrosion resistance of the 321 family while adding elevated-temperature mechanical performance.

What is the difference between TP321 and TP321H?

TP321H contains 0.04–0.10 % carbon against a 0.080 % maximum for TP321, and requires a minimum titanium content of 4 × carbon rather than 5 × carbon. The higher carbon level raises creep and stress rupture strength, and TP321H is tested to the elevated-temperature requirements of ASTM A213 T2.

At what temperature should TP321H be used instead of TP321?

TP321H is normally selected above roughly 540 °C under sustained load, where creep and stress rupture rather than short-time tensile strength control the design. Typical applications include superheater and reheater tubing, economisers, and reformer or cracking furnace service.

Which standards cover TP321H tubes?

TP321H seamless tubing is usually supplied to ASTM A213 / A213M T2, with ASME SA213 T2 referenced for boiler and pressure-part applications. Elevated-temperature tensile testing is performed per heat, and EN 10204 3.1 mill test certificates are standard.

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