ASME SA312 TP310S Stainless Steel Bright Annealed Seamless Pipe

What Is ASME SA312 TP310S Pipe?

ASME SA312 TP310S is the specification designation for seamless and welded austenitic stainless steel pipe of UNS S31008, technically identical to ASTM A312 TP310S and corresponding to JIS SUS310S. With nominally 25% chromium and 20% nickel, TP310S pipe is engineered for high-temperature service such as furnace tubes, heat exchanger tubing and steam piping, where resistance to oxidation and scaling is critical.

Typical applications include petrochemical furnaces, reforming and cracking units, heat exchangers, superheater and steam lines in thermal and nuclear power plants, and high-temperature process piping where continuous service temperatures up to about 1035 C are encountered.

Chemical Composition per ASME SA312

The table below gives the composition limits for TP310S as specified in ASME SA312/ASTM A312. Values are maximum percentages unless a range is shown.

Grade	UNS	C	Mn	P	S	Si	Cr	Ni
TP310S	S31008	0.08	2.00	0.045	0.030	0.75	24.0-26.0	19.0-22.0

Mechanical and Heat Treatment Requirements

Minimum tensile strength is 75 ksi [515 MPa] and minimum yield strength is 30 ksi [205 MPa], with minimum elongation of 35% in 2 in. The pipe is supplied in the solution-annealed condition: heated to at least 1040 C [1900 F] and then cooled rapidly in water or by another rapid-cooling medium, which dissolves carbides and restores the fully austenitic structure.

Property	Requirement per ASME SA312
Tensile strength min	75 ksi [515 MPa]
Yield strength min	30 ksi [205 MPa]
Elongation in 2 in min	35%
Heat treatment	Solution anneal at min 1040 C, rapid cool

Bright Annealing: Process and Benefits

Bright annealing is performed in a continuous furnace under a protective atmosphere of hydrogen or a hydrogen-nitrogen mixture. Because no oxygen reaches the surface during heating and cooling, no oxide scale forms and the pipe emerges with a clean, bright, smooth surface. This finish is often specified for TP310S tubes where surface cleanliness, uniform appearance and maximum resistance to localised attack matter. The process is applied after final sizing; precision cold rolling before annealing maintains tight dimensional accuracy of the inner and outer diameters, and the finished pipe has no welds or seams in the seamless form.

Quality and Testing

Pipe is commonly supplied with material test certificates per EN 10204 3.1, chemical and mechanical reports, non-destructive testing and dimensional verification. Standard supply lengths are 6000 mm or custom, in seamless or welded construction.

Frequently Asked Questions

Q1: What is the difference between TP310 and TP310S?

A1: The S denotes the low-carbon variant with maximum 0.08% carbon. TP310S is preferred for welded construction because it is less prone to sensitisation during welding.

Q2: What temperature can TP310S withstand?

A2: Commonly cited service limits are about 1035 C for continuous exposure and about 1150 C for intermittent exposure, subject to the actual stress, atmosphere and section thickness.

Q3: What is bright annealing?

A3: It is a final heat treatment in a protective atmosphere furnace. No scale forms on the surface, so the pipe has a bright, smooth, oxide-free finish with good corrosion behaviour.

Q4: Is TP310S pipe available as seamless and welded?

A4: Yes. ASME SA312 covers both seamless and welded construction, with the same composition and mechanical requirements.

Q5: What are the equivalent designations of TP310S?

A5: JIS SUS310S, EN 1.4845, GB 06Cr25Ni20 and UNS S31008 refer to the same type of material.

Q6: Is TP310S suitable for seawater service?

A6: No. The grade contains no molybdenum, so it is not recommended for chloride-rich or immersed seawater service; it is primarily a high-temperature heat-resistant grade.