310S/310H Stainless Steel Tube Specifications and Properties

310S and 310H Seamless Tube: What Buyers Specify

310S and 310H are the two heat-resisting austenitic grades most often ordered as seamless tube and pipe for furnaces, boilers and petrochemical plants. This guide collects the dimensional range, chemical composition and mechanical requirements that normally appear on a purchase order, together with the standards that govern them.

Dimensional and Supply Specifications

Item	Specification
Steel grade	300 series, 310S, 310H
Product type	Seamless round pipe and tube
Outside diameter	3.2-127 mm, or customised
Wall thickness	0.41-12.7 mm
Length	3000-6000 mm, or customised
Manufacturing route	Cold rolled, cold drawn
Surface finish	Pickled, bright annealed, brush polished
Governing standards	ASTM A213, ASTM A312, ASTM A269, ASTM A240

Chemical Composition of 310S and 310H

Both grades share the same 24.0-26.0% chromium and 19.0-22.0% nickel balance; they differ only in the carbon range, which controls whether the tube is optimised for weldability or for creep strength.

Grade	C (%)	Mn (%)	P (%)	S (%)	Si (%)	Cr (%)	Ni (%)
310S	0.08 max	2.00 max	0.045 max	0.030 max	1.50 max	24.0-26.0	19.0-22.0
310H	0.04-0.10	2.00 max	0.045 max	0.030 max	1.50 max	24.0-26.0	19.0-22.0

For reference, the parent grade 310 allows carbon up to 0.25%, which is why welded 310 assemblies often need post-weld heat treatment while 310S generally does not.

Mechanical Properties of TP310S and TP310H Tube

Grade	Tensile strength, min (MPa)	Yield strength, min (MPa)	Elongation, min (%)
310S	515	205	35
310H	515	205	35

These are room-temperature minima taken on the finished tube. Because 310S and 310H are designed for elevated-temperature service, high-temperature creep and stress-rupture data, rather than the room-temperature tensile values alone, normally govern the allowable design stress above about 550 °C.

Standards, Testing and Delivery Condition

Tubes are produced and tested against recognised specifications so that the composition, dimensions and mechanical properties can be verified independently.

ASTM A213: seamless ferritic and austenitic alloy steel tubes for boilers, superheaters and heat exchangers.

ASTM A312: seamless and welded austenitic stainless steel pipe for high-temperature and general corrosive service.

ASTM A269: seamless and welded austenitic tubing for general service.

ASTM A240 and ASTM A276 cover the corresponding plate, sheet and bar forms.

Equivalent designations for 310S include 06Cr25Ni20 in the GB/T 20878 system and 1.4845 in the DIN and EN systems.

Routine tests: chemical analysis, tensile test, flattening or reverse bend, hydrostatic or eddy current examination, and hardness where specified. Material certificates are issued with the heat number traceable to the tube bundle.

Applications and Selection Notes

310S and 310H seamless tubes serve as radiant tubes, furnace conveyor rollers, heat exchanger tubes in high-temperature gas service, superheater and reheater tube supports, incinerator and boiler components, and petrochemical cracking furnace tubes. Choose 310S where welding and thermal cycling dominate and the atmosphere is oxidising; choose 310H where the tube will operate under sustained load in the creep range, typically above 650 °C. Neither grade should be selected for wet chloride or strongly reducing sulphur environments, where rapid attack can occur.

Frequently Asked Questions

Q: What is the difference between 310S and 310H tube?
They share the same chromium and nickel range, but 310S is limited to 0.08% carbon for weldability while 310H uses 0.04-0.10% carbon for creep strength.

Q: Which standard covers 310S seamless tube?
Seamless boiler, superheater and heat exchanger tube normally follows ASTM A213, while pipe follows ASTM A312; general service tubing follows ASTM A269.

Q: What is the maximum continuous service temperature?
Both grades are used in continuous service up to 1150 °C, with intermittent exposure up to about 1200 °C.

Q: Are these tubes available in custom lengths and diameters?
Yes. Outside diameters from 3.2 to 127 mm and wall thicknesses from 0.41 to 12.7 mm are standard, with customised sizes produced on request.

Q: What surface finishes can be supplied?
Pickled, bright annealed and brush polished finishes are the usual options for cold drawn or cold rolled seamless tube.

Q: Do the tubes need post-weld heat treatment?
Fully annealed 310S generally does not, because its low carbon content limits carbide precipitation; 310H in the creep range is usually welded with controlled procedures instead.