ASTM A312 Stainless Steel Pipe Specification

ASTM A312 is the standard specification for seamless, welded, and heavily cold-worked austenitic stainless steel pipe designed for high-temperature and general corrosive service. Common grades include TP304/304L and TP316/316L, covering sizes 1/8" to 30" (NPS) and schedules 5S to XXS. It requires specific heat treatments and testing, such as flaring and flattening tests, to ensure weld integrity.

 

Manufacturing Type: Seamless (SMLS), Welded (WLD), Heavily Cold Worked (HCW)
Heat Treatment: All tubes must undergo solution annealing (e.g., TP304/304L water-quenched from above 1040°C).
Non-Destructive Testing: Each tube is required to undergo either eddy current testing or hydrostatic testing.
Mechanical Testing: Includes tensile testing and flattening testing.

 

Click to download the ASTM A312 standard PDF

 

ASTM A312 Stainless Steel Pipe Chemical Composition (%)

ASTM A312 specifies the chemical requirements for austenitic stainless steel grades.

Grade (UNS)	C (max)	Mn (max)	P (max)	S (max)	Si (max)	Cr	Ni	Mo	Other
TP304 (S30400)	0.08	2.00	0.045	0.030	1.00	18.0-20.0	8.0-11.0	-	-
TP304L (S30403)	0.035*	2.00	0.045	0.030	1.00	18.0-20.0	8.0-12.0	-	-
TP316 (S31600)	0.08	2.00	0.045	0.030	1.00	16.0-18.0	11.0-14.0	2.0-3.0	-
TP316L (S31603)	0.035*	2.00	0.045	0.030	1.00	16.0-18.0	10.0-14.0	2.0-3.0	-
TP321 (S32100)	0.08	2.00	0.045	0.030	1.00	17.0-19.0	9.0-12.0	-	Ti: 5x(C+N)-0.70
TP310S (S31008)	0.08	2.00	0.045	0.030	1.50	24.0-26.0	19.0-22.0	-	-

*Note: For seamless pipes, the maximum carbon content is 0.040% in some specific sub-grades.

 

ASTM A312 Stainless Steel Pipe Mechanical Properties

The pipes must meet the minimum requirements for tensile strength, yield strength, and elongation.

Grade	Tensile Strength (min)	Yield Strength (min)	Elongation in 2 in. (50mm)
	ksi [MPa]	ksi [MPa]	min %
TP304	75 [515]	30 [205]	35%
TP304L	70 [485]	25 [170]	35%
TP316	75 [515]	30 [205]	35%
TP316L	70 [485]	25 [170]	35%
TP321	75 [515]	30 [205]	35%
TP310S	75 [515]	30 [205]	35%

 

ASTM A312 Stainless Steel Pipe Annealing Requirements

Grade or UNS Designation ᴬ	Heat Treating Temperature ᴮ
All grades not individually listed below:	1900°F [1040°C]
TP321H, TP347H, TP348H
- Cold finished	2000°F [1100°C]
- Hot finished	1925°F [1050°C]
TP304H, TP316H
- Cold finished	1900°F [1040°C]
- Hot finished	1900°F [1040°C]
TP309H, TP309HCb, TP310H, TP310HCb	1900°F [1040°C]
S30600	2010–2140°F [1100–1170°C]
S30815, S31272	1920°F [1050°C]
S31254, S32654	2100°F [1150°C]

 

ASTM A312 Standard Pipe Schedules (ASME B36.19 Example)

Common sizes provided by Gnee:

NPS (Inches)	Outside Diameter (mm)	Sch 10S Wall (mm)	Sch 40S Wall (mm)	Sch 80S Wall (mm)
1/2"	21.34	2.11	2.77	3.73
1"	33.40	2.77	3.38	4.55
2"	60.33	2.77	3.91	5.54
4"	114.30	3.05	6.02	8.56
8"	219.08	3.76	8.18	12.70

 

Dimensional Tolerances (Per ASTM A999)

ASTM A312 pipes are manufactured according to ASME B36.19 dimensions. The following tolerances apply:

Nominal Pipe Size (NPS)	Over (inch [mm])	Under (inch [mm])
1/8 to 1-1/2 (incl.)	1/64 [0.4]	1/32 [0.8]
Over 1-1/2 to 4 (incl.)	1/32 [0.8]	1/32 [0.8]
Over 4 to 8 (incl.)	1/16 [1.6]	1/32 [0.8]
Over 8 to 18 (incl.)	3/32 [2.4]	1/32 [0.8]

 

Technical Testing & Inspection

Gnee ensures all ASTM A312 pipes undergo the following mandatory and optional tests:

Test Category	Description
Hydrostatic Test	Each pipe is subjected to water pressure to ensure no leaks (per ASTM A999).
Nondestructive (NDT)	Eddy Current or Ultrasonic Testing (UT) can be performed in lieu of hydrostatic test.
Mechanical Tests	Transverse or Longitudinal Tension Test, Flattening Test, and Flaring Test (for seamless).
Grain Size	Required for certain grades like TP304H or TP316H to ensure high-temperature strength.
Corrosion Test	Intergranular Corrosion Test (IGC) per ASTM A262 (Practice A, C, or E).
Visual/Dimensional	Verification of surface finish, length, and diameter.

 

Other Standard:SNT-TC-1A Personnel Qualification and Certification in Nondestructive Testing

 

 

Gnee maintains long-term strategic partnerships with major Chinese steel mills (such as TISCO, BAOSTEEL, and TSINGSHAN), ensuring that our raw materials are authentic and competitively priced. We provide complete Material Test Certificates (MTCs) that comply with EN 10204 3.1 or 3.2 standards. Third-party inspections (by SGS, BV, TUV, Lloyd's) can be arranged, including non-destructive testing (UT/ET), hydrostatic testing, intergranular corrosion testing, and more.
Custom Processing: We offer value-added processing services such as cutting, beveling, drilling, pipe bending, and other deep processing operations.
In addition to pipes, we can also supply a full range of matching pipe fittings-including flanges, elbows, and tees-to help customers streamline their procurement process and avoid the complexities of sourcing individual components.

 

Standard	ASTM A312
Process Classification	- Seamless (SMLS):  - Welded (ERW/EFW):
Material Grades	- Most Common: TP304, TP304L, TP316, TP316L. - High Performance/Heat-Resistant: TP321, TP347, TP310S, TP904L.
Specifications	- Outer Diameter (OD): From 1/8" (10.3mm) to 30" (762mm). - Wall Thickness (WT): SCH 5S, 10S, 40S, 80S (per ANSI B36.19).
Surface Treatments	- Pickled & Annealed: Industrial standard. - Bright Annealed. - Polished: 180#, 320#, 400#, etc. (as per customer requirements).

 

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Packaging Methods

End Protection: Both ends of the pipe are fitted with plastic caps to prevent the ingress of dust and foreign objects, as well as to protect the pipe ends from impact damage.
Surface Protection: Individual pipes can be enclosed in plastic sleeves.
Outer Packaging: Industrial-grade packaging involves wrapping the entire bundle in woven bags.
Premium/Small-Dimension Packaging: For high-value or smaller-sized products, we utilize export-specific wooden crates to prevent deformation caused by compression during transit.
Marking: Each pipe typically features clear stenciled markings indicating the grade, standard, dimensions, and heat number.