ASTM A312 Stainless Steel 904L Pipe is a highly alloyed, low-carbon, non-stabilized austenitic stainless steel. Copper is added to the 904L stainless steel pipe alloy. Therefore, its resistance to strong reducing acids such as sulfuric acid is very high. A large amount of nickel is added to the ASME A312 TP904L alloy, which enables the pipe to perform well even in high temperature environments. Stainless steel 904L pipe is not only a non-magnetic alloy, but also shows good resistance to stress-related corrosion cracking. The presence of molybdenum in the alloy reduces the occurrence of crevice corrosion. In addition to being used for medium and high temperature applications, ASTM A312 TP904L is mainly used for general corrosion applications.

In order to obtain good mechanical properties and corrosion resistance, 904L stainless steel pipe usually need to be solution heat treated. Solution treatment is to heat the steel pipe to 1050-1150℃, keep it warm for a certain period of time and then cool it quickly. This heat treatment can fully dissolve the alloy elements in the austenite matrix, eliminate the tendency of inter granular corrosion, and improve the corrosion resistance and mechanical properties of stainless steel.

What is an ASTM A312 pipe?

ASTM A312 is a standard specification for seamless, welded and cryogenic service austenitic stainless steel pipes developed by the American Society for Testing and Materials (ASTM). The standard covers a variety of austenitic stainless steel pipes and specifies the requirements for the size, chemical composition, mechanical properties, manufacturing process, inspection and testing of the steel pipes to ensure that the quality and performance of the steel pipes meet the needs of related projects and applications.

What material is A312 equivalent to?

Standard	ASTM A312, ASME SA312
Equivalent Standards	EN 10216-5, DIN 17458, GOST 9941-81, GOST 9940-81, ASME SA213, ASTM A213, DIN 17456

Equivalent Material of ASTM A312 Stainless Steel 904L Pipe

Material number	EN	ASTM
1.4307     –	X2CrNi18-9	A 312 Grade TP304L
1.4306     X 2 CrNi 19 11	X2CrNi19-11	A 312 Grade TP304L
1.4301     X 5 CrNi 18 10	X5CrNi18-10	A 312 Grade TP304
1.4541     X 6 CrNiTi 18 10	X6CrNiTi18-10	A 312 Grade TP321
1.4550     X 6 CrNiNb 18 10	X6CrNiNb18-10	A 312 Grade TP347
1.4404     X 2 CrNiMo 17 13 2	X2CrNiMo17-12-2	A 312 Grade TP316L
1.4401     X 5 CrNiMo 17 12 2	X5CrNiMo17-12-2	A 312 Grade TP316
1.4571     X 6 CrNiMoTi 17 12 2	X6CrNiMoTi17-12-2	A 312 Grade S 31635
1.4429     X 2 CrNiMoN 17 13 3	X2CrNiMoN17-13-3	A 312 Grade TP316LN
1.4436     X 5 CrNiMo 17 13 3	X3CrNiMo17-13-3	A 312 Grade TP316
1.4435     X 2 CrNiMo 18 14 3	X2CrNiMo18-14-3	A 312 Grade TP316L
1.4539     X 1 NiCrMoCuN 25 20 5	X1NiCrMoCu25-20-5	UNS N 08904 (904L)

ASTM A312 Specification

ASTM A312 Stainless Steel 904L Pipe specifications are mainly applicable to sizes ranging from 1/8” to 30” (DN6 to DN750). The wall thickness of these steel pipes must comply with ASME B36.19 standards, and the wall thickness grades are SCH 10, SCH 20, SCH 40, STD, XS, SCH 100, SCH 120, SCH 160, XXS.

Processing Method	Seamless and Welded
Size Range	1/8” – 30” / DN6 – 750
Thickness Schedule	SCH 10S- SCH 160, XXS
Length	6m or 12 m or Random
Standard	ASME B36.19
Surface Treatment	Polish , Mirror , Epoxy Powder FBE, 2PE, 3PE Coating
Material Grade	ASTM A312 TP304/304L/304H, 316/316L, 310S, 317, 347, 904L, S32205, S31803, 32750, 32760, S32550

A312 Pipe Manufacturing Types

ASTM A312 Stainless Steel 904L Pipe covers following manufacturing types (Including hot finished or cold finished):
a. Seamless Pipe (SMLS): It covers stainless steel seamless pipe that manufactured in any process that can not be involved in the welding process.
b. Welded Pipe (WLD): It covers welded pipe that manufactured by an automatic welding process that does not add filler metal during welding.
c. Cold Worked Pipe (HCW pipe): The heavy cold-worked pipe that apply cold working of not less than 35% reduction in thickness of both wall, and welded to the welded pipe prior to final annealing. Do not use fillers during welding.
d. Welded and HCW pipe: Welded pipe and HCW pipe of 14 and smaller than NPS 14 shall have a single longitudinal weld. After approval by the purchaser, the welded pipe and HCW pipe with an NPS greater than NPS 14 shall have a single longitudinal weld or shall be manufactured by forming and welding two longitudinal sections of flat stock. So each welds are to be tested, inspected, inspected or treated.

SS 904L Pipe HS Code

Material	HS code
904L SS	73044900

ASTM A312 Stainless Steel 904L Pipe Chemical Composition

CHEMICAL	LIMITS	C	Mn	P	S	Si	Ni	Cr	Mo	N
ASTM A312 TP904L	MIN						23.00	19.00	4.00
	MAX	0.020	2.00	0.045	0.04	1.00	28.00	23.00	5.00	0.10

Mechanical Properties of SS 904L Stainless steel Pipe

MATERIAL	T.S (MPA)	Y.S (MPA)	EL %
ASTM A312 TP904L	490min	215min	35min

Stainless Steel 904L Pipe Physical Properties

Grade	Density(kg/m3)	Elastic Modulus (GPa)	Mean Coefficient of Thermal Expansion (μm/m/°C)			Thermal Conductivity (W/m.K)		Specific Heat 0-100°C(J/kg.K)	Electrical Resistivity (nΩ.m)
			0-100°C	0-315°C	0-538°C	at 20°C	at 500°C
904L	7900	190	15			11.5		500	952

Stainless Steel 904L Pipe Dimension

 X1.1 Table X1.1 is based on Table number 1 of  the American  National Standard  for  stainless  steel  pipe  (ANSI B36.19).

TABLE X1.1 Dimensions of Welded and Seamless Stainless Steel Pipe
NOTE 1—The decimal thickness listed for the respective pipe sizes represents their nominal or average wall dimensions.
NPS	Outside Diameter				Nominal Wall Thickness
Designator	in.	mm	Schedule 5SA		Schedule 10SA		Schedule 40S		Schedule 80S
			in.	mm	in.	mm	in.	mm	in.	mm
1/8	0.405	10.29			0.049	1.24	0.068	1.73	0.095	2.41
1/4	0.540	13.72			0.065	1.65	0.088	2.24	0.119	3.02
3/8	0.675	17.15			0.065	1.65	0.091	2.31	0.126	3.20
1/2	0.840	21.34	0.065	1.65	0.083	2.11	0.109	2.77	0.147	3.73
3/4	1.050	26.67	0.065	1.65	0.083	2.11	0.113	2.87	0.154	3.91
1	1.315	33.40	0.065	1.65	0.109	2.77	0.133	3.38	0.179	4.55
1 1/4	1.660	42.16	0.065	1.65	0.109	2.77	0.140	3.56	0.191	4.85
1 1/2	1.900	48.26	0.065	1.65	0.109	2.77	0.145	3.68	0.200	5.08
2	2.375	60.33	0.065	1.65	0.100	2.77	0.154	3.91	0.218	5.54
2 1/2	2.875	73.03	0.083	2.11	0.120	3.05	0.203	5.16	0.276	7.01
3	3.500	88.90	0.083	2.11	0.120	3.05	0.216	5.49	0.300	7.62
4	4.000	101.60	0.083	2.11	0.120	3.05	0.226	5.74	0.318	8.08
4	4.500	114.30	0.083	2.11	0.120	3.05	0.237	6.02	0.337	8.56
5	5.563	141.30	0.109	2.77	0.134	3.40	0.258	6.55	0.375	9.52
6	6.625	168.28	0.109	2.77	0.134	3.40	0.280	7.11	0.432	10.97
8	8.625	219.08	0.109	2.77	0.148	3.76	0.322	8.18	0.500	12.70
10	10.750	273.05	0.134	3.40	0.165	4.19	0.365	9.27	0.500B	12.70B
12	12.750	323.85	0.156	3.96	0.180	4.57	0.375B	9.52B	0.500B	12.70B

Stainless Steel Pipe Permitted Tolerance in Wall Thickness

TABLE 3 Permitted Variations in Wall Thickness
	Tolerance,% from Nominal
NPS Designator	Over	Under
1/8 to2 1/2 incl ., all t/D ratios	20.0	12.5
3 to 18 incl., t/D up to 5% incl.	22.5	12.5
3 to 18 incl ., t/D>5%	15.0	12.5
20 and larger,welded,all t/D ratios	17.5	12.5
20 and larger, seamless, t/D up to 5%incl.	22.5	12.5
20 and larger, seamless, t/D>5%	15.0	12.5

where:

t = Nominal Wall Thickness

D = Ordered Outside Diameter

What is the difference between ASTM A312 and A358?

ASTM A312 standard: ASTM A312 Stainless Steel 904L Pipe standard covers austenitic stainless steel nominal pipes for seamless, welded and cryogenic service. It is mainly applicable to general-purpose stainless steel pipes, including pipeline systems that transport various fluids.

ASTM A358 standard: This standard is specifically for electric fusion-welded stainless steel pipes. It focuses on specifying the relevant requirements for stainless steel pipes manufactured by the electric fusion welding process, and is suitable for pipeline application scenarios with high requirements for welding quality and performance.

Stainless steel pipe manufactured under ASTM A312 and ASTM A358 standards have several advantages over other materials. They are highly durable, can withstand harsh environments, and need little maintenance, making them ideal for industrial applications such as food processing, petrochemical, pharmaceutical, and others. Additionally, they offer excellent corrosion resistance, good tensile strength, and easy weldability. Other benefits include good temperature resistance, low thermal expansion, and long service life.