ASTM A335 Pipe Specification

What is ASTM A335 material?

ASTM A335 is a standard specification for seamless ferritic alloy-steel pipe intended for high-temperature service.

This material is commonly used in power plants, refineries, and other industrial settings where high-temperature and high-pressure conditions are encountered.ASTM‎‏ A335 is made of alloy steel, which usually contains elements such as chromium, molybdenum and sometimes vanadium to improve its properties at high temperatures.

The specification covers seamless ferritic alloy-steel pipe for high-temperature service. The pipe shall be suitable for bending, flanging (vanstoning), and similar forming operations, and for fusion welding. Grade P2 and P12 steel pipes shall be made by coarse-grain melting practice. The steel material shall conform to chemical composition, tensile property, and hardness requirements.

Each length of pipe shall be subjected to the hydrostatic test. Also, each pipe shall be examined by a non-destructive examination method in accordance to the required practices. The range of pipe sizes that may be examined by each method shall be subjected to the limitations in the scope of the respective practices. The different mechanical test requirements for pipes, namely, transverse or longitudinal tension test, flattening test, and hardness or bend test are presented.

Popularity of ASTM A335 seamless steel pipes

ASTM A335 is often called chrome moly pipe because of the chemical composition of molybdenum (Mo) and chromium (Cr). Molybdenum increases the strength of steel, as well as its elasticity limit, wear resistance, impact resistance and hardenability. In addition, molybdenum increases resistance to softening, limits grain growth and makes chrome steel less susceptible to embrittlement. Moly is the most effective single additive that increases creep strength at high temperatures. It also improves the corrosion resistance of steel and inhibits pitting.

Chrome (or chromium) is the essential component of stainless steel. Any steel with 12% or more chromium is considered stainless. Chromium is virtually irreplaceable in resisting oxidation at high temperatures. Chromium increases tensile strength, yield strength and hardness at room temperature. The composition of chrome-molyalloy steel pipe makes it ideal for use in power plants, refineries, petrochemical plants and oilfield services where liquids and gases are transported at extreme high temperatures and pressures.

ASTM A335 seamless steel pipe is a popular choice for high-temperature applications because of a‎‏ number of important reasons:

1. Sizes and Dimensions ASTM‎‏ A335 pipe is available in a wide range of sizes and dimensions, ranging from NPS‎‏ 1/8 to NPS‎‏ 26 in nominal diameter. Wall thickness may vary depending on the nominal pipe size and grade. Standard pipe schedules such as SCH‎‏ 40, SCH 80, SCH 160, and XXS are commonly available for ASTM A335 pipe.
2. High Temperature Resistance: ASTM‎‏ A335 seamless steel pipe is designed to withstand high temperatures up to 600°C (1112°F), making it an ideal material for high temperature applications such as steam lines and heat exchangers.
3. Corrosion Resistance: ASTM‎‏ A335 seamless steel pipes exhibit good corrosion resistance in aggressive environments, such as those found in the chemical processing and oil and gas industries.
4. High strength: ASTM‎‏ A335 seamless steel pipes have high tensile strength and yield strength, making them ideal for use in high-pressure applications.
5. Good weldability: ASTM‎‏ A335 pipes can be welded using conventional welding methods such as SMAW (shielded metal arc welding), GTAW (gas wire arc welding) and GMAW (gas metal arc welding)
   Preheating and heat treatment after welding may be necessary to prevent cracking and ensure proper mechanical properties, especially for higher alloy grades.
6. Cost-effective: Despite its superior properties, ASTM‎‏ A335 seamless steel pipe remains an affordable option for high-temperature applications.

In short, ASTM‎‏ A335 seamless steel pipe is popular in high-temperature applications because of its high temperature resistance, corrosion resistance, high strength, good weldability, and cost-effectiveness. The combination of properties makes it an ideal choice for use in various high-temperature and high-pressure applications, especially in power generation, chemical processing, and oil and gas industries.

Matching fittings and flanges

ASTM‎‏ A335 alloy steel pipe can be used with ASTM A234 WPx series buttweld fittings (WP5, WP9, WP91) and A182 Fx forged fittings and flanges (A182 F5, F9, F11, F22, F91). All of these materials have similar chemical and mechanical properties and can be used with ASTM‎‏ A335 pipe.

ASTM‎‏ A335 properties

The types of alloy steel covered by ASTM‎‏ A335 specification are designed with prefix 'P' from P5 to P92. Grades P11/P22 and P91/92 are typically found in power stations, whereas grades P5 and P9 are more common for application in the petrochemical industry.

Chemical composition

ASTM A335 (Grades)	UNS equivalent	C	Mn	P	S	Si	Cr	Mo
P1	K11522	0.10-0.20	0.30-0.80	0.025	0.025	0.10-0.50	-	0.44-0.65
P2	K11547	0.10-0.20	0.30-0.61	0.025	0.025	0.10-0.30	0.50-0.81	0.44-0.65
P5	K41545	0.15	0.30-0.60	0.025	0.025	0.5	4.00-6.00	0.44-0.65
P5b	K51545	0.15	0.30-0.60	0.025	0.025	1.00-2.00	4.00-6.00	0.44-0.65
P5c	K41245	0.12	0.30-0.60	0.025	0.025	0.5	4.00-6.00	0.44-0.65
P9	S50400	0.15	0.30-0.60	0.025	0.025	0.50-1.00	8.00-10.00	0.44-0.65
P11	K11597	0.05-0.15	0.30-0.61	0.025	0.025	0.50-1.00	1.00-1.50	0.44-0.65
P12	K11562	0.05-0.15	0.30-0.60	0.025	0.025	0.5	0.80-1.25	0.44-0.65
P15	K11578	0.05-0.15	0.30-0.60	0.025	0.025	1.15-1.65	-	0.44-0.65
P21	K31545	0.05-0.15	0.30-0.60	0.025	0.025	0.5	2.65-3.35	0.80-1.60
P22	K21590	0.05-0.15	0.30-0.60	0.025	0.025	0.5	1.90-2.60	0.87-1.13
P91	K91560	0.08-0.12	0.30-0.60	0.02	0.01	0.20-0.50	8.00-9.50	0.85-1.05
P92	K92460	0.07-0.13	0.30-0.60	0.02	0.01	0.5	8.50-9.50	0.30-0.60

Mechanical properties

ASTM‎‏ A335	UNS Number	Yield Strength ksi	Tensile Strength ksi	Elongation %	Rockwell Hardness	Brinell Hardness
P1	K11522	30	55	30	–	–
P2	K11547	30	55	30	–	–
P5	K41545	40	70	30	–	207 max
P9	S50400	30	60	30	–	–
P11	K11597	30	60	20	–	–
P12	K11562	32	60	30	–	174 max
P22	K21590	30	60	30	–	–
P91	K91560	60	85	20	–	–

Diameter tolerances

A335 Pipe	Over		Under
INCH (DN)	in	mm	in	mm
1/8 to 1 1/2 (DN 6 to 40)	1/64	0.4	1/64	0.4
Over 1 1/2 to 4 (DN 40 to 100)	1/32	0.79	1/32	0.79
Over 4 to 8 (DN 100 to 200)	1/16	1.59	1/32	0.79
Over 8 to 12 (DN 200 to 300)	3/32	2.38	1/32	0.79
Over 12 (DN 300)	+/- 1% of the specified outside diameter

Cross reference DIN-EN-ASTM

DIN Werkstoff Nummer	EN	ASTM
1.5415	16Mo3	A335 Grade P1
1.7335	13CrMo4-5	A335 Grade P11, P12
1.7380	10CrMo9-10	A335 Grade P22
1.7362	X11CrMo5	A335 Grade P5
		A335 Grade P9
1.4903	X10CrMoVNb9-1	A335 Grade P91

Testing requirements

Transverse/longitudinal: tension and flattening, hardness, bend tests- for material that has been heat-treated in batch furnaces, these tests shall be made on the 5% of the pipes from each heat lot number. For smaller lots, one pipe at a minimum has to be tested

ASTM A335 Gr. P91 should have a hardness of 250 HB / 265 HV (25 HRC), hydro testing: be applied to any length of pipe, and a non-destructive electrical test is optional

Heat treatment

ASTM A335 pipes shall be reheated to the fully annealed, isothermal annealed, or normalized and tempered condition. When supplied in the normalized and tempered condition, the minimum tempering temperature for grades P5, P5b, P9, P21, and P22 shall be 1250°F [675°C], the minimum tempering temperature for grades P1, P2, P11, P12, and P15 shall be 1200°F [650°C].

Grades P1, P2, and P12 pipe, whether hot finished or cold drawn, may be given a final heat treatment of 650°C (1200°F)to 705°C (1300°F)instead of heat treatments.

Frequently used ASTM Grades

Material	Pipes	Fittings	Flanges	Valves	Bolts & Nuts
Carbon Steel Alloy High-Temp	A335 Gr.P1	A234 Gr.WP1	A182 Gr.F1	A217 Gr.WC1	A193 Gr.B7 A194 Gr.2H
	A335 Gr.P11	A234 Gr.WP11	A182 Gr.F11	A217 Gr.WC6
	A335 Gr.P22	A234 Gr.WP22	A182 Gr.F22	A217 Gr.WC9
	A335 Gr.P5	A234 Gr.WP5	A182 Gr.F5	A217 Gr.C5
	A335 Gr.P9	A234 Gr.WP9	A182 Gr.F9	A217 Gr.C12