ASTM A335 seamless ferritic alloy-steel pipes

Dec 04, 2025

What is ASTM A335 seamless ferritic alloy-steel pipes

ASTM A335/ASME SA335 High-Temperature Seamless Ferritic Alloy Steel Pipes‌ are high-performance steel pipes exhibiting ‌excellent high-temperature creep strength, prolonged high-temperature service life, and superior high-temperature oxidation resistance‌. They withstand pressure under elevated temperatures while maintaining sufficient strength and toughness to ‌ensure system safety and stable operation‌.

The specifications and dimensions of ‌ASTM A335/ASME SA335 High-Temperature Seamless Ferritic Alloy Steel Pipes‌ can be customized according to specific application requirements. Generally, these pipes feature an ‌outside diameter range of 21.3 mm to 762 mm‌ and a ‌wall thickness range of 3.0 mm to 130 mm‌.

‌ASTM A335/ASME SA335 High-Temperature Seamless Ferritic Alloy Steel Pipes‌ are widely used in high-temperature piping systems across petroleum, chemical, and power industries due to their ‌exceptional high-temperature resistance and reliable mechanical properties‌. For example, they serve as manufacturing materials for:

High-temperature, high-pressure pipelines, reactors, and heat exchangers in ‌oil refineries and chemical plants‌;

Critical components such as ‌boiler superheaters, reheaters, and steam pipes‌ in thermal power stations.

Chemical Composition:

Grade	UN Sequiv.	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

Tensile Requirements

Tensile Strength, min., psi	P-5	P-9	P-11	P-22	P-91
ksi	60	60	60	60	85
MPa	415	415	415	415	585
Yield Strength, min., psi
ksi	30	30	30	30	60
MPa	205	205	205	205	415

Mechanical Properties

Mechanical properties	P1,P2	P12	P23	P91	P92,P11	P122
Tensile strength	380	415	510	585	620	620
Yield strength	205	220	400	415	440	400

Heat Treatment Requirements

Grade	Heat Treatment Type P5, P9, P11, and P22	Normalizing Temperature Range F [C]	Subcritical Annealing or Tempering Temperature Range F [C]
A335 P5 (b,c)	Full or Isothermal Anneal
	Normalize and Temper	*****	1250 [675]
	Subcritical Anneal (P5c only)	*****	1325 – 1375 [715 - 745]
A335 P9	Full or Isothermal Anneal
	Normalize and Temper	*****	1250 [675]
A335 P11	Full or Isothermal Anneal
	Normalize and Temper	*****	1200 [650]
A335 P22	Full or Isothermal Anneal
	Normalize and Temper	*****	1250 [675]
A335 P91	Normalize and Temper	1900-1975 [1040 - 1080]	1350-1470 [730 - 800]
	Quench and Temper	1900-1975 [1040 - 1080]	1350-1470 [730 - 800]