The seamless pipe of ASTM A335 P11 is a typical Cr-Mo alloy steel pipe for high-temperature service. Also known as 1.25Cr-0.5Mo, the UNS designation of ASTM A335 P11 is K11597. Its ASTM equivalent includes ASTM A369 FP11 as well as ASTM A213 T11. Usually, the pipe shall be furnished with either butt welding(BW) or plain ends(PE).

1. Chemical Composition Requirements

ASTM A335 P11 Chemical Composition %
C	Mn	P	S	Si	Cr	Mo
0.05-0.15	0.30-0.60	≤0.025	≤0.025	0.50-1.00	1.00-1.50	0.44-0.65

*C – Carbon, Mn – Manganese, P – Phosphorous, S – Sulfur, Si – Silicon, Cr-Chromium, Mo – Molybdenum.

2. Mechanical Properties of ASTM A335 P11

The tensile strength shall be no less than 60 ksi (415MPa) while its yield strength shall be no less than 30 ksi (205MPa). The longitudinal and transverse elongation values measured in 2 inch or 50 mm (or 4D) shall be no less than 30% and 20% respectively.

3. Heat Treatment, Inspection & Test

Pipes of ASTM A335 P11 may be either cold drawn or hot rolled. Each pipe shall be reheated for heat treatment – full or isothermal annealing, normalizing and tempering at a temperature no less than 1200°F(650°C).

Hydrostatic test shall be performed on each pipe length of ASTM A335 P11 along with dimensional inspection and visual examination. Longitudinal or transverse tension test, flattening test, or bend test shall be performed for each heat number of furnace. When specified by the purchaser, one of the alternative nondestructive tests can be performed: ultrasonic test, eddy current test, or flux leakage examination. Hardness test is not necessary.

See more specification of the ASTM A335 seamless ferritic alloy steel pipe.