Designated as UNS K11597, ASTM A335 P11, is also known as 1.25Cr-0.5Mo. Generally, its minimum tensile strength and yield strength are respectively 415 MPa and 205 MPa at room temperatures. However, its tensile & yield strength values in different elevated temperatures should be considered in practice. These values shall be in accordance with Table U and Table Y-1 of ASME Boiler and Pressure Vessel Code Section II Part D.

Tensile Strength of ASTM A335 P11 at Elevated Temperatures

Temperature, °C	-30~40	100	150	200	250	300	325	350
Tensile Strength, MPa	414	414	414	414	414	414	414	414
Temperature, °C	375	400	425	450	475	500	525	550
Tensile Strength, MPa	414	414	414	404	390	371	349	-

*The tabulated tensile strength values are for use in design calculations. The temperature shall be interpreted as “not exceeding”.

Yield Strength of ASTM A335 P11 at Elevated Temperatures

Temperatures, °C	-30~40	65	100	125	150	175	200	225	250	275
Yield Strength, MPa	207	197	190	185	181	178	175	172	169	166
Temperatures, °C	300	325	350	375	400	425	450	475	500	525
Yield Strength, MPa	164	161	158	155	153	149	145	142	137	132

*The tabulated yield strength values are for use in design calculations. The temperature shall be interpreted as “not exceeding”.

See the allowable stress of ASTM A335 P11 seamless pipes.