Allowable Stresses of ASTM A350 LF3 in ASME B31.3

ASTM A350 LF3 forgings can be applied to services designed in accordance with ASME B31.3 Process Piping. According to the Code, ASTM A350 LF3 may be used in general metallic piping or high pressure piping applications. For the former, basic allowable stresses in tension are listed in Table A-1 & Table A-1M; for the latter, allowable stresses in tension are listed in Table K-1. Allowable stresses in shear shall be 0.80 times the basic/ or allowable stress in tension; Allowable stresses in bearing shall be 1.60 times that value; Allowable stresses in compression shall be no greater than the basic/ or allowable stresses in tension.

The high pressure piping usually refers to services exceeding that allowed by ASME B16.5 Class 2500 pressure-temperature rating for a particular material group. However, there are no pressure limitations for the application of these rules. High pressure piping is specified in Chapter IX of ASME B31.3. The allowable stresses provided in each table below shall be used in design calculation. Straight-line interpolation between temperatures is permissible. The minimum and maximum use temperatures of ASTM A350 LF3 according to ASME B31.3 are -101°C [-150°F] and 343°C [650°F].

Basic Allowable Stresses in Tension for ASTM A350 LF3

*Temp.	*S
100	23.3
200	22.9
300	22.1
400	21.4
500	20.3
600	18.8
650	17.9

*Temp.: at metal temperature, °F; *S: basic allowable stress in tension, ksi.
*100: from minimum use temperature -150°F to 100°F.
*All values are extracted from Table A-1 of ASME B31.3.

*Temp.	*S
*40	161
65	160
100	157
125	155
150	152
175	150
200	148
225	145
250	142
275	137
300	133
325	128
350	122

*Temp.: at metal temperature, °C; *S: basic allowable stress in tension, MPa.
*40: from minimum use temperature -102°C to 40°C.
*All values are extracted from Table A-1M of ASME B31.3.

Allowable Stresses in Tension for ASTM A350 LF3 for High Pressure Piping

*Temp.	*S
100	25.0
150	23.5
200	22.9
250	22.5
300	22.1
400	21.3
500	20.3
600	18.8
650	17.9

*Temp.: metal temperature, °F, not exceeding; *S: allowable stress in tension, ksi.
*100: from minimum use temperature -150°F to 100°F.
*All values are extracted from Table K-1 of ASME B31.3.