(a) The design pressure for steel pipe is determined in accordance with the following formula:
P = (2 St/D) × F × E × T
P = Design pressure in pounds per square inch (kPa) gauge.
S = Yield strength in pounds per square inch (kPa) determined in accordance with § 192.107.
D = Nominal outside diameter of the pipe in inches (millimeters).
t = Nominal wall thickness of the pipe in inches (millimeters). If this is unknown, it is determined in accordance with § 192.109. Additional wall thickness required for concurrent external loads in accordance with § 192.103 may not be included in computing design pressure.
F = Design factor determined in accordance with § 192.111.
E = Longitudinal joint factor determined in accordance with § 192.113.
T = Temperature derating factor determined in accordance with § 192.115.
(b) If steel pipe that has been subjected to cold expansion to meet the SMYS is subsequently heated, other than by welding or stress relieving as a part of welding, the design pressure is limited to 75 percent of the pressure determined under paragraph (a) of this section if the temperature of the pipe exceeds 900 °F (482 °C) at any time or is held above 600 °F (316 °C) for more than 1 hour.