# HAR 6-77-29 Design formula for steel pipe

- **operation:** document
- **citation:** HAR 6-77-29
- **title:** HAR 6-77-29 Design formula for steel pipe
- **source type:** regulation
- **agency:** Hawaii Public Utilities Commission
- **status:** current
- **official:** true
- **published on:** 1994-04-15
- **effective on:** 1994-09-03
- **summary:** determined in accordance with the following formula: P=(2 St/D) x F x E x T P = Design pressure in pounds per square inch gauge. S = Yield strength in pounds per square inch determined in accordance with section 6- 77-30. D = Nominal outside diameter of the pipe in inches. t = Nominal wall thickness
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- **source url:** https://puc.hawaii.gov/wp-content/uploads/2026/04/HAR-6-77-Transp-of-Gas-03-31-2026.pdf
**body:**

determined in accordance with the following formula: P=(2 St/D) x F x E x T P = Design pressure in pounds per square inch gauge. S = Yield strength in pounds per square inch determined in accordance with section 6- 77-30. D = Nominal outside diameter of the pipe in inches. t = Nominal wall thickness of the pipe in inches. If this is unknown, it is determined in accordance with section 6-77-31. Additional wall thickness required for concurrent external loads in accordance with section 6-77-28 may not be included in computing design pressure. F = Design factor determined in accordance with section 6-77-32. E = Longitudinal joint factor determined in accordance with section 6-77-33. T = Temperature derating factor determined in accordance with section 6-77-34. (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 seventy-five percent of the pressure determined under subsection (a) if the temperature of the pipe exceeds 900E F (482E C) at any time or is held above 600E F (316E C) for more than one hour. [Eff ] (Auth: HRS '269 -6) (Imp: 49 C.F.R. '192.105, October 1, 1990)
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