LAC 33:V.30161. Internal Design Pressure [49 CFR 195.106]

A. Internal design pressure for the pipe in a pipeline is determined in accordance with the following formula: P = (2 St/D) x E x F P = internal design pressure in p.s.i. (kPa) gauge. S = yield strength in pounds per square inch (kPa) determined in accordance with §30161.B. t = nominal wall thickness of the pipe in inches (millimeters). If this is unknown, it is determined in accordance with §30161.C. D = nominal outside diameter of the pipe in inches (millimeters). E = seam joint factor determined in accordance with §30161.E. F = a design factor of 0.72, except that a design factor of 0.60 is used for pipe, including risers, on a platform located off-shore or on a platform in inland navigable waters, and 0.54 is used for pipe that has been subjected to cold expansion to meet the specified minimum yield strength and is subsequently heated, other than by welding or stress relieving as a part of welding, to temperature higher than 900F (482C) for any period of time or over 600F (316C) for more than one hour. [49 CFR 195.106(a)] B. The yield strength to be used in determining the internal design pressure under §30161.A is the specified minimum yield strength. If the specified minimum yield strength is not known, the yield strength to be used in the design formula is one of the following: [49 CFR 195.106(b)] 1. the yield strength determined by performing all of the tensile tests of API Spec 5L on randomly selected specimens with the following number of tests: [49 CFR 195.106(b)(1)(i)] Pipeline Size | Number of Tests Less than 6-5/8 in. (168.3 mm) nominal outside diameter | One test for each 200 lengths 6-5/8 through 12-3/4 in. (168 through 323 mm.) nominal outside diameter | One test for each 100 lengths Larger than 12-3/4 in. (324 mm.) nominal outside diameter | One test for each 50 lengths 2. if the average yield-tensile ratio exceeds 0.85, the yield strength shall be taken as 24,000 psi (165,474 kPa ). If the average yield tensile ratio is 0.85 or less, the yield strength of the pipe is taken as the lower of the following: [49 CFR 195.106(b)(1)(ii)] a. eighty percent of the average yield strength determined by the tensile tests; [49 CFR 195.106(b)(1)(ii)(A)] b. the lowest yield strength determined by the tensile tests; [49 CFR 195.106(b)(1)(ii)(B)] 3. if the pipe is not tensile tested as provided in Subsection B, the yield strength shall be taken as 24,000 psi (165,474 kPa). [49 CFR 195.106(b)(2)] C. If the nominal wall thickness to be used in determining internal design pressure under §30161.A is not known, it is determined by measuring the thickness of each piece of pipe at quarter points on one end. However, if the pipe is of uniform grade, size and thickness, only 10 individual lengths or 5 percent of all lengths, whichever is greater, need be measured. The thickness of the lengths that are not measured must be verified by applying a gauge set to the minimum thickness found by the measurement. The nominal wall thickness to be used is the next wall thickness found in commercial specifications that is below the average of all the measurements taken. However, the nominal wall thickness may not be more than 1.14 times the smallest measurement taken on pipe that is less than 20 in. (508 mm) nominal outside diameter, nor more than 1.11 times the smallest measurement taken on pipe that is 20 in. (508 mm) or more in nominal outside diameter. [49 CFR 195.106(c)] D. The minimum wall thickness of the pipe may not be less than 87.5 percent of the value used for nominal wall thickness in determining the internal design pressure under §30161.A. In addition, the anticipated external loads and external pressures that are concurrent with internal pressure must be considered in accordance with §30163 and §30165 and, after determining the internal design pressure, the nominal wall thickness must be increased as necessary to compensate for these concurrent loads and pressures. [49 CFR 195.106(d)] E. The seam joint factor used in §30161.A is determined in accordance with the following standards incorporated by reference (see §30107). [49 CFR 195.106(e)(1)] Specification | Pipe Class | Seam Joint Factor ASTM A53 | Seamless | 1.00 Electric resistance welded | 1.00 Furnace lap welded | 0.80 Furnace butt welded | 0.60 ASTM A106/ | Seamless | 1.00 ASTM A333/A333M | Seamless | 1.00 Welded | 1.00 ASTM A381 | Double submerged arc welded | 1.00 ASTM A671/A671M | Electric fusion welded | 1.00 ASTM A672/A672M | Electric fusion welded | 1.00 ASTM A691/A691M | Electric fusion welded | 1.00 API Spec 5L | Seamless | 1.00 Electric resistance welded | 1.00 Electric flash welded | 1.00 Submerged arc welded | 1.00 Furnace lap welded | 0.80 Furnace butt welded | 0.60 1. The seam joint factor for pipe which is not covered by this Subsection must be approved by the commissioner/ administrator. [49 CFR 195.106(e)]