 Wall Thickness Calculation of Straight Pipes on Offshore Liquid Pipeline Systems Calculation as per Chapter IX by ASME B31.4 for D/t ≥ 20 (Enter values in yellow cells for calculations and in blue cells as information) DATA INPUT Diameter Nominal,  DN = 6 8 10 15 20 25 32 40 50 65 80 90 100 125 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 mm Material  = API-5L Gr.A25 API-5L Gr.A API-5L Gr.B API-5L Gr.X42 API-5L Gr.X46 API-5L Gr.X52 API-5L Gr.X56 API-5L Gr.X60 API-5L Gr.X65 API-5L Gr.X70 API-5L Gr.X80 ASTM-A53 Gr.A ASTM-A53 Gr.B ASTM-A106 Gr.A ASTM-A106 Gr.B ASTM-A106 Gr.C ASTM-A333 Gr.6 ASTM-A524 ASTM-A524 Gr.H ASTM-A139 Gr.A ASTM-A139 Gr.B ASTM-A381 Gr.Y35 ASTM-A381 Gr.Y42 ASTM-A381 Gr.Y46 ASTM-A381 Gr.Y48 ASTM-A381 Gr.Y50 ASTM-A381 Gr.Y52 ASTM-A381 Gr.Y56 ASTM-A381 Gr.Y60 ASTM-A381 Gr.Y65 External Diameter,  D = mm Design Temperature = 30 ᵒC Design temp. between −29°C and 120°C Location  = Pipeline Riser and platform piping Internal design pressure (gauge), Pi = barg See table A402.3.5-1 Hoop stress design factor, F1  = Water Depth, H = m See table A402.3.5-1 Water Density, ɣ = Kg/m³ External pressure (gauge), Pe = barg Allow. for corrosion, A = mm optional Spec. min. yield strength, Sy = MPa CALCULATIONS Check for Applicability Applicable allowable stress value, S = MPa D/t = D/t ≥ 20 Nominal thickness as per chapter IX, t = mm t = (Pi-Pe)D Minimum thickness required 20S Nominal thickness + Corr. Allow., tn = mm tn = t + A Nom. pipe wall thickness, T ≥ tn = mm From ASME B36.10M (Thickness most commonly used) SCH = (Minimum acceptable when applicable) - Additional information for pressure design can be found in API RP 1111, paras. 4.3.1 and 4.3.2. Wall Thickness Calculation of Straight Pipes on Offshore Liquid Pipeline Systems Calculation as per Chapter IX by ASME B31.4 for D/t ≥ 20 (Enter values in yellow cells for calculations and in blue cells as information) DATA INPUT Nominal Pipe Size,  NPS = 0.125 0.25 0.375 0.5 0.75 1 1.25 1.5 2 2.5 3 3.5 4 5 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 in. Material  = API-5L Gr.A25 API-5L Gr.A API-5L Gr.B API-5L Gr.X42 API-5L Gr.X46 API-5L Gr.X52 API-5L Gr.X56 API-5L Gr.X60 API-5L Gr.X65 API-5L Gr.X70 API-5L Gr.X80 ASTM-A53 Gr.A ASTM-A53 Gr.B ASTM-A106 Gr.A ASTM-A106 Gr.B ASTM-A106 Gr.C ASTM-A333 Gr.6 ASTM-A524 ASTM-A524 Gr.H ASTM-A139 Gr.A ASTM-A139 Gr.B ASTM-A381 Gr.Y35 ASTM-A381 Gr.Y42 ASTM-A381 Gr.Y46 ASTM-A381 Gr.Y48 ASTM-A381 Gr.Y50 ASTM-A381 Gr.Y52 ASTM-A381 Gr.Y56 ASTM-A381 Gr.Y60 ASTM-A381 Gr.Y65 External Diameter,  D = in. Design Temperature = ᵒF Design temp. between −20°F and 250°F Location  = Pipeline Riser and platform piping Internal design pressure (gauge), Pi = psig See table A402.3.5-1 Hoop stress design factor, F1  = Water Depth, H = ft See table A402.3.5-1 Water Density, ɣ = lb/ft³ External pressure (gauge), Pe = psig Allow. for corrosion, A = in. optional Spec. min. yield strength, Sy = psi CALCULATIONS Check for Applicability Applicable allowable stress value, S = psi D/t = D/t ≥ 20 Nominal thickness as per chapter IX, t = in. t = (Pi-Pe)D Minimum thickness required 2S Nominal thickness + Corr. Allow., tn = in. tn = t + A Nom. pipe wall thickness, T ≥ tn = in. From ASME B36.10M (Thickness most commonly used) SCH = (Minimum acceptable when applicable) - Additional information for pressure design can be found in API RP 1111, paras. 4.3.1 and 4.3.2.
 Discussion and References Information about Wall thickness calculation of straight pipes on Offshore Liquid Pipeline Systems: ASME B31.4 Transportation Systems for Liquids and Slurries, chapter IX. Tables and Standards - ASME B31.4 Specified Minimum Strength - US Units - ASME B31.4 Specified Minimum Strength - Metric - Table A402.3.5-1 Design Factors for Offshore Pipeline Systems - ASME B36.10M-Welded and Seamless Wrought Steel Pipe - ASME B36.19M-Stainless Steel Pipe - ASTM A377 Ductile Iron Pressure Pipe - ASTM A691 Electric-Fusion-Welded Steel Pipe for High-Pressure Service at High Temperatures Equations for Wall thickness calculation of straight pipes on Offshore Liquid Pipeline (chapter IX): For D/t ≥ 20, the wall thickness should be calculated by the equations: t = (Pi-Pe)D (U.S. Customary Units) 2S t = (Pi-Pe)D (SI Units) 20S tn = t + A Corrosion allowance is not included in the chapter IX It is optional to the designer its inclusion in the calculation. The parameters in the wall thickness calculation of straight pipes on Offshore Liquid Pipeline equations above are: Pe = external pressure, psig (barg). Pi = internal design pressure, psig (barg). D = external diameter, in. (mm). A = sum of corrosion allowance, slots, threads and safety in special areas, in. (mm). t = nominal thickness, in. (mm) as per chapter IX. S = Applicable allowable stress value, psi (MPa), as determined by the following equation: S = Fi(Sy) Where: F1 = hoop stress design factor from Table A402.3.5-1. Sy = specified  minimum  yield  strength, psi (MPa) * Additional information for pressure design can be found in API RP 1111, paras. 4.3.1 and 4.3.2.