1 · Design inputs

NPS 12 (12.75 in OD) API 5L X52 liquid transmission line to ASME B31.4 at 1,440 psi internal design pressure. Design factor F = 0.72, seamless/ERW joint factor E = 1.0, no temperature derating (T = 1.0), and no corrosion allowance taken (A = 0) so the pressure design thickness is seen bare.

2 · Method

Pressure design of straight pipe, Barlow form with the pipeline design factors applied to SMYS:

t = P·D / ( 2 · SMYS · F · E · T )

t_n = t + A

hoop utilization = P·D / ( 2·t_n ) / SMYS

B31.8 ¶841.1.1 states the same relation solved for pressure, P = (2·S·t/D)·F·E·T, where S is SMYS; B31.4 ¶403.2.1 and B31.11 ¶1104.1.2 fold F, E and T into the design stress before dividing. Here P is the internal design gauge pressure, D the outside diameter, SMYS the specified minimum yield strength from the pipe spec, F the design factor set by location class or fluid service, E the longitudinal joint factor for the pipe manufacturing process, T the temperature derating factor (1.0 where the Code applies none), and A the additional thickness allowance for corrosion, erosion and threading or grooving. Hoop utilization is reported as a fraction of SMYS so the delivered design can be compared directly against the factor that was claimed.

3 · Calculation

1. Design hoop stress basis: SMYS·F·E·T = 52,000·0.72·1.0·1.0 = 37,440 psi.
2. Denominator: 2·(SMYS·F·E·T) = 2·37,440 = 74,880 psi.
3. Numerator: P·D = 1,440·12.75 = 18,360 lb/in.
4. Pressure design thickness: t = 18,360 / 74,880 = 0.24519 in.
5. Nominal required thickness: t_n = t + A = 0.24519 + 0 = 0.24519 in.
6. Hoop utilization: P·D / (2·t_n) / SMYS = 18,360 / (2·0.24519) / 52,000 = 0.72 — with no allowance added, utilization returns exactly the design factor claimed, which is the arithmetic check on the whole calculation.

4 · Results COMPUTED

5 · Verification statement

The result values above are locked as fixture b31-pipeline-thickness.json, case “B31.4 liquid: NPS 12 X52 @ 1440 psi, F=0.72, E=1, T=1, A=0”, tolerance 0.00001, in the calc-core continuous verification gate (see https://pipingtoolset.com/trust/validation.html). Allowable-stress and factor data are user-supplied inputs; citations: ASME B31.4, Pipeline Transportation Systems for Liquids and Slurries — ¶403.2.1, internal design pressure and straight-pipe wall thickness (numbered ¶404.1.2 in older editions). · ASME B31.8, Gas Transmission and Distribution Piping Systems — ¶841.1.1 steel pipe design formula; design factor F by location class per ¶841.1.6, longitudinal joint factor E and temperature derating factor T per the same section — values user-supplied, not embedded. · ASME B31.11, Slurry Transportation Piping Systems — ¶1104.1.2, straight pipe under internal pressure. · ASME B31.4 ¶402.6 and ASME B31.8 ¶833 — longitudinal and combined stress limits for restrained and unrestrained pipe; outside the scope of this calculator. · API 5L (or the applicable material specification) — source of SMYS and of the pipe manufacturing process that governs E; entered by the user.