Meana Petro

Facilities & integrity

Pipe wall thickness & MAOP

Required wall thickness and maximum allowable operating pressure under B31.3, B31.4 or B31.8, with the class location, joint and temperature factors applied.

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Inputs

The MAOP is computed from this.

Results

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How it is calculated

  • B31.3 process piping: t = PD / (2(SEW + PY)), with Y the temperature coefficient.
  • B31.4 liquid pipeline: t = PD / (2 × 0.72 × SMYS × E) — the design factor is fixed by the code.
  • B31.8 gas pipeline: t = PD / (2 × SMYS × F × E × T), with F from the class location and T from the temperature derating table.
  • Ordered thickness = (required + corrosion allowance) grossed up for mill tolerance, so the thinnest delivered wall still satisfies the design.

Standards it speaks

Where this stops being true

This is the internal-pressure hoop stress calculation and nothing else. Real design also has to cover external pressure and collapse, bending and axial stress from soil movement, thermal expansion, vibration and fatigue, seismic loading, and — for anything sour — the materials requirements of NACE MR0175/ISO 15156, which frequently governs the grade selection outright. The temperature derating table here is abbreviated. A wall thickness from this tool is an input to a design, not a design.

The capability that automates this

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