ASME B31.3 Pipe Thickness Calculator

Written by Matt Milbury on . Posted in Calculators

The B31.3 Code contains requirements for piping typically found in petroleum refineries; chemical, pharmaceutical, textile, paper, semiconductor, and cryogenic plants; and related processing plants and terminals. This code prescribes requirements for materials and components, design, fabrication, assembly, erection, examination, inspection, and testing of piping. This Code applies to piping for all fluids including: (1) raw, intermediate, and finished chemicals; (2) petroleum products; (3) gas, steam, air and water; (4) fluidized solids; (5) refrigerants; and (6) cryogenic fluids. Also included is piping which interconnects pieces or stages within a packaged equipment assembly.

Wall thickness of a pipe is calculated using Pressure, Temperature and materials.

Piping dimensions can be found on our piping datasheets.

This calculator makes the calculation using the equation below:


Input Variables are as follows:

  • Design Pressure - Maximum pressure at expected conditions. Generally, the maximum flange pressure at design pressure is used.
  • Design Temperature - Maximum temperature at expected conditions.
  • Nominal Pipe Diameter - Pipe Size
  • Pipe Schedule - Thickness of pipe
  • Mechanical Allowances - This includes material removed from threading and corrosion allowances
  • Mill Tolerance - Allowable thickness variation from the mill that produced the pipe. This is defined by the governing specification. For A-53/ A-106 pipe, the mill tolerance is 12.5%
  • Type of Pipe - This is how the pipe is constructed. The pipe could be ERW or Seamless pipe. A less common type of pipe is furnace butt welded pipe.
  • Significant Figures - Describes how accurate you want the calculation to be.