Pipe Wall Thickness Calculation

Read about START-PROF pipe stress analysis software

Steel Pipes

Steel pipe nominal wall thickness is calculated as:

SSR + С,


Total Allowance, Mill Tolerance, Corrosion Allowance

Total allowance C is calculated as:

С = С1 + С2,


Note that nominal wall thickness  S should not be lower than values in standards, and that S is rounded up to the closest wall thickness according to standards or technical conditions.

Wall Thickness Analysis for Design Pressure

Prior to analysis (at the  input data logic check stage), START-PROF checks wall thickness for design pressure using:


Nominal wall thickness S and total allowance  C values are input in element properties. SR - minimum design wall thickness for design pressure according to standards selected in Project Settings.

For ASME code wall thickness is checked only for straight pipes and pipe bends. For all other fittings wall thickness is not checked.

Wall Thickness Analysis for Test Pressure

If test pressure value at manufacturing facility is lower than required, there must be a guarantee of the ability to run hydraulic tests during construction up to the pressure causing equivalent stress equal to:

Based on this, START-PROF checks wall thickness for test pressure using the formula (for GOST 32388-2013 only for sustained mode):


ST - minimum wall thickness for test pressure calculated according to standards selected in Project Settings. Test temperature Тtest is input in Project Settings, test pressure Ptest is input in element properties, material yield strength is in the  materials database.

Note that, according to  GOST 8731 and GOST 8733, carbon and low allow steel seamless pipes must withstand hydraulic pressure at allowable stress equal to 40% of tensile strength for the given steel brand σ = 0.4, which  does not always correspond to requirements of standards.

Pipes will meet  GOST 8731 and GOST 8733 criteria only if they meet the following condition:


Let's look at an example - steel 20. According to [2], tensile strength value at 20°C = 460 MPa, yield strength = 250 MPa; the condition is then:

0.4 460 < 0.9 250 MPa


184 < 225 MPa,

i.e., the condition is not met. This indicates that standard requirements regarding allowable test pressure are not met and the manufacturing plant must be given more strict conditions for tests at 225MPa pressure (GOST documents have a note regarding this).

Fiberglass Piping

Reinforced wall thickness is calculated as:




1. PB 03-585-03, rules of design of process piping, Moscow, 2003

2. GOST 34233.1-2017 Boiler and pressure vessels code