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Hydro-test for pipeline

asked Nov 16, 2015 in Calculation by khaled abd el aziz (155 points)
Dear sir

would you please to tell me how to calculate the hydrotest for the pipeline



2 Answers

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answered Nov 16, 2015 by TPham (5,010 points)

Please consider the following equation for hydrostatic pressure test:

Pe = 9.806(Pw)(X)  (Metric units)


P= (Pw/144)(X)  (Customary units)

Pe = External hydrostatic pressure, Pa (psi)
Pw = Density of external fluid, kg/m3 (lb/ft3)
X = Minimum pipeline depth below lowest astronomical tide (LAT), m (ft)


The minimum Test Pressure (Pt) should be determined from:

Pt = k(MAOP)

MAOP is Maximum Allowable Operating Pressure
k = 1.25, 1.40 or 1.50 depending upon the type of commissioning test and the piping code used

Note:  Refer to EPT 09-T-05 for the applicable piping code. The MAOP should not exceed the following:

  • The established pressure rating of the weakest component, including pipe
  • 80 percent of the Test Pressure (Pt)
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answered Nov 16, 2015 by TPham (5,010 points)

Not sure of what stage you want to hydrotest the pipeline, but beside the equation as shown, if it is during construction/commission and the entire length of the pipeline can be loaded on the vessel reel, a hydrotest of the pipeline should be performed in Contractor's yard to ensure that testings required by the client to confirm acceptable post-installation thermal performance.

In addition to the external hydrostatic pressure, calculations should also consider the resistance of pipelines to buckling and collapse due to the following combined actions which arise from the pipe mechanical and dimensional characteristics during the laying operations:

  • Bending stresses
  • Axial stresses

Hope that gives you some feedback on hydrotesting of the pipeline.