Hydrostatic Pressure Testing of New Pipelines

Maq - You are referring to a confidential document, so your request is somewhat inappropriate. However to answer your question just keep reading the document and you will see "note 3" on the next page to the formula to which you refer. This explains the meaning of unrestrained. The rest should be obvious.

You are referring to a confidential document, so your request is somewhat inappropriate

My dear, there are a lot of informations and data stated by the Pioneers and Originals who issuing the Codes and Standards such as :

API RP1110 Pressure Testing of Liquid Petroleum Pipelines.

ASME B31.4 Pipeline Transportation Systems for Liquid Hydrocarbons and Other Liquids.

ASME B31.8 Gas Transmission and Distribution Piping Systems.

Restrain section means the pipeline which does not move to the forces and expansion that is occurring the pipe during the operation condition, while the unrestrained section means the pipeline section that has they tendency of movement due to the operating forces. Usually the section which is comes out of the trench would be unrestrained.