A widely accepted method for validating pipeline integrity, hydrostatic testing (or hydrotesting, as it is commonly known) is performed before commissioning new pipelines or facilities and after the repair or replacement of an in-service pipeline section.
Hydrotesting enables Gas Distribution operators to identify manufacturing flaws or other defects, mitigate risk, and establish maximum allowable operating pressure (MAOP). In addition, hydrotesting is used to re-qualify a pipeline after a class location change.
Pigging services are used in a variety of pre- and post-hydrotesting activities, including:
TDW helps operators comply with regulations for the safe and effective hydrotesting of natural gas and liquids pipelines.
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Because they are efficient, effective, and easy to launch and retrieve, pigs are the preferred tools to prepare pipelines for hydrostatic testing (or “hydrotesting”) and to help return lines afterward to their operational state.
Pigging helps ensure the line is clean and free of debris that could damage hydrotesting equipment. Pigs are also used in filling the pipeline with water or other testing medium, and to dewater and dry the pipeline after the hydrotest is complete. Drying the pipeline prevents product contamination, eliminates downstream equipment freezing, and reduces the possibility of corrosion sites forming.
TDW can help Gas Distribution operators select and deploy the appropriate pigs for pre- and post-hydrotesting activities: cleaning, line filling, batching – which provides an easy-to-manage sealed interface ahead of the water or testing medium – dewatering, drying, and the application of chemicals, including corrosion inhibitors.
Pigs for line filling and batching:
Pigs for dewatering (liquids displacement):
Pigs for line drying:
Pigs for application of chemicals:
Technical assistance is available from TDW subject matter experts for special circumstances or if the path to a solution requires consultation.