Hydrostatic testing of pipelines – risks & solutions

July 2, 2024 2:38 pm Published by

A critical step in the building and upkeep of pipeline networks for the long-distance transportation of gas, oil, and other fluids is hydrostatic testing or hydro testing. To inspect for leaks or flaws in welds, joints, or the pipe material itself, entails pumping water or other inert fluids into the pipeline under high pressure. However, the process also comes with certain risks that need careful planning and mitigation measures to address.

Stress ruptures

While modern pipelines are designed with safety factors and constructed to stringent standards, flaws can potentially develop during fabrication or operation over time. A catastrophic failure during hydro testing can cause environmental damage, injury to nearby workers and communities as well as costly repairs and delays to commissioning projects. That’s why most regulations require independent hydro-test witnesses in Saudi Arabia and other regions to be present during critical pressure tests to monitor and verify procedures.

Managing test water

Another issue is managing the large volumes of test water that must be pumped in and then drained out safely without contaminating soil or water sources. Often test sections are conducted in remote pipeline routes through difficult terrain, requiring careful planning for water sourcing, storage, and disposal. Permitting related to water extraction and effluent discharge also needs to be handled meticulously to avoid any non-compliance.

Internal corrosion

Internal corrosion of the pipe’s internal surfaces over years of operation is a key factor that hydro testing aims to detect. However, cathodic protection and coatings may slow water’s access to problem zones, hindering timely detection. Advanced techniques like intelligent pigging can supplement hydrostatic testing by providing more accurate internal inspection. But pigs may not be feasible for all line diameters or conditions.

Unknown Future damage

While hydro testing is valuable, over-pressurizing pipelines to discover their absolute maximum tolerance can potentially cause unknown damage and result in future issues. A risk-based approach determines the optimal test pressure considering factors like pipe material, coating type, operating conditions, corrosion allowances, and expected design life. Hydro-test witnesses in Saudi Arabia play an advisory role here to validate if test pressures are commensurate with these system-specific criteria.

New technologies are now available for continuous monitoring of pipelines during hydro testing using distributed acoustic sensing or optical fiber reflectometry. Fiber optic cabling deployed along the route can pinpoint leak sounds or vibrations with very high spatial resolution. Such advanced “leak-before-break” solutions identify even minute defects at incipient stages, helping switch testing strategies proactively instead of facing emergencies.

Effective planning and independent oversight are crucial to balancing the risks and rewards of hydro testing pipelines. Quality assurance professionals are well-versed in regional regulations and familiar with the latest integrity evaluation methods that can significantly improve safety and reliability.

Tags:

Categorised in:

This post was written by Bin Dasmal Group

Comments are closed here.