pipeline commissioning procedure

O&G Pipeline Commissioning Procedure (& Pre-commissioning)

Before the commencement of full-scale operations, newly constructed pipelines are subjected to a series of checks which determine their suitability for their intended functions. These procedures include pipeline pre-commissioning and commissioning checks which are carried out one after the other.

Pre-commissioning is primarily done to ensure that all pipeline construction was satisfactory and meets the standard safety specifications. Commissioning activities can only be carried out after pipelines have been duly pre-commissioned and determined to be safe for initial testing.

Depending on the intended content a pipeline is meant to conduct, these pre-testing procedures may vary slightly.

Why is Pipeline Commissioning Procedure Important?

Oil and gas pipelines are designed to carry volatile and highly flammable contents over long distances. It is vitally important that these transport mechanisms are built to conform to the highest possible standards.

Outlined below are reasons why commissioning activities must be done before pipelines are granted full operational status.

Compliance with Safety and Manufacturing Standards

Pipeline pre-commissioning procedures help to verify that pipelines were constructed according to standard guidelines. This will ensure all further testing will be conducted in a safe and well-controlled environment with the minimum possible risk to the personnel conducting the checks.

Performance Analysis and Checks

Natural gas pipeline commissioning procedures provide valuable data that can be used to predict performance, longevity and improve transport efficiency.

pipeline pre-commissioning

Pipeline Pre-commissioning Procedure

Pretesting natural gas lines follows an ordered set of steps which allow for satisfactory performance analysis. Highlighted below are the key components of pipeline pre-commissioning and commissioning.

Pipeline Flushing/Cleaning

A significant majority of newly constructed pipelines will require initial cleaning before they can be cleared to deliver their intended payloads. Pipeline cleaning services can be carried out both at the pre-commissioning and commissioning phases of final testing.

Flushing out natural gas lines can be done with the help of mechanical devices (pigging) or chemically by forcing chemical compounds through the pipeline channels.


During a pigging operation, a device called a pig is driven through the interior of the pipeline system to clean it and flush out retained impurities. Pig devices can be used in new as well as in-service pipelines to help remove debris and halt the onset of corrosion.

Hydrostatic Pretesting

Hydrostatic testing involves passing a liquid through the newly constructed pipelines to detect areas of leakage. Water containing a dye is the typical medium utilized in this test. This type of screening test is the most commonly used method of checking for pipeline integrity.

Additionally, altering the pressure of the fluid during the hydrostatic test procedure for pipelines can help determine unusual pressure bleeding. A modified form of hydrostatic pressure testing can be done at intervals to ensure sustained flow line integrity.

Pipeline Dewatering

Hydrostatic testing processes leave moisture within the pipelines they check. The presence of vaporized water within the lumen of pipelines constitutes a potential impurity for fluids that are transported through them.

Pipeline drying services will remove the retained moisture from within the pipes and ensure the quality of the products transmitted through them.

Pipeline Purging

A vital aspect of natural gas pipeline commissioning procedures is the purging of flow lines. Atmospheric air present within newly forged pipelines will alter the quality of their intended gaseous or liquid cargo as it contains suspended impurities.

Pipeline purging is done as part of commissioning procedures and it involves using an inert gas (usually nitrogen) to replace the air contained within the flow line lumen. Nitrogen purging is an effective and cost-efficient method and can be carried out using on-site nitrogen generators.

Vacuum Drying

This process involves the use of a high-volume vacuum to manipulate the pressure within the pipeline system. At pressure levels 40 Torr or below, water deposited within the flow lines will vaporize and can then be displaced leaving the moisture content within the pipelines at minute quantities. The remaining moisture can then be eliminated by purging the lines with an inert gas.

Nitrogen Drying

The importance of properly drying pipeline networks cannot be overemphasized. Poorly dried pipelines are at a higher risk of corrosion, hydrate formation, and blockage. Utilizing nitrogen-based drying to clear out moisture will limit the onset of potentially hazardous leaks and minimize the cost of pipeline maintenance services.

Safety Tips for Pipeline Commissioning (& Pre-commissioning)

Pipeline safety precautions can maintain both the health of your workers and efficient operation. To avoid accidents and ensure the safety of the manpower involved in all aspects of pipeline pre-commissioning and commissioning, the following steps must be taken:

  • Proper training and briefing of all personnel on their safe performance of their duties, knowledge of emergency shut down and evacuation plans with the designation of multiple points of egress
  • Diligent instruments/apparatus (electrical wiring inspection, lubricant checks) with the replacement of faulty parts
  • Provision of and mandatory use of personal protective equipment

Trust NiGen for Your Pipeline Maintenance

Since its inception, NiGen International has remained dedicated to providing turnkey solutions required for optimal productivity in various manufacturing processes including applications in oil and gas industries. Our unique approach to industrial maintenance will ensure your pipelines receive the best quality treatment needed to keep them functioning at optimal levels.

Contact us online today for more information about our products and services.