Appropriate Methods for Repairing Pipelines

For several decades, the constantly expanding network of onshore and offshore pipelines has facilitated the transportation of increasing amounts of refined petroleum products, industrial chemicals, crude oil, and natural gas to commercial and residential customers.

North America exemplifies this trend with the largest network of gas and crude oil pipelines in the world, in addition to pipelines carrying petroleum products and natural gas liquids.

Recognizing the critical role of pipelines in safely distributing these essential but volatile substances, regulations mandate that pipeline operators maintain the integrity of their pipelines. This involves performing both preventive and regular routine maintenance and repairs to ensure optimal performance and prevent potential system failures.

However, the United States has experienced over 3,200 serious gas pipeline leaks since 1987, as reported by the Pipeline and Hazardous Materials Safety Administration (PHMSA).

Reasons for Failure

Despite stringent quality control inspections during pipeline section manufacturing, failures still occur due to:

Undetected manufacturing flaws that can deteriorate over time, leading to cracks or leaks if not discovered during regular pipeline inspections.

The conditions in which pipelines are buried, which can promote external and internal corrosion. Regular inspections and maintenance are crucial to detect and address corrosion or cracks throughout a pipeline’s average lifespan of 50 years.

Repair Options

Even with inspection procedures and advanced technology to minimize pipeline failure risks, the need for repairs is inevitable due to their longevity. Several repair options are currently available:

The most time-consuming and expensive option involves replacing the damaged pipeline section, which requires pipeline shutdown, isolation, and testing before reactivation.

Sleeve repairs, available as Type A and Type B, can be performed while the pipeline is in service.

Type A sleeves encircle the damaged section but do not directly contain pressure or leaks, while Type B sleeves are welded onto the pipeline surface and can repair leaks and reinforce defects.

Composite wraps are permanent, cost-effective solutions for non-leaking issues such as pits, dents, gouges, and external corrosion. They can be applied to pipelines in service and restore pressure-containing capability while inhibiting external corrosion.

Hot tapping repairs corrosion or mechanical damage or adds branches for system modifications. This method involves drilling or cutting into the pipe and welding while the pipeline is in operation, minimizing environmental damage and greenhouse gas emissions.

Mechanical bolt-on clamps or structural clamps encapsulate damaged or leaking pipes and restore pressure integrity through mechanical seals.

Selecting the most suitable repair method involves considering external factors like timing, material availability, regulatory requirements, and environmental concerns, as well as technical issues and the pros and cons of various repair solutions.

Ultimately, maintaining the integrity and safety of pipelines, which are crucial to modern economies, requires regular inspections, maintenance, and appropriate repairs throughout their lifespan.