Author: Chris Holliday

Pipeline Repair of Critical Pipeline System

Impact of an "atmospheric river" on an operator's critical pipeline system and the actions taken to restore operations

In a Nutshell:

On November 14, 2021, a huge storm – specifically termed an atmospheric river – dumped record rainfall across swathes of British Columbia, Canada. Thousands of people were forced to leave their homes; others became trapped on cut-off roads, and several towns were completely isolated. The National Oceanic and Atmospheric Administration defines an atmospheric river as

… relatively long, narrow regions in the atmosphere – like rivers in the sky – that transport most of the water vapor outside of the tropics. These columns of vapor move with the weather, carrying an amount of water vapor roughly equivalent to the average flow of water at the mouth of the Mississippi River. When the atmospheric rivers make landfall, they often release this water vapor in the form of rain or snow.

When this particular atmospheric river made landfall, it resulted in catastrophic damage. In this case study, we are focusing on the impact to an operator’s critical pipeline system and subsequent actions taken in order to restore operation.


ROSEN Canada has worked with Trans Mountain, formerly Kinder Morgan Canada, since 2009. During this time, the majority of our work has involved the utilization of our Diagnostic Services for the inspection of their pipeline and facilities assets, including most of our crack and corrosion detection technologies, along with mapping and routing services. This has resulted in over 10,000 km of inspected pipeline during this period. ROSEN and Trans Mountain have developed a strong relationship over the years based on exceptional service performance, common trust and the pursuit of mutually beneficial goals. A significant example of the trust Trans Mountain has placed in ROSEN is the successful inspection of the extremely challenging NPS 30 Hinton-to-Hargreaves segment during their reactivation work. This project included a full complement of ROSEN crack, corrosion and geometry services propelled by nitrogen where in-depth feasibility studies and simulation modelling were required to validate the proposed operational plan and tools selected. Most recently, the partnership has been significantly extended and strengthened through the provision of a number of time-sensitive critical integrity assessments in response to a major weather event, which presented Trans Mountain with substantial remediation challenges to ensure the integrity of their pipeline assets.

This case focuses on the integrity engineering assessments conducted by ROSEN to support the client with remediation of the pipeline system after the storm. There was a massive amount of work outside of this – including but not limited to surveying, in-ditch efforts and nondestructive testing – in order to repair the damage and restart the pipeline.

So what happened?

November 16, 2021: In response to forecasted heavy rainfall and extreme weather conditions, Trans Mountain safely conducted a precautionary shutdown of the pipeline. The pipeline in question is a critical piece of infrastructure for British Columbia and the State of Washington that supplies both refined products and crude oil, reinforcing the importance of maintaining safety as a top priority while at the same time executing the restart of the line as quickly as possible to maintain that artery for the affected regions. The shutdown led to an energy crisis in British Columbia and initiated the longest shutdown duration since the pipeline’s construction in 1953.

November 17 & 18, 2021: ROSEN’s Education Systems and Services business line hosted a two-day online course called “The Fundamentals of Defect Assessment.” The course covered a number of integrity threats and subsequent assessment procedures; one topic was bending strain. A colleague from Trans Mountain attended the course, which positively influenced their awareness of ROSEN’s capabilities to offer support in the resulting situation.

November 21 - 26: The pipeline remained shut down until detailed engineering assessments were carried out, remediation measures were taken where required, and the Canadian Energy Regulator (CER) gave approval. Throughout the shutdown period, the pipeline remained safely in a static condition, and there was no indication of any product release or serious damage to the pipe.

Trans Mountains’ Pipeline Integrity Team collaborated with ROSEN to carry out desktop assessments. ROSEN assisted with the engineering assessments and provided support and guidance to the field crews. ROSEN’s Engineering Department and Integrity Services business line supported Trans Mountain not just with the assessments themselves but also with presentation of the assessments to the CER. Between ROSEN Canada and ROSEN UK, 24/7, around-the-clock support was provided to Trans Mountain.

During the heavy floods, some major highways were completely washed away, and the ground surrounding the pipeline had completely given way. As a result, there were sections of free span, an unintentionally exposed section of pipeline that is no longer supported by the surrounding soil. ROSEN supported Trans Mountain with detailed assessments of the pipeline’s integrity based on field investigations. At the same time, a field crew supported the pipeline with side booms, and work began on the monumental effort to redirect the flow of the river and construct protective berms to protect the pipeline in the event of another flood.

What can we do without an inspection?

It was necessary to consider the failure modes of free span pipe and determine the credibility and consequential priority of each threat. Threats such as buckling, tensile fracture of circumferential flaws in the girth weld and vortex-induced vibrations were considered and discussed with Trans Mountain. Buckling and tensile fracture were deemed to be the most credible, and Trans Mountain began a campaign to visually inspect all free-span sites for evidence of buckling while ROSEN started the assessment of circumferential flaws.

As part of the process to safely restart the pipeline, it was necessary to calculate safe free-span lengths, but in addition, this 1953 pipeline would almost certainly contain preexisting girth weld flaws. These flaws could have grown in size while, moreover, new ones could have initiated due to the axial stresses from bending and the self-weight of the pipe as the free spans formed. To ensure the integrity of the girth welds on the spanned sections, the CER suggested nondestructive evaluation (NDE) of all girth welds on the spanned sections.

It was deemed highly likely that the NDE would identify girth weld flaws; therefore, ROSEN undertook an engineering critical assessment (ECA) utilizing the EPRG Tier 2 and BS 7910 methodologies, which account for the results from free-span calculations, to determine the dimensions of anomalies that could safely remain in the pipeline without further mitigation. Anomaly sizing from the infield NDE was then compared with the acceptable dimensions calculated by ECA and a "repair" or "no-repair" decision was made in real time.

Regular discussions regarding the safe return to operation of the pipeline were held between Trans Mountain and the CER. ROSEN employees were invited by Trans Mountain to join one of these meetings as pipeline integrity experts to explain the basis of the assessments and calculations we had conducted. Trans Mountain received approval from the CER to restart the pipeline at a reduced operating pressure based on Trans Mountains’ engineering assessment, which incorporated ROSEN’s support. A paper presented by Trans Mountain at the International Pipeline Conference (IPC) 2022 acknowledged ROSEN as a contributing service provider to successfully restarting the pipeline: "The success of safely restarting the Trans Mountain pipeline after a 21-day shutdown involved significant and sustained efforts from Trans Mountain Corporation and a wide range of service and technology providers. The primary service providers involved in this paper’s contents include ROSEN Integrity Services, T.D. Williamson, NDT Global, and BGC Engineering."

Back in action

The restart was successfully conducted on December 5, after 21 days of no flow, following the completion of all necessary assessments, repairs and construction of the protective earthworks needed for the pipeline to be returned to service.

Although this project was small in nature, primarily focused on approximately 500 m of free spans compared to the massive rehabilitation civil efforts and other work necessary as part of the restarting process, it is understood that the results of the ECA conducted by ROSEN allowed Trans Mountain to reduce the time to the restart of the pipeline by 3 days.

ROSEN’s technical credibility and ability to react on a moment’s notice to support one of the most critical and high-profile pipelines in Canada led to an explicit request from Trans Mountain Vice President of Engineering and Director of Pipeline Integrity to conduct a system-wide girth weld ECA of their entire 1,150-km-long pipeline.

Image of Chris Holliday


Chris Holliday

Principal Engineer, ROSEN Canada

Contact us
Close up of a hand holding a cell phone on which the facet newsletter can be seen.

Not yet registered to facets?

Register now if you would like to see more stories like this and receive the latest news and updates.
Read more