Paper over the cracks

From the very moment a pipeline is commissioned, it starts to deteriorate. Even with the best protection, systems and coatings, corrosion sets in. Over time, this will eventually compromise the pipe wall’s integrity. However, despite this slightly gloomy statement, today’s operators have new technologies available to them that allow them to not only detect defects but also bring them to heel.

In this respect, the oil and gas industry actually has much to cheer about. The latest figures suggest that pipeline failures are decreasing, suggesting a pervasive safety culture. However, the operators cannot afford to rest on their laurels. Even a miniscule crack on a pipeline – it may be almost invisible to the eye – can, if not treated, be catastrophic.

Traditionally, the leading cause of pipeline failure is damage resulting from outside force, which accounted for 35–50% of incidents in Europe and the US between 1970 and 2001. It still remains a serious challenge, as third-party damage – whether it be accidental or intentional – tends to still go unreported at the time of incident, allowing defects to fester over time.

According to the Pipeline & Hazardous Materials Safety Administration (PHMSA) – which comes under the US Department of Transportation and publishes statistics on the causes of pipeline incidents and failures – between 2004–18 the main causes of pipeline incidents were excavation damage (33%), incorrect operation (11.9%), other outside force damage (6.8%), manufacturing and equipment failure (6.9%), corrosion (5.6%) and natural force damage (4.6%).

The damage done

Damage by third party is the most common cause of pipeline incidents. What much of this boils down to is solid integrity management, as much as the pipeline itself. Pipeline failures aren’t necessarily related to age; a newly commissioned project carries just as much risk as a pipeline that has been in operation for decades.

Better pipeline integrity has also been facilitated in recent years by the introduction of new laws and regulations. As aforesaid, this has been twinned with new technologies coming to the market, such as smart tools for the detection of cracks. With the rise of the internet and social media, communication channels are also better than ever before, operators can be updated on a pipeline failure almost instantly. Staff have reams of technical information at their fingertips.

As the world’s first and only fullstream group, Baker Hughes, a GE Company, uses advanced technology to deliver pipeline safety and integrity. The company has built a reputation as a provider of reliable inspection data, with its solutions dating back to the development of magnetic flux leakage tools in the 1960s to manage corrosion and metal loss.

The group’s technologies allow the accurate location and highlighting of potentially dangerous cracks, and the identification of stress corrosion and cracks of unknown gestation. It also employs engineering techniques to predict rupture pressure, which occurs when adjacent cracks interact.

Stuart Clouston, in-line inspection product management leader, process and pipeline services at Baker Hughes is joined by Dr Phil Hopkins, one of the world’s foremost pipeline experts, and a visiting professor at Newcastle University, to discuss another of the upstream segment’s biggest headaches around pipeline integrity increasing rates of third-party damage. Oil theft reputedly cost the Chinese oil industry more than $124.6 million in one year alone, while between 2002–09 one unnamed company encountered 19,804 cases of oil stealing, involving drilling into oil pipelines, as well as 12,167 cases of direct theft from production wells. Companies that fail to tackle these are at risk of losing out on billions of dollars.

Baker Hughes has developed a technology, ThreatScan, which is able to assess construction and third-party damage and product theft. In the event of any impact on the pipe wall, acoustic waves are created, of which ThreatScan measures the timing and magnitude to determine the location and severity. Data is then transmitted to a central system for detection analysis and alarm confirmation. This all takes places within a few minutes. Another hot topic is line piggability. Pipeline inspection gauges (commonly abbreviated to PIGs) are devices mostly used to clean or clear the line of debris, which in turn allows a better flow of the product through the line while reducing the likelihood of contamination.

Smart PIGs are coming under increasing demand as operators look to detect the various elements of their pipeline. These devices are able to amass an array of information on everything from temperature and pressure to corrosion and metal loss, diameter, bend and curvature. This information is then processed to provide a clearer picture of a pipeline’s integrity.

This little piggy

Aside from issues caused by third-party sources, issues regarding the breakage or splitting of pipes can cause serious setbacks – with labour and economics taken into equal consideration.

Clouston knows all too well that cracks can develop, and where is most likely to be affected. “The types of cracks most likely to develop in operating pipelines are stress corrosion cracks (SCCs), fatigue cracks, hydrogeninduced cracks and sulphide corrosion cracks. They can occur in the base materialof the pipe, in welds and in the heat-affected zone adjacent to welds,” says Clouston. “Cracks can also appear in substandard axial and girth welds, and can occur in conjunction with other flaws such as dents, gouges and corrosion. Although a crack may be almost invisible to the eye, it can still weaken a pipeline enough to cause leaks or even failure.”

Hopkins agrees with Clouston, stating, “Today, the most common cracks leading to failures are cracks grown by fatigue, cracks caused by a combination of stress in the pipeline and corrosion. These are SCCs.” The threats posed by these cracks are managed by pipeline operators through a winning combination of good operating practices, hightechnology inspections and repairs.

“With regard to the aforementioned unpiggable pipes, pipelines around the globe cannot be inspected with in-line inspection tools, this is due to tight bends, multidiameters and plug valves, among other challenging features. However, inspection technologies can be engineered to overcome some of the common unpiggable challenges but our CPIG inspection tool, with its dual diameter capabilities, short length and low drag operation is particularly suited for these lines previously considered decidedly unpiggable.”

Clouston provides a solution, remarking that, “Baker Hughes offers a range of services to help operators meet these challenges, minimising disruption and replacement costs while meeting regulations. These include feasibility studies and customised cleaning programmess to determine the state of debris and build-up in a pipeline that could interfere with in-line inspection.”

In agreements, Hopkins ascertains that new pipelines are designed to be able to accommodate in-line inspection. These ‘smart pigs’ are facing an increasing demand, as older pipelines lack the technology, due to subsize valves, among other issues. However, Hopkins is optimistic in the capacity to refurbish older tools: “These older lines can be modified and upgraded,” he concludes.

Crash the third party

Third-party damage continues to be a threat to many pipeline operators. However, adoption of recognised good practices and intelligent technology can minimise the threat. Technologies such as aerial surveillance or use of protective measures, such as placing concrete slabs over a pipeline, are efficient with third-party damage.

“A far bigger threat to mitigate is theft,” says Hopkins. “There has been a startling increase in theft of product from pipelines. Historically, theft has been endemic in countries such as Nigeria and Mexico, but it is now becoming a worldwide problem. It is an increasing worry in Europe and also a problem in countries where poverty is the driver, or where high fuel costs are a factor, or where organised gangs can steal on an industrial scale and create major outlets for the stolen product.”

“Accidental or intentional third-party damage is especially dangerous for operators because it often goes unreported at the time of occurrence, allowing defects to deteriorate for months or even years,” Clouston agrees. “Product theft can be extremely dangerous with several attempts at theft resulting in casualties among perpetrators and innocent bystanders alike. Product theft also poses a threat to the future integrity of a line, and can impact pipeline operator’s revenue.”

To combat the prevalence of third-party intrusion, Baker Hughes’ ThreatScan technology is designed to detect impacts to the pipeline – these could be in the form of an attempted product theft or an anchor strike to a subsea pipeline.

An impact on a pipe wall will create acoustic waves. The ThreatScan technology measures the timing and relative magnitude of these waves to determine the impact location and severity. Data is immediately transmitted via any type of communication network to a ThreatScan supervision system for analysis and expert alarm confirmation.

The customer is notified within a few minutes to enable fast and effective reaction to the strike to protect the pipeline and to determine the cause of the strike. The sensor equipment attaches easily to aboveground pipeline features so no excavation is required and the system can be easily retrofitted to existing pipelines.