Troubling construction errors have beset an Equinor-operated vessel bound for harsh Arctic conditions in the Barents Sea, making it vulnerable to fatigue and accidents if it enters service, Bellona has warned the government in a series of two letters over as many weeks.

Major welding issues on the hull of the Johan Castberg, a production, storage and offloading vessel under construction in Singapore, came to light in October of 2019, and a grave flaw with the design software for measuring hull fatigue was discovered in April, Bellona President Frederic Hauge writes in his letters.

“Bellona would like to point out that this is very serious, with a significant potential for safety and financial consequences for the project,” writes Hauge. “With a storage capacity of 1.1 million barrels of oil, there is also a significant environmental risk should an accident occur. We also point out a significant lack of quality assurance through the design process, as this has only been discovered now.”

At worst, says Hauge, the software errors could mean that engineers have underestimated the effects of fatigue on the vessel’s hull, necessitating that several critical parts of the ship and its production facilities be rebuilt.

The software error comes in a program called Stofat, which was issued by DNV GL, the world’s largest accredited registrar and vessel classification society, which is headquartered in Norway. Because of that, Hauge has warned that the bug could have repercussions not just for the Johan Castberg, but other floating production storage and offloading units as well.

Frederic Hauge, Bellona.

Equinor has responded in Norwegian media, saying the that the safety issues posed to the Johan Castberg are “manageable” and that the software error will not require the FPSO’s redesign.

The software issue was first reported on Friday by Upstream, an industry trade magazine. According to the publication, Norway’s Petroleum Safety Authority (PSA) was not informed about the issues until meetings with Equinor in June and August of this year.

Hauge’s letters are addressed to Tina Bru, Norway’s minister of Petroleum, Torbjørn Røe Isaksen, the minister of labor and social affairs, as well as to the Petroleum Safety Authority and Norwegian Parliament’s Energy and Environment Committee.

In them, he writes that that the software error means that only load on the front portion of the ship has been calculated in its design and dimensioning. Load to the ship from the side, says the letter, has not been accounted for in the calculations, Hauge says.

“Bellona has in this case received warnings from several sources,” he writes. “This underscores for us the seriousness of this matter. In Bellona’s opinion, an independent investigation of the conditions described in our two notices should be initiated immediately.”

Upstream reports that delivery of the Johan Castberg has been pushed back by at least a year but could be delayed even further by Covid-19-related restrictions on welding and other manpower at the shipyard. The vessel was subsequently due to arrive this autumn at Kvaerner’s Stord yard in western Norway for installation of topsides modules being fabricated by the Norwegian contractor, Upstream reports.

Morten Ruth, who directs the Castberg project for Equinor, told the E24 news outlet that some three kilometers worth of welds will now be redone on the vessel now that the software error has been brought to light.

Ruth downplayed fears that the Johan Castberg would have to be completely rebuilt, saying that the miscalculations only impacted part of the overall design.

“Of course, we are not happy when we discover software errors,” Ruth told E24. “But for the Castberg project, this is manageable. We will send out a ship that has the necessary integrity.”

But Hauge criticized the apparent sluggishness with which the software error came to light, saying that Equinor and DNV GL should have reported the bug to PSA and other stakeholders far earlier than this summer.

“I am shocked by Equinor,” says Hauge. “They have known about this since April but did not inform the Petroleum Safety Authority Norway until this summer.”

Ruth pushed back on this, saying that Equinor’s safety routines had worked as planned. As far back as February, Ruth told E24, Equinor had been rechecking the Johan Castberg’s welds.

“We follow up welding, and when we see that the number of errors is too large, we increase our inspection rate,” he said. “It started already last autumn, when we saw that the error rate increased, and in February we decided to run a full check of the welds made in the dock.”

For its part, DNV GL has told Norwegian media that it has contacted builders that have licenses for the Stofat software and has issued an update to address the error and additionally published.

“In April 2020, DNV GL understood the consequences on how Stofat software was used for calculation of hull fatigue for certain combinations of wave conditions. The issue is mainly seen on FPSOs with weather-vaning capabilities and may impact the estimated fatigue life of the vessel, which has no immediate consequence for its structural safety,” the company writes. “License holders were immediately contacted in order for them to take appropriate action. Furthermore, DNV GL publicized the issue in the software status list, which is accessible through our website. In July 2020 a new version of Stofat was released addressing the issue. DNV GL is supporting affected customers to mitigate the potential consequences of the software issue.”