Equinor reveales the deviation in quality of welding and inspection of the Johan Castberg production vessel
An in-house investigation team from Equinor has studied the deviation in quality of welding and inspection of the Johan Castberg production vessel currently under construction at the Sembcorp Marine yard in Singapore. Extensive work is being carried out to quality assure and cross-check welds and repair welding defects, to ensure that the vessel meets applicable safety and integrity requirements before leaving the yard, according to the company's release.
During construction of the hull for the Johan Castberg production vessel at Sembcorp Marine in Singapore, Equinor has revealed quality deviations regarding both welding and welding inspection.
The yard is responsible for correcting all deviations in quality and costs related to repair of welding defects are covered by Sembcorp Marine, according to the contract. The cross-checks and improvements are almost completed and are followed up closely by Equinor.
The investigation team did not find any single event which can have been a direct cause for the welding quality issues, but have pointed out causal factors considered as having had an impact:
Contractor (SCM) failed to provide sufficient competent welders and welding inspectors for execution of the scope and did not sufficiently comply with processes and work routines for execution and follow up of welding and inspection activities.
Equinor has not sufficiently complied with its own work processes and procedures for risk management, construction management and follow-up at the construction site.
Even if Equinor’s follow-up team found signs of poor quality at an early stage, the extent and degree of seriousness were not understood. Sufficient measures were therefore not implemented.
Equinor’s follow-up team has not had enough personnel with experience and expertise in welding and welding control and has not utilized the company’s technical expertise in these areas early enough.
The investigation team has studied the causes of the deviations in welding quality in the period from January 2017 to October 2019.
Based on this work the team recommends Equinor to improve:
the prequalification process for new suppliers
the practice for follow-up at construction sites, including risk management
the recruitment process for follow-up teams and team composition
When Equinor in the summer of 2019 cross-checked Sembcorp’s ultrasonic inspection of welds in the moonpool area of the hull by using own personnel, they discovered a higher failure rate than reported. It was then decided to cross-check all assembly welds. Unusually high failure rates in fabrication welds were revealed later.
A reassessment of all structural welds has been made and extensive cross-checking is being carried out by use of non-destructive testing (NDT), including ultrasound.
The hull for the Johan Castberg production vessel is scheduled to be transported to Stord on board the Boka Vanguard heavy-lift vessel late 2021, however the Covid-19 pandemic still adds uncertainty to all schedules.
