The "Cracks in the Turbine
Exhaust Supports" Campaign
SubC Partner initiated the job at Dan FG the 27th September 2019 and completed the job the 11th October 2019 - precisely 14 days later despite of challenging weather conditions.
Cracks in the support structures
The Total-operated Dan FG platform is located in the Danish Sector of the North Sea. On Dan FG, cracks were observed in the support structures for the exhaust stacks for water injection and IP/HP compressor. To be exact the cracks were observed in the joint between the flange of the ring stiffener and the SHS beam welded to the ring stiffener. The support structures also contained the exhaust for the turbo generator stack, which needed to be shut down during the repairs.
Both exhausts are horizontally supported at two levels, El. + 46,500 and El. + 57,000, with 4 beams at each level (i.e. totally 16 off).
SubC was contacted by Total to repair the cracks in the support structures. This as a part of Totals W2W (Walk to Work) Boat Campaign. Since the temperature of the stacks reaches 340 degrees, a shut down during the repairs was unavoidable. The objective for solving the project was, therefore, to perform the work within a short time frame to reduce the costs due to shut down. Therefore, we decided to offer the most cost-effective, feasible solution; to complete the job within 14 days.
SubC completes the job within 12 workdays
14 days was our target and to keep the time the SubC crew, comprised of scaffolding workers, welders, smiths and painters, worked day and night; 46,5 metres and 57 metres above sea level. Our 20 colleagues out in the North Sea was met with challenging weather conditions, though.
Before we initiated the job, then the customer expressed some scepticism with the short time frame of the project. Thus, we had a particularly satisfied customer when we completed the job within the time frame.
Scope of work
- Project management and administration
- Onshore work preparations including method statement permit work orders and PIMS.
- Installation of scaffolding around the stacks and up to upper supports in El. + 57,000
- Installation of welding habitat
During this phase, we were forced to stop the work for 2 days due to severe windy weather. The project was therefore completed within 12 workdays, i.e. days the crew had a genuine possibility to perform their job.
The diameter of the exhausts is 2.763 metres respectively, and the area of the welding habitats is 45 square metres respectively.
- Replacement of 16 beams
The existing support was cut off and replaced with new. Afterwards, our completion of work included: bristle blasting, coating, As-Built documentation and updates of PIMS.
The support structures before and after we completed the job:
- Dismantling of habitat
- Dismantling of scaffolding and other equipment
Additionally, we performed NDT testing in breaks to put the time to good use.
All in all, a successful project despite severe windy weather during the entire Crack in Turbine Exhaust Supports Campaign.