Subsea pipes repaired due to underwater welding habitat

Oil and gas subsea pipelines require maintenance or improvement jobs to be done over time. To make these jobs, offshore service companies use rigid underwater welding habitat.

Those habitats are immersed and positioned on the pipe. Then, it seals perfectly around this pipe. Water is taken out and diver can go in to do the job.

Project’s requirements

Equinor, one of the major players in oil & gas and renewables markets, has to modify some subsea pipes. For this project, called Heimdal, two platforms are to be decommissioned and a bypass spool to be implemented between existing lines.

The first welding device was designed 25 years ago and already used our flexible doors. It was time to replace them and enjoy some technical improvements.

Perfect sealing is the key to these underwater operations, so our products had to very accurate in terms of dimensions to be as close as possible to the pipe. If not, water would come in and no job could be carried out.

Pronal’s solution, flexible doors for underwater welding habitat

Pronal has designed and manufactured two membranes:

the first one to be used on a 36” pipe
the second one to be used on a 32” ipe (on the opposite side).

Those membranes make the sealing around the pipe. they are vulcanized in one operation and thus completely homogeneous. This manufacturing process makes the product strong and reliable.

Because of the criticity of this product, testings are fundamental. Our customer shipped to our factory its test bench and a long batch of tests were done in-house. Quality tests went perfectly and the doors could then be installed in the habitat.

Test de porte souple pour habitats sous-marins

Why use flexible doors and not rigid doors?

Using flexible doors, instead of rigid ones, enables significant time savings. Due to the hydraulic brackets, where the doors are installed, all the devices could be run automatically.

No human actions are required to obtain the sealing on the pipe, the inside room of the habitat is fully hermetic No matter how deep the pipe is, our door does the job on their own. Using rigid doors will necessarily require human action.

Habitats sous-marins à portes souples automatiques

Conclusion

Those welding habitats are now equipped with brand new flexible doors. The inner room of the habitat can be hermetically closed. Subsea jobs can be carried out safely.