[The Perle repair project] Joining of the SSN sections in April

01 June 2021 Defense Naval Group Submarines Innovation Story

The project to repair the nuclear-powered attack submarine started in on the site of Cherbourg in November, after a fire the previous June that occurred while the vessel was in Toulon for a long technical stop. Sylvain Tirand, Deputy Director of the Perle program, and Guillaume Romain, department manager for the Perle operations, review project of joining of the SSN sections, citing the exceptional dedication of the team members to enable the vessel to return to its home port by the end of the year for the remaining work.

The repair solution selected consists in joining the rear of the Perle with the fore section of the Saphir, an SSN removed from active service in 2019. How was the junction operation organised?

Sylvain Tirand: The Perle arrived at the site of Cherbourg in early January where it was set down on the submarine launching facility (DME); the Saphir took its place mid-February.

Preparation of the cutting and joining areas of the submarines had started back in October in Toulon for the Perle and in November for the Saphir in Cherbourg. This work consisted in removing and dismounting the equipment in the cutting area to preserve its physical integrity throughout the operation.

The teams also performed electrical and alignment checks of all cables and repaired the collectors which will enable the back of the Perle to be joined to the front of the Saphir.

At the same time, the conventional tasks of a repair and overhaul (ROH) - dismounting operations and work on the hull - were started in November.

Over February and March, the teams in Cherbourg cut the two submarines open - both operations went very well. They then used a dual walking beam to move the submarine subsections, and aligned them for joining (welding of the pressure hull). This work has just been completed on the DME.

The Perle will be launched in June and transferred to the Homet site for the splicing and reconstitution work. The submarine will then return to Toulon in early November for the remainder of its ROH.

What skills are involved in this project?

Sylvain Tirand: All of the group’s resources are involved in this repair project, but most notably in the Services division. Engineering skills are needed to complete the upstream design studies of the new frame space and to produce the associated change orders as quickly as possible, but production requires skills in production engineering and those to perform the hull, mechanical and electrical works defined by the engineering teams. The project requires the unique and rare skills of submarine construction as well as those of our partners in Toulon.

But to succeed, it is commitment that counts above all: we needed our “experienced experts” as well as our younger or less experienced employees! The commitment of the new construction and ISS (In-Service Support) teams is also important as they have been collaborating closely to ensure the success of this project.

How do you organise this coordination between the Cherbourg teams and the work done by the remote teams?

Guillaume Romain: In spite of the high level of coactivity, coordination is excellent. Every morning, the production supervisors in Cherbourg and Toulon review the day’s work together with representatives from each speciality trade.

The project involves between 100 and 150 employees, including local partners, depending on the project phase. They have volunteered for this project and are working 900km from home until autumn 2021, on 2x8 or 3x8 hour shifts including Saturday mornings. Their commitment and enthusiasm for the project are truly exceptional!

We have a charter plane every Friday and Monday to take them home once a fortnight and adaptations have been made on site to welcome them - living areas with cloakrooms, offices and dining rooms – as well as a project coordination office.

What jobs are done by the Toulon teams?

Guillaume Romain: The Toulon teams have done all the preparation work for the cutting operation. They have been working in parallel on the hull restoration work required by the repair. This summer, they will also be responsible for splicing the connections and reconstituting the decks and internal partitions. The teams will also be responsible for finishing the repair and overhaul work when the Perle returns to Toulon.

Guillaume Romain