[Perle site] Joining the hull: a job for the experts

Antoine Butel

04 June 2021 Defense Naval Submarines Innovation Story

Stéphane Grout and Antoine Butel, Foreman and hull Work package manager respectively, share an office at the site of the Perle nuclear-powered attack submarine (SSN) project, providing the benefits of their complementary experience to work on the hull, thus optimising the repair schedule. We asked them about the hull joining operation, which began on 20 April, and involves the key skills on the site of Cherbourg.

The project benefits from the experience of a whole career

Since his apprenticeship with Naval Group in 1982-83, Stéphane Grout has gained exhaustive expertise in all jobs related to the hull, having worked mostly at the site of Cherbourg but also on temporary missions in Lorient, Brest and even Rio. After eighteen years in forming, he held positions in preheating-welding, forming, oxycutting, joining-keel block line installation-transfer (in collaboration with the dual walking beam system teams), as well as manufacturing the various elements of the submarine hull and structures.

This wide-ranging experience brought him to the position of Foreman in January 2021, to head the hull team on the Perle project, a position he will hold until he retires next June. “My job is to provide the human resources and equipment required for production,” he explained. “My knowledge of the different hull jobs and my large network in each area helps me to evaluate the exact requirements in terms of employees for the various stages of the project and to ensure efficiency without encroaching on the resources of the Barracuda programme. With Antoine Butel, I also make sure that the operators under my supervision have good working conditions. Some perform very physical and purely manual tasks, so we must guarantee their safety and pay attention to them so that they do not over-do it. Based on my experience, I try to ensure the serenity of the operations, although the pace will remain intense until the end of the project.”

Scheduling, another key to the success of the programme

Antoine Butel joined Naval Group four years ago, as Head of the hull system for the Barracuda programme including the test and acceptance phase of the Suffren last summer. He joined the Perle programme in October 2020 as Hull studies manager to coordinate the detailed studies of the cutting and joining operations on the nuclear-powered attack submarines (SSN), Perle and Saphir. At the end of December 2020, he became Work Package Manager (WPM) for the hull, coordinating the cutting and joining work to be done before the reconstituted Perle is launched again in June 2021.

“The complexity of this project is to complete a series of major operations within a short time,” he explained. “I am responsible for coordination and for making sure that we are always ready for the next step.
My previous job in studies helped me to develop an overview of every stage of the project so that I can refine and optimise the execution schedule.
My technical skills and network help me to be reactive in the field, to find technical solutions to make the operators’ work easier and limit the impacts of unexpected incidents. I also rely heavily on the experience of Stéphane Grout and the operators to help us to free up time whenever possible and organise coactivity in the work area, which is very limited.”

A unique project mastered by the site’s expert teams

At the beginning of April, the subsections were moved to align the fore section of the Saphir with the aft section of the Perle to enable joining of their hulls. The process actually began well before these movements, with the machining of the bevels on the section ends and the creation of new structures in the joining work area.
Welding commenced on 20 April with tack welding then laying the first welding seams. Grinding operations followed to prepare for the main phase of welding the entire thickness of the hull, which was performed over the whole of the following week.

“This joining and the associated preparation work represent an exceptional achievement,” emphasised Antoine Butel. “It required unique skills, those of the core activity on the site of Cherbourg. The shipwrights adjusted the subsection weighing over a thousand tonnes to within a millimetre, then the grinders manually machined more than a hundred metres of bevels with a very high degree of precision. Throughout the welding phase, the preheating workers controlled the temperature of the seam created by our highly qualified welders. We should also mention the less visible but equally important contribution of the inspectors, study and production engineering technicians, the Health and Safety at Work and Environment (H&SW/E) teams, as well as the occupational health and production support teams.
The smooth roll-out of these operations according to schedule also illustrates our operators’ commitment: they love their work!”

“The team members all have the same goal: getting the Perle back in the water in June,” confirmed Stéphane Grout. “We created an impetus to meet this technological challenge. In spite of the very intense schedule, the working atmosphere has been very good and solid relationships have developed during the project. I am delighted to finish my career with a mission like this one!”

Stéphane Grout