repair methods and specialist welding repairs

Repair by welding is applied to extend the service life of expensive or critical equipment, and the requirements and conditions of each repair need to be considered individually. When dealing with high value/high integrity plant there is very rarely a ‘typical’ repair.

Items that need to be considered when planning a repair operation include metallurgical condition of materials, service history, future operating conditions, environment that the repair is to be carried out in, restricted access and qualification of a repair procedure that may be totally different to the original fabrication procedure. It is often a requirement to maintain compliance with a construction or operating Code of Practice, and this can be a real challenge when carrying out a field repair using a welding procedure designed specifically for one application.

Repair welding is usually applied to ageing structures but not exclusively so. One very recent project involved a subsea repair to a newly installed oil platform in the South China Sea which was badly damaged during installation, requiring a through wall repair of 70mm thick material at a water depth of 10 metres.

Godfrey Welding Engineering Ltd personnel have built up a broad knowledge of successful complex repairs including:

  • Repair of a leaking tubesheet on a nuclear reactor in China
  • Repair of corrosion damage on a large petrochemical vessel in South Wales
  • Subsea repair of a Semi Submersible oil platform in the North Sea
  • Repair of one of the worlds oldest functioning nuclear reactors, located in Canada 
  • Repair of a major rail bridge over a six lane motorway, North West England
  • Subsea repair of badly damaged jacket structure in the South China Sea
  • Repair/replacement of 30 year old CrMo refinery vessel using Inco 82 for the tie in weld onto old material, to avoid PWHT to finished butt weld

Each project has started with a feasibility study to determine if a welded solution is possible, practical or desirable, and from there the repair concept is developed. Depending on the particular requirements of the project it may need no more than a specific welding procedure and careful supervision, or it may need extensive CTOD testing and approval from an independent regulator.

If you are faced with a complex repair situation, GWE Ltd can advise on feasibility, arrange for detailed NDT to determine the true extent of repair, develop a repair procedure and carry out on site supervision of the repair.