Repair of corroded mechanical joints
The left hand sketches show a common solution to this problem.
Alternatively; a corroded bolted connection (A) might be field repaired using TRICLAD transition joint by design B or completely replaced on new structures by design C.
In general terms, painting should be as recommended for aluminium hulls. However; antifouling paints containing copper, mercury or lead salts are not recommended as they may encourage galvanic corrosion.
The area either side of the joint should be thoroughly cleaned by wire brushing. An initial coat of approx 5/6 microns of etching primer should be applied. A second coat of chrome or zinc chrome prime, 40 microns thick, should then be applied. A two coats of marine undercoat each approx 40 microns thick, should then be applied. A final 40 micron thick coat of marine topcoat paint completes the painting.
Typical paint specs are
- Etch primer DEF Stan 80-15
- Primer DEF Stan 80-77
- Undercoat DGS 168A
- Topcoat DGS 168A
Read more about Triclad:
Triclad: welding aluminium to steel | Merrem & la Porte's involvement in Triclad | General background of explosion cladding | What is Triclad? | Triclad fabrication guidelines | Corrosion resistance | Welding parameters general guidelines | Frequently Asked Questions