General welding precautions (Panel repairs)

GENERAL WELDING PRECAUTIONS

For ease of reference the diagrams on the following pages show only the type of weld used in repair where it varies from that used in production.

When carrying out welding operations the following criteria must be observed:

• Where resistance spot welds have been used in production, these must be reproduced with new spot welds in replacement where possible. All such reproduction spot welds must be spaced 30mm apart.
• When spot welding, it is recommended that test coupons of the same metal gauges and materials are produced to carry out peel tests to ensure that welding equipment being used can produce a satisfactory joint. Plug welds must be used if a satisfactory spot weld cannot be produced.
• The electrode arms on hand-held spot welding guns must not exceed 300mm in length.
• Single-side spot welding is not acceptable.
• Brazing and gas welding are not acceptable EXCEPT where they have been specified in production.
• Where 3 metal thicknesses or more are to be welded together it is imperative to use MIG plug welds to ensure joint strength.
• MIG plug welds must be used in repair joints where there is no access for a resistance spot welder. To replace each production spot weld a hole must be drilled and/or punched, and a MIG plug weld then made in its place. The number of plug welds must match exactly the number of spot welds which have been removed.
• Where holes are left in an existing panel after removal of the spot welds, a single MIG plug weld will be made in each hole as appropriate.
• The replacement welds in the welding diagrams are denoted by the following symbols:

A. Single thickness plug welds

B. Multiple thickness plug welds

C. MIG seam weld