PANEL REPAIRS
77-2-16 WELDING PROCEDURES
General Welding Precautions
General
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.
The replacement welds in the welding diagrams are denoted by the following symbols:
a = Single/Multiple thickness plug welds
b = MIG seam weld
When carrying out welding operations the following criteria must be observed:
lWhere 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 30 mm (1.181) apart;
lWhen 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;
lThe electrode arms on hand-held spot welding guns must not exceed 300 mm (11.811) in length;
lSingle-side spot welding is not acceptable;
lBrazing and gas welding are not acceptable EXCEPT where they have been specified in production;
lWhere 3 metal thicknesses or more are to be welded together it is imperative to use MIG plug welds to ensure
joint strength;
lMIG plug welds must be used in repair joints where there is no access for a resistance spot welder. To replace
each production spot weld, an 8 mm (0.314) approx 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;
lWhere 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.
Electronic Control Units
The electronic control units (ECU) fitted to vehicles make it advisable to follow suitable precautions prior to carrying
out welding repair operations. Harsh conditions of heat and vibration may be generated during these operations which
could cause damage to the units.
In particular, it is essential to follow the appropriate precautions when disconnecting or removing the airbag DCU.
Equipment
Prior to commencing any test procedure on the vehicle, ensure that the relevant test equipment is working correctly
and any harness or connectors are in good condition. This particularly applies to electronic control units.
