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Northern tank scoops underwater welding work

Underwater welding consumables have been subjected to rigorous testing at TWI North.  The range of electrodes under test, five ferritic and one stainless steel in the initial phase of the programme, differ from dry welding electrodes by having a modified flux covering and a waterproof coating. This comprises a lacquer or a two-part polymer.

‘Our job was to co-ordinate welding trials carried out be welder divers to identify the good features and disadvantages of using each of the consumables’ said project leader David Abson. ‘The job specified performing single and multiple pass fillet welds and also some butt welds.  The completed joints have given us suitable specimens for mechanical testing’.

The work was carried out five metres underwater on 8mm thick plate in the vertical down and overhead positions.  It simulated the sort of welding required in repair of offshore structures, ship repair or harbour sheet pile work.  ‘The welding and evaluation of electrode operability were carried out by experienced welder-divers’ added Abson.  ‘Among their tasks they had to complete a questionnaire on various aspects of the electrodes’ behaviour.'

‘Even while they were at the bottom of the tank, they were interviewed, on the intercom, about how the electrode handled, the metal transfer characteristics, how the slag flowed, and whether it was easily removable. Some welds for instance needed considerable interrun grinding.  That’s important to know because it increases your dive time’.

The electrode operability influences the weld finish, which was very variable. The survey included an evaluation of the integrity of the finished welds and mechanical testing.

Subsequent surveys, following the same evaluation procedure, have been carried out on additional ferritic electrodes and some nickel-base electrodes.  

For information about TWI’s capabilities please email contactus@twi.co.uk

Underwater welding at TWI North
Underwater welding at TWI North
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