PIPEFITTERS are the latest trade to demand extra cash at Heathrow Terminal 5.
Around 500 fitters held a mass meeting on Tuesday night at the British Legion club next to the site to thrash out their cash claims.
The workers are demanding pay parity with electricians on the job, which would mean a wage rise of more than 50 per cent.
The current three-year pay deal covering the sector runs out in November and will be renegotiated between electrical union Amicus and the Heating and Ventilating Contractors Association.
Amicus regional official Frank Westerman said: 'The pipefitters are unhappy at T5 and they want the same deal as the sparks.
'They get the same bonus but their basic rates are much lower.' Electricians at T5 currently earn £17 an hour under the Major Projects Agreement, while pipefitters are paid a basic rate of £11.35.
Mr Westerman said: 'The fitters have seen the electricians pull away from them in pay terms ever since the Jubilee Line Extension job.
'They want to rectify that and see T5 as the ideal opportunity to put pressure on the national agreement talks.' T5 has been hit by a string of extra pay demands from electricians and steel erectors.
A site source said: 'BAA must have thought this was all sorted after thrashing out deals under the national agreements for the other trades.
'This is the only outstanding one that can affect them. I think people at BAA thought most of the pipework would be completed at T5 by November, but it looks like things are lagging behind a bit so a lot of them will still be on site when the new deal is due to come in.' An HVCA spokesman said: 'At this stage we are about to consult with our members about the offer to Amicus recommended by our Operative Standing Committee.
'This will then hopefully go to the Council of the Association for approval on March 9.
'Dates for negotiating meetings have not yet been fixed with Amicus.' A BAA spokeswoman said: 'These negotiations are between the unions and the trade association.'