John Mowlem & Company and John Mowlem Construction are suing Newport-based Rowecord Engineering for £881 716.96, alleging that steel beams supplied and installed by the company developed weld metal cracks in August 1994.
In the writ issued in the Technical and Construction Court last December, Mowlem claims defects in the web-to-flange welds in the beams were caused by Rowecord's failure to select sufficient pre-heat levels and its use of high diffusable hydrogen levels.
Mowlem claims a report by the Welding Institute confirmed that the defects had been identified as hydrogen-induced cracks. The report also said the reported minimum pre-heat and interpass temperature employed for the welding was inadequate. The writ states cracks were up to 12 mm deep and 2 mm wide.
Project engineering consultant Ove Arup & Partners refused to accept the steel beams and remedial work was carried out, which Mowlem claims cost £697 519.98. Mowlem is also claiming three separate sums of £304 687.50, £127 248 and £11 996.48 on the £46m project, which it says was paid to other trade contractors whose work was disrupted during repairs.
The building has already cost the government more than £900 000 in maintenance since its completion. In October, a cabinet subcommittee told MPs that the best way to recover money might be to sue Mowlem.
John Mowlem and Rowecord Engineering both refused to comment.