Module fabrication building

for Highlands Fabricators Ltd, Nigg

W. H. Mackay & Sons Ltd of Fearn have completed the European offshore industry’s largest fabrication facility in less than a year. Here they tell the story of its construction.

Main Contractor was Messrs Wimpey Construction and our contract was on a design and construct basis covering the supply and erection of 3,500 tonnes of structural steelwork. 48,000 sq m of single skin profiled steel cladding and 28 No. sliding door leaves.

The building is constructed in three bays which have the following dimensions:

Bays 1 and 2
Each 50 metres wide centre-to centre of crane rails and 25 metres clear height under the crane hook.

Bay 3
80 metres wide centre-to-centre of crane rails and 35 metres clear height under the crane hook.

The building is 117 metres long centre-to-centre of end frames and supports E.O.T. cranes of 120 tonnes, 50 tonnes and 20 tonnes capacity.

Full width doors are provided in each gable, so arranged to provide clear openings 50 metres wide x 25 metres high in Bays 1 and 2, and 80 metres wide x 35 metres high in Bay 3.

At the design stage the building was planned basically around bolted construction so that the large lattice columns and trusses could be manufactured piece small to permit shotblasting and painting within our Workshops without handling difflculties.

Units were then sub-assembled by separate crews on site prior to erection.

An analysis of the programme requirements indicated a commencement of erection on-site shortly before Christmas 1984, with a large proportion of erection and cladding work being undertaken during the worst period of Winter weather.

The height of the building and consequently the time involved In making adequate provision for Operators safety concerned us and after considerable discussion we adopted the Erection Method indicated In the accompanying photograph. This entailed splicing roof shaft column Just below main tie level and assembling at ground level a roof section 9 metres long x 56 metres wide In the case of Phase 1, and 86 metres wide in the case of Phase 2.

Roof cladding, rainwater goods, safety lines and scaffolding were fitted and the sections then lifted into position using dual Manitowac 4100 cranes In the case of the 56 metre span sections and dual ‘Skyhorse’ cranes In the case of the 86 metre section. Average lifting time per section was less than one hour and programme dates were achieved.

The design took recognition of the dual 11ft requirement and special lifting beams were incorporated into the structure and left In position as a permanent feature as it was not cost effective to remove them after erection.

Doors are a unique feature of the building as the gable of each span can be opened over its entire width enabling completed Modules to be skidded out without hinderance.

Highlands Fabricators Ltd claim that the building Is now the largest indoor fabrication facility In the European Off-Shore Construction Industry.

Originally published in
BCSA NEWS
June 1986