Slipforming completed

By Trude Meland, Norwegian Petroleum Museum

Slipforming of the cells on the concrete gravity base structure (GBS) for the Statfjord B platform started at the same time as the school summer holidays. This was important in order to recruit students and thereby obtain sufficient labour. The job was well paid, and it was not difficult to get workers. People had to be turned away.

— Slipforming at Statfjord B nearly completed. Photo: Leif Berge/Statoil

This was the most hectic period of the construction project, with 1 150 people at work. NC’s own personnel accounted for 860 of these. The slipforming continued around the clock for 27 days, making it the world’s biggest operation of its kind until then.

A total of 58 000 cubic metres of concrete were poured from wheelbarrows. Each of the latter held 80 litres and, to achieve the desired slipforming speed of 1.5 metres per day, one wheelbarrow had to be filled every three seconds.

About 700 students were hired as temporary labourers. Most of them pushed wheelbarrows, but a number also worked as iron fixers or assisted with formwork construction. NC held courses for them. [REMOVE]Fotnote: Steen, Øyvind. På dypt vann. Norwegian Contractors 1973-1993 . Oslo 1993, p 44.

The summer workers earned well, receiving about NOK 10 000 in gross pay over five weeks. That corresponded to 90 per cent of the piece work rates paid to the permanent workforce, and to almost NOK 34 000 in today’s money.

The work was heavy and a high pace was maintained. Workers were divided into four shifts. After six hours of pushing wheelbarrows or binding rebars, the body ached and fingers were stiff. Concrete was mixed in a plant on a barge moored alongside the GBS before being poured into the wheelbarrows.

A dozen temporary office buildings for administrators were also installed out in the fjord. Personnel were ferried to and from the GBS by high-speed craft. [REMOVE]Fotnote: VG , 12 June 1979.

Slipforming the cells was carefully planned, with no margin for error. Hundreds of hydraulic jacks controlled by laser beams thrust the formwork upwards.

The job was completed by 18 July, and a temporary halt was called to permit completion of the cells and make preparations for slipforming the shafts. That operation began the following January, and the top was reached on 24 February. The GBS was now no less than 174 metres high. Despite the tight schedule, work was finished a day early.

NC now had to reduce its workforce again, from 650 people to about 350. The 150 employees recruited for slipforming the shaft moved on to other jobs, while many of the remaining 150 returned to jobs with the partners in NC – Furuholmen, Høyer-Ellefsen and Selmer. NC found work for the rest elsewhere, including at Rosenberg Verft. The latter was in the middle of building the Statfjord B topside. [REMOVE]Fotnote: Rogalands Avis, 11 March 1980.

To learn more, see: Statfjord B – Building the concrete GBS