The National Physical Laboratory's Division of Maritime Science placed a research structure on the seabed in Christchurch Bay, off the south coast, to improve the safety and structural reliability of offshore structures and to provide data for legislation and certification procedures for offshore operators. It is secured with studs and nuts in Ferralium® 255.
The site was chosen because the sea conditions there, in relation to the size of the research structure, will provide in a comparatively short time the kind of data on average and peak wave conditions that full-sized offshore structures in northern waters experience over much longer periods.
Some of the data is processed by an on-board computer able to record over 2 million items of information in 20-minute sequences and to transmit it by radio link to the land base for immediate analysis. Recorded tapes of raw data are collected periodically for detailed study.
The research structure is a steel column 16 metres high, free standing in a mean water depth of 8.4 metres. The segmented column is instrumented for a two-year programme measuring the forces and pressures exerted by winds, waves and currents on the 60 tonnes structure, its 200 tonnes gravity base and the supporting seabed.
The column is secured to a circular steel plate encased in the concrete base by eighteen 1-7/8" diameter studs and nuts of Ferralium® 255 (UNS S32550, Alloy 255, DIN 1.4507, ASTM F61), chosen for this super duplex stainless steel's high strength allied with excellent corrosion resistance in marine applications.
