Brockington and Scott Ltd of Llandeilo, Carmarthenshire, make bellows expansion pieces from 0.7mm thick Ferralium® 255 (UNS S32550, Alloy 255, DIN 1.4507, ASTM F61) super duplex stainless steel plate, chosen for its excellent resistance to corrosion, heat and fatigue stress and for its ductility. The bellows absorb linear expansion in long, straight runs of large-diameter pipework, such as those on oil tankers.
Development work
The company produces bellows expansion pieces with bores from 15" up to 100", and is carrying out experimental development on a 19" bore bellows in Ferralium® 255. Brockington and Scott report no difficulty with either argon butt welding or resistance welding, and that only slight modifications to the forming techniques used on 18/8 alloys were needed. Preliminary mechanical and pressure-cycle tests to determine fatigue life and overall efficiency are encouraging.
