Line shaft pumps supplying sea water to North Sea oil platforms normally operate at depths of over 100 feet, permanently submerged and subject to corrosive attack. The muff couplings that join the drive shafts are cast in Ferralium® 255 super duplex stainless steel (UNS S32550, Alloy 255, DIN 1.4507, ASTM F61).
The drive shafts, in manageable individual lengths, are secured to the couplings by "hot-headed" bolts of the same Ferralium® 255 material.
