A vessel owner arranged to have the heads of several ballast tank vents replaced with new ones. The owner’s team specified that the heads were to be the type to bolt onto an 8″ vent line. Upon arrival of the vent heads, it was found that the top elements of the heads were several inches larger in diameter than the original ones, although they mated to the 8″ line. In order to accommodate the larger vent heads, a number of nearby handrails had to be modified, requiring hot work when no hot work would otherwise have been needed. This resulted in considerable extra cost to the owner.
Lesson learned: the owner’s team should confirm in advance the suitability of all aspects of the geometry of replacement parts, not just one or two key measurements.