Owner and Class (NKK) tried to blame a sticky P/V valve.
But the crew testified they had tested the valve at 0800
45 minutes before the rupture
and tests and inspection immediately
after the casualty found the valve working properly
and in good shape.
Singapore also issued a report to IMO
which apparently leans to the sticky P/V valve theory
which would exonerate NKK and indirectly the flag state,
and put the blame on the crew for poor valve maintenance.
But CTX has no located a public copy of this report.
Ship had a very poor port state inspection record,
with 43 deficiencies in last 4 inspections.
Intertanko incorrectly lists this casualty as an explosion.
The CTX sides with the port state.
The most likely cause of this structural failure
was poor construction and welding, and faulty weld repairs
none of which was apparently caught by NKK surveys.