There is particular concern about tank testing during the construction of new ships especially when the newbuilding project involves a series of ships.
Akti Miaouli, Piraeus-based Marine Technical Managers Association (Martecma) has written to IACS expressing its grave concern at classification’s approach to hydrotesting.
Martecma points out Solas Part B-2 Regulations 11.2 and 11.3 require tightness and structural strength tests with no exemptions. But on the same issue, IACS has issued Unified Requirement S14 "Testing Procedures of Watertight Compartments" [revised five times up to September 2013] proposing arbitrary and unilateral relaxation of SOLAS requirements, allowing leak testing for watertightness and thorough visual inspections of the structure on sister vessels, in lieu of a full scale structural hydrotest.
At the same time, Martecma notes Japan has submitted a document for discussion in IMO's sub-committee on ship design and construction asking for the development of a “Guidance on verification of the quality management systems for shipyards” which will allow if / when implemented the exemption of certain types of tank testing on ships.
Martecma says in its letter to IACS its "members who have vast experience in shipbuilding, strongly believe hydrotesting of all tanks on a ship should not be waived". Martecma points out “many structural design defects have been discovered during hydrotesting” and contends “many damages have taken place due to the lack of hydrotesting before the delivery of ships”.
"We have witnessed several failures in the past, some of them in reputable yards, and some experts maintain some of the latest high profile casualties due to structural failures could have been avoided if proper hydrotesting had taken place," says Martecma.
The technical body says tank testing is a condition excessively stressing the watertight boundaries, slightly above their normal operating condition. "This fact, combined with the associated high cost and time consuming operation, are some of the main reasons yards try to omit hydrotesting. However, hydrotesting is the only reliable check to ensure the structure has been properly designed and constructed, free from serious defects, such as materials, welding and alignment to mention few which are common in shipbuilding," says Martecma.
Martecma notes, “shipyards claim the purpose of the hydrotest is only to confirm the design while the proper construction is confirmed through the inspections and the non destructive examinations. On this basis shipyards propose for the tests of the sister ships to be omitted”.
"This does not serve the concept of the rules. If we assume the inspections and the random NDTs [non destructive testing] are an adequate method to confirm a sound construction, then we would not need to structurally test other structures and equipment,” says Martecma in its letter.
A challenging question is asked: "If we only rely on the tank test for the first ship of a series, how can we ensure the yard will not apply different construction standards for the actual ship to be tested and for the ships that will be delivered without tests?" The implementation of "Shipyard Quality Standards" is a solution that has been tested in the past and failed.
Martecma maintains any revisions proposed to Solas or other international conventions should be supported by sufficient evidence justifying the need for such changes from a safety and an environmental point of view. "Until changes to Solas are in force by IMO, IACS members should not deviate from Solas requirements, unless an exemption is granted by the flag state," says Martecma.
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