A defect causing holes in the piping has been discovered on the Daegu-class (3,100 tons) escort vessel of the navy, with Hanwha Ocean emphasizing that there are no issues with the design. However, there are criticisms that such defects could not have been foreseen during the design phase. Hanwha Ocean is competing with HD Hyundai Heavy Industries for the contract of the next-generation Korean destroyer project (KDDX - Korea Destroyer neXt generation).
In the defense industry, there are analyses suggesting that this escort vessel defect could be a setback for Hanwha Ocean. The basic design of the Daegu-class escort vessel was entrusted to Hanwha Ocean's predecessor, Daewoo Shipbuilding & Marine Engineering, in 2011. The change of the piping material from copper-nickel alloy to stainless steel is pointed out as the cause, as it could imply that the problem was not anticipated.
The defect found in the Daegu-class escort vessel occurred because the stainless steel piping could not withstand seawater, causing holes to form through which seawater infiltrated the fuel tank. Hanwha Ocean maintains that the stainless steel used was the highest performance at the time, and thus there is no design issue.
Hanwha Ocean chose stainless steel (SUS316L) instead of a copper-nickel alloy, while a partner company used a different stainless steel (SUS304L). The first hole was discovered in the piping of the vessel mistakenly used by the partner company, but similar issues were found in the vessel that used the stainless steel selected by Hanwha Ocean.
In the industry, there are also criticisms suggesting that the design did not adequately consider the marine environment. A source from the defense industry noted, "Parts are always at risk of failing depending on the environment. We replaced the parts, assuming they would be fine, but if issues arose, then that judgment was incorrect."
The fuel tank through which the problematic piping passes is where fuel for the generators inside the escort vessel is stored. It is reported that it is not a significant issue as it does not pertain to vital components such as weapon systems or engines. The design of the fuel tank to allow for piping passage was intended to provide a workspace for generator maintenance.
A military official stated, "Typically, there are tens of thousands of pipes involved, and if routed outside the tank, it would reduce the maintenance space." It is also said that many of the escort vessels currently in operation by the navy were designed with piping passing through the fuel tanks.
Military authorities and the Defense Acquisition Program Administration (DAPA) have changed the structure of the piping to bypass the fuel tank. The choice of stainless steel piping by Hanwha Ocean during the design process, which began in 2011, was due to the formation of precipitates when copper-nickel alloy piping comes into contact with fuel.
Even though the piping structure has changed after recent repairs, it is reported that the military and Hanwha Ocean are considering changing the piping material for escort vessels that will need future repairs without causing operational issues.
Hanwha Ocean and HD Hyundai Heavy Industries are fiercely competing over the construction of the KDDX detailed design and lead ship (ship No. 1). In this process, the two companies have also engaged in legal battles, mentioning each other's past cases.
DAPA stated that the escort vessel defect is not directly related to the KDDX project. A DAPA official remarked, "The escort vessel project and KDDX are separate projects," adding that it would not have a direct impact on the decision-making regarding KDDX project promotion.