Welding problems found in Virginia class submarines

The Navy has discovered "weaknesses" in some of the non-nuclear piping welds inside Virginia-class attack submarines that could result in leaky pipe joints.

Navy officials said Monday that the welding problems did not endanger the safety of the crews or the submarines and that actions are under way to fix the existing deficiencies and to prevent a recurrence in future vessels.

An investigation traced the weaknesses to "inadequate processes" at shipbuilder Northrop Grumman Newport News. The yard "allowed the improper use of the wrong weld filler metal in non-nuclear piping systems over an extended period of time," the Navy said in a statement.

Non-nuclear piping in subs is used for such things as water and wastewater systems.

The Navy, Northrop Grumman and its submarine-building partner, General Dynamics Electric Boat, are conducting a detailed assessment of completed welds using record reviews, additional inspections and testing. The assessment is expected to be completed this week.

"Extensive laboratory testing and engineering analysis demonstrates that the worst-case scenario as a result of this problem is that the piping joints may leak at some point" during the service life of the ships, the Navy said.

The two yards so far have delivered three of the Virginia-class subs to the Navy - the North Carolina is the fourth. They are in various stages of production on six others.

Until this problem was discovered, Northrop Grumman officials had been upbeat about the stealthy, 377-foot North Carolina. After running a year late and 25 percent over budget last year on the Texas - the first sub the yard had delivered in 10 years - the shipbuilder was aiming to deliver the North Carolina on time and close to budget.

Now, the welding problems have contributed to delays in the sea trials and the delivery of the submarine to the Navy, the shipbuilder said Monday. Last week, without explanation, the yard said delivery of the vessel had been pushed to January, missing its December contract date.

The sub's $2.6 billion price tag - in 2005 dollars - is about 2 percent over the Navy's initial budget, according to an analysis in late July by Congress' investigative arm, the Government Accountability Office. It could not be determined Monday how the boat's cost might be affected by the welding issues.

The weeklong inspections also have delayed a planned under way period for the sub Virginia, the Navy said.

The welding problem was first reported by the Defense Daily Network, a Web publication that covers the defense and aerospace industry.

In a statement Monday, Northrop Grumman said changes have been made in yard welding-control processes and that welders and welding foreme n will undergo an eight-hour specialized briefing to avoid future mistakes.

The company said it is "taking appropriate actions" with individuals involved in the errors, but did not elaborate.

"The quality of our work is something we take very seriously," the shipyard said in a statement.

The Navy said the first indications of a problem surfaced when two failures occurred during routine testing of the piping welds - one in August and another in October. That led to a broader investigation.

The failures, the Navy said, were caused by trace amounts of copper alloy filler material incorrectly welded into corrosion-resistant steel socket-welded joints. Using a copper alloy filler in that type of piping joint can cause the joints to crack, resulting in leaks.

The Navy said it traced the problem to the Newport News shipyard in mid-November.

Jon W. Glass, (757) 446-2318, jon.glass@pilotonline.com