A manufacturing problem with the U.S. Navy's new Virginia class SSNs (nuclear attack subs) has delayed the commissioning of a new boat, the USS New Mexico. The ceremony will be delayed from November 21st, to sometime in January or February. The problem has to do with bolts that were not manufactured to specifications. These bolts hold together the track system that is used to move torpedoes and other weapons around the "weapons room". The poorly manufactured bolts will hold the tracks together under peacetime conditions. But in the stress of combat (like depth charges or violent maneuvers) they are likely to fail. The navy not only wants to get the proper bolts, but also is inspecting hundreds of other bolts in the weapons room, and perhaps other items as well. This anxiety is because the bolt situation is not the first manufacturing problem the Virginias have encountered lately.
Earlier this year, the navy expanded its re-inspection of welds on recently built ships. This meant additional inspections on nine submarines and four Nimitz class carriers. This is all about quality control, or, rather, that lack of same. It all began when a weld inspector at the Newport News shipyard was found to be falsifying the inspection of welding jobs on four Virginia class submarines and a Nimitz class carrier. Some 10,000 welds had to be re-inspected, as these are how many the now dismissed inspector handled in four years on the job. Each Virginia class sub has about 300,000 welds that have to be inspected. Normally, only a few will fail inspection and have to be redone.
A few defective welds can cause the loss of a submarine, or serious damage aboard a carrier. Two methods are used to inspect welds, magnetism, or a special liquid. It's easy to fake the inspection, thus these quality control inspectors must be carefully selected.
It was two years ago that the navy found some bad welds on a Virginia class submarine, and this led to some re-inspections. The decision to do massive re-inspection goes back to the loss of the nuclear submarine Thresher in 1963. This disaster was traced to bad welds. Reforms in how the welding was done, and inspected, seemed to have eliminated the problem, at least for about four decades.
The current problem may, in part, be the result of changing the way welders are trained. In the last decade, training has come to include a growing amount of computer based instruction. In the past, all the teaching was one-on-one with an experienced welder teaching the student welder. But the bad bolts are blamed on sloppiness at several levels, and just increases navy anxiety over the declining quality of construction work done on warships. It's not a new problem, and it appears to be getting worse.