Repair Of Naval Vessel Aided By Power Team Hydraulic Rams

Repair of the guided-missile frigate USS Samuel B. Roberts entailed a massive lifting exercise in which twenty 100-ton aluminum hydraulic rams operating at 10,000 psi were systematically applied to raise the damaged stern of the 3,700-ton vessel to its normal position.

Bath Iron Works (BIW) of Bath, Maine, which built the Roberts in 1986, was contracted by the Navy to repair damage inflicted by an Iranian mine in the Persian Gulf. The lifting project was the largest ever undertaken by the shipbuilder.

The ship's stern, which had sagged 36 inches as a result of the explosion and subsequent flooding, was hinged about 130 feet inward.

The hull of the 445-foot vessel had to be cut through up to the main deck so the stern could be jacked up, properly aligned and repaired while in drydock at BIW's Portland facility.

The rams—RA1006 aluminum models from Power Team—were chosen largely for their relatively light weight and BIW's previous experience with that line of hydraulic products. At 49-1/2 pounds, they are approximately half the weight of steel rams of the same capacity.

Ten jacking stools beneath the stern each supported two rams, which were powered by one 10,000- psi Power Team PE172 electric/ hydraulic pump. Operators of the pumps were directed via radio communications to preload the rams to compensate for weight shifts and to elevate them simultaneously in required increments, a critical phase of the project.

The rams were jacked only 2 to 3 inches per lift to prevent the stern from swinging and causing off-center loading. Oak wedges were installed for cribbing after each lift until the 36-inch correction had been achieved.

In addition to restoring the ship's stern, BIW crews cut out a section of the Roberts for a new engine room module and installed a 10- foot-square patch over the hole blasted by the mine explosion. The engine room module, under construction at Bath, will be barged to Portland for installation.

More information on the hydraulic equipment used in this project is available from Power Team. For free literature, Circle 80 on Reader Service Card

Other stories from February 1989 issue


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