BREMERTON, Wash. –
A new KNES 25-ton portal crane with a unique capability arrived at Puget Sound Naval Shipyard & Intermediate Maintenance Facility July 14.
Crane 52 is part of a $67 million contract to bring four new cranes to PSNS & IMF to support the mission of maintaining, repairing, modernizing and retiring U.S. Naval vessels. The new cranes were designed and built by Konecranes Nuclear Equipment and Services, which gets shortened KNES.
According to Pat Gerdes, lead mechanical engineer, Code 713, Crane Engineering and Procurement, Cranes 53 & 54 were already delivered to Trident Refit Facility-Bangor, with Crane 51 scheduled to arrive at PSNS & IMF later this year. Given the space limitations on Delta Pier at TRF-Bangor, portal cranes 3 and 4 were hauled off for recycling by the contractor after cranes 53 & 54 were delivered.
New cranes 51 & 52 will join the stable of cranes at PSNS & IMF, to increase the command’s general lifting and handling capability. While the new cranes weren’t designed with world-class lifting capacity, they do have a couple of differences from all the other cranes currently in operation at PSNS & IMF.
“While the crane controls themselves are similar to other portal cranes, these cranes will behave very differently than our existing cranes,” said Gerdes. “The biggest example is that these cranes are level-luffing cranes, which means that when the operator luffs (raises or lowers the boom), the hook block travels a near horizontal path between the starting radius and end radius of the luff operation.”
“This means that as the operator booms, the distance between the hook block and the boom changes, but the hook height relative to the crane rail does not change,” he continued. “On our existing portals, the hook reeving uses a deflector sheave at the base of the boom, which means that the distance between the hook and the boom stays constant while booming, but both the load height and the load radius change simultaneously as the operator booms in or out.”
According to Travis Mays, electrical engineering technician, Code 713, the new cranes have a couple of other differences from existing PSNS & IMF cranes.
“This is our first portal crane that does not utilize DC (direct current) motors for major motion functions,” Mays said. “The new crane uses AC (alternating current) induction motors. This is our first portal crane painted with a polyurethane coating system, which should weather better than the coating systems used on our legacy portals.”
Gerdes said Crane 52 and its “sister” crane bring welcome capacity to PSNS & IMF.
“These are a new class of crane, and will not replace any other cranes here,” he said. “However, they’ll be able to take over a lot of the lifts done with the 60-ton portals, freeing those cranes up for other work. Since they are lower capacity and for general purpose service only, they have a faster hook speed -- and can go even faster than rated speed when unloaded -- which will help increase efficiency for projects that need a lot of light cargo moved. They also have relatively long booms. The only existing crane with similar reach in the yard is Crane 62.”
Before the crane begins lifting loads in support of the PSNS & IMF mission, there are some final preparations to be completed.
“There are improvement items that have been prioritized for accomplishment prior to initial crane certification, and there are also other improvement items that will be rolled out over the next few annual service periods,” said Mays. “Some of the more critical improvement items include the addition of a lockable disconnect switch for aircraft warning lights, installation of a wind deflector for the main hoist hook block, installation of first-aid kit, installation of eye wash station, installation of toolbox, among others.”
He said the contract requires the contractor to provide training for operators upon acceptance of the crane, even though the controls in the operator’s cab are laid out approximately the same as existing PSNS & IMF portal cranes.
Portal cranes are characterized by a rotating upper works and a lower gantry portion that allows foot and vehicle traffic to pass under the crane when it’s not in use. Given their size, the cranes at PSNS & IMF can be seen from almost anywhere around Sinclair Inlet. They could be considered part of the PSNS & IMF “brand.”