An alternative design to the temporary padeyes used during submarine overhauls will reduce labor and material costs. NMC photo
The Navy Metalworking Center (NMC) is working with PNS and the other naval shipyards to develop and evaluate an alternative to the current temporary padeyes that would reduce labor and material costs.
Portsmouth Naval Shipyard (PNS) is seeking alternatives to the current design of temporary padeyes used during submarine overhauls. The current padeye is fillet welded and requires 160 man-hours of labor to install and then remove.
The leading candidate for this application is a swivel hoist ring mounted on a threaded HY-80 stud. Work included developing optimized stud welding parameters and selecting the correct swivel hoist rings. The stud-mounted swivel hoist rings were tested to demonstrate that they consistently meet lifting and handling requirements. This project also identified and determined the effects of any errors that might be made during installation. Previous research conducted at PNS indicates that this technology is very likely to be successful.
Based on PNS data, there is a potential cost avoidance of $235K per overhaul from reducing the labor associated with installing and removing padeyes. Although the largest part of the cost reduction is from reducing the welding labor, there are also significant savings to be realized by reducing the effects of installation and removal on the special hull treatment and internal hull insulation. Over a five-year period, the estimated cost avoidance is approximately $2.4M.
Although, the results of this project will be applicable to all submarine classes, the majority of the savings will be realized during overhauls of Los Angeles Class submarines. The solution will be implemented at PNS in June 2012 for the overhaul of the USS TOPEKA (SSN 754). The other three naval shipyards are also expected to implement the results. Implementation will require approval from shipyard Lifting and Handling authorities and procedure changes.
Naval Sea Systems Command (NAVSEA)
Norfolk Naval Shipyard
Portsmouth Naval Shipyard
Pearl Harbor Naval Shipyard
Puget Sound Naval Shipyard