Original Date: 07/21/2003
Revision Date: 01/18/2007

In support of Electric Boat Corporation, Quonset Point Facility’s modular construction manufacturing practice, the company fabricates and assembles pipe packages in temporary fixtures in its pipe shop. These packages are then transported to the submarine hull section or module for final installation. This approach improved safety and quality and decreased labor costs and span times.

Traditionally, submarine construction programs consisted of four sequential, labor-intensive phases: manufacturing; structural assembly; installation; and test. Installation of piping was accomplished after the structural assembly was completed. Pipe details fabricated within Electric Boat Corporation, Quonset Point Facility’s (EBQP’s) pipe shop were transported piece-by-piece to the submarine hull section as needed for installation (referred to as stick building). Problems with this approach were that the installation sequence for the components was critical, the work had to be accomplished in extremely congested areas, and general working conditions were inefficient. As a means of reducing construction time and cost, EBQP took advantage of advances in submarine designs, information technology, equipment technology, and manufacturing integration by using the design model to develop larger and more complete pipe packages. EBQP focused on moving cleaned pipes directly from fabrication workstations to manufacturing workstations where the pipes are assembled in temporary fixtures, containing two to three pipe details or banks of pipes. After completion of a pipe package, the entire fixture is then transferred to the appropriate hull section or module. Foundations are located, the hangers are welded into place, the temporary fixture is removed, and assembly is complete. EBQP’s engineers determined that assembly, which requires one hour in the pipe shop, takes four hours in the unit and ten hours in a sealed hull. Thus, pipe packaging for modular construction saves labor and span time and improves safety and quality.

This process was originally implemented for the 688 and Trident Class programs. EBQP extended the lessons learned from pipe packaging and is now creating dedicated workstations for specific, repetitive packages. Currently, a material pick list is given to EBQP’s material department to collect and deliver to an area selected for manufacture of that package. While the mechanic waits for material to be delivered and inventoried, specialty tooling or support equipment needed to complete the job is collected from around the shop. With recent procedural changes, each workstation now contains all the equipment, fixtures, and tooling necessary to assemble certain packages. Workstations are located in areas with suitable clearance and power supply. Pipes, valves, and related components are no longer stored in a material warehousing area, but are delivered directly to the workstation from the bending stations. Once the package is permanently fitted into its design location and the temporary fixture is removed, the fixture is refurbished and returned to the workstation for its next use.

EBQP’s pipe packaging methods emphasize quality. Using photogrammetry, mechanics establish soft targets in the shop environment to template the actual construction conditions. This process ensures that, after a critical pipe detail is manufactured, it will fit the as-built condition. Cost savings have been realized with the reduction in set-up time and the elimination of two material handling steps. First, is the movement to the staging area as pipes emerge from the cleaning facility; second is the re-issuing of material as it is picked by the material department. These improvements enable management to incorporate the mechanic’s experience and learning curve into the manufacturing plan. EBQP shared this practice and advised its teaming partner, Northrop Grumman Newport News, on methods of achieving similar results.

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