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Original Date: 07/21/2003
Revision Date: 01/18/2007
Best Practice : Process Control Techniques for Pipe Manufacturing
Electric Boat Corporation, Quonset Point Facility solved its welded pipe manufacturing scheduling and work-in- process control problems by applying creative color-coding and labeling techniques to part travelers and work staging areas.
Tight schedules, unique configurations, and variable quality standards pose challenges for Electric Boat Corporation, Quonset Point Facility (EBQP) in tracking work-in-process within its Pipe Manufacturing Shop and ensuring that pipes are fabricated and packaged to exacting standards and schedules. Producing approximately 10,000 welded pipes annually, a number of techniques have been developed to move work through pipe manufacturing in the correct sequence, in minimal time, and with complete quality control accountability. These techniques include:
Color Coded Bag System: During pipe welding, there are two types of joints (controlled and non- controlled), each with different handling and accountability requirements. Controlled joints require that certain steps be taken to ensure quality and accurate record keeping are performed for each welded pipe joint. These are monitored by EBQP’s Quality Assurance (QA) personnel, require Non-Destructive Testing (NDT), and have clear traveler bags. Non-controlled joints are not monitored by QA, and are identified by the Color Coded Bag System and moved through the process faster once they are welded. By color-coding the traveler bags, EBQP personnel have a clear visual aid to determine which items can be shipped immediately. Pipes with non-controlled weld joints have red traveler bags, and pipe-only travelers have a clear bag with a large “X” on the outside. Typically, pipe-only orders are processed in a one-day cycle time. EBQP’s Color Coded Bag System resulted in reducing cycle times from 17 days to 10 days (41%), reducing work-in-process, clear identification of pipes requiring QA, and clear identification of welded pipes that require welding by a certified welder.
First-In-First-Out Pipe Rack System: With hundreds of pipe details and assemblies being produced weekly (each consisting of one to nine individual pipes), tracking, scheduling, and controlling each piece through the pipe manufacturing shop is a difficult process. To solve this problem, EBQP implemented a labeled pipe rack system. Pipes are identified, cut to length, and placed on the “bend” racks labeled #1 and #2. This enables the pipe bending mechanic to hold to the first-in-first-out discipline and bend pipes of similar size with the same set- up, thus reducing bending machine changes. From the bending operation, the bent components are moved to fit-up and weld where a similar first-in-first-out technique has been implemented. Fitted and tacked pipe assemblies are placed on weld racks which are labeled by the days of the week, allowing welders to clearly see which assemblies are next in the cue for welding.
P2 Logbooks: EBQP initiated P2 Logbooks to track non-controlled pipe joints which do not require QA intervention. Because EBQP had many P2 joints that leaked during hydrostatic testing, the company was unable to identify the welder who had welded the joint. The P2 Logbook enables EBQP to track pipe joints from start to finish, even if multiple welders are involved. This ensures that corrective and preventive action is taken. The P2 Logbook is also a vehicle for material identification prior to welding.
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