Original Date: 07/21/2003
Revision Date: 01/18/2007
Best Practice : Point of Execution Pipe Cleaning
Electric Boat Corporation, Quonset Point Facility’s original methods to internally clean pipes were time consuming and labor intensive. The company adopted an innovative process using Goodway’s Jet Cleaner Pneumatic Cleaning Gun and Foam Pellet which cleans pipes in only a few minutes.
The cleanliness of piping systems installed on U.S. Navy submarines must be indisputable, as piping services the nuclear reactor, propels the ship, and supplies potable water. Unfortunately, dirt and debris are introduced by mandrels during the bending process. Therefore, Electric Boat Corporation, Quonset Point Facility (EBQP) must clean all pipes produced in its facility based on requirements set forth in Standard Procedure 1.8.
Previously, pipes were soaked in a tank of trisodium phosphate solution that must be kept at a depth of 38” and temperatures of 170° to 180° for two hours. The pipes were then rinsed in a separate tank of deionized water maintained at temperatures of 165° to 185°. Because the local water supply did not meet standards, deionized water had to be made in-house, requiring additional equipment and labor costs and taking daily samples from both tanks for chemical analysis by a laboratory service chemist. Mechanics used rags soaked in alcohol drawn through the pipes on nylon lanyards. The rag cleaning process could only be used on pipes of smaller diameters, which was repetitive, time consuming, and difficult to complete on pipes with multiple bends. After cleaning, pipes were moved to the stave installation area in the cleaning facility. Staves are metallic insulation, secured to the exterior of pipe to reduce noise and vibration. EBQP realized it was labor intensive and time consuming to move pipes from bending to the laundry facility staging area, to the cleaning tanks, to the stave installation area, and out of the laundry for fit-up. EBQP shifted the responsibility of keeping all materials clean from the cleaning facility mechanic to the mechanic who fabricated the piping details. This same mechanic also notified the stave installer in advance about details emerging from the bending and cleaning process, allowing the stave installation to be accomplished in the fabrication area.
In early 2002, EBQP implemented its Point of Execution Pipe Cleaning to achieve these goals. The Goodway Jet Cleaner Pneumatic Gun and cylindrical foam pellets (Figure 2-8), soaked in a cleaning solution of one part Bruelin (a mild detergent) to10 parts water, is now used. The mechanic selects a foam pellet and head attachment for the air gun that fits the pipe detail to be cleaned. The jet cleaner is attached to an air hose and placed at the end of the pipe. The mechanic pulls the trigger and the foam pellet is shot through the pipe into a collection bag at an average of 100 psi. The pellet is shot through until the pipe meets cleanliness standards, usually no more than six times. EBQP is currently using this process for pipes up to four inches in diameter, but cannot use the method on pipes with fittings because grease fills the crevice between the fitting and the pipe. At least 70% of the pipes cleaned at EBQP meet these requirements, reducing cleaning time from two to three hours to less than five minutes per detail. While the foam pellets are expensive (a box of 25 costs approximately $100), they can be reused in some cases. EBQP is investigating methods to wash and reuse all pellets.
EBQP is procuring enough jet cleaners to assemble on mobile carts. The carts will be stationed at the pipe bending work area, and pipe shop mechanics will be responsible for cleaning. After cleaning the pipe, the mechanic will cap and seal all pipe ends. The seal contains information on the cleaning process, including the badge number of the mechanic, and end-caps cannot be removed without breaking the seal. This ensures the integrity of the cleaning is maintained. The stave installation will also occur at the bending workstation. Pipes will be delivered directly from the bending area to the manufacturing area, by-passing the cleaning facility. EBQP estimates that this process will eliminate seven to eight handling steps, provide ergonomic benefits, reduce cleaning tank costs, reduce the crane time necessary to move certain pipes, and increase safety.
Figure 2-8. Goodway’s Jet Cleaner Pneumatic Cleaning Gun and Foam Pellet
For more information see the
Point of Contact for this survey.