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2.6.3. Large Punctures and Holes. Large holes in pipelines usually create a welding safety hazard
because of the spills that have saturated the ground. Clamping a steel plate of the same curvature as
the pipe over the damaged area, using petroleum-resistant rubber for a seal, makes temporary line
repairs; the area may then be cleared of all hazards. The steel plate clamped over the leak can be
permanently welded to the pipe. For most welding operations, the pipeline can stay in service during
repairs; however, if there is danger of the arc penetrating the pipe (thin wall or badly corroded pipe),
the system should be shut down during repairs. All hot work must be approved by the command
fuels engineer, base safety, base bioenvironmental engineer, and base fire department.
2.7. Major Repairs. Major repairs involving several sections of pipe can be done by two methods:
2.7.1. If the pipeline can be taken out of service, replace the damaged section with new pipe.
2.7.2. If the pipeline cannot be taken out of service, a casing can be welded over the damaged
sections. Casings are considered temporary and should be used only under extreme conditions.
2.8. Pipeline Cleaning. Pipelines are cleaned with line scrapers forced through the line by the liquid
being pumped. Intervals between cleanings vary with the size of the pipe and the type of liquid. A drop
in the flow rate, the continual presence of dirt, rust, or particulate in basket strainers, and or shortened
filter life may indicate a need for cleaning. Batching pigs are used to separate fuels and prevent
contamination. Treatment of batching pigs is the same as for line scrapers. Water slugs are not
permitted to separate batches.
2.8.1. Scraper Operation. Decide on the scraper best suited for the operation. Check specifications
to be sure it will pass through all valves and bends. Keep accurate records of the time the scraper is
started and quantity of fuel pumped to trace the progress of the scraper and find the time of its arrival
at the receiving station. It is good practice to bypass meters while scraper sediment is in the line.
The scraper should be run at the minimum velocity (3.2 kilometers per hour [two miles per hour])
with no shutdowns while the scraper is in the line. Shutdowns will permit the scrapings to settle in
front of the scraper, causing it to become stuck (this usually requires cutting the line to retrieve it).
2.8.2. Scraper Tracing. Several methods are used to find scrapers stuck in lines. The knife-type
scrapers make sufficient noise to be followed by line walkers. Brush-type scrapers are relatively
silent and require a transmitting device to reveal their exact location. Their general location can be
found from the time and quantity of fuel pumped before the stoppage occurred. Special devices
18.104.22.168 Noisemakers fastened to the scraper.
22.214.171.124. Radioactive material that can be found with a Geiger counter.
126.96.36.199. Magnetized core in the scraper that can be detected with a magnetometer.