service for maintenance immediately after the test. The schedule for these tests should be convenient, but
the scheduled interval between tests for an individual gate should not exceed 10 years.
3.4 Auxiliary Piping Systems
Auxiliary piping systems include domestic, fire protection, and cooling water systems, hydraulic and
lubricating oil systems, and service air systems. In most cases, oil systems require little maintenance other
than repair of an occasional leak. Due to corrosion, most water systems do require maintenance and,
eventually, replacement. The life of a water system will depend a great deal on the corrosiveness and
mineral content of the water it carries.
Since determining the internal condition of water piping is very difficult, the first indication of a problem
may be a leak or the failure of a valve or other component. Although a leak or valve failure may just be an
isolated event, frequently it may be an indication of the condition of the entire system. By monitoring the
condition of a piping system, maintenance and replacement can be scheduled, preventing an unscheduled
outage. Partial disassembly of a piping system can provide a good indication of the condition of the entire
system, but it may damage the piping and valves. Nondestructive tests, such as radiographs or ultrasonic
tests, can be used to determine the condition of a piping system. Radiographs will not only show pipe wall
thickness but also the amount of scale buildup inside the pipe.
Service air systems may also suffer corrosion damage if excessive moisture is allowed into the system.
Scale and rust particles can damage pneumatic tools and cause pneumatic cylinders to stick. If moisture in
air piping is a problem, a moisture separator or an air dryer should be installed.
If a piping system fails prematurely because of a corrosion problem, it may be beneficial to replace the
piping with a nonmetallic material. Pipe constructed of fiberglass and polyvinyl chloride (PVC) as well as
other plastics have been used successfully in corrosive environments. Before switching to one of these
materials, give careful consideration to their temperature and pressure limitations. If PVC or fiberglass is
used, the installation instructions should be followed carefully. Pipe hanger requirements and joining
procedures are significantly different from steel pipe. Fiberglass and plastic piping should not be used in
compressed air systems.