Auxiliary Piping Systems Inspection Interval
Power Penstock Guard Gate and Valve Closure Tests
Balanced closure tests (FW, CG, RS, RF,
SG, CY, RG, BV)
Unbalanced, emergency closure tests (FW,
CG, RS, RF, SG, RG, BV)
Pipe and fittings - exterior surface
Pipe and fittings - interior surface
21. Gate valves, globe valves, plug valves, etc.
22. Check valves
23. Pressure regulating and pressure relief valves
A - Annual
NS - Not scheduled (extraordinary maintenance; usually 5-year or longer intervals)
TY - 10 years. Interval between tests not to exceed 10 years. Actual interval should be between
5 and 10 years.
Penstocks and Outlet Pipes
Annual. Check concrete supports for cracks, spalling, or signs of movement. Check lubrication
of sliding supports and clean exposed bearing surfaces. Make sure sliding surfaces are not
2. Expansion Joints
Annual. Check leakage past packing and tighten as necessary. Sliding surfaces should be clean of
rust and scale. Clean as required.
Not Scheduled. Remove old packing, thoroughly clean packing area and sliding surfaces, and
install new packing.
Annual. Inspect surface for deterioration of paint and for corrosion, paying particular attention to
rivets, bolts, and welds. Prepare corroded or deteriorated surfaces by sandblasting or other
acceptable means and repaint. Steel pipe, where it emerges from concrete, is subject to galvanic
corrosion. These areas should be repaired by thoroughly cleaning, sandblasting, and painting with
a zinc rich primer. Look for leakage from gasketed joints such as mandoors or at drain or fill