Inspection Checklist
Penstocks and Outlet Pipes Gates and Valves
Inspection Interval
1. Supports A NS
2. Expansion joints A NS
3. Exterior A NS
4. Interior A NS
Abbreviations in parenthesis refer to the types of gates or valves a particular
inspection item refers to.
FW - Fixed wheel gate DG -Drum RG -Radial gate
gate
CG - Coaster gate JF -Jet flow gate BV -Butterfly valve
RS -Ring-seal gate SG -Slide gate HJ -Hollow jet valve
RF -Ring-follower gate CY - TV -Tube valve
Cylinder gate
BH -Bulkhead gates or stop logs
5. General inspection (FW, CG, RS, RF,
BH, DG, A NS
JF, SG, CY, RG, BV, HJ, TV)
6. Seals and seal seats (FW, CG, RS, RF, A NS,
BH, DG
JF, SG, CY, RG, BV, HJ, TV)
7. Gate frames and tracks (FW, CG) NS
8. Roller and wheel assemblies (FW, CG, NS
RS)
9. Pivot pins and hinges (DG, RG) A
10. Gate frames and bonnets (RS, RF, JF, A NS
SG)
11. Gate leaf, skin plates, and structural A NS
members BV)
(FW, CG, RS, RF, BH, DG, JF, SG, CY,
RG,
12. Valve body (BV, HJ, TV) and valve A NS
needle or
tube (HJ, TV)
Gate and Valve Operators and Hoists
13. Threaded stem hoist and mechanical
A
operators NS
(FW, CG, RS, RF, JF, SG, CY, HJ, TV)
14. Chain hoists (FW, CG, RG) A NS
15. Wire rope hoists (FW, CG, BH, RG) A NS
16. Hydraulic hoists (FW, CG, RS, RF, JF, A NS
SG, CY, BV, HJ)
Auxiliary Piping Systems Inspection Interval
Power Penstock Guard Gate and Valve Closure Tests
17. Balanced closure tests (FW, CG, RS, RF, A SG, CY, RG, BV)
18. Unbalanced, emergency closure tests (FW, TY CG, RS, RF, SG, RG,
BV)
19. Pipe and fittings - exterior surface A
20. Pipe and fittings - interior surface NS
21. Gate valves, globe valves, plug valves, etc.A NS
22. Check valvesNS
23. Pressure regulating and pressure relief valvesA NS
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
1. Supports
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 obstructed.
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.
3. Exterior
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 lines.
4. Interior
Annual. Inspect surface for paint deterioration, corrosion, and cavitation
damage, paying particular attention to rivet heads and welded and bolted
joints. Check condition of tie rods and supports at bifurcations. Prepare
corroded or deteriorated surfaces by sandblasting or other acceptable
means and repaint with an appropriate paint.
Not Scheduled. Sandblast and paint entire interior surface when condition
of paint has reached the point that spot repairs are no longer adequate.
Gates and Valves
5. General Inspection (FW, CG, RS, RF, BH, DG, JF, SG, CY, RG, BV, HJ,
TV)
Annual. Inspect exposed and accessible components for corrosion,
deterioration of paint, or any other damage. Unwater penstock or water
conduit and inspect downstream portion of gate or valve. Where guard
gates are available, inspect upstream portion as well. If possible, operate
gate through it full range of travel.
Not Scheduled. Install stop logs or bulkhead gates to inspect portions of
gates or valves normally inaccessible. Remove or disassemble gate or valve
as necessary to replace or renew seals or guides, to sandblast and repaint, or
to repair any other damage.
6. Seals and Seal Seats (FW, CG, RS, RF, BH, DG, JF, SG, CY, RG, BV,
HJ, TV)
Annual. Check for excessive leakage. Adjust seals or schedule
maintenance as required. Leakage, especially through high pressure gates
or valves, can cause further damage if not corrected. Where accessible,
check rubber seals for cracking or other signs of deterioration and bronze
seals for wear, cavitation erosion, or galling.
Not Scheduled. Unwater as required and check for damaged or missing
seals, seal retainers, and bolts. Check that water actuated seals are free to
move and that water lines and ports are clear. Check seal seats, wallplates,
gate sills, and adjacent concrete for wear or other damage. Look for signs of
misalignment such as uneven wear on the seals or seal seats.
7. Gate Frames and Tracks (FW, CG)
Not Scheduled. A thorough inspection of the tracks and gate frames in most
cases will require the installation of either bulkhead gates, stop logs, the use
of divers, or a remote controlled underwater vehicle. The tracks for the
rollers or wheels should be checked for deformation, corrosion, and missing
clamps or bolts. The gate frame should be checked for deformation,
corrosion, and cavitation damage and for any missing bolts.
8. Roller and Wheel Assemblies (FW, CG, RS)
Not Scheduled. Removal or disassembly of the gate is usually required for
inspection of roller and wheel assemblies. Roller assemblies should be
checked for any damaged rollers, pins, or links. Rollers and wheels should
be checked for free movement and for flat spots or other indications that the
rollers or wheels have been sliding and not rolling. Antifriction bearings
(roller or ball bearings) should be checked for free rotation, adequate
lubrication, corrosion, and replaced as necessary. Bronze bushings should be
checked for scoring or adequate lubrication. Bearing seals should be
replaced if there is any sign of damage. The bearing journal should be
checked for scoring, corrosion, or any other damage. The bearing journal of
self-lubricated bushings can sometimes corrode due to a electrolytic reaction
from the graphite in the bushing. If this is noted, the bushings should be
replaced with a nongraphite, self-lubricated bushing or a plain bronze
bushing with some type of lubrication system.
9. Pivot Pins and Hinges (DG, RG)
Annual. Check general condition of pivot pin or hinge, looking for bent or
damaged parts. Check that pivot pins are properly lubricated. Inspect
concrete adjacent to anchors or pivot pins for cracking or spalling.
10.Gate Frames and Bonnet (RS, RF, JF, SG)
Annual. If accessible, inspect interior of fluidway, checking for any
cavitation erosion, corrosion, or other damage. Check bonnet cover for
cracks or leaky gaskets. Check for excessive leakage past gate stem and
position indicator rod packing and tighten as required. If equipped with a
lower bonnet drain, flush silt from bottom of bonnet.
Not Scheduled. Disassemble gate and inspect for any cracks, corrosion,
cavitation erosion, or any other damage. Sandblast or clean by acceptable
method and paint interior of bonnet as necessary.
11. Gate Leaf, Skin Plates, and Structural Members (FW, CG, RS, RF, BH,
DG, JF, SG, CY, RG, BV)
Annual. Accessible portions should be checked for corrosion, cavitation
erosion, missing or damaged bolts or rivets, or any other damage. Check
flexible drain hoses of drum gates to ensure they are clear and unplugged.
Not Scheduled. Disassemble gate or install bulkhead gates and unwater to
allow inspection of entire gate or gate leaf. Check bottom of the gate leaf or
gate for cavitation erosion. Sandblast or clean by acceptable method and
paint as necessary. Check structural members for cracked welds, missing or
damaged bolts or rivets, or any other damage. On drum gates and some
radial gates, check interior of gate for leaks, plugged drain holes, and general
condition. Drum gate flexible drain hoses should be cleaned with a rotary
drain cleaner.
12. Valve Body (BV, HJ, TV) and Valve Needle or Tube (HJ, TV)
Annual. Exterior of valve should be checked for leakage, cracks, and
corrosion. If accessible, interior of valve should be checked for corrosion,
cavitation erosion, scale buildup that may interfere with valve movement or
sealing, and any other damage. Check lubrication to bearings and oil level of
gear boxes.
Not Scheduled. Unwater water conduit or penstock or disassemble valve to
allow inspection of all valve components. Check for parts damaged by
cavitation erosion or corrosion. Check water and oil seals and replace as
necessary. Polished surfaces of hydraulically operated hollow jet valves
should be checked for any damage and built up by welding or other process,
remachined, and repolished if necessary. Check bearings and bronze seal
rings for wear or other damage and replace if necessary.
Gate and Valve Operators and Hoists.
13.Threaded Stem Hoist and Mechanical Operators (FW, CG, RS, RF, JF,
SG, CY, HJ, TV)
Annual. Inspect gear cases for leaks or other damage. Check motor coupling
for misalignment. Check oil in gear boxes for water contamination and for
proper level. Check grease coated gears, stems, and stem nuts for dirt or dust
contamination of grease. Check gears, stem, and stem nut for wear, galling,
or other damage. Grease bearings or other components equipped with grease
fittings being careful not to over grease and damage grease seals. During
operational test, check for unusual or excessive vibration or noise.
Not Scheduled. Drain gear boxes and refill with new oil. Grease coated
gears and stems should be cleaned and recoated with new grease.
Disassemble as required to check condition of gears, bearings, or other
components normally inaccessible.
14. Chain Hoists (FW, CG, RG)
Annual. Inspect chain for corrosion and deformed chain links or pins. Check
sprocket for damaged teeth. Apply appropriate lubricant to chain. Check oil
in gear boxes for water contamination and for proper level. Check condition
of grease for dirt or dust contamination on grease coated gears. Grease
sheave, drum, and gear shaft bearings equipped with grease fittings being
careful not to overgrease and damage grease seals. Check gears for uneven
wear, galling, or signs of misalignment. Check brake shoes and brake drums
for signs of overheating or other damage.
Not Scheduled. Drain gear boxes and refill with new oil. Grease coated
gears should be cleaned and recoated with new grease. Disassemble as
required to check condition of gears, bearings, or other components
normally inaccessible.
15. Wire Rope Hoists (FW, CG, BH, RG)
Annual. Inspect wire rope for broken wires, worn or abraded wires,
corrosion, and crushed or flattened strands. See Section 6, Cranes, Hoists,
and Rigging Equipment for replacement requirements. Inspect rope drum
and sheaves for wear and spooling characteristics of the drum. If possible,
apply lubricant to entire length of wire rope. Check oil in gear boxes for
water contamination and for proper level. Grease sheave,
drum, and gear shaft bearings equipped with grease fittings. Check gears for
uneven wear, galling, or signs of misalignment. Check condition of brake
shoes and brake drums for signs of overheating or other damage.
Not Scheduled. Drain gear boxes and refill with new oil. Grease coated
gears should be cleaned and recoated with new grease.
16.Hydraulic Hoists (FW, CG, RS, RF, JF, SG, CY, BV, HJ)
Annual. Check entire hydraulic system for leaks, including piping, valves,
and packing. Drain accumulations of water and sediment from oil reservoir
and lower end of hydraulic cylinders. Prior to scheduled maintenance, take
oil sample after operating system for sufficient time to allow the oil and any
contaminants to mix. Oil sample should be checked for water content,
viscosity, acidity, and solid contaminants. Based on results of oil tests, drain
system, filter oil, and clean oil reservoir with lint free rags. Add oil to
system if necessary to bring oil to proper level, making sure oil added is
exactly the same type and viscosity as the oil in the system. Clean or replace
oil filters. Calibrate pressure gauges and pressure switches. Check setting
and operation of pressure relief valves. Operate gate or valve through a
complete openclose cycle under balanced conditions, checking the opening
or closing times and noting any unusual or excessive noise or vibration. If
there is a significant increase in either the opening or closing time, determine
the reason for increase. Check surface condition of piston stem for rusting,
scoring, or other conditions that could impair operation or cause leakage.
Check position indicators to ensure wire rope and sheaves or chains and
sprockets move freely.
Not Scheduled. Remove cylinder head and inspect cylinder wall looking for
signs of corrosion pitting or scoring. Check condition of stems and stem
couplings, applying a coating of water proof grease to couplings normally
submerged or exposed to moisture.
Guard Gate and Valve Closure Tests
17. Balanced Closure Tests (FW, CG, RS, RF, SG, CY, RG, BV)
Annual. Perform gate or valve closure test under balanced, no flow
conditions following test procedure for particular gate or valve being tested.
Test procedure should be for the specific gate or valve being tested and not a
similar one. Contact the Hydroelectric Research and Technical Services
Group, D-8450, if a procedure is not available or if there is any uncertainty
about the procedure that is available.
18. Unbalanced, Emergency Closure Tests (FW, CG, RS, RF, SG, RG)
Ten Year. Perform gate or valve closure test under full flow conditions
following test procedure for the gate or valve being tested. Test procedure
should be for the specific gate or valve being tested and not a similar one.
Contact the Hydroelectric Research and Technical Services Group, D-8450,
if a procedure is not available or if there is any uncertainty about the
procedure that is available.
Auxiliary Piping Systems
19. Pipe and Fittings - Exterior Surface
Annual. Visually inspect all threaded, welded, and flanged fittings checking
for any leaks or corrosion. Replace or tighten fittings or pipe as required.
Check pipe hangers and supports to make sure they are carryin their share of
the load and that anchors are tight. Examine paint for cracking, chalking, or
other deterioration. Remove corrosion by wire brushing, sandblasting, or
other acceptable method and repaint.
20. Pipe and Fittings - Interior Surface
Not Scheduled. Partially disassemble piping or utilize a nondestructive test
method to determine condition of interior surfaces. Measure pipe wall
thickness and compare to original thickness.
21. Gate Valves, Globe Valves, Plug Valves, etc.
Annual. Check valve stem packing for leaks and tighten packing gland as
required. Operate valve through its full range of movement several times.
With valve closed under pressure, listen for leakage past valve and correct as
required. Lubricate valve stems, plug valve seats, and other components as
required with appropriate lubricant.
Not Scheduled. Disassemble valve and inspect condition of valve body,
stem, and sealing surfaces and repair as required. Completely remove old
valve stem packing and install new packing.
22. Check Valves
Not Scheduled. Check for leakage past valve while under full operating
pressure. Disassemble and replace or regrind valve seats as required.
23. Pressure Regulating and Pressure Relief ValvesAnnual. Check operation
and setting of pressure regulating and pressure relief valves.Not Scheduled.
Disassemble valves and remove any scale buildup that interferes with the
operation of the valve. Reassemble and check operation and settings of
valves.
Inspention report.
