Hydro Plant Risk Assessment Guide

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Table 21 – Seals, Sealing Surfaces, and Packing Results Good – Seals are in good condition with less than normal leakage (< 12.5 gpm or < 0.8 liters/s), seal surfaces are parallel (to each other) and in good condition with minimal pitting and cavitation damage. Seal will function adequately for ≥ 10 years. Moderate – Seals and sealing surfaces are in serviceable condition with moderate leakage (≥ 12.5 and < 25 gpm or ≥ 0.8 and < 1.6 liters/s). There are some small dimensional discrepancies or cavitation damage. Seal or seal surface can be adjusted for a better seal. Seal will function adequately for ≥ 7 and < 10 years. Severe – Large volume of leakage (≥ 25 gpm or ≥ 1.6 liters/s) caused by significant damage or dimensional discrepancy. Seal will function adequately for < 7 years. Shaft trunnion seals or packing leak excessively. Seal or seal surface cannot be adjusted for a better seal. Adjustment to Condition Index Score Add 0.5 No Change Subtract 0.5 Test T2.2.6: Valves – Bearings and Bushings Valve bearings and bushings tend to have a limited amount of wear since they do not experience very many cycles per year of operation. Deficiencies are usually from improper installation, manufacturing or material defect, and/or lack of preventative maintenance. Bushings are very difficult to inspect while installed; usually the poor condition of a bushing is not known until total failure. A grade of moderate should be given unless bearings and bushings can be inspected directly. Table 22 – Bearings and Bushings Results Good – Bearings and bushings are in good shape with no apparent eccentric wear or misalignment. Moderate – Bearings and bushings are worn in accordance with their age and are still in serviceable condition. Severe – Bearings and bushings are wearing eccentrically and/or are not installed concentrically with shaft. Apparent manufacture or material defect. Total failure. Adjustment to Condition Index Score Add 0.5 No Change Subtract 0.5 E11-22
Test T2.3: Gates and Valves Operators Operators – Structural Integrity Gate and valve operators are usually hydraulic cylinders, hydraulic hoists, or electric-driven hoists. This section is concerned with the structural integrity of the gate and valve operators including: • Corrosion • Anchoring • Yielding, Fracture and Fatigue and Fabrication Discontinuities • Improper Field Repair and Modification • Miscellaneous Damage and Condition Note: Bridge and gantry cranes that are used for emergency closure shall not be inspected or rated using this section. Bridge and gantry cranes have specific inspection requirements that are described in applicable Federal, State, Provincial laws and regulations. See Appendix E9: Crane Condition <strong>Assessment</strong>. Test T2.3.1: Operators – Corrosion Some major contributing factors to corrosion are: the pH and ion concentration of the river, relative humidity of 40% or more, ineffective protective coatings (due to age, improper formulation, or improper application), cavitation, and malfunctioning or improperly maintained cathodic protection systems. Also, dissimilar metals in contact can cause a dielectric reaction and cause one of the metals (usually carbon steel) to corrode at an accelerated pace. Table 23 – Corrosion Results Good – Corrosion is mainly superficial, hoist drums and sheaves are in good shape, little or no pitting, welds have not been reduced in area, corrosive protective coating is in serviceable condition. Moderate – There is some pitting and more sever corrosion. Protective coating needs some attention in the near future. Corrosion will not affect structural integrity for ≥ 7 and < 10 years. Severe – Metal is deeply pitted and/or has reduced metal crosssectional area significantly in structural elements such as lifting beams, anchor bolts, shafts, etc. Corrosion will likely effect structural integrity in < 7 years. Adjustment to Condition Index Score Add 1.0 No Change Subtract 1.0 Test T2.3.2: Operators – Anchoring For inspection purposes, it is very difficult to adequately assess if anchoring was properly designed and is adequate, however, portions of the anchoring can be inspected for failure. E11-23
Page 1 and 2: September 2006 Hydro Plant Risk Ass
Page 3 and 4: qualified personnel that are compet
Page 5 and 6: Condition Indicator 2 - Physical Co
Page 7 and 8: Table 3 - Valve Physical Condition
Page 9 and 10: power supply, inspections, exercisi
Page 11 and 12: Table 6 - Intake Valve Operator (Hy
Page 13 and 14: E11.11 TIER 1 - EMERGENCY CLOSURE S
Page 15 and 16: • Miscellaneous Damage or Other C
Page 17 and 18: Note: If the gate performs unaccept
Page 19 and 20: Test T2.2: Valves Valves - Structur
Page 21: Valves - Functional Operation Test
Page 25 and 26: Table 26 - Improper Field Repair an
Page 27 and 28: Table 29 - Hydraulic Systems Result
Page 29 and 30: Table 32 - Actuation Performance Re
Page 31 and 32: extensive wearing. Extreme - Brake
Page 33 and 34: Table 39 - Gearboxes, External Gear
Page 35 and 36: Table 43 - Maintenance Escalation R
Page 37 and 38: EMERGENCY CLOSURE GATES & VALVES TI
Page 39 and 40: EMERGENCY CLOSURE SYSTEM TIER 2 CON
Page 47 and 48: Part II: Calculate the Net Emergenc
Page 49 and 50: Porosity Crack at flange diaphragm
Page 51: Weld performed by nonqualified weld

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