B.08.03 48 13 13.01 26_am0005.pdf

The appendix starting on page 84 has been added as part of (am0005) on February 7, 2022

02 – NORFORK DAM EFFICIENCY TEST BY GIBSON METHOD UNIT NO D 1945

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PN501258

TURBINE REPLACEMENT AND GENERATOR REWIND

NORFORK LAKE, DAM AND POWERHOUSE

BAXTER COUNTY, ARKANSAS SOLICITATION NO. W9127S21R0001

SECTION 48 13 13.01 26

HYDRAULIC TURBINE

PART 1 GENERAL

1.1 GENERAL INFORMATION

1.1.1 Existing Units

The existing Norfork Units 1-2 turbines are vertical Francis type supplied by S. Morgan Smith . The turbines, which were placed in service in the early 1940's , are rated at 42,000 hp at a net head of 160 feet. At the the maximum generator overload capacity ( 115%), they operate at about 62,860 hp. The turbine runner has 17 blades and a runner discharge diameter of 145.56 inches, with 20 steel wicket gates. The distributor centerline is at an elevation of 386.0 ft. The wicket gate pad height is

36.9425 inches. The units turn in a clockwise direction when viewed from above, at 128.6 RPM. The generators, which were supplied by Westinghouse Electric , are rated at 44,750 KVA and 0.90 power factor, and efficiency of 98%. The primary purpose is to improve hydraulic efficiency and increase reliability. The secondary purpose for replacing the turbine runner is to improve discharge dissolved oxygen (DO) levels across the load range.

After the original construction, a modification was done to the bottom of the penstock to scroll case transition. A profiled concrete filler was poured at the bottom of the penstock, downstream of the elbow. It is assumed that this was done in order to improve the hydraulics. The concrete filler effectively decreased the overall wetted perimeter in this area. Contractor should be aware of this modification and implement it into the design of new turbine runner. Original documentation regarding this modification will be attached at the end of this section in Appendix

A - FORMS AND ATTACHMENTS.

1.1.2 Additional Modifications/Replacements

a. Non-contracted turbine modifications or replacement components must not be incorporated in the model or prototype turbines without the written approval of the Government.

b. Unless otherwise specifically stated in these specifications, the Government does not intend to change the existing surface profile, finish (roughness), or fairness (waviness) of the turbine water passage elements. Hollows, depressions and projections resulting from existing surface profile deviation and various types of surface pitting will not be changed by the Government. Damage in excess of that described above and features in non-compliance with specification drawing dimensions (including IEC 60193 allowances for similarity and uniformity) will be repaired by the Government (refer to paragraph 1.5.3.1 for more details). If the Contractor determines better surface conditions are required to meet their performance or cavitation guarantees, they must rehabilitate the surfaces at their expense.

1.1.3 Replacement Turbine Assembly

The existing runners must be replaced with a stainless steel aerating turbine designed to provide (am0004) a minimum of 6.0 mg/L of dissolved oxygen (DO) (am0004) in the downstream discharge (assuming 0.0 mg/L in the upstream water) while producing 63,630 hp at the maximum power output for

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a net head of 175 feet. (refer to paragraph 1.5.1 for more details). The Contractor must provide all that is necessary to furnish and install two rehabilitated turbines that are geometrically similar to the Contractor's model turbine and which achieves the performance guaranteed in the contract. The assembly must interface with existing, modified, refurbished or replacement structural, mechanical and electrical components to produce a satisfactory operating generating unit. Each respective replacement runner must not cause the existing generating unit's electrical or mechanical characteristics to be altered or degraded in any way, unless otherwise specified herein or as approved. This section pertains to both units that must be rehabilitated. Components and structures affected by the Contractor's work, including component replacement or modification, must be evaluated by the Contractor to determine if they are adequate for the intended future operation. Any modifications or equipment replacements to make these affected components useful and safe for future operation must be at the Contractor's expense.

In the event that Contractor approved modifications impact other systems or components, the Contractor must modify or provide said systems or components in such a manner as to maintain the functions and functionality which existed prior to commencing the refurbishment.

1.1.4 Lifting and Handling

Additional lifting devices must be furnished by the Contractor to handle the turbine parts and assemblies during the erection or disassembly of the unit, from above, as required to compliment and supplement existing Government devices and handling facilities, refer to any requirements in DIVISION 01 - GENERAL REQUIREMENTS and 48 13 13.02 26.

1.1.5 Minimum Requirements

The following articles and paragraphs in SECTION 48 13 13.01 26, except for those that specify requirements for spare parts and special wrenches and tools, prescribe the minimum requirements for a turbine.

The Contractor must provide replacement Francis runners that meet the hydraulic conditions, efficiency requirements, and cavitation requirements as prescribed in paragraph 1.5. The replacement runners must also meet the aeration requirements of paragraph 1.6. These conditions are considered the minimum requirements, and include both operational and environmental parameters. The aeration system(s) must be tested to demonstrate the DO (am0004) capabilities of the replacement (am0004) units . DO test measurements must be performed during the (am0004) peak low DO season and air flow measurements must be performed during operational testing after reassembly and during the (am0004) peak low DO season for each unit.

1.2 REFERENCES

The publications listed below form a part of these specifications to the extent referenced. The publications are referred to in the text by basic designation only. Unless otherwise indicated or noted, use the most recent publication at time of contract solicitation from the following publications:

AMERICAN WELDING SOCIETY (AWS)

AWS A5.4/A5.4M Specification for Stainless Steel Electrodes for Shielded Metal Arc Welding

- 11th Edition

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ASME INTERNATIONAL (ASME)

ASME B1.1 Unified Inch Screw Threads (UN and UNR Thread Form)

ASME B18.2.1 Square, Hex, Heavy Hex, and Askew Head Bolts and Hex, Heavy Hex, Hex Flange, Lobed Head, and Lag Screws (Inch Series)

ASME B18.2.2 Nuts for General Applications: Machine Screw Nuts, Hex, Square, Hex Flange, and Coupling Nuts (Inch Series)

ASME B18.3 Socket Cap, Shoulder, Set Screws, and Hex Keys (Inch Series)

ASME B18.6.2 Slotted Head Cap Screws, Square Head Set Screws, and Slotted Headless Set Screws (Inch Series)

ASME B18.6.3 Machine Screws, Tapping Screws, and Metallic Drive Screws (Inch Series)

ASME B18.21.1 Washers: Helical Spring-Lock, Tooth Lock, and Plain Washers (Inch Series)

ASME PTC 18 Hydraulic Turbines and Pump-Turbines

ASME BPVC SEC VIII Boiler and Pressure Vessel Codes: Section VIII Rules for Construction of Pressure Vessel

ASTM INTERNATIONAL (ASTM)

ASTM A27/A27M Standard Specification for Steel Castings, Carbon, for General Application

ASTM A148/A148M Standard Specification for Steel Castings, High Strength, for Structural Purposes

ASTM A176 Standard Specification for Stainless and Heat-Resisting Chromium Steel Plate, Sheet, and Strip

ASTM A193/A193M Standard Specification for Alloy-Steel and Stainless Steel Bolting for High Temperature or High Pressure Service and Other Special Purpose Applications

ASTM A194/A194M Standard Specification for Carbon Steel, Alloy Steel, and Stainless Steel Nuts for Bolts for High Pressure or High Temperature Service, or Both

ASTM A240/A240M Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications

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ASTM A283/A283M Standard Specification for Low and Intermediate Tensile Strength Carbon Steel Plates

ASTM A285/A285M Standard Specification for Pressure Vessel Plates, Carbon Steel, Low- and Intermediate-Tensile Strength

ASTM A380 Standard Practice for Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment, and Systems

ASTM A449 Standard Specification for Hex Cap Screws, Bolts, and Studs, Steel, Heat Treated, 120/105/90 ksi Minimum Tensile Strength, General Use

ASTM A479/A479M Standard Specification for Stainless Steel Bars and Shapes for Use in Boilers and Other Pressure Vessels

ASTM A516/A516M Standard Specification for Pressure Vessel Plates, Carbon Steel, for Moderate- and Lower-Temperature Service

ASTM A563 Standard Specification for Carbon and Alloy Steel Nuts

ASTM A609/A609M Standard Specification for Castings, Carbon, Low-Alloy, and Martensitic Stainless Steel, Ultrasonic Examination Thereof

ASTM A668/A668M Standard Specification for Steel Forgings, Carbon and Alloy, for General Industrial Use

ASTM A743/A743M Standard Specification for Castings, Iron-Chromium, Iron-Chromium-Nickel, Corrosion Resistant, for General Application

ASTM B21/B21M Standard Specification for Naval Brass Rod, Bar, and Shapes

ASTM B22 Standard Specification for Bronze Castings for Bridges and Turntables

ASTM B98/B98M Standard Specification for Copper-Silicon Alloy Rod, Bar, and Shapes

ASTM B584 Standard Specification for Copper Alloy Sand Castings for General Applications

ASTM F436 Hardened Steel Washers

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CAHIER DES CHARGES HYDRAULIQUES (CCH)

CCH 70-4 Specification for Inspection of Steel Castings for Hydraulic Machines

INTERNATIONAL ELECTROTECHNICAL COMMISSION (IEC)

IEC 60193 Hydraulic Turbines, Storage Pumps and Pump Turbines - Model Acceptance Tests

IEC 60609-1 Hydraulic turbines, storage pumps and pump-turbines Cavitation pitting evaluation Part 1: Evaluation in reaction turbines, storage pumps and pump-turbines

INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS (IEEE)

IEEE 810 Hydraulic Turbine and Generator Shaft Couplings and Shaft Runout Tolerances

INTERNATIONAL ORGANIZATION FOR STANDARDIZATION (ISO)

ISO 1940-1 Mechanical Vibration - Balance Quality Requirements for Rotors in a Constant (Rigid) State - Part 1: Specification and Verification of Balance

SOCIETY OF AUTOMOTIVE ENGINEERS INTERNATIONAL (SAE)

SAE J462 Cast Copper Alloys

SAE J429 Mechanical and Material Requirements for Externally Threaded Fasteners

1.3 SUBMITTALS

Government approval is required for submittals with a "G" designation;

submittals not having "G" designation are for Information Only. When used, a designation following the "G" designation identifies the office that will review the submittal for the Government. The following must be submitted in accordance with SECTION 01 33 00, "SUBMITTAL PROCEDURES":

SD-02 Shop Drawings

Drawings of All Steel Castings, Showing the Location of Tension and Bend Test Specimens; G 90 calendar days prior to foundry work.

Detailed, Assembly, Sectional, Etc. Drawings of All New, Modified and Refurbished Components; G 120 calendar days following the date of formal written notice to proceed with prototype runner fabrication, but in no case later than 30 calendar days prior to commencing fabrication, rehabilitation, modification and/or replacement.

Runner Nameplate Drawing; G 30 calendar days prior to delivery of the turbine runner.

SD-03 Product Data

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Manufacturer's Data; G Manufacturer's catalog cuts and descriptive literature for standard products to be incorporated into the work must be submitted at least 90 days prior to purchase of equipment or site work/installation, whichever comes first.

SD-04 Samples

Upon Written Request, Samples of materials; G Within 10 calendar days of request.

SD-05 Design Data

Deviations In Material Specifications; G A minimum of 90 calendar days prior to use of materials.

Upon Written Request, Design Data and Calculations On Specific Systems Or Components; G Within 15 calendar days from the date of request.

Static Balancing Results; G Within 7 days of completion of balance.

Blade Shape Numerical File; G 60 calendar days following the date of formal written notice to proceed with prototype runner fabrication.

Runner/Shaft Coupling Fastener Preload and Stress Calculations; G 60 calendar days following the date of formal written notice to proceed with prototype runner fabrication.

(am0004)Hydraulic Thrust Load Finite Element Analysis Report; G Submitted a maximum of 90 days following the acceptance of the model test.

SD-06 Test Reports

Dissolved Oxygen Test Plan; G 30 calendar days prior to date of aeration performance test or low DO season test.

Dissolved Oxygen Test Report; G 60 calendar days following date of final performance prototype testing.

For Each Component, Contractor's Internal Quality, NDT and Dimensional Inspection Reports; G Including material test results. Within 7 calendar days of performing the inspection.

Prototype Blade Geometric Similarity / Uniformity Report; G Within 7 calendar days of final checks.

Air Flow Test Report; G 30 calendar days after installation of flowmeter.

Runner Stress Analysis; G

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90 calendar days following date of formal written notice to proceed with prototype runner fabrication.

Heat Treat Inspection Report; G Preliminary report seven calendar days in advance of the date scheduled for the inspection, final report within 14 calendars of the completion of the inspection.

In-process runner shop inspection report Preliminary report seven calendar days in advance of the date scheduled for the inspection, final report within 14 calendars of the completion of the inspection.

Finished Runner Shop Inspection Report; G Preliminary report seven calendar days in advance of the date scheduled for the inspection, final report within 14 calendars of the completion of the inspection.

SD-07 Certificates

Notice of Coupon Removal At least 30 calendar days in advance, or 60 days for countries that require a Passport/Visa for U.S. visitors.

Notice of Final Casting Witness Inspection At least 30 calendar days prior to the commencement of the work, or 60 days for countries that require a Passport/Visa for U.S.

visitors.

Notice of In-Process Runner Inspection At least 14 calendar days in advance, or 60 days for countries that require a Passport/Visa for U.S. visitors.

Notice of Finished Runner Inspection At least 30 calendar days in advance, or 60 days for countries that require a Passport/Visa for U.S. visitors.

SD-08 Manufacturer's Instructions

Method and procedure For determining the volume of cavitation damage; G A minimum of 30 calendar days prior to the inspection, if needed.

Cavitation Repair Procedure; G A minimum of 30 calendar days prior to commencement of the work.

Welding Repair Procedure; G A minimum of 7 calendar days prior to repair.

Procedure For Checking Geometric Similarity Between Design And Prototype; G 150 calendar days following the date of formal written notice to proceed with prototype runner fabrication.

Runner Manufacturing Plan and Work Schedule; G Within 30 calendar days of the formal written notice to proceed with prototype runner fabrication.

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1.4 STRESS REQUIREMENTS

1.4.1 Working Stresses

a. Appropriate safety factors must be used throughout the design, especially in the design of all parts subject to alternating stresses or shock. Maximum unit stresses in tension and compression for parts of the turbine under normal operating conditions must not exceed the values in the following table:

Allowable Maximum Unit Stress

Material Maximum Allowable Stress

Cast Iron 2,000 psi Tension & 10,000 psi Compression

Steel & Other Ductile 20% of ultimate strength or 33% Materials of yield strength

b. The unit stress for ductile materials must be defined as the combined stress calculated for a triaxial stress state using the three principal stresses. The combined stress must be calculated using the distortion-energy (von Mises-Hencky) theory.

c. The following must be considered normal operating conditions to be assumed for the stress calculations:

(1) Operation throughout the net head and tail water range identified in paragraph 1.5.1, from speed-no-load up to and including the gate openings at which the turbine is capable of producing 63,630 hp.

(2) Load rejection at worst case condition of any head, flow, or wicket gate position, or combination thereof, with no load on the generator except windage and friction. The wicket gates are timed to move a full closing stroke with the turbine watered in 8 seconds.

1.4.2 Higher Allowable Stresses

Unit stresses higher than those permitted by 1.4.1 above, but not to exceed two-thirds (2/3) of the yield point, must be permitted for all affected parts of the turbine runner when operating at maximum runaway speed under conditions of maximum head with the wicket gates at the maximum runaway position and no load on the generator. Additionally, stresses in the wicket gate should not exceed two-thirds (2/3) of the yield point at squeeze or shear pin/linkage breakage.

If a finite stress analysis is performed on a component and local stress exceeds the levels identified above in paragraph 1.4.1, the Contractor must demonstrate to the satisfaction of the Government that the elevated stresses do not jeopardize the function or life expectancy of the component. The component design must be modified, if necessary, to address the Government concerns.

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1.5 TURBINE PERFORMANCE CONDITIONS AND GUARANTEES

1.5.1 Hydraulic Operating Conditions

The replacement runners must be rated for a net head of 175 feet. The minimum head is 160 feet and the maximum head is 205 feet, each unit must operate safely with no more vibration and noise than the existing runners, as tested before disassembly. The replacement runners must operate safely, effectively, and efficiently over a range of net heads and flows as described in Table 3 and the Table 2 tailwater elevations. The centerline of the turbine is located at an elevation of 386.00 feet. The measurement of net head is described in paragraph 1.5.8.3.

1.5.2 Turbine Guarantee

a. The Contractor must guarantee a weighted prototype hydraulic efficiency. The weighted efficiency must be calculated as follows:

Step 1 - Determine the expected turbine prototype hydraulic efficiencies at twenty (20) operational conditions ( 160 , 170 175 , 190 , and 205 feet net head at each horsepower presented in Table 1).

Step 2 - Multiply each of the twenty efficiencies in Step 1 by its corresponding weighting factor listed in Table 1.

Step 3 - The weighted efficiency is the sum of the twenty products calculated in Step 2.

b. The guaranteed weighted prototype efficiency must be no less than

89.5 %.

c. The guaranteed efficiencies must be valid for the hardware configuration offered. The verification of the Contractor's guaranteed weighted turbine efficiency must be based on the SECTION 48 13 13.00 26 model testing and the field performance testing as specified in this section.

d. The adjustment for efficiency to be applied for a runner of different diameter must be half of the correction factor determined by the Moody formula (see SECTION 48 13 13.00 26). The prototype turbine must be designed to have good efficiencies throughout a wide load range and over its operating head range.

Turbine weighted efficiency must be confirmed by model test and prototype tests. The predicted prototype efficiencies must be evaluated as part of the economic evaluation, see SECTION 00115 and 00130. The Contractor must propose prototype efficiency guarantees for the following conditions:

TABLE 1

Turbine Prototype Hydraulic Parameters

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Prototype Net Head (ft)

Efficiency Factor @ HP

Efficiency Factor @ HP

Efficiency Factor @ HP

Efficiency Factor @ HP

160 0.001 27,000 0.003 40,500 0.005 48,100 (am0004) 0.003

50,600

170 0.040 32,000 0.084 45,000 0.140 54,000 0.110 58,000

175 0.052 35,000 0.107 47,800 0.180 57,200 0.141 63,630

190 0.009 36,300 0.019 47,800 0.031 57,100 0.025 63,630

205 0.005 38,200 0.011 47,800 0.019 57,100 0.015 63,630

1.5.3 Cavitation

1.5.3.1 Cavitation Guaranteed Operating Region

a. The Contractor must guarantee that the cavitation requirements must be met within the operating region described by the Table 2 tailwater elevations and the net heads and corresponding turbine output ranges indicated in Table 3.

b. The Contractor must guarantee that while operating within this region, the turbine must meet the cavitation requirements as specified in SECTION 48 13 13.00 26. The verification of the guaranteed operating range must be based on the SECTION 48 13 13.00 26 model testing.

c. The Contractor must guarantee/warrant the new, refurbished and modified turbine components, and rehabilitated water passage surfaces, against excessive pitting due to cavitation for a period of two (2) calendar years of operation or 10,000 hours of operation (whichever is reached first). Adjacent surface areas to those mentioned above must be similarly guaranteed/warranted against excessive pitting with the following stipulations. The Contractor and the Government will jointly identify areas of existing cavitation damage that require repair. This inspection must be performed within 30 days of disassembly. The Government will repair the agreed upon areas of pre-existing cavitation damage prior to unit re-assembly, but only to the quality or roughness of adjacent surfaces. Adjacent surfaces must be guaranteed against pitting in excess of the amounts that exist at re-assembly, after the Government. has completed the agreed upon repairs.

The Contractor must not be responsible for repair of pre-existing cavitation damage that has not worsened beyond the pre-existing condition. The cavitation guarantee period must commence at the completion of the 72-hour operational test, as specified in SECTION 48 13 13.02 26.

d. The Contractor's guarantee of the turbine against pitting due to cavitation must be based on operation for not more than 3% of the operating time during the warranty period at turbine output ranges less than the minimum output and for not more than 1% of the operating

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time during the warranty period at outputs greater than the maximum turbine outputs specified in the Table 3 Cavitation Guaranteed Operating Range. At no time will the turbine be operated more than 2% above the maximum turbine output limit of the cavitation guarantee, with the rare exception for turbine performance testing identified in this contract.

e. Prior to the expiration of the guarantee period, the Contractor and Government will jointly inspect and measure any cavitation damage, unless waived in writing. The Government will notify the Contractor a minimum of 14 days in advance of the inspection date. The Government will de-water the unit, remove it from service, and install the draft tube platform to ready the unit for inspection. If excessive pitting occurs, the Contractor must, immediately, unless otherwise approved, repair all cavitation damaged areas, and reshape and/or resurface the cavitated areas and/or adjacent areas by grinding, polishing, building up by welding or other approved means, to remedy the cause insofar as possible. Material for weld build up must be a cavitation resistant material such as NOREM, CaviTec, Hydroloy 914, or equivalent. The Contractor must propose and implement corrective action to mitigate future damage. Repairs must be at the expense of the Contractor.

Upon completion of the repairs, the cavitation guarantee must be renewed for an additional two calendar years or 10,000 hours. The cavitation guarantee must be renewed a maximum of two times, resulting in a maximum of three Contractor cavitation repairs. Following the completion of the third repair the Contractor must pay damages to the Government as described (am0004) in paragraph 1.5.3.4 .

TABLE 2

Cavitation Guaranteed Operating Range

Flow Range (cfs) Minimum Tailwater Elevation (ft msl)

Less than 1,000 373

1,001- 2,000 374

2,001 - 3,000 375

3,001 - 4,000 376

4,001 - 5,000 376.5

5,001 - 6,000 377

6,001 and Greater 378

TABLE 3

No Visible Cavitation Guaranteed Operating Range

Determined by Model

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Net Head (ft) Minimum (hp) Maximum Power (hp)

160 27,000 50,600

170 32,000 58,000

175 35,000 63,630

190 36,300 63,630

205 38,200 63,630

The Contractor must confirm the values required in TABLE 3 with their proposal.

1.5.3.2 Excessive Pitting

a. Excessive pitting caused by cavitation will be defined as the removal of 0.000006D^2 pounds of metal per operating hour (D is the runner reference diameter in feet). In addition, pitting is defined as the removal of metal to a depth exceeding 0.125 inch anywhere within an area of 2 square inches or greater. Erosion or damage caused by suspended matter in the water, or corrosion that may occur at the boundary of corrosion-resistant material and adjacent mild steel material, is not intended to be covered by the Contractor's guarantee.

b. The amount of damage must be determined by evaluating the volume of material needed to restore the area to its original undamaged surface shape and multiplying this volume by the density of the damaged material. The depth, area, and volume of metal lost must be determined as set forth in SECTION 10 of IEC 60609-1 , except that English Units of measurement must be used, unless otherwise specified herein, and no measuring inaccuracy must be considered. The Government and Contractor will jointly outline the areas of damage. The Contractor must then make sketches on transparent material, which depict the areas and give each area identification, the Contractor may suggest alternate methods to depict areas for approval. The Contractor must submit a method and procedure for determining the volume of cavitation damage. A digital planimeter must be used to determine area, unless otherwise approved. Area may be determined from a sketch replica of the area or by using the planimeter on the actual water passage surface. The Contractor's volume estimate(s) and calculations of metal loss must be submitted for approval. The Government will witness the taking of measurements for the determination of the excavated volume, unless otherwise indicated in writing. The weight of metal loss must be determined by multiplying the volume (V) by the density of the material damaged. Other methods of determining metal loss may be submitted for consideration and approval.

1.5.3.3 Repairs

a. The Contractor's cavitation repair procedure must be subject to review and approval. All repair work must be coordinated with and will be witnessed by the Government unless otherwise waived in writing. The Contractor must make suitable template checks, vent

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measurements, and other dimensional checks to demonstrate to the Government that the proper hydraulic shapes and profiles of the runner and water passage elements are maintained or changed to mitigate cavitation damage.

b. For the turbine inspection and for any repairs, the Government will un-water the turbine and will install and remove the working platform under the runner. In addition, the Government will provide electrical power and compressed air at no charge to the Contractor from existing locations, in quantities and amounts commensurate with system capacities.

c. Templates must be furnished at the Contractor's expense and constructed from the blade shape numerical file. The templates must be turned over to the Government at the site following the cavitation repair. Any additional special tools, jigs, fixtures, etc. needed or recommended to facilitate cavitation damage repair must be provided at the Contractor's expense, and turned over to the Government at the site.

d. The Contractor must provide the services of a qualified engineer/individual for turbine inspection and repairs to review the extent of pitting and ensure proper repair and/or remedial work is undertaken.

1.5.3.4 (am0004) Missed Cavitation Guarantee

The parties to the contract agree that the Government will incur financial damage if excessive pitting due to cavitation occurs and can not be resolved. Recognizing that actual damages are difficult to determine with precision, the parties to the contract agree that the following sum reasonably represents the damages that the Government will incur. In the event that cavitation damage in excess of the amount allowed under SECTION 48 13 13.01 26 Paragraph 1.5.3 is discovered after the Contractor has completed two repairs for previous excessive damages, the Contractor shall perform a third repair and pay to the Government a lump sum of $268,140 for each applicable unit.

1.5.4 Speed and Runaway Speed

a. The rated speed at which the turbine must operate is 128.6 rpm, this is the synchronous speed of the existing unit.

b. All parts modified, replaced, rehabilitated, or reused by the Contractor must be designed and constructed to safely withstand the stresses resulting from operation at the maximum runaway speed. The maximum runaway speed of the rebuilt turbine operating with the Contractor's supplied runner must not exceed the generator design runaway speed of 245.6 rpm at any head including 205 ft net head, tailwater elevation, or wicket gate position, or combination thereof, with no load on the generator except windage and friction.

1.5.5 Thrust Bearing Capacity

a. Any Contractor recommendation to modify or replace the thrust bearing assembly, will be first approved by the Government.

b. The maximum design thrust bearing load, when operating with the Contractor supplied replacement runner at steady state conditions, SECTION 48 13 13.01 26 Page 13

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must not exceed the existing load on the thrust bearing. It must be assumed that the existing turbine runner weight is 90,950 pounds and the existing maximum hydraulic down thrust is 229,000 pounds. 319,950 pounds is available for the Contractor's replacement runner and hydraulic down thrust.

c. Calculations based on the results of the SECTION 48 13 13.00 26 hydraulic model testing showing the maximum prototype axial thrust, including the runner hydraulic down thrust and the weight of the prototype runner, are addressed as part of the model testing reports required under SECTION 48 13 13.00 26.

(am0004) d. If the hydraulic thrust of the new runner exceeds 229,000 pounds, the Contractor must conduct a finite element analysis (FEA) study showing the stress and strain impacts on the thrust load supporting components. The analysis must include calculations demonstrating that, based on the maximum hydraulic thrust as determined during the SECTION 48 13 13.00 26 model testing, the stresses in the thrust bearing, thrust bearing bracket, and other associated components respect the allowable values listed in SECTION 48 13 13.01 26, paragraph 1.4. The Hydraulic Thrust Load Finite Element Analysis Report must be submitted to Government approval. This study and report will be paid under an optional CLIN.

1.5.6 Stability, Vibration, and Noise

a. The existing turbines when operating with the existing runners do not experience power swings or draft tube instabilities. The refurbished turbines when operating with the Contractor supplied replacement runners must operate in a similar manner, without hydraulic introduced instabilities to include vibrational abnormalities, over the range of operation defined by paragraph

1.5.1. The vibration levels in the new runners must not exceed the existing runners as must be tested during the predisassembly operational tests. The maximum magnitude of the peak-to-peak draft tube pressure pulsations, verified based on turbine model testing and field testing after reassembly, is defined in SECTION 48 13 13.00 26 paragraph 3.1.11.

b. During non-aerating periods of operation, the turbines must operate smoothly without additional air admission, other than the atmospheric air available through the existing head cover mounted gate operated air valve, which must be retained.

c. A reasonable effort must be made to ensure that the noise level is equal or less than existing levels caused by the components (new or refurbished) associated with this project. See SECTION 48 13 13.02 26.

d. Any vibrational abnormalities that the existing runners experience when operating must be measured and recorded during the predisassembly wet (operational) testing required under SECTION 48 13 13.02 26. Any vibrational abnormalities experienced by the refurbished turbines must be less severe than those measured during the predisassembly wet testing.

1.5.7 Previous Test Data(am0004) and Historic Plant Readings

a. The Government conducted a field test of an existing Norfork Unit 2 in 2014 . Results of this testing is included in Appendix A - FORMS

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AND ATTACHMENTS. Electronic pressure transducers were used in lieu of mercury manometers to plot the Gibson tap's pressure versus time.

b. Gibson tests were conducted to verify prototype performance in 1946 after initial installation and following modification of penstock to add concrete filler. Results of this testing are included in Appendix

A - FORMS AND ATTACHMENTS.

c. Complete data from these tests is available upon request.

(am0004) d. Historic plant readings of various parameters are included in Appendix A - FORMS AND ATTACHMENTS. These include exceedance curves for total power generation flow, tailwater elevations, and gross head as well as heatmaps of generator output vs. gross head.

1.5.8 Prototype Testing

1.5.8.1 Performance Test

a. After the turbine has been installed, commissioned, placed in satisfactory operation, and has met the SECTION 48 13 13.02 26 "72-Hour Operational Test", it may be tested by the Government at its option and expense. The intent of Government-conducted testing is to determine whether or not third-party testing must be performed. If the Government exercises its option, testing will be performed within 1 year following the completion of the unit's SECTION 48 13 13.02 26 "72-Hour Operational Test". Turbine performance testing will be conducted on one unit and will be considered representative of performance for all units.

b. The Contractor must notify the Government if the Contractor desires to be present during the performance testing. The Government will notify the Contractor a minimum of 14 calendar days, or as early as practicable, before the date scheduled for the beginning of the testing.

c. The Government and the Contractor (if the Contractor chooses to participate) will inspect the interior of the turbine from the scroll case prior to the onset of the testing. The draft tube platform will not be installed. Should such inspection disclose any damage or wear to have taken place that will impair the efficiency or capacity of the turbine and which is not covered by the warranty, the Government will, at its expense, restore such work or damaged parts as nearly as practicable to their rehabilitated condition. The Government will not rehabilitate water passage elements not refurbished by the Contractor, unless specified herein. Additional rehabilitation of the water passage that the Contractor feels is necessary for the unit to meet its performance guarantees must be at the Contractor's expense.

d. Government conducted capacity and efficiency testing will be considered "in-house" and will be used to verify Contractor's performance guarantees as well as determining if an independent third party performance test is warranted. The results of the Government's "in-house" performance test will NOT be used as a vehicle for monetary assessment in case the Government's results shows that the Contractor's performance guarantees are not met. In the event that the Government's testing show that the Contractor's performance guarantees are deficient, an independent third party test must be conducted at the Government's option, and monetary assessment must be made based on

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third party testing, see paragraph 1.5.8.4.

e. Except as otherwise specifically provided herein, the capacity and efficiency tests will be conducted in accordance with the ASME PTC 18 Code for performance testing of Hydraulic Turbines.

f. Performance testing will be conducted near the rated net head of 175 feet. The efficiency and power output will be adjusted from the as-tested net head to the guaranteed net heads using the performance and model test results according to ASME PTC 18.

g. Measurement, instrumentation or other inaccuracies will not be used in altering the head or any other measurement and the results will be presented as-is, without any adjustment for measurement, instrumentation, or other inaccuracies.

1.5.8.2 Performance Requirements

The prototype turbine performance requirements of the specification will be deemed to be met if the Contractor's guaranteed prototype hydraulic weighted efficiency, in both aerating and non-aerating modes, is met or exceeded and Contractor provided guarantee power results are confirmed.

The provided runner will be evaluated by the performance requirements in paragraph 1.5.2 and the aerating requirements in paragraph 1.6 to meet all performance guarantees.

1.5.8.3 Discharge, Head, and Power Measurement

a. The quantity of water passing through the turbine will be measured by the pressure-time method using a differential pressure transducer.

Penstock diameters and length as presented in the March 1943 Gibson Test of Unit 2 must be considered representative of current penstock condition. The Government does not intend to resurvey the flow measurement section in the penstock prior to testing. The estimated uncertainty in flow measurements is 1%.

b. Net head is defined as the difference between the total energy contained in the water at the inlet net head Piezometer taps and the total energy contained in the water at the draft tube stop log slot.

The level in the draft tube stop log slot is measured at the tailrace deck by pressure transducers installed in stilling wells located on the sides of the slot, or by radar level sensors. The estimated uncertainty in head measurement is 0.25%.

c. At the time of testing, existing metering transformer current and potential must be used for power measurements, unless they are replaced under this contract. A Generator Field Test must performed on the first unit and must be considered representative for all units.

Generator losses will be based on the results of the field test. The Generator Field Test must need to be completed before any turbine runner performance testing can occur. No efforts will be made to re-test the generator for either the Government's and/or third party's test turbine runner performance test. The uncertainty estimated in power measurement is 0.5%.

1.5.8.4 Independent Third Party Performance Test

If the Government conducted field performance test determines that the prototype turbine fails to achieve the Contractor's guaranteed prototype

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hydraulic efficiency, the Government will arrange for an additional performance test to be conducted by an independent third party acceptable to both the Contractor and the Government. The independent third party must have no contractual or employment relationship with the Contractor and must not enter into such relationship while the third party has been hired to perform any performance tests related to this contract. The third party test must be conducted according to the requirements of methods set forth above and must be conducted within 1 year following the completion of the Government conducted field performance test. The Contractor must be present to witness the test. If the third party test determines that the Contractor's prototype meets the Contractor's performance guarantees, the Government will pay for the test. If, however, the third party test determines that the prototype fails to achieve guaranteed efficiency and/or power output values, the Contractor must reimburse the Government for the cost paid to the third party, or alternatively the Government will withhold an amount equal to the amount paid to the third party from Government payments due the Contractor. In the case of a failure to achieve guaranteed efficiency, remedies must be based on the amount of the third party determined deficiency.

1.5.8.5 (am0004) Prototype Turbine Runner Missed Performance Guarantees

The parties to the contract agree that the Government will incur financial damage if the hydraulic performance guarantees are not achieved due to lost energy generation produced from decreased efficiency and/or decreased horsepower. Recognizing that actual damages are difficult to determine with precision, the parties to the contract agree to the following:

1.5.8.5.1 (am0004) Efficiency Guarantee Based on Field Performance Testing

Each prototype turbine supplied by the Contractor shall meet or exceed the Contractor's guaranteed minimum weighted prototype hydraulic efficiency.

The determination that this efficiency guarantee has been met will be accomplished in accordance with SECTION 48 13 13.01 26 Paragraph 1.5.2.

Should the weighted efficiency, during non-aeration operation, be less than the guaranteed minimum amount and the turbine be in otherwise satisfactory operational condition, the Contracting Officer may conditionally accept the unit as a non-conforming item. In that event, the Contractor agrees to pay the government, or have monies withheld which would otherwise be due, in the amount of $82,129 per unit for each 0.1% of deviation below the guaranteed weighted efficiency. If the field test determined weighted efficiency is less than the value guaranteed by the Contractor by an amount exceeding 1%, the Contracting Officer may reject the turbine.

1.5.8.5.2 (am0004) Power Output Guarantee Based on Field Performance Testing

Each prototype turbine supplied by the Contractor shall meet or exceed the Contractor's guaranteed maximum turbine power output. The determination that the maximum power guarantee has been met will be accomplished in accordance with SECTION 48 13 13.01 26 Paragraph 1.5. Should the maximum turbine power output be less than the 63,630-horsepower guarantee by the Contractor, but more than 63,356-horsepower, and the turbine be in otherwise satisfactory operation condition, the contracting officer may conditionally accept the unit as a non-conforming item. In that event, the Contractor agrees to pay the government, or have monies withheld which would otherwise be due, in the amount of $2,120 per unit for every

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horsepower that the field test determined output is less than the value guaranteed by the Contractor. If the field test determined maximum turbine power output is less than 63,356 horsepower, the Contracting Officer may reject the turbine.

1.6 TURBINE AERATION REQUIREMENTS

The design of new aerating technology must be limited to the turbine area only. Aeration improvements for the reservoir and the tailwater regions are outside the scope of this design.

1.6.1 Environmental Operating Conditions

Environmentally, the Norfork reservoir is typical of reservoirs where there is a depletion of oxygen at the lower levels as thermal stratification occurs during the summer through fall months. When the water with the depleted oxygen is released through the turbines, the low downstream dissolved oxygen levels threaten the downstream river ecology and fail to meet state and federal water quality standards. A dissolved oxygen (DO) (am0004) output of a minimum of 6.0 mg/L (assuming an initial DO level of 0.0 mg/L) is required for Norfork to meet water quality standards. As an example, if the initial upstream DO level is measured to be 2.0 mg/L, the required increase output DO level would need to be 4.0 mg/L to achieve a (am0004) minimum level of (am0004) downstream DO of 6.0 mg/L. The required DO level of 6.0 mg/L must be considered a minimum measurement and not a daily average or any other interpretation.

While aerating, the (am0004) turbines must operate safely, efficiently, and without excessive vibration over a range of net heads between 160 feet to 205 feet with a tailwater elevation of 373 feet msl to 380 feet msl. At the turbine intake, DO levels are estimated to be 0.0 mg/L for this Contract. The 6.0 mg/L DO level must be attained during the following operational parameters: a single and both units in operation during the low DO months ( June-December ) when the net head is close to 175 feet msl.

The lowest DO levels occur historically during the month of November . The measurement of dissolved oxygen (am0004) output is described in paragraph 1.7.

1.6.2 Turbine Aeration Methods

(am0004) Norfork powerhouse currently has a negative air pressure imbalance inside the powerhouse. Any introduction of air into the water way, must pull air in such a manner, that the air is pulled from outside of the powerhouse or from a closed system seperate from the powerhouse ambient atmosphere. Turbine aeration methods that utilize an open system, must route the air intake ducting/piping from the outside ambient atmosphere to the turbine runner. Any ducting/piping installed can not impede walkways, hallways, or other areas that require personel or equipment to pass through. Any aeration system used, can not excarebate the negative air pressure inside the powerhouse. The turbine design must utilize the latest technology and state of the art modeling such as Computational Fluid Dynamics (CFD). The Contractor must include some or all of the following three natural aspiration methods in their aeration design: 1) Distributed, 2) Peripheral, and/or 3) Central. In addition, should the Contractor require additional DO capabilities outside of the naturally aspirated methods; a fourth option, forced aeration, is available for achieving the 6.0 mg/L (am0004) output requirement. The four aeration methods are defined as follows:

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1.6.2.1 Distributed

The distributed method uses air passage ways in the turbine runner to introduce air into the water passage way. Should this method be used, the Contractor must provide a bellmouth type inlet with debris strainer and provisions for air flow measurement. Inlet(s) must have electrically controlled flanged full port ball valves (am0004) to allow for open/close operation from a single control panel mounted in the turbine pit as well as controls located in the control room. In addition to the electrically controlled valves, a manually operated flanged full port ball valve (am0004) . The manual valve should be installed to allow for isolation and maintenance of the electrically controlled valve.

1.6.2.2 Peripheral

The peripheral method uses air passage ways located just downstream of the runner, in the periphery of the draft tube liner. Should this method be used, the Contractor must provide a bellmouth type inlet with debris strainer and provisions for air flow measurement. Inlet(s) must have electrically controlled flanged full port ball valves (am0004) to allow for open/close operation from a single control panel mounted in the turbine pit as well as controls located in the control room. In addition to the electrically controlled valves, a manually operated flanged full port ball valve (am0004) . The manual valve should be installed to allow for isolation and maintenance of the electrically controlled valve.

1.6.2.3 Central

The central method results in air that is drawn through the generator stub shaft openings, passes through the bore of the generator and turbine shafts, and exits through the runner nose cone (deflector). The Contractor may choose to modify the existing turbine components, such as the stub shaft, generator, and turbine shafts. Should this method be used, the Contractor must provide a venturi with provisions for air flow measurement. For additional detail and information see paragraph 3.9.

1.6.2.4 Forced

Forced aeration method(s) are those that rely on blowers, compressors, fans or other methods to inject the air into the hydraulic passageways of the turbine. If forced aeration methods are utilized by the Contractor, the air flow rates and piping utilized in the aeration system must be designed to ensure there are no effects of water hammer or potentially damaging shock wave effects by high Mach (M) numbers. If forced aeration methods are proposed by the Contractor, piping systems must be sized to ensure the Mach number is M=<0.5. Should this method be used, the Contractor must provide provisions for air flow measurement.

The Contractor must design the runners by incorporating one or more of these methods of aeration. A forced air aeration design may be utilized only if the Distributed, Peripheral, and/or Central aerations designs will not be feasible in terms of meeting the DO output requirement.

1.6.3 Turbine Efficiency Loss Due to Aeration

The new aerating turbine must have the capability to increase dissolved oxygen (DO) concentration by 6.0 mg/L…