Fort Peck U2 TGB Specifications.pdf

SECTION 48 13 13.07 26

GUIDE BEARING INSPECTION & REFURBISHMENT

12/2020

PART 1 GENERAL

1.1 GENERAL INFORMATION

1.1.1 Description of Work

The section governs the offsite refurbishment of one bearing and the machining of the ID of one spare to a new inner diameter. The work includes shipping between the project and the Contractor's refurbishment workshop.

The damaged bearing and spare bearing will both ship to the Contractor's factory at the same time, but the spare bearing shall be shipped back separately as soon as it is finished for installation in the unit.

1.1.2 Description of Guide Bearings

The Fort Peck unit 2 turbine guide bearing is a shell type, see Drawing No.

2TFV07-0100-02324057.

Dimensions, fits and estimated weights are based on original design drawings, design criteria and/or calculations. The Government does not warrant or guarantee that these values are accurate.

1.2 REFERENCES

The publications listed below form a part of this specification to the extent referenced. The publications are referred to in the text by basic designation only.

AMERICAN SOCIETY FOR NONDESTRUCTIVE TESTING (ASNT)

ASNT-TC-1A (2016) Personnel Qualification and Certification in Nondestructive Testing

ASME INTERNATIONAL (ASME)

ASME BPVC V (2017) Boiler and Pressure Vessel Code;

Section V, Nondestructive Examination

ASTM INTERNATIONAL (ASTM)

ASTM B 23 (2000; R 2014) Standard Specification for White Metal Bearing Alloys (known Commercially as "Babbitt Metal")

ASTM E 114 (2015) Standard Practice for Ultrasonic Pulse-Echo Straight-Beam Examination by the Contact Method

ASTM E 165 (2012) Standard Test Method for Liquid Penetrant Examination

AMERICAN WELDING SOCIETY (AWS)

AWS D1.1 (2020) Structural Welding Code - Steel

INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS (IEEE)

IEEE 1095 (1994) Guide for Installation of Vertical Generators and Generator/Motors for Hydroelectric Applications

1.3 SUBMITTALS

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

submittals not having a "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.

NOTE: For all submittals to be reviewed by the Hydro-Electric Design Center, so indicated by a "G, HDC" designation or an "F, HDC" designation, submittals and cover sheets/forms shall be sent via FTP or email in Adobe Acrobat PDF format.

SD-03 Product Data

Certified Chemical Analysis of Babbitt and Tin;

Submit 10 calendar days prior to tinning," Paragraph 2.1.d, Babbitting Materials".

NDT Personnel/Laboratory Qualifications;

Submit 10 calendar days prior to tinning of shoes," Paragraph 3.4.2.1, Examination of the Babbitt Bonding".

SD-04 Samples

Samples of Materials;

Submit within 10 days of request, PART 2," Paragraph 2.2, Material and Workmanship".

SD-07 Certificates

Notice of Turbine Guide Bearing Finished Inspection;

Submit 7 calendar days in advance of inspection," Paragraph 3.2.6.a, Turbine Guide Bearing Finished Inspection/Final Report".

SD-08 Manufacturer's Instructions

Turbine Guide Bearing Refurbishment Procedure; G, HDC

Submit 14 calendar days in advance of repairs," Paragraph 3.2.1.a, Turbine Bearing Refurbishment Including Babbitting (Optional)".

Procedure for Repair of Turbine Bearing Split Faces; G, HDC

Submit 14 calendar days in advance of repairs," Paragraph 3.2.4.b, Turbine Bearing Split Flange Face and Spigot Fit(s) Refurbishment (Optional)".

Procedure for Repair of Turbine Bearing OD Spigot Fit Diameters;

G, HDC

Submit 14 calendar days in advance of repairs," Paragraph 3.2.4.c, Turbine Bearing Split Flange Face and Spigot Fit(s)Refurbishment (Optional)".

SD-09 Manufacturer's Field Reports

Turbine Guide Bearing As Found Report; G, HDC

Submit 5 calendar days following inspections," Paragraph 3.2.2 As Found Inspection.

Turbine Guide Bearing Finished Inspection Report; G, HDC

Submit 5 calendar days following inspections and prior to shipment," Paragraph 3.2.6.k, Turbine Guide Bearing Finished Inspection/Final Report".

1.4 FINAL INSPECTION AND ACCEPTANCE

A final inspection will be performed at the refurbishment location. Final acceptance will be made by the Government upon safe delivery to the project. Any materials or workmanship not complying with the provisions of these specifications will be cause for rejection. Corrections shall be made at the expense of the Contractor, and are subject to approval.

Tests will be at the Contractor's expense if the refurbished components do not meet contract requirements.

1.5 WARRANTY

The refurbished bearing shall be warranted to conform to these specifications for three years after receipt and acceptance at delivery site or 8000 hours of unit operation after installation, whichever comes first.

PART 2 PRODUCTS

2.1 BABBITTING MATERIALS

a. The babbitt metal shall be new material conforming to ASTM B 23 Alloy 2.

b. The tin used for tinning shall be 99 percent pure.

c. Use of reclaimed tin or Babbitt will not be acceptable.

d. The Contractor shall submit a Certified Chemical Analysis of Babbitt and Tin material prepared by an independent testing laboratory prior to performing any tinning.

2.2 MATERIAL AND WORKMANSHIP

All materials, parts, and components supplied shall be new and unused and of the best available kind and quality. Workmanship shall be of the highest grade and in accordance with the best modern standard practice.

Samples of Materials shall be made available upon request.

PART 3 EXECUTION

3.1 SHIPMENT

3.1.1 Shipping General

The following general requirements apply:

A. The Government will package the bearings and load bearings onto a Contractor provided truck for shipment to the factory. The bearings will be shipped in two identical boxes. The Contractor shall be responsible to provide shipping to and from the Contractor's factory.

The address of the powerhouse is "Fort Peck Project, 215 Yellowstone Road, Fort Peck, MT 59223".

b. All components shall be prepared for shipment in a manner to protect them from damage and the Contractor shall be responsible for and make good at no extra cost to the Government damage resulting from improper preparation, as well as for damage occurring during inspection, shipping, or refurbishment. The weight of the box and bearing is about 2500 lbs for each bearing. The dimensions of each crate (WxLxH): 48”x42”x39”.

c. Prior to shipment, coat components with a suitable preservative and cover all inlets and outlets to exclude dirt, water, etc.

d. If steel banding is used, it shall have adequate protection so that it does not harm the bearing.

e. All packaging materials used shall become the property of the Government.

3.2 TURBINE GUIDE BEARING REFURBISHMENT

3.2.1 General Requirements

The spare bearing shall be inspected to confirm it is still within specification and then machined to the inner diameter required in para

3.2.3 and NDT performed. The damaged bearing shall refurbishment including babbitting, refurbishment of the split flange faces and refurbishment of the OD spigot fit(s), and replacement flange hardware. General requirements that apply for all refurbishment listed below:

a. The Contractor shall submit a detailed Turbine Guide Bearing Refurbishment Procedure a minimum of 10 calendar days prior to commencing work. The procedure shall include a detailed step-by-step babbitting procedure including tinning method, shell and babbitt temperatures, mandrel design, spin casting speeds, and cooling rates.

The method for establishing the bearing centerline prior to Babbitt final machining shall be provided. The Contractor shall not perform any work until receiving written approval from the Government.

b. A proposed schedule, i.e. dates and times, shall be submitted for all phases of the bearings refurbishment a minimum of 10 calendar days in advance of the beginning of the work. The schedule shall be updated and revised as required.

c. Build up of the split flange faces and/or O.D. spigot fits, shall be performed prior to babbitting. Finish machining of the built-up faces shall be performed following babbitting, but prior to babbitt finish machining.

d. Runout checks shall be made with the bearing on the machining device.

f. Following the completion of the work, the Contractor shall protect the bearing from damage and corrosion with appropriate coatings and packaging.

3.2.2 As Found Inspection

Clean the bearing as required to perform the following inspections. Prior to taking measurements, the vertical flange bolts shall be torqued to 450 ft-lbs (lubricated). A Turbine Guide Bearing As Found Report shall be submitted.

Inspection of the turbine guide bearing shall at a minimum consist of the following:

a. The entire bearing shall be visually inspected. The inspection report shall include comments regarding any damage, irregular or unacceptable surface condition, or deterioration noted during the inspection.

b. Measure and record the Babbitt surface finish.

c. Measure the babbitt bore diameter at three elevations top, middle and bottom. Take four measurements on 45-degree increments per elevation.

d. Measure the OD in the middle of the machined spigot fit area(s).

Take four measurements at each fit on 45 degree increments.

e. Measure the bearing OD at the mounting flange, mounting flange thickness, bearing height and babbitted height.

f. Using feeler gauges, measure the O.D. and I.D. gap at the bearing split lines along the lines entire length. Record any gap

0.001 inch or larger listing width, length and approximate depth.

g. When the bearing halves are unbolted from each other for the visual inspection of the split line flanges, note any resulting distortion or mismatch.

h. Visually inspect the split line flange fasteners and fitted fastener holes. Determine and report the approximate fitted fastener contact area.

i. Visually inspect the split line flange faces noting any damage, irregular or unacceptable surface condition, or deterioration. The surface contact area at the split line flanges shall be determined using a bluing process. The area of contact shall be mapped, including dimensions, and the percent contact area calculated.

3.2.3 Turbine Bearing Refurbishment Including Babbitting

The Contractor shall refurbish the turbine guide bearing as specified below. Refurbish means removing the existing babbitt, spin casting new babbitt, finish machining and painting of the shells exterior. Additional requirements are listed under Paragraph 3.2.1 above.

a. The Contractor shall prepare the bearing for babbitting according to the procedure approved by the Government. Remove the existing Babbitt and tinning material. Machine or shot blast to bare metal, including dovetail grooves, and proceed immediately with tinning.

Special care shall be taken to protect all holes and surfaces of the bearing not receiving babbitt. Plug such holes with a heat resistant filler material. Before bolting the split lines together for tinning, place heat resistant material in the joints to prevent leakage.

b. When a dovetail falls on a split line, a mill cut may be taken the length of the joint to remove the dovetail and create a square land parallel to the joint face.

c. A sample of the babbitt shall be taken and marked for identification at the time that the babbitt is poured. A sample shall be taken for each heat. An independent testing laboratory shall analyze each sample with the results included in the final report.

d. The bearing shall be spin cast with the bearing axis horizontal and the Babbitt poured at a high temperature. The bearing shell, and mandrel if used, shall be pre-heated. The pouring shall be continuous. Precautions shall be taken to minimize bearing distortion during babbitting.

e. The centerline of the babbitted bore shall be established from the machined OD spigot fits and flange face mounting surface. If required for the purpose of establishing the centerline, a full-face skim cut may be made on both faces of the mounting flange, however, no more than

0.015 inch shall be removed from each face without the Government's approval. If an upper spigot fit does not exist, a skim cut reference diameter may be established on the OD at the bearing's upper end, however the depth of cut shall not exceed 0.015 inch.

f. The requirements for the finish machined babbitt bore are as follows:

(1) Babbitt Inner Diameter: 21.496 to 21.498 inches.

(2) Runout: maximum 0.002 inches T.I.R

(3) Concentricity: Concentric with the machined spigot fit OD(s) to within 0.002 inches T.I.R.

(4) Perpendicularity: Perpendicular to the horizontal flange mounting surface to within 0.002 inch.

(5) Surface Finish: maximum 32 microinch, free of chatter and abnormal tool marks.

g. Replacement studs, nuts, dowels and any other flange hardware shall be replaced in kind or slightly oversized to match need.

h. Machine the oil supply grooves and other details as found on the existing bearing following removal from the turbine, as directed by the Government.

i. Perform NDT of the babbitt bond according to Paragraph 3.4.

j. Surfaces not exposed to direct contact to oil or oil vapors shall be prepared and painted Glyptal 1201 or similar according to the manufacturer's instructions. All painting shall be accomplished after babbitting, and the babbitted and finished machined surfaces shall not be exposed to abrasives or paints. Finished mating surfaces, top and bottom of the bolting flange, babbitted surfaces, the finished fits, threaded holes, and temperature detector holes shall not be painted.

These surfaces and holes shall be thoroughly cleaned and coated with a suitable rust resistant compound.

3.2.4 Turbine Bearing Split Flange Face and Spigot Fit(s) Refurbishment

A. Split Flange Faces. The Contractor shall submit a Procedure for Repair of Turbine Bearing Split Faces. One possibility for refurbishing the split faces is to machine the faces without buildup.

Another possibility is to buildup the split faces using a low heat welding process and appropriate filler metal, or by flame spraying.

Weld overlay or flame spraying shall be performed prior to babbitting.

Finish machining of the overlaid faces shall be performed following babbitting, but prior to babbitt finish machining. The refurbished split faces shall have a minimum 90 percent evenly distributed contact over the vertical height of the mating flanges, which shall be verified using a bluing process. The joints shall be sufficiently tight to assure that a 0.002 inch feeler gauge will not pass through the O.D. or the I.D. of the joint line. Finish machined overlaid or sprayed surfaces shall be liquid penetrant examined. Additional requirements are listed under paragraph 3.2.1 above.

c. OD Spigot Fit(s). The Contractor shall provide a Procedure for Repair of Turbine Bearing OD Spigot Fit Diameters. Refurbishing the spigot fit(s) shall consist of building up the fit OD by weld overlay using a low heat welding process and an appropriate filler metal, by flame spraying, or by the installation of a make-up ring. The buildup shall be performed prior to babbitting. Finish machining shall be performed following babbitting, but prior to babbitt finish machining. Finished machined overlaid or sprayed surfaces shall be liquid penetrant examined. The tolerance for the finished machined OD shall be -0.002 / + 0.000 inch with the total indicated runout be no greater than 0.002 inches and the surface finish 63 microinch or better. Additional requirements are listed under paragraph 3.2.1 above.

3.2.5 Not Used

3.2.6 Inspection of Finished Turbine Guide Bearing / Final Report

a. The Contractor shall notify the Government 7 calendar days in advance of all inspections, including Notice of Turbine Guide Bearing Finished Inspection, and all inspections may be witnessed by the Government at its discretion.

b. The finished turbine guide bearing shall be inspected while on the machining device for the purpose of verifying the paragraph 3.2.3.f requirements.

c. The inspection shall include the Paragraph 3.4 NDT of the Babbitt bond.

d. Measure the babbitt bore diameter at three elevations top, middle and bottom. Take four measurements on 45-degree increments per elevation.

e. Measure the OD in the middle of the machined spigot fit area(s).

Take four measurements at each fit on 45 degree increments.

f. Measure the bearing OD at the mounting flange, mounting flange thickness, bearing height, babbitted height.

g. Measure and record the Babbitt surface finish, and the surface finish for any other contractor machined surfaces.

h. Using feeler gauges, measure the O.D. and I.D. gap at the bearing split lines along the lines entire length. Record any gap 0.001 inch or larger listing width, length and approximate depth.

i. All measurements shall be taken with calibrated instruments accurate to the nearest 0.001 inch, unless otherwise indicated.

Calibration certification for all equipment shall be furnished with the report of findings.

j. All data shall be recorded on the Contractor supplied inspection sheets which shall be provided to the Government inspector prior to departure from the Contractor's facilities.

k. A Turbine Guide Bearing Finished Inspection Report and measurement report including the results of the Babbitt bonding NDT shall be submitted prior to shipment and shipment shall not be made until the authorized in writing by the Government.

3.3 NOT USED

3.4 BABBITT BOND NDT

The paragraph 3.4 NDT shall be performed for guide bearing shells that have been rebabbitted.

3.4.1 General

The babbitt to base metal bond shall be examined using the Ultrasonic Test (UT) and Liquid Penetrant (PT) method of nondestructive testing.

The Pulse-Echo Method of UT inspection shall be employed. Examination shall be made from the babbitt side and 100 percent of the babbitted area shall be inspected. UT examination shall be performed in accordance with the applicable portions of ASTM E 114 or of Article 5 of the ASME BPVC V.

The UT procedure which is to be used shall be submitted for approval. The Government at its discretion my witness any and all inspections.

3.4.2 UT Inspectors Qualifications

3.4.2.1 Examination of the Babbitt Bonding

NDT Personnel/Laboratory Qualifications shall be submitted. The laboratory shall be a member in good standing of the American Council of Independent Laboratories (ACIL). The laboratory shall be mutually agreeable between the Government and the Contractor. Prior to the performance of any tests, the laboratory name, location and qualifications shall be submitted.

3.4.2.2 Technician(s)

Technician(s) performing the inspection shall be certified in accordance with the American Society for Nondestructive Testing (ASNT). The inspector who is performing the UT inspection or who is acting as a representative from an independent testing lab shall, as a minimum, be NDT:ASNT-TC-1A level 2 qualified, with a minimum of 3 years experience at Level 2 in the last 5 years. Prior to the performance of any tests, the inspector's qualifications shall be submitted. The inspector shall locate bonded and unbonded areas on the "Reference Blocks" in the presence of the Government's quality assurance representative.

3.4.3 Equipment

a. Search Unit.

(1) All testing of the babbitt bond shall be performed with a

2.25 MHz or 5 MHz longitudinal wave crystal.

(2) Transducer diameter shall be between 0.25 inch and 1 inch.

(3) Transducer gloves or delay lines shall be made of Lucite or other materials with similar sonic properties.

b. Couplants used for testing shall be either lightweight oil or glycerin, the viscosity of which is no more than SAE 30 oil.

c. Reference Blocks.

(1) A reference block shall consist of a soundly babbitted steel block with a scanning surface and babbitt thickness representative of the shoes being tested. The block shall be used to set the sensitivity of the instrument. A reference block with artificially unbonded areas shall be provided for comparison of indications for areas showing bond and lack of bond.

(2) Test sensitivity shall be such that the babbitt-to-base material interface is readily identified on the CRT. Details of sensitivity calibration and determination of bonded and unbonded areas shall be defined in the UT procedure.

(3) Reference blocks shall be kept available for frequent reference during actual testing.

3.4.4 Procedure

The entire babbitt surface of each shoe segment shall be scanned, overlapping scan paths by at least 20 percent of the effective transducer width. Scanning rates shall not exceed 3 inches per second. Unbonded babbitt areas will result in an increase in the size of the reflection or indications of multiple reflections at the interface of the babbitt and base metal. Babbitted areas located over anchoring dovetail grooves will be excluded from UT inspection.

All unbonded babbitted areas shall be carefully scanned to determine their size and configuration. The outside edges of all unbonded areas shall be marked on the surface of the Babbitt and recorded on inspection sheets.

3.4.5 Liquid Penetrant (PT) Testing

a. After the ultrasonic testing is completed all exposed babbitt to backing material bond lines, including dovetails if applicable, shall be examined with the liquid penetrant (PT) method. This shall be done using a solvent-removable visible dye. The purpose of the PT bond line examination is to define the babbitt to backing material bond at edges, which the UT examination may not reveal. The PT method that the Contractor proposes to use shall be submitted for approval and shall be in accordance with ASTM E 165. Lack of bond indications greater than ¾ inches in length shall be marked on the bearing shell or pads and mapped on inspection reports or documented in photos.

b. The surface area of the babbitt, including oil grooves, shall be PT examined for cracks and any and all indicated cracks recorded on inspection sheets or documented in photos.

3.4.6 Acceptance Standards

Babbitt bond acceptance criteria is defined below as a function of zones and the bearing backing material:

a. Perimeter & Holes. Zone defined as bond surface area within 1 inch from any edge or hole having an exposed bond line. The maximum dimension of any individual unbonded area shall be less than 1/2 inch, with acceptable unbonded areas located no closer than 2 inches apart.

(1) For steel backed shells or pads the total unbonded area shall be no larger than 5 percent of the total zonal area.

(2) For cast iron the total unbonded area shall be no larger than 15 percent.

b. Corners. Zone defined as bond surface area within 1 inch from any corner having an exposed bond line. Corners shall have no unbonded areas.

c. Dovetails. Zone defined as the entire surface area over a dovetail. Dovetails are exempt from UT examination.

d. Bond Lines. Defined as exposed lines at the babbitt to base metal interface.

(1) For steel backed shells or pads, PT indications of lack of bond totaling over 10 percent of the length of a particular edge shall be unacceptable. Any PT detected lack of bond over 3/4 inch in length shall be re-examined by the UT method, using a 0.250 inch diameter transducer. Unbonded areas extending more than 1/8 inch away from an edge shall be unacceptable.

(2) For cast iron backed shells or pads, bond lines at pressurized edges shall meet the same criteria as for steel shoes.

Pressurized edges include pressurized oil supply grooves/holes, shell split lines, etc. Bond lines at unpressurized edges, are exempt from PT examination. Unpressurized edges include pad edges, bearing ends, unpressurized grooves, etc.

e. Remainder of Shell or Pad. Zone defined as bond surface area other than perimeters, holes, corners and dovetails. The maximum area for any individual unbonded area shall be less than 1 sq. inch or 3 percent of the total zonal area, whichever is less. Acceptable unbonded areas shall be located no closer than 2 inches apart.

(1) For steel backed shells or pads the total unbonded area shall be no larger than 5 percent of the total zonal area.

(2) For cast iron backed shells or pads the total unbonded area shall be no larger than 15 percent.

f. Additional Requirements. The babbitt surface shall have no visible porosity, blow holes shrinkage or cracks. The exposed bond line shall have no visible disbonding.

3.4.7 NDT Inspection Report

A babbitt bond NDT inspection report shall be submitted as part of the bearing final report. The report shall include a complete description of the UT procedures used, equipment used, a mapping of the areas tested, shell/pad number, and interpretation of results. The report shall specifically address areas of lack of bond between the babbitt and the shell/pad and their accumulated total surface area relative to the area allowed for the zone. PT results shall include a mapping of the indications at the bond lines or photos. The report shall also address porosity and any cracking that is found.

3.4.8 Repairs

If repairs are required to the babbitt surface or to the babbitt to backing material interface a repair procedure shall be submitted, if not already submitted as part of the rebabbitting procedure. Puddling will be acceptable for small areas on the surface, and to correct a lack of bond between the babbitt and backing material, however, the total lack of bond repaired by puddling shall not exceed 10% of the total babbitted surface.

3.4.9 Babbitt Bond Acceptance

If a bearing's babbitt bond does not meet the above acceptance criteria it shall be repaired or completely rebabbitted and retested at the Contractor's expense until the level of defects are acceptable in accordance with these specifications.

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