Attachment A SECTION 48 13 13.07 26 Guide Bearing Inspection & Refurbishment.pdf

SECTION 48 13 13.07 26

GUIDE BEARING INSPECTION & REFURBISHMENT

4/2022

PART 1 GENERAL

1.1 GENERAL INFORMATION

1.1.1 Description of Work

The section governs the offsite refurbishment of one bearing. The work includes shipping between the project and the Contractor's refurbishment workshop.

1.1.2 Description of Guide Bearings

The Fort Peck unit 5 turbine guide bearing is a four part shell type with an upper and lower taper fit, and two .005 full face shims at each split line. The split line shims allow for field adjustment of the bearing ID.

See Drawing No. 02-502-742.

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 (2020) Personnel Qualification and Certification in Nondestructive Testing

ASME INTERNATIONAL (ASME)

ASME BPVC V (2021) Boiler and Pressure Vessel Code;

Section V, Nondestructive Examination

ASTM INTERNATIONAL (ASTM)

ASTM A193/A193M (2020) Standard Specification for Alloy-Steel and Stainless Steel Bolting Materials for High-Temperature Service and Other Special Purpose Applications

ASTM A194/A194M (2020a) Standard Specification for Carbon Steel, Alloy Steel, and Stainless Steel Nuts for Bolts for High-Pressure or

High-Temperature Service, or Both

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

ASTM E 114 (2020) Standard Practice for Ultrasonic Pulse-Echo Straight-Beam Examination by the Contact Method

ASTM E 165 (2018) 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 (2012) 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 segments," 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.a, Turbine Bearing Split Flange Face and Taper Spigot Fit(s) Refurbishment (Optional)".

Procedure for Repair of Turbine Bearing OD Taper Spigot Fit Diameters; G, HDC

Submit 14 calendar days in advance of repairs," Paragraph 3.2.4.b, Turbine Bearing Split Flange Face and Taper 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 Fort Peck 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 HARDWARE

a. Studs and Bolts shall be made of ASTM A193/A193M, Grade B7 unless otherwise approved.

b. Nuts shall be made of ASTM A194/A194M, Grade 7 unless otherwise approved.

2.3 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 bearing and load bearing onto a Contractor provided truck for shipment to the factory. 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". Receiving hours are Monday to Thursday 0700 to 1630.

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 2600 lbs for each bearing. The dimensions of each crate (WxLxH): 47”x47”x32”.

c. Prior to shipment to Fort Peck, 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 bearing refurbishment includes babbitting, refurbishment of the split flange faces and refurbishment of the OD taper spigot fit(s), and replacement flange hardware and replacement shim sets. 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. taper 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 fully assembled and torqued 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 for long term storage.

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 300 ft-lbs (lubricated with light oil). 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 and compare to OEM drawing.

d. Measure the taper of the upper and lower machined taper spigot fit area(s) and compare to OEM drawing.

e. Measure the bearing OD at the mounting flange, mounting flange thickness, bearing height and babbitt height and compare to OEM drawing.

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

g. When the bearing sections 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.

j. Note any feature present or missing on the bearing when compared to the OEM drawing.

k. Measure the dimensions of the split line face shims for reproduction.

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 ID and taper, and painting of the shells exterior. The OEM drawing requires two .005" full face shims in each of the four split line joints during final machining (a total of eight shims). An additional set of .003" full face shims (eight shims) are also required for future additional adjustment. Additional requirements are listed under Paragraph 3.2.1 above.

a. The Contractor shall prepare the bearing for babbitting according to the rehabilitation 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 babbitt bore shall be established from a machined OD flange face mounting surface. If required for the purpose of establishing the centerline, a full-face skim cut may be made on the OD face of the mounting flange, however, no more than 0.015 inch shall be removed from each face without the Government's approval.

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

(1) Babbitt Inner Diameter: As shown on OEM drawing 02-502-742

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

(3) Concentricity: Concentric with the machined fit OD 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. Studs, nuts, dowels and any other flange hardware shall be replaced in kind or slightly oversized to match need. The OEM material of "ACM 1420" is no longer available, see paragraph 2.2 for replacement hardware material. The original material was a mild steel.

h. Machine the oil supply grooves and other details as found on the existing bearing drawing.

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.

k. Provide a set of eight full face split line shims, using .005 steel shim stock, and a set of eight .003 shims, that both match the profile of the as-found shims. Include proper packing to ensure safe storage and transportation.

3.2.4 Turbine Bearing Split Flange Face and Taper 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. Finish machined overlaid or sprayed surfaces shall be liquid penetrant examined. Additional requirements are listed under paragraph 3.2.1 above.

b. OD Taper Spigot Fit(s). The Contractor shall provide a Procedure for Repair of Turbine Bearing OD Taper Spigot Fit Diameters.

Refurbishing the taper spigot fit(s) shall consist of building up the taper 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 taper shall match the original drawing. The taper surface finish shall be 125 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.

f. Measure the taper of the two machined taper spigot fit area(s) at 90-degree increments.

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 larger than

0.005 inch, list width, length, and approximate depth of any large gap.

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 (if applicable) 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 segments 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 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 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 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, 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, bond lines at pressurized edges shall meet the same criteria as for steel segments. 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 segment 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 the total unbonded area shall be no larger than 5 percent of the total zonal area.

(2) For cast iron backed shells 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 number, and interpretation of results. The report shall specifically address areas of lack of bond between the babbitt and the shell 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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