Bearing_Rehabilitation_0003.pdf

BEARING REHABILITATION

PART 1 GENERAL

1.01 SUMMARY

The Contractor shall perform Ultrasonic Testing of Turbine and Pump Guide Bearings and Thrust Bearing and results shall be reviewed by USBR. Upon review of testing results, USBR shall determine if bearings can be reused, or if machine finishing or complete rehabilitation will be required. The Contractor will be responsible for inspection, testing, transportation, machining, rebabbitting, rehabilitation, and packaging of bearings as directed by USBR after receiving and reviewing inspection reports for the following:

1. Turbine Guide Bearing

2. Pump Guide Bearing

3. Thrust Bearing Segments

PART 2 PRODUCTS

2.01 SYSTEM DESCRIPTION

The worn bearing components removed may require rehabilitation. Contractor shall receive USBR approval prior to performing any repairs on the used set of bearings. Approval will be based on inspection survey and proposed repair report from Contractor. The used set of bearings will become the new set of spares at the facility and will need to be packaged and coated for long term storage.

2.02 MATERIALS

A. Corrosion Preventative - MIL-C-16173E, Grade 3.

B. Taper Pins - ASME B18.8.

C. Tinning Metal - ASTM B339 Grade "A".

D. White Metal Bearing Alloy - ASTM B 23 Grade 2, 89.0% tin, 7.5% antimony, 3.5% copper. Only virgin white metal allowed.

2.02 WORK DESCRIPTION

A. TURBINE AND PUMP GUIDE BEARINGS

1. Inspection:

a. Visual (VT) and Ultrasonic (UT) inspection in as found condition

b. Provide report to USBR prior to proceeding with any repair work to include the following:

1. Inclusions

2. Porosity

3. Fatigue cracking

4. Detailed UT bonding test results

5. Any other defect or issue that could require repair work

2. Rehabilitation and/or repairs:

As approved by USBR, conduct the following:

a. Restore bearing finish to 125 micro-inches or smoother

b. Guide and Pump bearing Babbitt rehabilitation

c. Centrifugally cast Babbitt in accordance with industry standards

d. Machine to original drawing dimensions, maintaining proper assembled clearances including oil relief grooves as specified in drawing

e. VT and UT inspection of Babbitt post rehabilitation and repair

f. Penetrate (PT) testing of edge bonding post rehabilitation and repair

g. Inspect entire surface of the bearing lining using pulsed reflection ultrasonic inspection techniques per DOD-STD-2183

h. Minimum bonding requirements:

1) No single un-bonded area of Babbitt greater than .5-square inch

2) No un-bonded areas allowed on leading edge of any bearing.

3) No individual area of un-bond have a major dimension greater than .5-inch

4) Total un-bonded area not exceed 10% of the Babbitted surface

i. Machining: Dimensions lacking tolerances shall be held to ASME B4.1 Grade 8 or better

j. De-burr any nonbearing surface tool marks

k. Babbitt surfaces shall be 63 micro-inches or smoother as per original drawings

l. Clean dowel holes and provide replacement dowels pins

m. Machine hole for RTD for bearing temperature indication

n. Protective coating for storage, MIL-C-16173E, Grade 3

B. THRUST BEARING

1. Inspection:

a. Visual (VT) and Ultrasonic (UT) inspection in as found condition

b. Provide report to USBR prior to proceeding with any repair work to include the following:

1. Inclusions

2. Porosity

3. Fatigue cracking

4. Detailed UT bonding test results

5. Any other defect or issue that could require repair work

2. Rehabilitation and/or repairs:

a. Clean, etch, flux, tin, rebabbitt in accordance with American Babbitt industry standards and or DOD-STD-2188

b. Statically or centrifugally cast Babbitt in accordance with industry standards

c. Machine to original drawing dimensions

d. VT, PT, and UT inspection of Babbitt post rehabilitation or repair

e. Penetrate (PT) testing of edge bonding

f. Inspect the entire surface of the bearing shoe using pulsed reflection ultrasonic inspection techniques per DOD-STD-2183

g. Sketch of the un-bonded Babbitt areas.

h. Minimum bonding requirements:

1) No single un-bonded area of Babbitt greater than .5-square inch

2) No un-bonded areas allowed on leading edge of any bearing.

3) No individual area of un-bond have a major dimension greater than .5-inch

4) Total un-bonded area not exceed 10% of the Babbitted surface

i. ASME B4.1 Grade 8 or better for machining dimensions lacking tolerances.

j. 250 micro-inch roughness average or smoother for all surfaces lacking roughness designations.

k. Deburr RTD hole to provide a uniform and smooth bore surface after machining

l. Protective coating for storage, MIL-C-16173E, Grade 3

PART 3 EXECUTION

3.01 EXAMINATION

A. Inspect the components and document their condition prior to any corrective action.

B. Prepare and submit an as-found inspection, and dimensional report with recommended repairs per component to USBR for review. Proceed with any corrective action after the USBR accepts the recommended repair actions.

3.02 PREPARATION

A. Remove existing coatings and prepare surfaces for recoating. Machined surfaces not to be painted shall be masked or otherwise protected to prevent damage to these surfaces while existing coatings are removed.

B. Remove all existing white metal from each section or segment of the bearings. Care shall be taken to not warp the bearing shells during this process.

3.03 PROTECTION

A. Protect babbitted surfaces.

B. Crate and package for long term storage.

3.04 GOVERNMENT INSPECTION

A. USBR has the right, at all reasonable times, to inspect the Contractor's work, material, and equipment as applicable to the work covered by this Specification.