Attach. 1 - SOW - CENTAC 1 Overhaul - 19 Nov 24.pdf

Minimum Requirements Document

CENTAC 1 Overhaul

Document Date: 19 November 2024

Background & Scope: The Component Research Air Facility (CRAF) of the Aerospace Systems

Directorate at Wright-Patterson Air Force Base owns and operates two (2) Model 9000882-01

Ingersoll-Rand 5500 HP six stage Centac centrifugal air compressor systems and the first four stages are designated Model C-150.

Model and Serial Numbers for Centac 1 are as follows: Stages 1-4 (Centac-4C-150), Serial

Number (M79-1657); Stages 5-6 (Centac-5CII (2CIIB2)), Serial Number (M79-1667). Stage 4 of

Centac 1 has exhibited significant signs of degradation in capability over the last 6 months, and the Air Force seeks to restore the 4C section of the machine to achieve full operational capability to support propulsion technology such as Turbine Combustion Engine research and

Hypersonic engine research.

Requirements/Salient Characteristics: AFRL/RQOO’s intent is to perform total machine refurbishment of the Centac-4C-150 to the maximum extent (as feasable) needed to restore the

Centac 1 Stage 4 Compressor to as new (or better) capability given its present state and facility operating methodology. Further, in consideration of the operational methods and resource restrictions, AFRL/RQOO prefers to invest in refurbishment strategies that will enhance the durability and sustainability of the refurbished machine to achieve longer than normal duration between non-routine maintenance activities. A similar repair was conducted on the sister machine, Centac 2, in 2016. Lessons learned from that overhaul are incorporated into this project SOW.

Inspection, overhaul, and repair activities shall be in accordance with applicable API standards, specifically API-RP 687 and API 672.

Inspection and Disassembly:

1.1 The contractor shall witness and participate in a compressor pre-teardown checkout run to access the condition of the compressor. The contractor shall provide guidance and a list of operating parameters for this run.

1.2 A machine alignment and Ludeca thermal growth study shall be made for the machine during the pre-teardown checkout run. The results shall be provided prior to disassembly. The contractor shall measure existing “as found” shaft alignment data and record for comparison with the final alignment data to be gathered at reassembly.

Upon reassembly, the machine shall be aligned by the contractor in accordance with the alignment study recommendations, after RQOO approval. Record all final alignment data.

FA2396-25-R-B006 RQOO

CENTAC 1 Overhaul

1.3 All controls, instrumentation, control power cables, instrumentation piping and conduit required to be removed for the disassembly of the machine shall be identified and submitted to RQOO and will be removed by others. The contractor should allow for 10 working days for AFRL/RQOO to accomplish this work.

1.4 The 4C Sections are defined as follows:

a. The Casing houses the rotor assemblies and diffusers.

b. The Casing Cover houses the intercoolers, moisture separators, and air passages to divert air flow from stage to stage.

1.5 Removal of compressor oil piping to and from the 4C section is the responsibility of the contractor. The seal air piping to the 4C section is the responsibility of the contractor.

The cooling water piping to and from the 4C section is the responsibility of the contractor. The compressed process air piping and supports between stages 4 and 5 along with the intake piping up to the inlet valve is part of the contractor’s scope of work. Note: A second compressor sharing the same intake, discharge and water piping will be operating during the period of this refurbishment, therefore, proper isolation devices shall be installed by the contractor.

1.6 The isolation valves for process air, seal, air, and cooling water, along with the auxiliary lube oil pump starter, shall be locked out by both a RQOO representative and the contractor’s site supervisor. The contractor shall provide all proper LOTO devices to maintain a safe work environment. Contractor supplied blind flanges at the high-pressure discharge air main will be required to provide the contractor with a safe work site.

1.7 Only assembly drawings are available for reference, contractor shall document existing dimensionality and clearances as necessary upon or during removal.

1.8 Contractor shall separate couplings, measure and record axial and angular as-found alignment data to +/- 0.0001 inch or better. At no time shall the compressor or motor be rotated with improper tools or without oil system operation. Devices leaving discernable marks shall not be used to rotate the motor / compressor. The contractor will be responsible for repair of any damage that is caused by improper tools being used to rotate the machine during this overhaul.

1.9 Inspect the jack shaft gear couplings for damage and wear, record all inspection data.

(Clearances, alignment, wear compared to original specifications).

1.10 Unbolt and remove compressor housings as well as all other components required to safely disassemble the compressor. These components shall be placed in the same basement where the machine is located and shall sit on contractor supplied plywood or rubber matting or in shipping containers to protect the floor and the components.

Equipment shall be properly protected by the contractor to prevent debris from entering the disassembled compressor.

1.11 Check and record the location and clearance between the impellers and diffusers.

Inspect for damage, wear and fouling on the impellers and diffusers.

1.12 Remove and inspect all intercooler discharge condensate lines, traps and separators for clogging and damage. Clean or replace based on RQOO’s direction.

1.13 Cooler housing shall be sandblasted clean. All welds shall be magnetic particle tested and re-welded in the shop if welds fail inspection.

1.14 Inspect for weld cracks on the inlet pipe to stage one.

1.15 Clean and inspect all air flow paths within the compressor, including the flow paths through the Casing Cover. Remove all debris and fouling in the flow paths.

1.16 Evaluate the oil seals at the pinion shafts and bullgear shaft and measure clearances.

1.17 Evaluate air seals at all stages and the seal air supply system. Record wear and condition.

1.18 Disassemble each stage line and thrust bearings. Inspect and record the clearances between the shaft bearing journals and bearing seals. Make and record measurements of bearing and thrust clearances.

1.19 Disassemble the bull gear line and thrust bearing. Inspect and record the clearances between the shaft bearing journals and bearing seals. Make and record measurements of bearing and thrust clearances.

1.20 Inspect bearings for wear marks and damage.

1.21 Inspect and repair all defects in the Casing, Casing Cover mounting plates in the process air, water, seal air and oil passages.

1.22 Inspect the check valve between stages 4 and 5.

1.23 After the major machine components have been removed, clean equipment frame and floor to remove excess oil and debris. Used oil shall be managed in accordance with all Federal, State, and local regulations.

1.24 If shipping is required, provide proper storage and shipping crates for all compressor housings and all the components of the machine. Provide proper crates for all the parts shipped. The contractor is responsible for rigging, crating, shipping and coordination of shipping activities on and off site. The contractor shall follow API-RP-687 Chapter 0, Section 7.

1.25 Provide a copy of the onsite recorded data in field format, called for in the above section. All recorded data and measurements shall be included. Provide report of as found conditions, recommendations, remedies, and field recorded data prior to removal of the 4C machine from site.

Inspection and Analysis

2.1 All non-destructive testing (NDT) of selected components shall conform to the following guidelines. Prep surface and perform inspection according to the manufacturer’s recommendations with proper light source. Inspections shall be by a trained Level II inspector, in accordance with the requirements of SNT-TC-1A. In addition, Fluorescent Penetrant process for testing shall meet the requirements of ASTM E-1417 and ASTM E- 165.

2.2 Clean and inspect all compressor components and stow all parts for later use.

2.3 Remove and inspect (4) pinion gears and (1) bull gear for wear and damage. Inspector shall use magnetic particle inspection method. Record all tolerances data and as-found dimensions.

2.4 Inspect the pinion shafts and bullgear shaft for wear, straightness and damage.

Inspection shall use magnetic particle inspection method. Record all damage, tolerances data and as-found dimensions.

2.5 Inspection of pinion and bullgear shafts shall include a Total Indicated Runout (TIR) analysis of the shaft at the location of the vibration proximity probes. Measure TIR by slow rolling in V-blocks using a Bently Nevada probe in accordance with Bentley Nevada runout minimization procedure. Perform a check on residual magnetism at the probe surface using a gauss meter. Check for mechanical runout using an eddy current proximity probe.

2.6 Inspect all demisting materials after the intercoolers of each stage for debris from the stage.

2.7 After inspection, the contractor shall submit an inspection report on as-found conditions and a proposal with individual pricing to RQOO for any repair recommended including all dimensionality and tolerances data, NDT inspection results, and photographic supporting data. Provide a list of recommendations for repair or replacement. Include with this list of repairs, painting and touchup recommendations.

Repair

3.1 Repairs are to be made only after RQOO reviews the contractor’s reports and recommendations for the compressor components and only with RQOO written approval via contract change. Repairs, replacements and refurbishment shall follow the agreed scope and duration after final evaluation by RQOO.

3.2 If any of the compressor shafts require plate build up, the contractor shall only apply plating at a minimum thickness of 5 thousandths or more. No plating of the vibration proximity probe tracks will be permitted within 3 diameters of the probe.

3.3 Replace stage 1 pinion shaft with larger diameter to meet newer standards.

3.4 After inspection, repair or replacement, the pinion / impeller assemblies shall be final balanced. Balance the bare shaft. Progressively and dynamically balance pinion / impeller assembly to manufacturer’s specifications at operating speed.

3.5 Polish all pinion shaft journals to remove pitting if deemed acceptable for reuse.

3.6 The bullgear/shaft assembly shall be final balanced. Balance the bare shaft.

Progressively and dynamically balance bullgear/shaft assembly to manufacturer’s specifications at operating speed.

3.7 Based on the Total Indicated Runout (TIR) analysis of the shafts. The contractor shall determine if there is an indication of more than two gauss on the shaft. If required, degauss or demagnetize the shaft (rotor). Diamond burnish the shaft, if required, and repeat until expected runout values are measured at all four compressor impeller assemblies. Perform runout reduction efforts to achieve a less than 0.3 mil TIR at the (4) impeller assemblies as measured by an eddy current proximity probe. Polished probe tracks shall be 3 times the width of the probe head. (See the Bently Nevada attachment for detailed shaft preparation for probe tracks)

3.8 Bore and sleeve diffuser housing for each stage to bring back into specification.

3.9 Inspect and repair all cracks and defects in the stage to stage air passages of the Casing

Cover. Weld procedure for sister machine included a 2 hour 500 F heat soak post weld.

3.10 Replace cooler mist eliminator mesh.

3.11 Replace all shaft seals, oil seal, and air seals.

3.12 Replace all plane and thrust bearings. Planer bearing temperature sensors shall be embedded in the back side of the expected hot spot in the babbit. Two Type-T thermocouples shall be installed for redundancy.

3.13 Contractor shall plan on at least 2 visits by RQOO, to their facility; once after they have the items inspected and reported and the other after they have refurbished everything but before shipment back to WPAFB.

3.14 No reassembly is to begin until all contracted repairs have been performed and approved by RQOO.

3.15 A permanent name plate shall be mechanically attached to the machine with the contractor’s name and address, contract #, and the date of the contract. Remove and reattach new and all existing placards and plates. Do not discard any placards. (All placards shall be returned to the owner re-installed.)

3.16 Ship back to Wright-Patterson Air Force Base (WPAFB) for re-installation. Use proper shipping containers and well-maintained trucks to transport machine parts. Improper or unsafe shipping containers or transport trucks will be rejected at contractor’s expense.

Reassembly and Checkout

4.1 Reassemble the machine in reverse order of disassembly. Realign all motor and compressor assemblies. Alignment shall start at the four-stage compressor then the motor followed by the two-stage compressor. Provide new isolation washers and bushings for re-assembly of the couplings each time the couplings are reassembled.

4.2 The 4C section is used as the anchor for aligning the motor then the booster. If realignment is necessary, the contractor shall drill or re-drill all dowel pin holes and replace with new tapered pins at the compressor to match existing.

4.3 Replace all gaskets, seals and flange supporting hardware with new materials, for disassembled components. Gaskets shall be Flexitallic to match existing dimensions and conditions. Replace oil drain flex elbows. Keep equipment connections protected until the piping is reinstalled. Do not allow debris to enter the machine through the water and lubrication ports. Maintain flange or equipment covers/protection applied by others as well.

4.4 Upgrade all red rubber seals with appropriate materials approved by RQOO.

4.5 Reinstall any piping and components that had been removed during compressor disassembly by the repair contractor. Replace the interconnecting compressor piping between stages 4 and 5. Replaced piping shall be upgraded to 304 schedule 40 stainless steel pipe. Contractor shall match existing piping while accommodating new gasket thickness and new instrumentation taps. Inspect check valve for proper operation prior to re-assembly.

4.6 All controls, instrumentation, water, oil lines and power will be reconnected by others.

(Allow 30 days for this).

4.7 The contractor shall provide all necessary personnel (minimum of 1) to assist with startup and checkout. The compressor can be only run after 4:00 PM or on the weekend with RQOO’s approval. No daytime running will be available. See table 1A for maximum acceptable operating levels. If vibration, pressure, temperature and flow levels deviate greater than the listed acceptable limits, the unit must be investigated, corrected and retested. The final checkout operation shall be performed with the last 4 hours being at full capacity proceeded by 4 hours at 500 PSIG.

4.8 Maximum allowable bearing temperatures shall be 220 F or less during all times of operation. The maximum allowable vibration displacement of the compressors rotating components in the X and Y-axis with the machine at speed is listed below.

Table 1A Performance Requirements

Sensor Location Acceptable Level

Vibration MILS

Max after Rebuild

Refer to API 672 (6.7.4)

Cold Temp Difference

(CTD)

Compressor Minimum Output

Flow @ Pressure

Stage 1 0.96 MILS 14-17 Deg F

Stage 2 0.84 MILS 16-19 Deg F

Stage 3 0.71 MILS 16-19 Deg F

Stage 4 0.64 MILS 16-19 Deg F

Bull Gear @C4 0.02 (in/sec)

Compressor

Overall

Performance

16 lbm/sec @ 735

PSIG

18 lbm/sec @ 600

PSIG

20 lbm/sec @ 500

PSIG

General Requirements

5.1 All non-magnetic components shall be fluorescent dye penetrant inspected. All ferro-magnetic components shall be wet magnetic particle inspected.

5.2 The contractor shall furnish electronic copies of all reports in PDF format. Reports are required for tests and inspection data as noted in each of the four phases of the rebuild and all required proposals. The reports shall contain detailed photos with highlighted areas of discussion, dimensions and tolerances, description of damage and possible reasons for damage, description of component fouling and possible reasons for, recommended action for each part along with cost and time frame for component correction or replacement.

5.3 The contractor shall furnish a detailed schedule for all phases of the work from date of contract. Schedule should include breaks where RQOO’s approval is required.

Contractor shall also include its facilities prolonged holiday and yearly shutdown periods if greater than 2 days.

5.4 The contractor shall guarantee their work for one year from final acceptance of the work.

5.5 Equipment used to remove the compressors shall be in good mechanical order, have proper brakes, and have a current certification of serviceability or the equipment / subcontractor’s service will be rejected due to safety concerns at the contractor’s expense.

5.6 Floor shall be covered with plywood or rubber matting in the work area and at any lay down areas, and cleaned at the end of each day that work is performed. At the completion of the project the contractor shall clean the entire construction area floor with a power scrubber.

5.7 No Teflon tape shall be used on the threads of oil piping.

5.8 RQOO must be notified about any deviation from this specification, for written approval before proceeding.

5.9 All gaskets, sealants, etc. must be replaced with new non-asbestos material The new material must be suitable for the intended purpose (Temperature, pressure, oil, water, etc.).

5.10 A new specification sheet shall be prepared showing all clearances inside the machine, bearing dimensions, journal dimensions, slow roll total indicated runout, allowable bearing temperature (high and high-high), and allowable shaft vibration (mils) (high and high-high). The new tolerances shall not exceed original tolerances for parameters listed above.

5.11 Standard work hours may be from 0600 to 1700 Monday through Friday. Due to power demand limitations at WPAFB, the compressor can be only run after 1600 or with RQOO’s approval, on the weekend. No daytime running will be available.

5.12 A Burn permit is required before using any open flame or welding equipment. Permits will be issued by RQOO daily if needed.

5.13 The contractor must furnish all labor, equipment, materials, tools, lifting, rigging equipment, material handling equipment, machining services, and parts, including bottle gases to complete this contract. All under hook lifting devices shall be of proper capacity and comply with OSHA regulations. If coupling removal or installation requires an oven or dry ice the contractors shall supply these items.

5.14 The contractor shall maintain positive control of all tools and equipment they have brought on to the base and all items shall be put away at the end of each workday.

Equipment and toolboxes shall be marked to identify it as belonging to the contractor or it may be assumed to be government property.