Eagle Strain Gauge WI.pdf

USCGC EAGLE (WIX-295) DRYDOCK AVAILABILITY FY2027

42 (Rev-0)

24300_0723_BMG_295

WORK ITEM 10: Propulsion Shafting, Strain Gage Alignment, Drydock, Check

1. SCOPE

1.1 Intent. This work item describes the requirements for the Contractor to perform strain gage alignment inspections prior to vessel dry-docking, during dry-docking, and after refloating.

1.2 Government-furnished property.

None.

2. REFERENCES

COAST GUARD DRAWINGS

Coast Guard Drawing 327 WIX 4301-013, Rev A, Propulsion Shaft Machining Details

Coast Guard Drawing 327 WIX 4301-014, Rev A, Propulsion System Arrangement Drawing

Coast Guard Drawing 327 WIX 4302-002, Rev -, Stern Tube and Bearing

Coast Guard Drawing 327 WIX 4400-005, Rev -, Propeller Drawing

COAST GUARD PUBLICATIONS

Coast Guard Technical Publication (TP) 11026, SWBS 835, Propulsion System Replacement – Book of Calculations, May 2017

Surface Forces Logistics Center Standard Specification 0000 (SFLC Std Spec 0000), 2022, General Requirements

OTHER REFERENCES

None.

3. REQUIREMENTS

3.1 General.

3.1.1 CIR.

None.

43 (Rev-0)

3.1.2 Tech Rep. The Contractor must provide the services of a Qualified Tech Rep who is familiar with the shaft alignment by strain gauge method to accomplish the following on site:

Advise on manufacturer's proprietary information pertinent to the system.

Assist with proper alignment, clearances, and repair methods for the propulsion shaft system.

Ensure compliance with manufacturer's procedures and standards during all phases of inspection.

3.1.2.1 Ensure the Tech Rep has experience with the system/equipment stated above and demonstrated on their résumé.

3.1.2.2 Submit the name and résumé of the Tech Rep to the COR at the Arrival Conference.

3.1.3 Protective measures. The Contractor must furnish and install all protective measures in accordance with SFLC Std Spec 0000, paragraph 3.3.3 (Vessel component, space, and equipment protection).

3.1.4 Interferences. The Contractor must handle all interferences in accordance with SFLC Std Spec 0000, (Interferences). Known interferences include, but are not limited to the below:

Mechanical seal

Bulkhead seal

3.2 Definitions and standard units. For the purposes of this specification and any reports generated, the following definitions apply.

3.2.1 Optimal alignment. “Optimal alignment” is defined as a state of shaft alignment (though all phases of bearing wear down) where:

Bearing loads are within a satisfactory range

Bending stresses are minimal

Gear box bearings loads (Fwd and Aft) always remain positive and are near equal at midlife wear

Shaft slope through long bearings matches the bearing slope within a reasonable range

Horizontal loads are minimized as much as practical

NOTE

“Optimal alignment” is the goal when components are being moved or relocated e.g. foundations altered, chockfast poured, new strut being installed, new stern tube installed, etc.

3.2.2 Acceptable alignment. “Acceptable alignment” is defined as a state of achievable shaft alignment, whereby components are constrained (movement/relocations not within work scope) but:

Current bearing loads are within a satisfactory range and if possible remain satisfactory though continued bearing wear down

Horizontal loads are minimized as much as practical

44 (Rev-0)

NOTE

“Acceptable alignment” is the goal whenever “optimal alignment” cannot be achieved because the scope of associated work does not provide for relocation of components necessary to obtain optimal alignment.

3.2.3 Standard units. All reports, correspondences, and discussions must be in Standard / US Customary Units and not in SI / Metric Units.

3.3 Strain gauge alignment check. The Contractor must perform the specified actions in Table 1 below using Coast Guard Drawings 327 WIX 4301-013 and 327 WIX 4400-005 as guidance.

TABLE 1 - TASKS

# TASK TYPE OTHER REQUIREMENTS

1 Propulsion Shaft Alignment

Check, Afloat, Pre-Repair Accomplish prior to drydocking.

2 Propulsion Shaft Alignment Check, Drydock, Pre-Repairs

Accomplish after drydocking the vessel and before performing any hot work and/or structural modifications.

3 Propulsion Shaft Alignment Check, Drydock, Post-Repair

Accomplish in drydock after all structural and other shafting repairs and modifications have been completed, and before re-floating the vessel.

4 Propulsion Shaft Alignment Check, Afloat, Post-Repair

Accomplish after re-floating the vessel.

3.3.1 Shaft alignment assessment method. The Contractor must calculate vertical and horizontal bearing reactions using the strain gauge method for evaluating alignment.

3.3.1.1 Furnish and install all equipment necessary to accomplish measurements.

3.3.1.2 Perform all measurements under the direct supervision of the Qualified Tech Rep.

3.3.1.3 Measure reactions on all propulsion shaft bearings, to include reduction gear, line shaft, and waterborne bearings.

3.3.1.4 All strain gages must remain at the same locations throughout all required inspections. Do not duplicate cost of installation if strain gauges are already installed from previous evolutions.

3.3.2 Alignment check prerequisites, afloat. The Contractor must ensure the following conditions are met for afloat inspections:

All shaft components are installed

The vessel is in the water for at least 24 hours before alignment inspection

All permanent ballast is in place

Fuel, water, and temporary ballast tanks are filled to normal operating levels, generally half to 75% capacity.

Vessel is on an even keel

NOTE

It is highly recommended that the Cutter get the pre-dock strain gauge reading done in advance instead of shortly prior to the dry-docking.

45 (Rev-0)

All major machinery weighing over 500 pounds is either installed or simulated by equivalent weights appropriately located

The shafts must be free to rotate and the stern tube face seal must not be any tighter than necessary

NOTE

Small boats are not considered major machinery and therefore do not need to be simulated by equivalent weights in their absence.

3.3.3 Alignment check prerequisites, drydock. The Contractor must ensure the following conditions are met for drydock inspections:

All shaft components are installed

The shafts must be free to rotate and the stern tube face seal must not be any tighter than necessary

3.3.4 Strain gauge report. The Contractor must submit a written report of results via CFR with the following information to the COR within 24 hours after each alignment check:

All bearing reactions (six inboard, two outboard), bearing offsets, bearing influence numbers, allowable bearing load, bearing clearances, etc

A description of the alignment procedures used to obtain the bearing loads

Strain gage locations

Bearing locations and reactions in shaft modeling

Detail dimensions and configuration of the shaft model

All mathematics values used in the shaft model such as material properties, spring constant, thermal growth effects, bearing offsets, all concentrated weights, etc

All assumptions applied in the shaft model

All constant values used in the shaft model

Any indication of misalignment

Bearing reactions at the calculated optimum shaft alignment condition

Any recommended corrective procedures. The recommended corrective procedures must include, but not be limited to:

New bearing off-sets to achieve an optimum shaft alignment

New bearing off-sets to achieve a satisfactory (acceptable) shaft alignment

Other alternative to achieve an optimum shaft alignment

Detailed procedures to achieve shaft alignment

3.3.5 Strain gauge report analysis. The Contractor must provide comparative analysis of strain gauge reports, including any substantive changes in loading or trends identified between reports. This analysis may be furnished with the Strain Gauge Report described in paragraph 3.3.4.

46 (Rev-0)

4. NOTES

4.1 Results submittal. The COR will forward a copy of shaft alignment related inspection results to the Engineering Branch of the applicable Product Line.