U.S.NAVY UNDERWATER SHIP HUSBANDRY MANUAL

CHAPTER -13

PROPULSION SHAFT COVERING REPAIR

TABLE OF CONTENTS

CERTIFICATION SHEET RECORD OF CHANGESAFETY SUMMARYSECTION 1 - INTRODUCTION13-1.1 PURPOSE13-1.2 SCOPE13-1.3 APPLICABILITY13-1.4 MAIN PROPULSION SHAFTING DESCRIPTION

13-1.5 MAIN PROPULSION SHAFT COVERINGS13-1.6 MAIN PROPULSION SHAFT FAIRWATERS

SECTION 2 - PLANNING AND PREPARATION13-2.1 SYNOPSIS OF THE REPAIR PROCEDURE

13-2.2 REFERENCE DOCUMENTS13-2.2.1 Technical Manuals13-2.2.2 Military Specifications and Standards13-2.2.3 Ship Drawing Index

13-2.2.4 Underwater Hull Inspection Report13-2.3 PROPULSION SHAFT INSPECTION13-2.4 SPECIAL REQUIREMENTS

13-2.4.1 NDT Qualified Personnel13-2.4.2 Ship Availability/Support13-2.4.3 Repair Activity Training13-2.5 SPECIAL TOOLS AND MATERIALS13-2.6 HABITAT SELECTION

SECTION 3 - REPAIR PROCEDURE13-3.1 DRY HABITAT REPAIR OF EXTENDED LIFE SHAFT COATINGS

13-3.2 PROPULSION SHAFTING FAIRWATER REMOVAL13-3.3 REPAIR HABITAT PREPARATION

13-3.4 INITIAL SHAFT SURFACE PREPARATION (IN THE WET)13-3.5 REPAIR HABITAT INSTALLATION

13-3.6 PRIMARY SHAFT SURFACE PREPARATION (IN THE DRY)13-3.7 NDT INSPECTION OF SHAFT SURFACE13-3.8 EXPOSED SHAFT SURFACE FINAL CLEANING AND FAIRING

13-3.9 CHECK SHAFT SURFACE TEMPERATURE13-3.10 PREPARATION OF EPOXY RESIN

13-3.11 APPLICATION OF EPOXY RESIN AND FIBERGLASS COVERING13-3.12 NEW COVERING INSPECTION

13-3.13 PAINTING OF REPAIR AREA13-3.14 REMOVE THE HABITAT FROM THE SHAFT13-3.15 RE-INSTALL THE FAIRWATERS13-3.16 FINAL PROCEDURES13-3.16.1 Take Inventory13-3.16.2 Debrief Ship's Force13-3.16.3 Final Report

LIST OF APPENDICESAPPENDIX A - IDENTIFICATION OF NAVSEA SHAFT HABITATS AND DRAWINGS

LIST OF ILLUSTRATIONS13-1 Main Propulsion Shafting General Arrangements13-2 Typical Strut Bearing Fairwater

13-3 Shaft Assessment Message Form

13-4 Preheat Setup and LocationA-1 NAVSEA Shaft Repair Habitat - DoghouseA-2 NAVSEA Stern Tube Habitat - RectangularA-3 NAVSEA Stern Tube Habitat - SquareA-4 NAVSEA Contour Templates

LIST OF TABLES13-1 Equipment and Materials Required for the Shaft Covering

Delamination Repair

CHAPTER 13

PROPULSION SHAFT COVERING REPAIR

SAFETY SUMMARY

GENERAL SAFETY PRECAUTIONS

The following safety precautions supplement the specific warnings in this chapter. These general precautions are related to the task of waterborne main propulsion shaft covering repair and replacement. They are precautions that shall be understood and applied before and during work on shaft protective coverings. In addition to the following precautions, personnel shall be familiar with and observe safety precautions set forth in the following publications:

a. OPNAV Instruction 5100.19 (series), Navy Occupational Safety and Health (NAVOSH) Program Manual for Forces Afloat

b. Technical/Operating manuals for equipment

c. U.S. Navy Diving Manual, SS521-AG-PRO-010

d. NSTM Chapter 074 (Volume l), Welding and Allied Processes

e. NSTM Chapter 243, Propulsion Shafting

f. MIL-STD-2199, Glass Reinforced Plastic Coverings for Propeller Shafting (Metric).

Do Not Repair or Adjust Alone

Do not repair or adjust energized equipment alone. The presence of a qualified individual capable of rendering aid is required. Always protect against grounding hazards and make adjustments with one hand free and clear of equipment. Be aware that even after equipment has been de-energized, dangerous electrical hazards can exist due to capacitors retaining electrical charges. Circuits shall be grounded and capacitors discharged.

Equipment in Motion

Remain clear of equipment in motion. A safety watch will be posted if the equipment requires adjustment while in motion. The safety watch shall be in communication with divers and have immediate access to controls which are capable of stopping equipment. If at any time the repair habitat or other equipment appears to be out of control, stop the equipment immediately.

Exercise caution when moving equipment and tools between repair habitat and the surface.

First Aid

Attend to all injuries, however slight, by obtaining first aid or medical attention immediately.

Resuscitation

Personnel working with or near high voltage shall be familiar with approved resuscitation methods. Begin resuscitation immediately if someone is injured and stops breathing. A delay could cost the victim's life. Resuscitation procedures shall be posted where electrical hazards exist.

Minimizing Relative Motion

Relative motion is the movement of two or more objects in relation to each other. This poses unique hazards to divers. A common example is a group of ships swaying and bouncing against each other because of wind and wave action. This motion would easily crush a diver caught between the two ships. To reduce the hazards of relative motion and to simplify the task, suspend the work platform and rigging from fittings on the ship.

WARNINGS AND CAUTIONS

Specific warnings and cautions appearing in this chapter are summarized for emphasis and review in the material that follows.

WARNINGSUsing open bottom double wall void areas of the habitat for

variable buoyancy control while the habitat travels up or down in the water column may result in loss of control and is

not recommended. Using open bottom void areas for increasing habitat buoyancy is only intended to aid in shifting

habitat position along the shaft. Positive control rigging techniques in accordance with a maintenance activity

approved rigging plan are required. NAVSEA doghouse habitats have internal sealed double wall buoyancy intended to maintain neutral buoyancy regardless of habitat depth in

the water column.

Power tools used in the confines of a habitat can cause hazardous flying debris. Eye protection and breathing

apparatus is necessary.

Solvents, paints, and epoxies have toxic fumes. Adequate ventilation or breathing apparatus is necessary. Refer to

Section 8-11.4.2, Enclosed Space Safety Precautions of the U.S. Navy Diving Manual for the warning associated with submarine ballast tank entry. Ensure proper eye and skin

protection is provided.

When handling resin, guard against getting any in the eyes. Avoid skin contact. In case of contact with eyes flush with

water and call physician. Remove from skin with dry cloth or paper towel. Wear goggles, impervious rubber gloves, and

coveralls during mixing and application.

CAUTIONSDue to the significant dynamic loading of the shaft, any

damage to the covering that results in exposure of bare metal to seawater must be identified immediately.

Tools used during the covering removal process can damage the shaft. Care should be taken not to damage the surface of

the shaft while removing the shaft covering.

Habitat installation or removal can damage the shaft covering if not installed properly. Exercise care during installation and

removal.

Shaft covering can be damaged during fairwater installation. Care must be used to prevent damaging additional areas of the shaft covering when reinstalling the two halves of the

fairwater or maneuvering a fairwater near the shaft.For all shafts with extended service life coatings (epoxy under

coat with conventional GRP top coat) modify the section 3 repair procedure as indicated in step 13-3.1.

CHAPTER 13 PROPULSION SHAFT COVERING REPAIR

SECTION 1 - INTRODUCTION

13-1.1 PURPOSE

The purpose of this chapter is to provide NAVSEA approved procedures for waterborne repair of the main propulsion shaft coverings found on Naval ships. Strict adherence to the procedures provided in this chapter will ensure that the under- water tasks are completed in a safe and efficient manner, and that quality control requirements are met throughout the waterborne repair evolution.

13-1.2 SCOPE

The information and procedures provided in this chapter cover underwater repair of surface ship waterborne main propulsion shaft coverings. This chapter does not supersede any information contained in the U.S. Navy Diving Manual or the Naval Ships’ Technical Manual (NSTM).

13-1.3 APPLICABILITY

This chapter provides repair activities with concise procedures for performing the underwater work required in the repair of main propulsion shaft coverings. This chapter serves as a guide and reference for all personnel involved in planning and performing such work. It is important that this chapter be used by repair officers to aid in the scheduling and coordination of tasks. It should also be used by on-site supervisors to monitor underwater work and to ensure that strict quality control is maintained throughout the task.

13-1.4 MAIN PROPULSION SHAFTING DESCRIPTION

The main propulsion shafting transmits torque from the main engine to the propeller, and axial thrust from the propeller to the hull. The main propulsion shafting passes through the hull via the stern tube and terminates just aft of the propeller. The external shafting is supported by bearings located in struts that are attached to the underside of the hull. Depending on ship class, there are either one or two sets of struts. Figure 13-1 shows the two most common types of propulsion shafting arrangements used for U.S. Naval surface vessels.

13-1.5 MAIN PROPULSION SHAFT COVERINGS

All shafting exposed to seawater must be coated to prevent corrosion, which can lead to fatigue failure. Currently, two types of coverings may be found in use on U.S. Navy propulsion shafting. By far the most common, Glass Reinforced Plastic (GRP) applied in accordance with MIL-STD-2199, consists of four alternately wrapped layers of fiberglass cloth. GRP coverings are repaired waterborne by installing a new GRP wrap in a dry habitat environment. Rubber, once an optional material for shaft covering, is no longer being used to protect shafts, and MIL-R-15058, the material specification for rubber, has been cancelled. However, older ships may still have shafts with rubber covering. Minor rubber shaft covering repairs performed in a dry habitat shall be accomplished by use of the following acceptable commercial material: Haartz-Mason N-29 Cold Bond Coating and Adhesive and Haartz-Mason Cold Bond Sheet Stock, manufactured by Haartz-Mason Inc., 270 Pleasant Street, Watertown, MA 02272-9128.

13-1.6 MAIN PROPULSION SHAFT FAIRWATERS

Fairwaters are cone shaped covers that fit on strut bearings and stern tubes. Fairwaters come in many different shapes and sizes. Fairwaters are normally composed of Copper Nickel (Cu-Ni), but sometimes are made of fiberglass. Shaft covering is sometimes damaged right next to a strut such that the damage cannot be properly repaired without removing the strut fairwater. Figure 13-2 illustrates a typical strut bearing fairwater. For Cu-Ni fairwaters, removal and replacement will involve material analysis and welding concerns. If the fairwater is fiberglass, removal is difficult because the bolting arrangement has typically been covered with fiberglass and is inaccessible. Replacement is usually difficult due to damage incurred during the removal process. Before attempting removal and replacement of any fairwater, review the ship's "Ropeguard and Fairwater" drawing to get a thorough understanding of the particular configuration. Never remove fairwaters for shaft covering repair unless necessary. Replacing fairwaters can be quite difficult.

SECTION 2 - PLANNING AND PREPARATION

13-2.1 SYNOPSIS OF THE REPAIR PROCEDURE

Divers will inspect the shaft, determine the shaft diameter, identify the existing covering material, mark the exact location and extent of shaft covering damage, and select a suitable repair habitat. The shaft coating repair procedures include cleaning the repair area, removing damaged covering down to the shaft, sounding covering areas on the shaft fore and aft, cleaning and inspecting the shaft for damage, applying a new covering of GRP, and painting the new covering. A repair habitat is installed on the shaft for the repair procedures that require dry conditions. Shaft fairwaters may or may not have to be removed to facilitate covering repair.

13-2.1.1 Application of the new GRP covering will begin with application of resin to the cleaned shaft surface. The layers of fiberglass tape are applied as spirals criss-crossing from opposite ends of the repair section to provide better adhesion and strength. Each layer of fiberglass tape is wrapped around the shaft in the opposite direction of normal (ahead) shaft rotation in order to provide less chance for the wrap to delaminate due to frictional forces. After each layer of tape is wrapped, additional resin is applied.

13-2.2 REFERENCE DOCUMENTS

Technical information and engineering data essential to proper planning, preparation, and performance of work on propulsion shaft protective coverings are available in a variety of source documents. MIL-STD-2199 covers every aspect of the shaft covering process and is an essential document for any repair. All available references should be consulted before beginning the task and should be referred to frequently while performing the task.

13-2.2.1 Technical Manuals. The Naval Ships' Technical Manual (NSTM) and other technical manuals provide operation and maintenance information, personnel qualifications, inspection criteria, technical and administrative information, and instructions to assist in managing ship systems and equipment. The technical manuals and other materials applicable to propulsion shaft coating repair tasks are listed below:

a. NSTM Chapter 243, Propulsion Shafting, b. NSTM Chapter 074, Welding and Allied Processes.

13-2.2.2 Military Specifications and Standards.

a. MIL-STD-2199, Glass Reinforced Plastic Coverings for Propeller Shafting (Metric) b. NAVSEA Technical Publication T9074-AS-GIB-010/271, Requirements for Nondestructive Testing

Methods c. MIL-STD-2035, Non-Destructive Testing Acceptance Criteria.

13-2.2.3 Ship Drawing Index. Shafting drawings are typically found in the 200 functional group (Standard Work Breakdown Structure). There is usually a shafting general arrangement drawing that will reference the detailed drawings for the particular section of shaft damaged. The "Ropeguard and Fairwater" drawing is also helpful and should also be referenced on the shafting general arrangement drawing.

13-2.2.4 Underwater Hull Inspection Report. The latest hull cleaning/inspection report available from the ship will provide details of shaft condition at last inspection.

13-2.3 PROPULSION SHAFT INSPECTION

CAUTIONDue to the significant dynamic loading of the shaft, any

damage to the covering that results in exposure of bare metal to seawater must be identified immediately.

Complete a thorough shaft inspection to gather the information required to complete the “Shaft Assessment Message Form” (Figure 13-3). Release the completed message to the message addresses indicated in Figure 13-3 or a local Fleet technical support activity for analysis and repair recommendations.

13-2.4 SPECIAL REQUIREMENTS

13-2.4.1 NDT Qualified Personnel. The repair activity must have diver personnel qualified to perform non-destructive testing (NDT) of all exposed shaft surfaces in accordance with NAVSEA Technical Publication T9074-AS-GIB-010/271,

Requirements for Nondestructive Testing Methods . The preferred method of inspection is liquid penetrant in the dry habitat environment to ensure complete coverage. An acceptable alternative is magnetic particle inspection in the wet prior to habitat installation. NAVSEA 00C5 contract personnel qualified to perform NDT inspection as an assist to IMA dive lockers are available.

13-2.4.2 Ship Availability/Support. The ship should be berthed with the damaged shaft towards the pier for ease of habitat installation. Each section of damage to be repaired normally takes seven days (12 hour/day) to repair, including installing and removing the habitat. For repairs requiring a stern tube habitat (see Figures A-2 and A-3, Appendix A), several days could be added to the repair effort. Shaft covering cannot be attempted if the shaft temperature is below 60°F. Controllable Pitch Propeller (CPP) ships can circulate hydraulic oil through the shaft to heat the surface for curing. Non-CPP ships must heat the covering from the outside inward via welder’s preheats suspended close to the shaft after the covering is installed. Consideration of temperature concerns is important.

13-2.4.3 Repair Activity Training. If the repair activity has no experience with shaft covering repairs, it is strongly advised that the habitat and a dummy shaft (same approximate diameter as shaft to be repaired) are used to perform full scale mock-up practice repairs prior to performing the actual repair. Practice repairs performed on the surface in the habitat should be done with diving helmet/mask worn. This will provide a realistic mock-up of tight operating conditions and reveal any problems with umbilical management in the habitat. This training will also identify two-man teams for wrapping which have the highest aptitude for GRP repairs. Ensure sufficient quantities of consumables (epoxy resin, tape, solvent) are ordered to allow for training if required.

13-2.5 SPECIAL TOOLS AND MATERIALS

Table 13-1 provides a list of the special tools and materials required to perform waterborne shaft covering delamination repair.

13-2.6 HABITAT SELECTION

The doghouse habitat is preferred and can be used whenever there is at least 26 inches clearance between the top of the shaft and the hull at the damage location. If there is not sufficient clearance, then the box habitat with top section fabricated on site must be used.

SECTION 3 - REPAIR PROCEDURE

CAUTIONFor all shafts with extended service life coatings (epoxy primer under the conventional GRP top coat) modify the

section 3 repair procedure as indicated in step 13-3.1 below.

13-3.1 DRY HABITAT REPAIR OF EXTENDED LIFE SHAFT COATINGS

13-3.1.1 Remove minimal length GRP topcoat section covering the area of damage only. Stop GRP topcoat removal when full bonding of the topcoat to the epoxy primer is reached. The epoxy primer appears as a light colored paint layer on the steel shaft under the GRP wrap

13-3.1.2 Inspect exposed epoxy primer for areas of mechanical damage indicated by bleeding rust or removal of primer sections that may have adhered to the removed GRP topcoat.

13-3.1.3 Feather all areas of mechanically damaged or missing epoxy primer into well-adhered epoxy primer using an 80 grit sanding disc.

13-3.1.4 Clean feathered bare metal shaft areas and complete NDT inspection in accordance with step 13-3.7.1 on all bare metal areas.

13-3.1.5 Clean dye penetrant inspection residue from all bare metal areas and paint all bare metal areas with Hycote 151 anti-corrosive paint. Hycote painting shall extend approximately two inches beyond bare metal areas to tie into well-bonded epoxy primer.

13-3.1.6 When Hycote has cured to tacky condition, proceed with replacement of removed section of GRP coating over the repaired epoxy primer in accordance with step 13-3.11.

13-3.1.7 Inspect cured GRP topcoat in accordance with step 13-3.12.

13-3.2 PROPULSION SHAFTING FAIRWATER REMOVAL

13-3.2.1 (TOP, DV) If the damaged shaft covering area extends under the fairwater based on visual and physical inspections detailed in Section 13-3.4.2 the fairwaters will have to be disassembled and removed to provide the required access to the shaft to successfully execute the repair.

13-3.3 REPAIR HABITAT PREPARATION

The drawings referenced in Appendix A provide details of any on-site preparation or fabrication required. Modifying existing previously used doghouse habitat sealing doors for a different shaft size may often be more costly and time consuming than simply fabricating new doors based on measurements detailed in the doghouse habitat drawings (see Appendix A). Using additional sealing rubber in an attempt to fit oversized sealing doors to a smaller diameter shaft is not approved or recommended.

13-3.4 INITIAL SHAFT SURFACE PREPARATION (IN THE WET)

CAUTIONFor all shafts with extended service life coatings (epoxy primer under the conventional GRP top coat) modify the

section 3 repair procedure as indicated in step 13-3.1.

Damaged shaft covering areas or areas of excessive porosity (pits in the covering that expose the shaft surface to sea-water) must be removed from the shaft and replaced with a new covering.

NOTEIn order for the habitat to seal properly around the shaft, the repair area cleaned should be at least equal to the length of

the repair habitat being used.

13-3.4.1 (DV) Use wire brushes or hydraulic scrubber brush to remove any marine growth on the shaft section being repaired.

CAUTIONTools used during the covering removal process can damage the shaft. Care should be taken not to damage the surface of

the shaft while removing the shaft covering.

13-3.4.2 (DV) The covering should be removed around the full shaft circumference on both sides of the damage until undamaged, fully bonded, covering is reached. Covering must be visually inspected in accordance with MIL-STD-2199 Section 5.6.2 a, b, and d. Physical inspection with the aid of a thin, flexible paint scraper has proven effective in determining if the covering is fully bonded to the shaft. Particular attention must be paid to the areas where the covering joins or laps on the shaft sleeve as directed by MIL-STD-2199 Section 5.6.2 d. If the covering is rubber, it is best to wait until the shaft is dry in the habitat and use a sharp edged paint scraper and a mallet to dig up the fore and aft edges of the pieces that are being pulled up. Double the separated flap of material back out of the way during the removal process.

13-3.5 REPAIR HABITAT INSTALLATION

WARNINGUsing open bottom double wall void areas of the habitat for

variable buoyancy control while the habitat travels up or down in the water column may result in loss of control and is

not recommended. Using open bottom void areas for increasing habitat buoyancy is only intended to aid in shifting

habitat position along the shaft. Positive control rigging techniques in accordance with a maintenance activity

approved rigging plan are required. NAVSEA doghouse habitats have internal sealed double wall buoyancy intended to maintain neutral buoyancy regardless of habitat depth in

the water column.

CAUTIONHabitat installation or removal can damage the shaft covering if not installed properly. Exercise care during installation and

removal.

13-3.5.1 (TOP, DV) Install and dewater the appropriate dry habitat in accordance with a regional maintenance activity approved rigging plan specific to the type of habitat used, the actual ship class involved, and the specific shaft location to be installed on. Positive control rigging techniques shall be employed at all times.

13-3.6 PRIMARY SHAFT SURFACE PREPARATION (IN THE DRY)

WARNINGPower tools used in the confines of a habitat can cause hazardous flying debris. Eye protection and breathing

apparatus is necessary.

CAUTIONFor all shafts with extended service life coatings

(epoxy primer under the conventional GRP top coat) modify the section 3 repair procedure as indicated in

step 13-3.1.

13-3.6.1 (DV) Use a pneumatic grinder with wire wheel and sanding discs to clean the shaft surface. Bevel the edges of the adjacent undamaged covering 1 to 2 inches back.

WARNINGSolvents, paints, and epoxies have toxic fumes. Adequate ventilation or breathing apparatus is necessary. Refer to

Section 8-11.4.2, Enclosed Space Safety Precautions, of the U.S. Navy Diving Manual for the warning associated with submarine ballast tank entry. Ensure proper eye and skin

protection is provided.

13-3.6.2 (TOP, DV) Clean the shaft surface with a chlorinated solvent (Philadelphia Resins PRT-59 or equivalent) by saturating rags with the solvent and sending them to the habitat in a watertight container. The divers use a stiff bristled paint brush to scrub the shaft after wetting with the rags. Re-wipe with clean rags to remove all contaminants. Send all rags and brushes to the surface for proper disposal.

13-3.7 NDT INSPECTION OF SHAFT SURFACE

CAUTIONFor all shafts with extended service life coatings (epoxy primer under the conventional GRP top coat) modify the

section 3 repair procedure as indicated in step 13-3.1.

Divers conducting and certifying NDT procedures must be qualified in accordance with NAVSEA Technical Publication T9074-AS-GIB-010/271, Requirements for Nondestructive Testing Methods.

13-3.7.1 (DV) Inspect all bare metal shaft surfaces by liquid penetrant or magnetic particle method in accordance with NAVSEA Technical Publication T9074-AS-GIB-010/271, Requirements for Nondestructive Testing Methods and acceptance criteria in MIL-STD-2035. NSTM Chapter 243 paragraphs 1.1.7.1 and 1.1.9.1 detail inspection criteria and repair requirements for all shaft surface pitting or cracking.

13-3.8 EXPOSED SHAFT SURFACE FINAL CLEANING AND FAIRING

CAUTIONFor all shafts with extended service life coatings (epoxy primer under the conventional GRP top coat) modify the

section 3 repair procedure as indicated in step 13-3.1.

The shaft surface needs to be cleaned again to remove any residues left from NDT inspections.

13-3.8.1 (DV) Clean the surface as detailed in step 3.6.2

13-3.8.2 (DV) Fair shaft surfaces which required repair grinding or interface areas between the shaft sleeves. The preferred shaft fairing material which should be using as a replacement for Phillybond is:

Thiokol 2282Manufactured by Polyspec L.P.

6614 Gant RoadHouston, TX 77066PH: 281-397-0033

http://www.thiokolpolysulfide.com/pages/732453/index.htm

13-3.9 CHECK SHAFT SURFACE TEMPERATUREThe ideal temperature is 73°F for GRP installation. The surface temperature cannot be below 60°F for acceptable installation. Controllable Pitch Propeller (CPP) ships can use the internal shaft hydraulics to heat the shaft surface to acceptable levels. Non-CPP ships may attempt to raise shaft surface temperature above 60°F using preheats as shown in Figure 13-4. Higher temperatures (80 - 90°F) will significantly reduce working or "gel" time of the epoxy resin. For example, MIL-STD-2199 only requires an 18-minute gel time for resin at 90°F. All work (each wrap) must be completed prior to gel of epoxy resin.

13-3.9.1 (DV) Use a metal surface contact thermometer to check temperature of shaft surface at the repair area.

13-3.10 PREPARATION OF EPOXY RESIN

WARNING:When handling resin, guard against getting any in the eyes. Avoid skin contact. In case of contact with eyes flush with

water and call physician. Remove from skin with dry cloth or paper towel. Wear goggles, impervious rubber gloves, and

coveralls during mixing and appli-cation.

13-3.10.1 As temperatures within the habitat reach working levels, the epoxy resin should be prepared. Because epoxy resins have a limited pot life, especially in warm temperatures, separate batches of resin need to be prepared for each of the four layers of fiberglass tape to be applied. A fifth patch of resin is applied to wet out the whole area after all four wraps arecomplete. The appropriate amount of hardener shall be added to each batch separately just before application in accordance with the manufacturer's directions. MIL-STD-2199 Section 5.4.4 is helpful in estimating the required quantity of epoxy for each wrap.

NOTE:In warm weather the resin may be cooled to extend the pot life of the resin/hardener mixture. Additional information on the

pot life should be obtained from the resin manufacturer.

NOTE:Plastic stir paddles are to be used when mixing the resin with the hardener because wooden stir paddles tend to absorb the

hardener.

13-3.10.2 (TOP) Prepare premixed batches of resin and hardener by measuring out and placing the two parts in a watertight container and mixing thoroughly with a plastic stir paddle. Take care not to create any air bubbles in the resin that can become sources for delamination and air pockets between the wraps after the covering cures. The paint containers that the resin comes in can serve as the watertight containers if properly resealed.

13-3.10.3 (TOP) Pass the first resin/hardener batch, fiberglass tape, plastic stir paddles, paint brushes, and a squeegee (all in watertight containers) down to the divers in dry transfer bags and dry pot (items 6 and 7, Table 13-1). Ensure each roll of tape sent to the divers is pre-measured to be long enough to complete the total wrap (See MIL-STD-2199 Section 5.4.4).

13-3.10.4 (TOP) Provide premixed batches of resin/hardener and tape as required by the divers.

13-3.11 APPLICATION OF EPOXY RESIN AND FIBERGLASS COVERING

CAUTION:For all shafts with extended service life coatings (epoxy primer under the conventional GRP top coat) modify the

section 3 repair procedure as indicated in step 13-3.1.

(DV) Install the four wrap GRP repair in accordance with the detailed procedures of MIL-STD-2199. Follow the instructions for installation on a stationary shaft. Premixed resin and hardener batches will be provided to the divers as required for each of the four wraps. The four wraps should be applied in the opposite direction of the shaft rotation (ahead) with the first and third layers proceeding forward to aft and the second and fourth layers proceeding aft to forward along the shaft. Wrapping opposite the direction of shaft ahead rotation ensures shaft rotation will not tend to peel the covering off. Alternating the start of each wrap at opposite ends of the repair section will help ensure that the spiral plies of each wrap criss-cross each other to

provide better adhesion and strength. Start each wrap by winding one complete circumferential turn of tape around the shaft to completely cover the tape end. Then gradually, in two or three turns, decrease the tape overlap and work into a spiral with edges of the tape butted closely together to avoid gaps in coverage. When the wrap progresses to the opposite end of the repair section gradually increase the tape overlap and work into a single circumferential turn at the end.

13-3.11.1 If the shaft had to be preheated with the preheat arrangement shown in Figure 13-4, then after the final wrap is complete the preheat must be repositioned to maintain the surface temperature of the shaft throughout the curing process.

13-3.11.2 Mount a video camera in the habitat during the curing process to monitor the water level below the shaft and the thermometer for temperature level.

13-3.12 NEW COVERING INSPECTION

Perform a final inspection of the repair in accordance with MIL-STD-2199 Section 5.6.1. Section 5.6.1.1 of the MIL-STD details the corrective actions required if defects are found in the final inspection. High voltage spark tester equipment is not currently available for use in the dry habitat, so a careful visual and sounding inspection is critical.

13-3.13 PAINTING OF REPAIR AREA

WARNINGSolvents, paints, and epoxies have toxic fumes. Adequate ventilation or breathing apparatus is necessary. Refer to

Section 8-11.4.2, Enclosed Space Safety Precautions, of the U.S. Navy Diving Manual for the warning associated with submarine ballast tank entry. Ensure proper eye and skin

protection is provided.

13-3.13.1 Paint all GRP repair surfaces with Hycote 151 anti-corrosion coating system. The anti-corrosion paint provides secondary corrosion protection because the GRP repair cannot be spark tested for complete integrity in accordance with MIL-STD-2199 within the dry habitat. Experience and testing has shown that there are no anti-fouling coating systems suitable for application inside the high humidity environment of the habitat.

13-3.14 REMOVE THE HABITAT FROM THE SHAFT

WARNINGUsing open bottom double wall void areas of the habitat for

variable buoyancy control while the habitat travels up or down in the water column may result in loss of control and is

not recommended. Using open bottom void areas for increasing habitat buoyancy is only intended to aid in shifting

habitat position along the shaft. Positive control rigging techniques in accordance with a maintenance activity

approved rigging plan are required. NAVSEA doghouse habitats have internal sealed double wall buoyancy intended to maintain neutral buoyancy regardless of habitat depth in

the water column.

CAUTIONHabitat installation or removal can damage the shaft covering if not installed properly. Exercise care during installation and

removal.

13-3.14.1 (TOP, DV) Remove the habitat.

13-3.15 RE-INSTALL THE FAIRWATERS

CAUTIONShaft covering can be damaged during fairwater installation. Care must be used to prevent damaging additional areas of the shaft covering when reinstalling the two halves of the

fairwater or maneuvering a fairwater near the shaft.

13-3.15.1 (TOP, DV) Re-install all removed fairwaters.

13-3.16 FINAL PROCEDURES

13-3.16.1 Take Inventory. (TOP) Collect, inventory, and pack all equipment and tools.

13-3.16.2 Debrief Ship’s Force. (TOP) The lead dive supervisor should debrief the pertinent ship's officers on the final status of the shaft covering repair. Ship systems that were closed and tagged out for the accomplishment of the shaft covering repair only may be returned to operation.

13-3.16.3 Final Report. (TOP) Prepare a final report documenting the accomplished repair. Documentation should consist of Inspection Reports, NDT Inspector/Diver Certifications, Nondestructive Test Reports, 35mm still photographs, and video logs.

13-3.16.4 The final report should also include details regarding any problems encountered, new or special tools needed, or modifications to tools or procedures found to facilitate shaft covering repair. The final report shall be forwarded to:

CommanderNaval Sea Systems Command (SEA 00C5)1333 Isaac Hull Avenue S.E. Stop 1075Washington Navy Yard, DC 20376-1075

APPENDIX A

IDENTIFICATION OF NAVSEA SHAFT HABITATS AND DRAWINGS

FM (MAINTENANCE STAFF)TO COMNAVSEASYSCOM WASHINGTON DC//05Z//00C5NAVSURFWARCENSHIPSYSENGSTA PHILADELPHIA PA//9323//BTUNCLAS //N04700//MSGID/GENADMIN/ //SUBJ/SHAFT DAMAGE ASSESSMENT//RMKS/

1. UNDERWATER INSPECTION OF USS ________________________ SHAFT REVEALED THE FOLLOWING DAMAGE TO (RUBBER or FIBERGLASS) COVERING:

A. LOCATION - (PORT OR STBD)(INBOARD OR OUTBOARD FOR FOUR SHAFT SHIPS) SHAFT, _____ INCHES FORWARD OF MAIN STRUT FAIRWATER, OR (FORWARD OR AFT) OF INTERMEDIATE STRUT FAIRWATER, OR AFT OF STERN TUBE FAIRWATER. IF THE SHIP HAS A SHAFT COUPLING COVER IN WAY OF INTERMEDIATE STRUT FAIRWATER OR STERN TUBE FAIRWATER THEN MEASURE DAMAGE LOCATION TO CLOSEST END OF COUPLING COVER.

B. DESCRIPTION - COVERING IS (NICKED, CUT, MISSING) ON AN AREA (_____ INCHES BY ______ INCHES or _______ INCHES LONG, 360 DEGREES AROUND SHAFT).

C. COVERING APPEARS TO BE UNBONDED FROM THE SHAFT (FOR______ INCHES) (FORWARD or AFT) OF THE DAMAGE.

D. CORROSION - SHAFT CORROSION (IS or IS NOT) VISIBLE. PITTING (IS or IS NOT) VISIBLE. DEEPEST PIT DEPTH IN SHAFT METAL SURFACE IGNORING THICKNESS OF GRP SHAFT COATING IS _____ INCHES (PIT DEPTH SHALL BE ACCURATELY MEASURED USING A PIT GAUGE). (IF MULTIPLE DAMAGE LOCATIONS EXIST, REPEAT ITEMS 1. A, B, C, and D FOR EACH LOCATION).

2. FOLLOWING IS SHAFT HISTORY: A. DATE SHAFT WAS LAST CONFIRMED WITHOUT DAMAGE BY (UNDERWATER INSPECTION or

UNDOCKING) - (MONTH, YEAR). B. DATE OF CURRENT INSPECTION - (MONTH, YEAR). C. ESTIMATED NUMBER OF SHAFT REVOLUTIONS FROM ITEM 2.A. TO DATE - _______ REVS.

3. FOLLOWING IS SHIP'S OP PROFILE: A. DATE OF NEXT DRYDOCKING (MONTH, YEAR). B. ESTIMATED NUMBER OF SHAFT REVOLUTIONS PER MONTH BETWEEN NOW AND NEXT

DRYDOCK- ________ REV/MONTH. 4. REQUEST NAVSEA REVIEW DATA AND PROVIDE REPAIR RECOMMENDATION.

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