AMC-997-1A Drydocking and Routine Drydock Work.pdf

AMC-997-1A

JUNE 1989

SUPERSEDING

AMC-997-1

MARCH 1988

NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION (NOAA)

ATLANTIC MARINE CENTER

STANDARD SPECIFICATION AMC-997-1A

DRYDOCKING AND ROUTINE DRYDOCK WORK

1. SCOPE. This specification contains the general requirements for drydocking and routine drydock work on NOAA ships.

2. REFERENCES.

a. Docking Report, Form 2410

3. REQUIREMENTS.

3.1 Submittals. Prior to drydocking the ship, submit to the

COTR the following:

3.1.1 Provide a certification signed by a qualified

independent firm attesting that the drydock or railway, and associated controls and machinery, are in good sound condition and have adequate capacity to safely drydock the ship. The certification shall be based on a visual inspection of the facility within the 12-month period immediately preceding the scheduled drydocking, operating and maintenance records of the facility, and recent demonstration of the facility's capacity (e.g., record of the largest ship drydocked during the preceding 6 months). Submittal of a NAVSEA certification that the drydock or railway meets the requirements of MIL-STD-1625 A/B(SH) may be substituted for the independent firm certification.

3.1.2 Provide a letter certifying that the dockmaster in

charge of the docking and undocking evolutions is professionally qualified, through training and experience, to conduct the evolutions in a safe and reliable manner. Include a copy of the dockmaster's resume attached to the letter.

3.1.3 Prepare and submit a drydocking and undocking

procedure which includes operating practices, special precautions that are required by the characteristics of the dock or ship, depth of water, and tide and current conditions which will exist.

3.2 Preparations for Drydocking.

3.2.1 Arrange the blocks in the Contractor's drydock or

railway in accordance with the ship's docking plan. Blocks shall be positioned to haul the ship in the position specified in the detail specification item. In the event the detail specification item does not specify a docking position, the COTR shall specify the docking position.

3.2.2 The minimum height of keel blocks shall be as *

specified on the ship's docking plan or the detail * specifications. In event a conflict exists between the docking * plan and the detail specifications, the detail specifications * take precedence. If not specified on docking plan or in the * detail specifications, the minimum height shall be 36 inches. * All keel blocks shall have 2 inches minimum soft wood caps. *

3.2.3 Insure that all sea chests, discharges, transducers, domes, and other appurtenances are clear of all blocks. There shall be no obstructions between the floor surface of the drydock and the hull, hull openings, appendages, and fittings. Ample horizontal and vertical clearance shall be provided for removal and replacement of rudders, bow thrusters, fathometers, sea scanners, and sonar gear on the ship, whether or not such removals or replacement are known to be required.

3.2.4 Record the fore and aft draft mark readings of the

ship prior to drydocking and after undocking.

3.3 Drydocking.

3.3.1 After obtaining the consent of the COTR, carefully

haulout the ship without strain or injury, in a drydock or marine railway. If any tendency to strain or injure the ship is observed, immediately refloat the ship and rearrange the blocks or make other corrections required to relieve the condition.

Wash down the dock basin to remove silt, mud, and debris immediately after the ship is drydocked.

3.3.2 Prior to the keel clearing the water, attach two

grounding cables from the ship's hull to ground to protect against lightning or other static discharges. One of the cables shall be connected near the bow and the other cable shall be connected near the stern. Each cable shall be a minimum size of 500,000 circular mils.

3.3.3 The ship shall be drydocked within the first

25-percent of the time allowed for the contract performance period.

3.3.4 Hold the ship out of the water for the period required

to perform all contract work which necessitates drydocking.

3.4 Cleaning.

3.4.1 As soon as practical, but in all cases within 12 hours

after drydocking the ship, clean the entire underwater hull and boottopping of all marine growth, dirt and loose paint using stiff bristle brushes, scrapers, and high pressure fresh water.

Included shall be sea strainer plates, sea chests, bow thrusters, rudders, propellers, shafts, struts, and other underwater hull appendages.

3.4.2 Exercise extreme care to avoid scratching, gouging or * otherwise damaging any transducers, dome windows, shaft coverings * or other appendages. *

3.4.3 Clean fiberglass surfaces using non-metallic scrapers * and bristle brushes. Clean transducers using non-metallic, * non-abrasive brushes. Do not use scrapers on transducers. *

3.5 Miscellaneous Requirements.

3.5.1 All hull discharge openings and scupper drains shall *

be fitted with discharge fittings and be fitted with spigots and * hoses to direct liquids away from the hull. Hull discharge * openings which will not be in service while the ship is in * drydock may be plugged in lieu of being fitted with the fittings, * spigots and hoses. *

3.5.2 Within 24 hours after drydocking, remove all sea chest

covers, strainer plates, rope guards, and fairwaters. After completion of all inspections and acceptance of inspection condition reports by the COTR, reinstall the items removed.

3.5.3 Provide adequate staging, or other safe means

acceptable to the COTR, to accomplish all contract work and to permit a thorough inspection (see below) of the underwater body.

3.5.4 Clean all anodes with a wire brush to remove all

corrosion products. Polish propellers and bow thrusters to bright metal.

3.5.5 While the ship is in drydock, install temporary

closures over all hull openings during all hours outside the normal work shifts. Blank flanges and closure plates shall have sufficient strength to prevent water entry into the hull in the event of drydock failure or flooding.

3.5.6 Provide to the COTR a "marked-up" copy of the docking

plan showing all alterations and modifications made to the underwater hull during the contract.

3.6 Docking Inspection. Within 48 hours after drydocking, a

joint inspection of the ship's underwater hull shall be conducted by the Contractor, the COTR, and the Commanding Officer/Master's representative. Submit a Condition Report of the inspection findings, including a completed preliminary copy of reference 2.a. A blank copy of reference 2.a will be provided to the Contractor by the COTR. The inspection shall include the following:

3.6.1 Condition of the hull, particularly inspecting for

evidence of structural damage and deterioration of plating, welds, and fasteners.

3.6.2 Condition of anodes and paint system.

3.6.3 Condition of propellers, rudders, sea chests, shafts, overboard discharge piping, bilge keels, transducers, and all other underwater hull appendages. Inspect for evidence of leaks, damage, and deterioration.

3.7 Void Inspections. Remove the void plugs in underwater hull rub rails, rudders, struts, fairing plates, bilge keels, and other inaccessible underwater voids. As the plugs are removed, inspect for drainage of water from the voids. If water is present, advise the COTR prior to proceeding. After the source of the water has been determined and all additional work authorized by the Contracting Officer has been completed, fill the voids with a rust preventive compound complying with MIL-C-16173, Grade 5. Drain the rust preventive compound and reinstall the plugs using an anti-seize compound on the threads.

3.8 Packing Renewal. Remove the packing glands and existing

packing from the rudders and tailshafts. Thoroughly clean the glands. Cut and fit new rings of TFE-impregnated square flax packing in the rudder and tailshaft glands. Packing shall not contain graphite. Stagger the butts. The number of packing rings shall be as shown on applicable drawings if available.

Otherwise, the number of packing rings shall be same as removed.

Reinstall glands. After the ship is undocked, readjust the tailshaft glands such that a fine trickle of water provides cooling.

3.9 Clearance Readings.

3.9.1 While the packing is removed, take a complete set of

rudder stock and pintle bearing clearance readings. Also check and record the vertical movement of the rudders. Raise the rudders approximately 1/8-inch to relieve weight from the thrust plates. Disassemble the upper support bearing assembly for inspection. Clearance readings of the rudders are to be taken at both the lower hull penetration and the internal upper bearing surfaces. Measure weardown of all packing gland sleeves. After completion of inspections, reassemble all bearings.

3.9.2 Take clearance readings of each propulsion shaft

cutlass bearing at 90-degree intervals around the shafts' circumferences. Clearances of strut bearings shall be taken at both the forward and aft sides of the struts. While packing is removed, measure and record the weardown of the shafts and sleeves at the packing gland.

3.10 Runout Readings. Take runout readings of the propeller

shafts in place while the packing is removed. If the propellers are removed under another contract item, set up a dial indicator to bear on the after end of the shafts. If the propellers are not removed, set the dial indicator to bear on another convenient machined surface as near the end of the shafts as practical.

Read and record the dial indicator deflections as the shafts are rotated 360 degrees. Set up a dial indicator and measure the shaft deflections at each strut and stern tube bearing while the shafts are rotated 360 degrees.

3.11 Transducers. Clean, protect, and paint all transducers as * follows: *

3.11.1 Clean the exposed surfaces of each transducer while *

the surfaces are still damp. Clean transducers with non-metallic * brushes. Do not use scrapers. *

3.11.2 Degrease the faces of rubber-faced transducers with *

mineral spirits and rinse with fresh water. Do not use * detergents on the rubber faces. Swab metallic-faced transducers * with a solution of one part nitric acid to five parts fresh * water, and follow with rich soapy water wash and fresh water * rinse. Polish metallic-faced transducers with crocus cloth. *

3.11.3 Coat all metallic-faced transducers with one coat of * anti-foulant same as prescribed for the remainder of the * underwater hull. This is to be accomplished by removing the * plywood protective covers immediately prior to applying the last * coat of paint to the underwater hull. If the underwater hull is * not being painted, apply one coat of anti-foulant same as exists * on underwater hull. All painting shall be in accordance with the * paint manufacturer's printed recommendations and instructions. *

3.11.4 Coat all rubber-faced transducers with two coats, 2.0 * dry mils each, of MIL-P-22298 Formula 133 and two coats, 2.0 dry * mils each, of MIL-P-22299 Formula 134 in accordance with the * paint manufacturer's printed recommendations and instructions. *

3.11.5 NOAA reserves the right to inspect and adjust

transducers.

3.11.6 Except when work is being performed on the

transducer, cover the transducer faces with a plywood protective cover. Do not apply props or forced pressure on the face of the transducers.

3.12 Undocking.

3.12.1 After all work requiring drydocking has been

completed, carefully undock the ship. Flood the drydock or lower the railway until as many underwater openings as possible are covered with water, but without lifting the ship off the blocks.

Provide adequate personnel and check for leaks. If leaks are found, redock the ship and repair the leaks. If no leaks are found or after repair of all leaks, continue with undocking the ship.

3.12.2 Unless authorized by the Contracting Officer, the *

ship shall not be undocked until all work which requires * drydocking has been completed, including all work included in the * initial contract award and all additional work authorized or * being negotiated. In the event the Contractor desires to undock * the ship and subsequently redock the ship for completion of work, * submit to the Contracting Officer a letter request which clearly * outlines the reasons for the request. If the Contracting Officer * decides to grant the request, the extent of Government's * liability for costs related to the undocking and redocking shall * be limited to the additional layday costs for which the * Government would be liable if the ship were not undocked and * redocked. *

4. QUALITY ASSURANCE.

4.1 After the blocks have been set and before lowering the

drydock or railway for hauling the ship, a final inspection of the blocking shall be conducted by the COTR and the dockmaster.

Measurements shall be rechecked as necessary to satisfy the COTR that the block locations are in accordance with the docking plan and other contract requirements have been met. Acceptance of the blocking arrangement by the COTR in no way relieves the Contractor of the responsibility for safely drydocking the ship without strain or damage.

END OF SPECIFICATION