Structural Assessment. USS Yorktown CV-10

Transcription

1 Structural Assessment of USS Yorktown CV-10

2 Assessment Team

3 USS Yorktown History Constructed December January 1943 Essex Class CV th USS Navy Aircraft Carrier Served in WWII Modified in 1955 Served in Vietnam Decommissioned in 1970 Moved to Patriots Point in 1975

4 USS Yorktown Length: 888-ft (originally 872-ft) Beam (at waterline): 101-ft (originally 93-ft) Draft: 30-ft

5 USS Yorktown Profile

6 Assessment Tasks Task 1 - Assessment of Exterior Hull Above the Mud Line Task 2 - Assessment of Exterior Hull Below the Mud Line Based on Literature Task 3 - Assessment of Exterior Hull Below the Mud Line Based on Inspection Task 4 - Visual Assessment of Accessible Compartments in the Bow Region Task 5 - Visual Assessment of all Accessible Compartments in the Remainder of the Vessel Task 6 - Estimation of Rates of Corrosion and Development of Ongoing Maintenance Plan Task 7 - Interpretation of the Structural Assessment and Repair Recommendations

7 Task 1 Assessment of Exterior Hull Above the Mud Line Galvanic Inspection Level I Dive Inspection of entire hull Level II Dive Inspection at 12 locations Level III Dive Inspection at 12 locations Visual Review from Jon Boat

8 Exterior Hull Exposure Zones

9 Task 1 Level II and III Dive Inspection Locations Frame 50 Stern Bow Frame 50

10 Task 1 Observations

11 Task 1 Observations

12 Task 1 Observations

13 Task 2 Assessment of Exterior Hull Below the Mud Line Based on Literature Literature Survey of below mud line corrosion Review of Task 1 results Review of Galvanic Inspection results Previous Assessment Experience with Similar Vessels Expect to see more significant corrosion in the following areas: o Areas with poor galvanic protection o Interface of mud/water o Interfaces of different soils o Interfaces of different metal types

14 Task 3- Assessment of Exterior Hull Below the Mud Line Based on Inspection Frame 50 Stern Bow Frame 50 Local, temporary removal of Mud to a Depth of 6 feet to perform: o Level II Dive Inspection at 7 locations o Level III Dive Inspection at 7 locations

15 Major Findings of Tasks 1 and 3 Task 1 - Tidal & Submerged Zones o Typical layer of marine growth approximately ½ in. thick o Pitting corrosion, typically 1/8 in. to 1 in. diameter o Up to 1/16 in. penetration of pitting corrosion on all areas exposed for inspection o Up to 6.06% loss of section was observed o Average of 2.48% loss of section was observed Task 3 Below the mudline o Pitting corrosion, typically 1/8 in. to 1 in. diameter o Up to 1/16 in. penetration of pitting corrosion on all areas exposed for inspection o Up to 5.60% loss of section was observed o Average of 3.57% loss of section was observed

16 Tasks 4/5- Visual Assessment of Accessible Compartments from 4 th Deck Down Through Hold Review of accessible compartments at 4 th Deck, 1 st Platform, 2 nd Platform and Hold levels Ultrasonic thickness measurements of exterior hull plate, where accessible Task 4 Forward of Frame 50 Task 5 Aft of Frame 50

17 Task 4/5 Assessment Areas

18 Task 4/5 Observations A-504A SD Stores, Frames A-504A SD Stores, Frames A-605A SD Stores, Frames A-605½M Incendiary Bomb Magazine, Frames 18-25

19 Task 4/5 Observations Chain Locker, Frames 7-12½ A 712T WT Trunk, Frames 50-51

20 Task 4/5 Observations A 612M Small Arms, Frames A 526G Gasoline Pump Room, Frames A 620C Damage Control Station, Frames A 625C Plotting Room, Frames 74-79

21 Task 4/5 Observations Forward AMR, Frames Forward AMR, Frames No. 1 Fire Room, Frames C 518E Steering Gear Ram Room, Frames 191½-198

22 Task 4/5 Observations C 606M 5 Powder Magazine, Frames C 610 1AE, Diesel Fire Pump Room, Frames C 702E Shaft Alley (Port), Frames C 701E Shaft Alley (Stbd), Frames

23 Task 4/5 Observations A 403A Electrical Storeroom, Frames A 504A SD Stores, Frames A 504A SD Stores, Frames A-605½M Incendiary Bomb Magazine, Frames 18-25

24 Task 4/5 Observations A 523M Universal Bomb Storage, Frames A 523M Universal Bomb Storage, Frames A 523M Universal Bomb Storage, Frames A 525½T Bomb Elevator, Frames 55-58

25 Task 4/5 Observations A 613ET WT Trunk, Frames A 523M Universal Bomb Storage, Frames A 523M Universal Bomb Storage, Frames A 523M Universal Bomb Storage, Frames 50-58

26 Task 4/5 Observations A 541ET Bomb Elevator, Frames B-1-1 Fwd AMR, Frames C 610 1AE Diesel Fire Pump Room, Frames C 701E Shaft Alley (Stbd), Frames

27 Task 4/5 Observations C 516A Vestibule, Frames C 605E JP5 Pump Room, Frames C 606M 5 Powder Magazine, Frames C 607A Air Flask, Frames

28 Major Findings of Tasks 4/5 Flooding and/or severe deterioration on 4 th Deck level forward of Frame 19 Flooding and/or severe deterioration on 1 st Platform level forward of Frame 26 and at isolated spaces in forward and aft areas of Task 5 Flooding and/or severe deterioration on 2 nd Platform level forward of Frame 26 and between Frames 38 and 42 and at isolated spaces in forward and aft areas of Task 5 Flooding and/or severe deterioration on Hold level forward of Frame 26 and between Frames 44 and 50 and at isolated spaces in forward engineering flats and isolated compartments in aft areas

29 4 th Deck Frame 50 Frame 50 1 st Platform Frame 50 Frame 50

30 2 nd Platform Frame 50 Frame 50 Hold Frame 50 Frame 50

31 Task 6 Estimation of Rates of Corrosion and Development of Ongoing Maintenance Plan Review all collected data from previous tasks Estimate corrosion rate of hull plate Develop corrosion protection plan Develop ongoing maintenance plan

32 Task 6 Findings/Recommendations Highest rates of hull plate corrosion found in Splash Zone; approximately.002 to.007 in. loss of section per year Localized areas with 70%-80% loss of section Isolated areas with up to 100% loss of section Rates of hull plate corrosion in tidal & submerged zones found to be approximately to.0015 in. loss of section per year Regular inspection to ensure watertight integrity of vessel Maintenance of paint and coatings in areas exposed to weather Maintenance of existing Cathodic Protection System to minimize corrosion in submerged areas

33 Task 7 Interpretation of the Structural Assessment & Repair Recommendations Labor and materials costs to perform structural repairs: Estimated repair costs for deteriorated areas forward of Frame 50: $28,679,541 Estimated repair costs for deteriorated areas aft of Frame 50: $9,809,330 Total estimated repair costs: $38,488,871

34 THANK YOU!