US 5,189,975 AGranted

Method for reconfiguration tankers

AssigneeMobil Oil Corporation

InventorsJay J. Zednik, Paul C. Dahan

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Abstract

A method for converting a single-hull tanker to a mid-deck configuration is disclosed. The midship cargo section of the tanker is cut longitudinally along a horizontal plane well below the normal laden water line. A spacer member including a new transverse mid-deck is interposed between the lower and upper portions of the midship cargo section. The port and starboard outer sections of the midship cargo section of the vessel are cut longitudinally away from the central portions of the midship sections of the vessel, and new longitudinal bulkheads are added. In this way the vessel is provided with port and starboard wing ballast tanks between the hull plating and the port and starboard wing cargo tanks. The center cargo tank is also divided the upper and lower sections, such that the lower section can be converted to ballast in the event double-hulled tankers become mandatory for oil transport.

Claims14

Dependent claims

A method of reconstructing a tanker having a bow section, a stern section, and a midship cargo section, said midship cargo section including hull bottom plating, deck plating, port and starboard outer plating, continuous port and starboard longitudinal bulkheads, and a plurality of continuous transverse bulkheads, whereby a plurality of center cargo tanks are formed between said port and starboard longitudinal bulkheads, said transverse bulkheads, and said bottom and deck plating, a plurality of port wing cargo tanks are formed between said port outer plating, said port longitudinal bulkhead, said transverse bulkheads, and said bottom and deck plating, and a plurality of starboard wing cargo tanks are formed between said starboard outer plating, said starboard longitudinal bulkhead, said transverse bulkhead, and said bottom deck plating, said method comprising the steps of:

(1) separating a lower portion of the midship cargo section from an upper portion thereof by:
(a) cutting said port and starboard outer plating apart along horizontal cutting lines extending the length of said midship cargo section;
(b) cutting said continuous port and starboard longitudinal bulkheads apart along horizontal cutting lines extending the length of said midship cargo section;
and
(c) cutting each of said continuous transverse bulkheads apart along horizontal cutting lines extending transversely across said midship cargo section;
(2) cutting said bow and stern sections free from said upper portion of the midship cargo section, and elevating said upper portion of said midship cargo section with respect to said lower portion thereof;
(3) inserting a spacer member between said separated upper and lower portions of said midship cargo section, said spacer member including new insert sections of said port and starboard outer hull plating, of said port and starboard longitudinal bulkheads, and of said transverse bulkheads, said spacer member further including a new horizontal mid-deck;
(4) welding said separated lower portion of the midship cargo section to a lower longitudinal edge of said spacer member, and said separated upper portion of the midship cargo section to an upper longitudinal edge of said spacer member;
and
(5) welding said upper portion of said midship cargo section to said bow and stern.

7 more elements

A method of reconstructing a tanker having a bow section, a stern section, and a midship cargo section, said midship cargo section including hull bottom plating, deck plating, port and starboard outer plating, continuous port and starboard longitudinal bulkheads, and a plurality of continuous transverse bulkheads, whereby a plurality of center cargo tanks are formed between said port and starboard longitudinal bulkheads, said transverse bulkheads, said bottom plating, and said deck plating, a plurality of port wing cargo tanks are formed between said port outer plating, said port longitudinal bulkhead, said transverse bulkheads, said bottom plating, and said deck plating, and a plurality of starboard wing cargo tanks are formed between said starboard outer plating, said starboard longitudinal bulkhead, said transverse bulkheads, said bottom plating, and said deck plating, said method comprising the steps of:

(1) separating a lower portion of said midship cargo section from an upper portion thereof by:
(a) cutting each of said port and starboard outer plating along horizontal cutting lines extending the length of said midship cargo section;
(b) cutting each of said continuous port and starboard longitudinal bulkheads along horizontal cutting lines extending the length of said midship cargo section;
and
(c) cutting each of said continuous transverse bulkheads along horizontal cutting lines extending transversely across said midship cargo section;
(2) cutting said bow and stern free from the upper portion of the midship cargo section;
(3) (a) cutting each said transverse bulkhead along two pairs of vertical cutting lines, one pair of said cutting lines being disposed between each of said port and starboard outer plating and the corresponding longitudinal bulkhead, at least one of each pair of vertical cutting lines extending vertically upwardly to intersect said deck plating, said pairs of vertical cutting lines extending downwardly to intersect said horizontal cutting lines extending across said transverse bulkheads, and said pairs of vertical cutting lines being joined by cutting lines at upper extremities thereof, whereby a continuous cutting line extends along the entire periphery of port and starboard scrap sections of each transverse bulkhead;
and
(b) cutting said deck plating longitudinally along two parallel lines extending the length of said midship cargo section, said two parallel lines along which said deck plating is cut longitudinally coinciding with the intersection with said deck plating of said at least one of each of said pairs of vertical cutting lines, whereby portions of said port and starboard outer plating are separated from said central portion of said upper portion of said midship cargo section;
(4) removing said separated portions of the port and starboard outer plating;
(5) removing said port and starboard scrap sections of each transverse bulkhead;
(6) inserting a horizontal spacer member between said upper and lower portions of said midship cargo section, said horizontal spacer member including a new mid-deck, and insert sections for said port and starboard outer plating, port and starboard longitudinal bulkheads, and for said transverse bulkheads;
(7) inserting vertical spacer members on either lateral side of the central portion of the upper portion of the midship cargo section, said vertical spacer members each including a new vertical longitudinal bulkhead and inserts replacing said port and starboard scrap sections removed from each transverse bulkhead;
(8) welding said vertical spacer members to the transverse bulkheads along weld lines substantially corresponding to laterally inward lines of said pairs of vertical cutting lines;
(9) welding said separated lower portion of the midship cargo section to port and starboard lower longitudinal edges of said horizontal spacer member, and said separated upper portion of the midship cargo section to upper edges of said horizontal spacer member;
(10) replacing said removed outer portions of the port and starboard outer plating;
and
(11) welding said replaced outer portions of the port and starboard outer plating to said vertical spacer members along weld lines substantially corresponding to laterally outward lines of said pairs of vertical cutting lines, and to said insert sections for said port and starboard outer plating of said spacer member.

15 more elements

Dependencies are inferred from the claim text.