Independent tank with curvature change section, and manufacturing method for independent tank

Patent metadata

Field	Value
Publication number	US-2016068235-A1
Application number	US-201414785843-A
Country	US
Kind code	A1
Filing date	Jun 5, 2014
Priority date	Jun 20, 2013
Publication date	Mar 10, 2016
Grant date	—

Abstract

Provided is an independent tank, and a manufacturing method therefor, for which local bending stress occurring on the vicinity of a boundary portion (welded portion) can be reduced without increasing plate thickness. An independent tank has at least one curvature change portion in which the curvature along the axial direction of plate members that form the tank changes along the axial direction. Both the inner peripheral surface and the outer peripheral surface of the plate member on the small curvature side are not flush with respect to the inner peripheral surface and the outer peripheral surface of the plate member on the large curvature side. The plate thickness center of the plate member on the small curvature side is offset toward the radial direction inner side or the radial direction outer side with respect to the plate thickness center of the plate on the large curvature side.

First claim

1 . An independent tank comprising:
at least one curvature change portion in which a curvature along an axial direction of plate members that form the tank changes along the axial direction, wherein both an inner peripheral surface and an outer peripheral surface of the plate member having a lower curvature are not flush with an inner peripheral surface and an outer peripheral surface of the plate member having a higher curvature, respectively, and a plate thickness center of the plate member having a lower curvature is offset toward a radial inner side or a radial outer side with respect to a plate thickness center of the plate member having a higher curvature.

2 . The independent tank according to claim 1 ,
wherein the plate thickness center of the plate member having a lower curvature is offset toward the radial outer side from a position where stress that occurs at an outer surface of the tank and stress that occurs at an inner surface of the tank become equal to each other with respect to the plate thickness center of the plate member having a higher curvature.

3 . The independent tank according to claim 1 ,
wherein the plate thickness center of the plate member having a lower curvature is offset toward the radial outer side by a manufacturing error from a position where stress that occurs at an outer surface of the tank and stress that occurs at an inner surface of the tank become equal to each other.

4 . The independent tank according to claim 1 ,
wherein the plate thickness center of the plate member having a lower curvature is offset toward the radial outer side from the plate thickness center of the plate member having a higher curvature to be at a position where stress that occurs at an outer surface of the tank and stress that occurs at an inner surface of the tank become equal to each other.

5 . The independent tank according to claim 1 ,
wherein a joint portion between the plate member having a lower curvature and the plate member having a higher curvature is shifted toward a side of the plate member having a higher curvature from the curvature change portion between the plate member having a lower curvature and the plate member having a higher curvature.

6 . The independent tank according to claim 1 ,
wherein the plate member having a lower curvature has a cylindrical shape, and the plate member having a higher curvature is an end plate.

7 . The independent tank according to claim 1 , loaded on a ship or an offshore structure.

8 . A ship with the independent tank according to claim 1 loaded thereon.

9 . A method of manufacturing an independent tank which includes at least one curvature change portion in which a curvature along an axial direction of plate members that form the tank changes along the axial direction, the method comprising the processes of:
preparing the plate member having a lower curvature so that both an inner peripheral surface and an outer peripheral surface of the plate member having a lower curvature are not flush with an inner peripheral surface and an outer peripheral surface of the plate member having a higher curvature, respectively, and a plate thickness center of the plate member having a lower curvature is offset toward a radial inner side or a radial outer side with respect to a plate thickness center of the plate member having a higher curvature; and joining the plate member having a lower curvature and the plate member having a higher curvature together.

10 . A method of manufacturing an independent tank which includes at least one curvature change portion in which a curvature along an axial direction of plate members that form the tank changes along the axial direction, the method comprising the processes of:
preparing the plate member having a lower curvature so that both an inner peripheral surface and an outer peripheral surface of the plate member having a lower curvature are not flush with an inner peripheral surface and an outer peripheral surface of the plate member having a higher curvature, respectively, and a plate thickness center of the plate member having a lower curvature is offset toward a radial outer side from a position where stress that occurs at an outer surface of the tank and stress that occurs at an inner surface of the tank become equal to each other, with respect to a plate thickness center of the plate member having a higher curvature; and joining the plate member having a lower curvature and the plate member having a higher curvature together.

11 . A method of manufacturing an independent tank which includes at least one curvature change portion in which a curvature along an axial direction of plate members that form the tank changes along the axial direction, the method comprising the processes of:
preparing the plate member having a lower curvature so that both an inner peripheral surface and an outer peripheral surface of the plate member having a lower curvature are not flush with an inner peripheral surface and an outer peripheral surface of the plate member having a higher curvature, respectively, and a plate thickness center of the plate member having a lower curvature is offset by a margin of a manufacturing error toward a radial outer side from a position where stress that occurs at an outer surface of the tank and stress that occurs at an inner surface of the tank become equal to each other, with respect to a plate thickness center of the plate member having a higher curvature; and joining the plate member having a lower curvature and the plate member having a higher curvature together.

12 . A method of manufacturing an independent tank which includes at least one curvature change portion in which a curvature along an axial direction of plate members that form the tank changes along the axial direction, the method comprising the processes of:
preparing the plate member having a lower curvature so that both an inner peripheral surface and an outer peripheral surface of the plate member having a lower curvature are not flush with an inner peripheral surface and an outer peripheral surface of the plate member having a higher curvature, respectively, and a plate thickness center of the plate member having a lower curvature is offset toward a radial outer side from a plate thickness center of the plate member having a higher curvature to be at a position where stress that occurs at an outer surface of the tank and stress that occurs at an inner surface of the tank become equal to each other; and joining the plate member having a lower curvature and the plate member having a higher curvature together.

13 . The method of manufacturing an independent tank according to claim 9 ,
wherein a joint portion between the plate member having a lower curvature and the plate member having a higher curvature is shifted toward a side of the plate member having a higher curvature from the curvature change portion between the plate member having a lower curvature and the plate member having a higher curvature.

Assignees

• Mitsubishi Heavy Ind Ltd

Inventors

• Ohtsuka Hirotomo
• Miyazaki Satoshi
• Watanabe Michihisa

Classifications

• F17C2201/0104

  cylindrical · CPC title

• F17C2270/0105

  Ships · CPC title

• B63B25/16 Primary

  heat-insulated (insulating panelling B63B3/68; heating or cooling B63J) · CPC title

• F17C2221/033

  Methane, e.g. natural gas, CNG, LNG, GNL, GNC, PLNG · CPC title

• F17C2209/221

  Welding · CPC title