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

Patent metadata

Field	Value
Publication number	US-9868493-B2
Application number	US-201414785843-A
Country	US
Kind code	B2
Filing date	Jun 5, 2014
Priority date	Jun 20, 2013
Publication date	Jan 16, 2018
Grant date	Jan 16, 2018

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

The invention claimed is:

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;
a first plate member including a transition portion that has a varying plate thickness toward an end, the first plate member having a cylindrical shape;
a second plate member having a higher curvature along the axial direction than the first plate member, the second plate member having a hemispherical shape, wherein
the end of the first plate member and an end of the second plate member are joined together,
both an inner peripheral surface and an outer peripheral surface of the first plate member are not flush with an inner peripheral surface and an outer peripheral surface of the second plate member, respectively, and a plate thickness center of the first plate member is offset toward a radial inner side or a radial outer side with respect to a plate thickness center of the second plate member.

2. The independent tank according to claim 1 ,
wherein the plate thickness center of the first plate member 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 second plate member.

3. The independent tank according to claim 1 ,
wherein the plate thickness center of the first plate member 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.

4. The independent tank according to claim 1 ,
wherein the plate thickness center of the first plate member is offset toward the radial outer side from the plate thickness center of the second plate member 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 welded portion between the first plate member and the second plate member is shifted toward a side of the second plate member from the curvature change portion between the first plate member and the second plate member.

6. The independent tank according to claim 1 ,
wherein the second plate member 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, a first plate member including a transition portion that has a varying plate thickness toward an end, the first plate member having a cylindrical shape, and a second plate member having a higher curvature along the axial direction than the first plate member, the second plate member having a hemispherical shape, the method comprising the processes of:
preparing the first plate member so that both an inner peripheral surface and an outer peripheral surface of the first plate member are not flush with an inner peripheral surface and an outer peripheral surface of the second plate member having a higher curvature, respectively, and a plate thickness center of the plate member is offset toward a radial inner side or a radial outer side with respect to a plate thickness center of the second plate member; and
joining the end of the first plate member and an end of the second 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, a first plate member including a transition portion that has a varying plate thickness toward an end, the first plate member having a cylindrical shape, and a second plate member having a higher curvature along the axial direction than the first plate member, the second plate member having a hemispherical shape, the method comprising the processes of:
preparing the first plate member so that both an inner peripheral surface and an outer peripheral surface of the first plate member are not flush with an inner peripheral surface and an outer peripheral surface of the second plate member, respectively, and a plate thickness center of the first plate member 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 second plate member; and
joining the first plate member and the second plate member 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, a first plate member including a transition portion that has a varying plate thickness toward an end, the first plate member having a cylindrical shape, and a second plate member having a higher curvature along the axial direction than the first plate member, the second plate member having a hemispherical shape, the method comprising the processes of:
preparing the first plate member so that both an inner peripheral surface and an outer peripheral surface of the first plate member are not flush with an inner peripheral surface and an outer peripheral surface of the second plate member, respectively, and a plate thickness center of the first plate member 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 second plate member; and
joining the first plate member and the second plate member 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, a first plate member including a transition portion that has a varying plate thickness toward an end, the first plate member having a cylindrical shape, and a second plate member having a higher curvature along the axial direction than the first plate member, the second plate member having a hemispherical shape, the method comprising the processes of:
preparing the first plate member so that both an inner peripheral surface and an outer peripheral surface of the first plate member are not flush with an inner peripheral surface and an outer peripheral surface of the second plate member, respectively, and a plate thickness center of the first plate member is offset toward a radial outer side from a plate thickness center of the second plate member 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 first plate member and the second plate member having a higher curvature together.

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

Assignees

• Mitsubishi Heavy Ind Ltd

Inventors

• Ohtsuka Hirotomo
• Miyazaki Satoshi
• Watanabe Michihisa

Classifications

• B63B25/16 Primary

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

• F17C2203/0604

  Liners · CPC title

• F17C13/00

  Details of vessels or of the filling or discharging of vessels · CPC title

• F17C2209/232

  of walls · CPC title

• F17C13/002

  for vessels under pressure (F17C13/008 and F17C13/02 - F17C13/12 take precedence) · CPC title