Method for constructing triple-shell tank
A method for constructing a triple shell tank including an inner tank, an intermediate tank, and an outer tank each having a roof and a side plate includes the following procedure. As construction entrances, a first construction opening is opened in an outer tank side plate, a second construction opening is opened in an inner tank side plate, and a third construction opening is opened in an intermediate tank side plate, each during the installation of the corresponding side plate. The construction openings are opened so as to partially overlap with one another in a circumferential direction and a height direction of the triple shell tank. The first construction opening and the second construction opening are opened so as to satisfy a relationship AR 1 ≥AR 2 , where AR 1 is an opening area of the first construction opening and AR 2 is an opening area of the second construction opening.
1 . A method for constructing a triple shell tank including an inner tank, an intermediate tank, and an outer tank each having a roof and a side plate, the method comprising processes of:
as construction entrances, opening a first construction opening in the outer tank side plate when installing the outer tank side plate, a second construction opening in the inner tank side plate when installing the inner tank side plate, and a third construction opening in the intermediate tank side plate when installing the intermediate tank side plate; and
sealing the second construction opening after completion of work inside the inner tank, then sealing the third construction opening after completion of work inside the intermediate tank, and subsequently, sealing the first construction opening after completion of work inside the outer tank,
wherein the first construction opening, the second construction opening, and the third construction opening are opened so as to at least partially overlap with one another in a circumferential direction and a height direction of the triple shell tank, and
the first construction opening and the second construction opening are opened so as to satisfy a relationship of
AR
1
≥
AR
2
where AR 1 is an opening area of the first construction opening and AR 2 is an opening area of the second construction opening.
2 . The method for constructing a triple shell tank according to claim 1 , wherein
the first construction opening, the second construction opening, and the third construction opening are opened so as to satisfy a relationship of
AR
1
≥
AR
3
≥
AR
2
where AR 3 is an opening area of the third construction opening.
3 . The method for constructing a triple shell tank according to claim 1 , wherein
the first construction opening and the second construction opening are opened so as to satisfy a relationship of
H
1
≥
H
2
where H 1 and H 2 are an opening height of the first construction opening and an opening height of the second construction opening, respectively.
4 . The method for constructing a triple shell tank according to claim 3 , wherein
the first construction opening, the second construction opening, and the third construction opening are opened so as to satisfy a relationship of
H
1
≥
H
3
≥
H
2
where H 3 is an opening height of the third construction opening.
5 . The method for constructing a triple shell tank according to claim 1 , wherein
the outer tank side plate, the inner tank side plate, and the intermediate tank side plate are assembled by stacking a plurality of circular steps formed by arranging a plurality of side plate pieces in a circular ring shape, and
the first construction opening, the second construction opening, and the third construction opening are opened by pulling out one or a plurality of the plurality of side plate pieces constituting the circular step.
6 . The method for constructing a triple shell tank according to claim 5 , wherein
the side plate pieces have rectangular shapes of identical or approximate sizes,
the first construction opening is opened by pulling out the side plate pieces for a plurality of adjacent N steps of circular steps constituting the outer tank side plate, and
the second construction opening and the third construction opening are opened by pulling out the side plate pieces for (N−1) steps of circular steps constituting the inner tank side plate and the intermediate tank side plate, respectively.
7 . The method for constructing a triple shell tank according to claim 5 , wherein
the side plate pieces have rectangular shapes of identical or approximate sizes,
the first construction opening is opened by pulling out side plate pieces of a lowermost circular step and a second circular step of the circular steps constituting the outer tank side plate,
the second construction opening is opened by pulling out a side plate piece of a lowermost circular step of the circular steps constituting the inner tank side plate, and
the third construction opening is opened by pulling out a side plate piece of a second circular step on a lowermost circular step for height matching of the circular steps constituting the intermediate tank side plate.
8 . The method for constructing a triple shell tank according to claim 7 , wherein an upper end of an anchor strap extending from a tank base is connected to a circular step constituting the intermediate tank side plate for height matching of the intermediate tank side plate.