Installation technology of dry gas holder

1 Project overview and characteristics
1.1 Project overview
Twenty-thousand cubic meters of Wiggins dry-type gas tank is used to store low-pressure gas in oil refining and chemical enterprises. Its structure is composed of vertical edge, tank bottom, tank wall, tank top, T-rail and T-rail rack, piston bottom plate and piston column, leveling device, sealing device and other accessories. The cabinet specification is @ 34377x4.5 (6) x28500, and the total weight of the gas tank is 574698kg (excluding the weight of the piston concrete dam).
1.2 1: Process characteristics
The gas holder has complex structure, large construction workload and long construction period; There are many assembly rings with high accuracy requirements: there are many welds on thin plates and section steels, and the welding deformation is difficult to control; There are many lifting operations and it is difficult to lift on site.
2 Construction scheme
The installation manufacturer of dry-type gas cabinet learned that the cabinet body adopts the "formal installation method", and is assembled in the order of first the cabinet bottom and piston bottom, then the wall plate (lower, middle and upper circles), and finally the cabinet top. The cabinet bottom plate and piston bottom plate shall be laid and welded on site. In order to reduce the workload of field and high-altitude operations, the "cabinet wall panel" is divided into 54 pieces (7 pieces with "columns" on both sides, 27 pieces without "columns" on both sides, and the "columns" are H-shaped steel), which are prefabricated on the mould in the plant. After being transported to the site, the "cabinet wall panel" is assembled into a whole cabinet wall by pressing down, middle and upper three circles (18 pieces in each circle, 9 pieces in each circle are columns on both sides). T fence and T fence flocculent platform, piston fence and annular platform are also prefabricated in the workshop in sections, and hoisted and assembled on site. After the cabinet top and its accessories are assembled and welded on the cabinet bottom plate and piston bottom electrode, they are lifted to the top of the column as a whole.
2.1 Main construction procedures
(1) Installation of column base;
(2) Cabinet base plate laying, assembly welding and vacuum leak test:
(3) Piston base plate laying, upper surface welding, piston ring beam installation:
(4) Installation of 18 wall panels in the lower circle, and installation of 7.5-meter circular walkway:
(5) Assembly and welding of the top of the cabinet and installation of its accessories: construct on the piston base plate at the bottom of the cabinet that has been assembled and welded, set up 36 stools and several auxiliary supports, and assemble and weld the ring beam, framework and cover plate on it, but the outer edge ring plate with the width of 300 mm will not be assembled and welded temporarily (it is left to be assembled and welded after the cabinet top is lifted to the top of the column and the installation and welding of the rib between the framework and the top of the column are completed):
(6) The installation of 18 wall panels in the middle circle and 18 wall panels in the upper circle, as well as the installation of corresponding 19.5m and 28.5m circular walkways: