Application of Hydraulic Jacking Inversion Method in Large External Floating Roof Storage Tank

In recent years, hydraulic jacking upside-down construction technology has been widely used in the construction of large storage tanks for its advantages of high safety and less material input. This paper describes the selection, arrangement, installation, lifting and welding of hydraulic jacking equipment and summarizes the key points of quality control through the installation and construction of 100,000 m3 storage tank of 1.4 million m3 crude oil commercial storage project of the customer. Using this construction technology, the installation of 4 sets of 100,000 m3 storage tanks has been successfully completed, and good results have been achieved.

I. Inversion system and its composition

1, Basic principle

The basic principle of hydraulic lifting is to use the built-in expansion ring as a force transmission mechanism, and the hydraulic lifting column as a lifting point. After the panel group is set and welded, the hydraulic lifting column is used to raise the expansion ring welded on the inner wall of the tank to the installation height of the next circle of wall panels, and a series of procedures such as assembly, welding and lifting are completed alternately. The expansion ring is divided into several sections according to the inner circumference of the tank, and each two sections are expanded tightly on the tank wall with a jack. The force transfer of the expansion ring to the tank body is ensured by a welded reinforced plate.

2, System composition

The hydraulic lifting system is mainly composed of a power distribution box (control cabinet), a centralized control operation box (central console), a pumping station and its control box, a high-pressure hose assembly and a hydraulic cylinder system, which is composed of a single acting hydraulic cylinder (hydraulic jack) and a spinner assembly.

The spreader assembly includes sling, expansion ring, baffle and lifting lug, etc. In this project, the expansion ring is made according to the inner diameter of the storage tank and divided into 12 sections, and the hydraulic jack is used to tighten each section (see Figure 1), and the dragon door plate is set to make it tight with the tank wall to achieve a good force transmission effect.

3, Equipment selection

According to the data provided by the customer, after calculation and verification, we recommend the hydraulic lifting system model YT25-2700, the system's single-column rated lifting mass is 25t, the hydraulic cylinder stroke is 2700mm, can achieve single-column lifting and centralized control lifting.

II. Upgrade system Settings

According to the structural data and construction technology, the maximum lifting quality of inversion is 941t, including 776.5t of wall panels, 164.5t of accessories such as wind resistance ring, strengthening ring and expansion ring.

After repeated calculations, it is believed that 59 lifting columns can meet the needs, but for ease of control, we choose 60 lifting columns, all of which are donated.

According to the construction drawing and layout drawing, the upper and lower panels are staggered by 1/3 board length, that is, about 4m. Considering that the operating space requirement of the welding machine is about 1.8m, the starting position of the jack is set at 2m away from the weld, that is, 1/6 of the board, and the distribution can meet the requirements in turn.

Install the lifting column, hydraulic control system and center console as per equipment operating manual. This system is a tow five central control, six sets of two-in-one central control mode.

III. Upgrade implementation

1, Installation of the first section wall panel and auxiliary facilities

It is divided into the installation of the pad, the first section of the wall panel installation adjustment and welding, and the installation of the lifting system.

2, Follow the steps above to raise the third to ninth panels. With the increase of lifting weight, the thickness of the baffle shall increase correspondingly with the wall thickness. According to the position of the wall panel accessories, the wind ring, reinforcement ring, fire sprinkler support, insulation support, ladder support, electrical and instrument support, etc. should be installed in sequence during the lifting process.

3, The welding of the vertical seam is similar to that of the forward installation method, and the equipment is slightly different, while the biggest difference between the circular seam welding and the forward installation method is the setting and adjustment of the track, and the equipment operation and parameters are the same as that of the forward installation method. The inner track is arranged on the inside of the tank bottom edge plate, and the outer track is formed by the foundation ring beam and the edge plate.

IV. Quality control points

Through the construction of the above storage tank, we think that the three geometric dimensions of the storage tank perpendicularity, roundness, diameter and edge Angle are the key control dimensions of the construction of large storage tank flip.

The storage tank is constructed by inverted loading method, which reduces the high altitude operation and cross operation process, reduces the safety risk, and is obviously superior to the traditional direct loading method in terms of construction period, quality, safety and economy. It has become a developing trend for petrochemical engineering and other similar projects to adopt the inversion method. The construction practice of this large storage tank inversion method has certain reference value.

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