5.2.1. Introduction to technology.
With the continuous increase of the scale of construction, the construction of rows of pipelines involved in various industrial and civil buildings is increasing. With its advantages of fast, safe and environmentally friendly, the construction technology of high-altitude pipeline rows is more and more widely used in the construction of rows of pipelines. The construction efficiency of this technology is high. After the ground is welded into sections, the rows of pipelines are lifted in sections, which greatly improves the construction efficiency and reduces costs. Quality and safety are guaranteed. On the ground, groove treatment, welding preheating, welding process is easier to control, and the welding quality can be more guaranteed. Work on the ground to reduce the frequency of accidents such as electric shock and mechanical injury. It is suitable for hoisting pipes in rows of pipes and pipes with large diameters in dense pipelines, especially for floor heights of 3Hoisting of rows of pipes in machine rooms and pipe corridors above 5m.
5.2.2 technical points.
1) Install the bracket column first, and the support and hanger should be based on the position of the pipe during installation, and the elevation center and horizontal center should be corrected, and the maximum area of the support and hanger should be contacted with the fixed plate during installation, and the full length of the full welding shall not be less than 4mm.
Figure 52.2-1 Forming pipe support.
2) The pipeline is welded into sections on the ground, and before welding, the dirt such as soil clods and dirt in the pipe should be removed, and the surface rust on the edge of the pipe and the weld on both sides of the weld should be removed within the range of not less than 10 15mm until the metallic light appears. And the position of the weld should be set in accordance with the distance between the center surface of the two butt welds on the straight pipe section: when the nominal diameter is greater than or equal to 150mm, it should not be less than 150mm;When the nominal diameter is less than 150mm, it should not be less than the pipe diameter. The distance between the weld and the bending point of the elbow (excluding the pressed elbow) shall not be less than 100mm, and shall not be less than the diameter of the pipe.
The distance between the circumferential weld and the support and hanger shall not be less than 100mm, and shall not be located in the casing and support and hanging through the floor slab.
on the shelf. Do not make holes in the welds and edges of the pipe.
3) Rows of pipes are lifted in sections.
a.Pipe lifting.
Before hoisting, the construction of the vertical support of the pipeline is completed, and the cross arm of the support is not welded first. According to the load distribution, calculate the bending moment, deflection and other parameters of the cross arm, select the specifications and models of the cross arm that meet the requirements, and the load borne by the support and hanger is: the pipe load between the center of the distance between the two adjacent supports, when the support is equally spaced, it is equal to the load between the two supports. Now take the selection of 200 200h section steel to make the hoisting cross arm as an example, weld the lifting lug and baffle. The thickness of the steel plate and the selected bolt type are determined according to the size of the pipe being hoisted. The steel pipe is welded into two pipe sections side by side (a cross arm for hoisting is added under the pipe in advance).
Lifting points are set up from the middle of the hoisting pipe section to 6 meters each at both ends, and lifting lugs are installed on the beams on both sides above the lifting point. Four lifting points were lifted at the same time with four sets of 10t inverted chains. Pay attention to the synchronization of hoisting during the hoisting process.
After the pipe is lifted beyond the installation position, the formal bracket cross arm is welded and connected to the vertical bracket as a whole. Slowly loosen the inverted chain and install the pipe segment to the bracket. Hoisting is complete.
The following figure is a schematic diagram of hoisting (the big pipe is two cranes hanging together or a single crane).
For pipelines that are not suitable for overall lifting, a single hoisting and erection platform welding method is adopted.
Figure 52.2-7 hoisting schematic.
6) Fixed weld welding mounting bracket cross arm: first determine the position of fixed weld and rotating weld. In order to reduce the difficulty of cross installation and improve the construction speed, the pipes are installed in rows as a whole, and the pipes of the same layer used in the construction are hoisted and welded as a whole, and the levelness of the pipelines is controlled by means of tools such as levels.
Figure 52.2-8 Pipe Perpendicularity Correction Figure 52.2-9 in-place pipe welding.