The method of the groove of seamless steel pipe can be determined according to the pipe diameter and type, groove situation, the surrounding environment of the construction site and construction equipment. Generally speaking, the car type or crawler crane should be used to pipe down. When the road beside the ditch is narrow, the surrounding trees and telegraph poles are more, and the pipe diameter is small, the pipe has to be manually pipe down.
1. Tube under way
(1) The pipe is concentrated in the ditch edge somewhere down to the ditch, and then the pipe is transported to the required position in the ditch. Suitable for poor soil quality and support, or underground obstacles, not easy to disperse under the pipe.
(2) The lower pipe is arranged along the edge of the ditch in order to go down into the ditch. Installation of cast iron pipe mainly uses this method.
(3) Combined lifting. Weld several pipes into sections and run them into the trench.
2. Before piping is ditched, piping should meet the following requirements
(1) Before the trench, the trench should be collapsed in the square soil, stones, rain, oil and snow and other clean.
(2) The depth, elevation and section size of the trench or culvert should be checked, and should meet the design requirements.
(3) Stone section trench, soft cushion thickness shall not be less than 300mm, the bottom of the trench should be flat, no stone.
3. The tube method
(1) The wheel type or crawler type crane is used in the down-pipe method of crane. This is shown in Figure 1.
FIG. 1 Crawler crane tube down
Special nylon spindles must be used to move the crane along the groove when the pipe is lowered. The appropriate lifting height is 1m. After lifting the pipe, rotate the lifting arm to move the pipe to the top of the pipe trench, and then gently place the pipe to the bottom of the trench. The crane should be located at a distance from the edge of the ditch so as not to collapse due to excessive soil pressure. The two ends of the pipe are tied with ropes, which are pulled by people to adjust the direction at any time and prevent the pipe from swinging. Do not damage the anticorrosive layer. For pipes whose outer diameter is greater than or equal to 529mm, three pipe cranes should be used to lift them at the same time when going down the ditch. When the diameter of the pipe is less than 529mm, the pipe lifting machine shall not be less than 2.
If only two or three pipes are welded together, one pipe lifting machine can be used to pipe.
During pipeline construction, the stress on the pipeline should be reduced as much as possible. When hoisting, reduce pipe bending as far as possible to prevent cracks between pipe and anticorrosive layer. The pipe should be properly placed in the trench to prevent additional stress on the pipe.
The pipe shall be placed in the center of the trench, and the allowable deviation shall not be greater than 100mm. The crowbar or roller used for moving the pipe should be coated with rubber hose to protect the anticorrosive layer from damage.
(2) Manual tube method
1) The pressure rope tube method sets a large rope at both ends of the pipe (the choice of rope thickness is determined by the weight of the pipe). With the help of tools, the rope is slowly relaxed, so that the pipe rolls slowly into the trench along the trench wall or by the bar of the trench wall. This method is used for casting iron pipes. Have anticorrosive coating steel pipe when using this method, should be managed in a lower berth rollarounds rubber hose, smooth surface of the board or coat with a coat of rubber hose steel crowbar be moved to the river bank (such as to have a heap of soil should be having a heap of soil lay flat), in the trench wall leans rollarounds, with two big rope in on both sides of the pipe end 1/4 through the tube end, at the edge of the tube into the crow in the soil or riser, Wrap the big rope in the crowbar or riser for two or three circles, manually pull the big rope, lever the steel pipe, gradually relax the rope, so that the steel pipe slowly falls into the ditch along the rolling bar of the ditch wall. The bottom of the ditch shall not have bricks, stones and other hard objects, shall not fall the steel pipe into the ditch. As shown in figure 2.
FIG. 2 Compression rope by standpipe method
2) Tower down tube method
Use the complex block installed on the tower, guide chain and other equipment for pipe down, the pipe is rolled on the roller to the rack across the groove of the springboard, and then the pipe is lifted, after the removal of the springboard, the pipe down to the groove. The number of pylons depends on pipe diameter and pipe length. The spacing should not be too large to prevent damage to the pipe and anticorrosion layer. FIG. 3 shows the bottom tube of the three-legged tower; FIG. 4 shows the lower pipe of the tower; Figure 5 shows the lead chain down tube.