The reinforced concrete drainage pipe lined with PVC is a new type of composite drainage pipe . The lining PVC refers to modified polyvinyl chloride. The pipe structure consists of the pipe body and the inner lining. The appearance quality requires that the pipe should be flat on the outside. There should be no sticky skin, pitted surface, honeycomb, slump, exposed ribs, hollow drums, etc., the inner and outer surfaces should be bright, the modified PVC layer lined should be free of damage or pinholes, and cracks are not allowed on the exterior of the pipe, but Surface cracks and shrinkage cracks in mortar layers are not limited.
Concrete strength requirements for pipe manufacturing: The concrete strength level of concrete pipes for general excavation construction methods should not be lower than C50; the concrete strength level of reinforced concrete pipes for jacking construction methods should not be lower than C55. The impermeability level of concrete should not be lower than S6, and the concrete strength should not be lower than 90% of the planned strength when the product leaves the factory.
The inner lining layer should be fixed into the inner wall of the pipe with a fixed key, and the fixed key should be tightly connected to the pipe body. The pull-out strength of the fixed key from the concrete should not be less than 14N / ㎜.
Aiming at the now-produced lined PVC corporate pipes, what are the key control points at the time of production:
1.PVC film processing
1.1 The fixed length (perimeter) of the film can be determined according to the perimeter of the lower end of the core mold. When welding, overlap 20㎜, that is, the film should be 20㎜ smaller than the perimeter of the core die, so as to ensure that the film is clamped to the core die and finished. The tube does not show film wrinkling. It is necessary to ensure that the film is flat and soft when sizing.
1.2 Longitudinal length should ensure that the T key length is 2500㎜ (because it will be shortened by 20㎜ after being inserted into the core mold), and the keyless part is not required to be 30㎜. Be sure to be flush with the lower side after inserting into the core mold. Uneven phenomenon, only to ensure that there is no leakage or less leakage at the lower end.
1.3 The overlap welding part should ensure that the width is 20㎜, the welding should be full and flat, and there is no open welding, missing welding, charring (scorching). Before welding, the influence of the T key should be fully considered, and the center of the T key and the T key should be ensured. The center interval is not more than 67㎜, when it is more than 67㎜, the T key must not be removed.
2. Mandrel processing
2.1 Drill several steam holes evenly at the lower end and the middle of the core mold, and first introduce air during demolding to reduce drag.
2.2 The core mold should be processed before being inserted into the film. The ash deposit on the excitation ring should be cleaned and cleaned, and the dry ash residue on the plane of the core mold should be cleaned. Brush the core mold with good oil again to reduce the resistance to demolding.
2.3 Four jacks (spread at 90o) are set in the foundation pit, and the orientation is set under the bottom tray, which is convenient to apply the top force to the bottom tray first during demolding and reduce the overhead load.
3. Film is inserted into the core mold
3.1 Hang the bottom tray into the inner mold with the outer mold, place it on the excitation ring, and then hang the outer mold out.
3.2 In order to ensure the temperature in the workshop, all the doors should be fully closed before the film is set to avoid the sudden drop in temperature and the film to harden. Choose a film that meets the softness level. For faster operation, it is best to cooperate with 6 people. Each person serves as a board. When hanging the film, ensure that the circumference is evenly distributed. The overhead crane moves quickly to the upper end of the core mold until it is close to the upper cover of the core mold. Then lower the speed. It is best to ensure that 4 people are on the core mold and 2-3 people in the foundation pit when the film is lowered. When the film is placed in the core mold, the person kicks the film to make it fall smoothly. The film can be 1 meter high. Remove the board, and then the vibrator can be opened. The personnel in the foundation pit hold down the T key of the film and pull it down, but be careful not to push outwards to avoid deformation of the film.
3.3 After inserting the film, you should carefully check whether there are any problems with the film, such as: bulging, length, missing key, perimeter, flat bottom, open welding, etc. After admitting that there is no problem, use a plugging agent to seal the gap between the film and the bottom tray. Plug it, then put it into the outer mold, put it into the reinforced skeleton. When lowering the skeleton, you should pay attention to the pads of the inner ribs and put them into the two T keys. Hook the upper end of the film with a rubber strip to start production.
4. Fabric production
4.1 In order to avoid slurry leakage at the lower end of the pipe, the first plate of concrete is fed directly, and the vibrator is opened when the second plate is fed. The concrete fluidity and distribution opening should be ensured so that the concrete can be leveled and liquefied in time. The water / cement ratio of the last tray is much smaller than before, which is convenient for the formation of the socket.
4.2 After the cloth is finished, remove the rubber strip. When rubbing, you should always check whether the rubbing plate can hold the film.
5.1 Before demoulding, first open the jack in the foundation pit, make the jack press against the bottom tray, open the air pressure steam into the hole in the inner mold together, and use the steam to blow the film to reduce the friction between the film and the core mold. The crane works with the jack and the air compressor. Pay attention not to move only one of them.
5.2 Pause when demolding to 500㎜ high, several people cooperate to put an inner ring on the upper end of the inner wall of the tube to prevent the film from falling. After taking out the inner mold completely, after processing the ash deposit on the film, the inner end of the tube was also added with the inner ring.
5.3 Lift the mold to the steaming area to remove the outer mold.
In order to avoid high temperature steaming, which will cause the film to blister, the steaming temperature should be controlled to 55 ° C; to ensure the strength of the tube, steaming for 16 hours, and the steam will be closed in 12 hours to naturally cool down the temperature and avoid cracks on the outer wall of the tube .
7 socket end film processing
Because the project requires the film to be flush with the upper mouth of the tube, when cutting, use a cutting film to cut off the part of the film without the T key.
8 treatment of the outer wall of the pipe and the socket surface
8.1 Brush the water tar on the outer wall. Add water to the water tar according to 1: 1.
8.2 After repairing the socket and socket, brush the primer twice and the top coat twice, and the thickness of epoxy coal tar paint not less than 1.2㎜.