1. To check whether the conduit has water leakage, air leakage phenomenon, to ensure the quality of filling concrete.
2. Check whether the wall of the conduit and welded seam compressive strength to meet the construction requirements II. Requirements and methods of conduit pressure watertightness test should be used to inject water into the tube pressure method, is strictly prohibited to use the method of pressure gas pressure conduit watertightness test detection.
Pressure steps:
1. Check each section of the conduit has no obvious holes, check each section of the conduit sealing ring intact, all the conduit should strive to make strong, the inner wall should be smooth, straight, clean and no local defects. The inner diameter of each section of conduit should be the same size, the deviation is not greater than ± 2mm.The missing or worn out conduit found on the scene, should be removed in time to replace or add.
2. Select the site, is the conduit on the ground level docking, docking sections of the conduit according to the order of the number, first of all, the conduit head and tail with sealing fasteners connected. The conduit can be pre-assembled in sections next to the borehole, and then assembled section by section when lifting. Segment assembly should be carefully checked.
3. Installation of the two ends of the conduit closure device, closure device using both pressure sets. Installation so that the two holes are located directly above the pipeline, so that when the water injection air from the air overflow.
4. Installation of the water pipe to the conduit injection of water, water injection to the other end of the pipe out of the water to stop, and should ensure that the conduit flushing to reach more than 70% before stopping.
5. Will be sealed at one end of the injection hole, the other end of the air press and air pressure machine connection, check the conduit connection at the closed end of the installation, check the qualified pressure fan pressure, water tightness test water pressure should not be less than the depth of water in the hole or mud depth of 1.3 times, maintain pressure for 15 minutes P can be calculated in accordance with the formula P = γchc?γwHw: where:
P -- the maximum internal pressure that the conduit may be subjected to (kPa);
γc -- the heaviness of the concrete mix (take 24kN/m3);
hc- -maximum height of the concrete column in the conduit (m), in terms of the full length of the conduit or the expected maximum height;
γw-heaviness of the water or mud in the borehole (11.7KN/m3); Hw- the depth of water or mud in the borehole (m).
6. Check the overflow of water at the joint of the conduit, make a record of the overflow, roll the conduit 180, pressurize it again, keep the pressure for 15 minutes, check the situation and make a record. After 15 minutes without overflow is qualified.
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