In the high-pressure grouting construction, at the end of grouting, the flow resistance of cement slurry is very large (generally 5MPa), the working pressure of the hydraulic system is very high, a large amount of hydraulic oil flows back to the oil tank through the bypass, and the reversing valve is at 0 position. At this time, restart, there will be motor, oil motor rotation, and hydraulic cylinder does not move, resulting in a crash.. This is the result of the equipment safety protection device. The plug wire at the center of the end cover of the reversing valve must be removed, the valve core shall be moved with a steel bar, and then the plug wire shall be screwed properly before normal operation. In the actual construction, whether the grouting is terminated or the pipe is blocked, there will be a crash.
The above operation is not only a waste of time and oil, but also inconvenient. So we try to replace the plug wire with the stop valve (valve switch) in the liquefied gas pipeline. In case of crash, turn the stop valve core 90 °, the small hole is open, insert the reversing valve with No.8 iron wire (or copper welding strip), reset the valve core, pull out the iron wire, and close the stop valve to resume work. This greatly simplifies the operation and facilitates the specific use.
When grouting is interrupted due to grouting termination or pipe plugging accident, in order to prevent deposition in the pump or high-pressure rubber pipe, the slurry in the high-pressure rubber pipe must be drained out, and the grouting pump and high-pressure rubber pipe must be flushed with clear water.
The traditional method is to remove the high-pressure rubber pipe joint and drain it directly. Due to the high pressure of cement slurry in the high-pressure rubber hose, it is easy to cause personal injury accidents, site pollution and civilized construction.
According to the analysis, we think that the vent valve can solve this problem better, so a tee with a stop valve is added at the cement slurry outlet of the high-pressure grouting pump. In case that the choke pipe needs to be emptied, open the stop valve (switch valve) on the tee to relieve the pressure, and then remove the rubber hose, avoiding all kinds of dangers of directly unloading the joint head, and simplifying the operation.
After comparison, the workers reflected well. The high-pressure grouting technology is used in the foundation pit slope protection, and the two kinds of valves play a due role in the grouting construction. When dealing with the accident, it is easy to operate, time-saving and labor-saving, the position of oil discharge and slurry discharge is clear, the control is flexible, and the site sanitation is ensured. This is in sharp contrast to the first-class situation when other construction teams randomly twist and arrange grouting. The equipment is not changed much, but the effect is obvious, which is well received by the owner and the supervisor.