Precautions for Pipeline Valves Installation

In the process of engineering construction, many construction technicians do not have much research on hydropower specifications, resulting in many fatal problems in the construction of hydropower installation projects. Today, we intend to share some precautions for pipeline valves installation, so as to offer everyone study.

1. The pipeline valve is directly buried in frozen soil and untreated loose soil. The distance and position of pipe buttresses are improper, even in the form of dry bricks. These methods will cause the pipeline to be damaged in the process of backfill compaction due to the unstable support, so as to cause reworking and repairing. The solution is not to bury the pipeline on frozen soil and untreated loose soil, and we should make the space of buttresses meet the requirements of construction specifications. The support pad should be firm and should not bear shear force. Brick buttresses should be built with cement mortar to ensure integrity and firmness.

2. The material of the expansion bolt for fixing the pipe support is poor. If the hole diameter of the expansion bolt is too large or the expansion bolt is installed on the brick wall, the pipe support will be loose, deformed and even fall off. The solution is to select qualified expansion bolts and carry out test and inspection. The hole diameter for installing the expansion bolt should not be larger than the outer diameter of the expansion bolt. 

3. The strength of flange and gasket of pipeline connection is not enough. Rubber pad is used for heat pipe and asbestos pad is used for cold water pipe. The result is that the flange connection is not tight or even damaged, resulting in leakage. When the flange gasket protrudes into the pipe, it will increase the flow resistance. Therefore, the flange and gasket used in the pipeline valves must meet the requirements of the designed work pressure. The gasket of the flange should not protrude into the pipe. Bevel pads or several pads should not be placed in the middle of the flange. The bolt diameter of the connecting flange should be 2mm smaller than the flange hole diameter.

4. During the hydrostatic strength test and tightness test of the pipeline valve system, only observing the pressure value and water level change will cause the leakage phenomenon after the operation of the pipeline system, thus affecting the normal use. In order to solve this problem, the pipeline system should be tested according to the designed requirements and construction specifications. In addition to recording the pressure value or water level change within the specified time, we should check carefully.

5. Failure to conduct closed water test for sewage, rainwater and condensate pipes may cause water leakage and user loss. Therefore, the closed water test should be strictly checked and accepted in accordance with the specifications. The sewage pipe, rainwater pipe and condensate pipe installed in the underground should not leak.

6. The pipeline valve system is not washed carefully before completion, and the flow speed cannot meet the requirements of pipeline flushing. If the water quality fails to meet the operation requirements of the pipeline system, the pipeline section will be reduced or blocked. The maximum designed flow rate should be used for flushing.

Water pressure test should be carried out under negative temperature during winter construction. Due to the rapid freezing in the pipe during the hydrostatic test, the pipe will freeze. The water pressure test should be carried out before winter construction as far as possible, and the water in the pipeline valve should be cleaned after pressure test.