5. Using the ordinary flange for the
butterfly valve. The flange used for the butterfly valve is different from the ordinary flange in the size. Some ordinary flanges have small diameters, while the butterfly valves may have large
valve clacks, which will cause the butterfly valves can not be opened smoothly or that the butterfly valves may break down if they are opened by the brute force. The flange used for the butterfly valves should be selected according to the specifications of the
butterfly valves.
6. The water pressure test of the
valve is carried out under the negative temperature in winter. Under this condition, the water in the valve must be totally removed, or the valve will be frozen and damaged. If it is in winter, the water pressure test of the
valve is supposed to be carried out under the room temperature.
7. There are no holes and embedded parts in the construction of the building, or the sizes of the reserved holes are small and the embedded parts are not marked. In the construction, if the reinforced steel is cut off, it may affect the safety performance of the building. Carefully get familiar with the construction drawings, the locations of the holes and marks of the embedded parts, and take the initiative to seriously cooperate with the construction according to the needs of pipes' installation, the design requirements and construction specifications.
8. When two pipes are being welded, the centers of the two pipes are not in a center line. There is no gap left between the two pipes. The thick walls of pipes are not bevelled. All these factors will make the width and height of the welding seam unable to meet the construction requirements. The centers of two pipes being not in a center line will directly affect the quality and appearance of the welding seam; the no gap between the two pipes will cause the width and height of the welding seam can not reach the strength requirements of the construction.
9. In the water pressure test for strength and the tightness test of the pipe system, only the pressure value and water level changes are observed and whether the pipe or the
valve have any leakage is ignored. If the leakage happens after the pipeline system operates, the proper operation of the pipeline system will be affected. Thus, when the water pressure test for strength and the tightness test are carried out, besides the pressure value and water level changes, the leakage should also be paid great attention to.
