The valve is the most common equipment in chemical enterprises. It seems easy to install the valve, but if it is not carried out in accordance with the relevant technology, it will cause safety accidents. Today I would like to share some experience and knowledge about valve installation.
Taboo 1
Hydrostatic test is carried out under negative temperature during winter construction.
Consequence: due to the water pressure test tube quickly frozen, so that the tube frozen bad.
Measures: try to carry out water pressure test before winter application, and after pressure test, the water must be blown clean, especially the water in the valve must be removed from the net, otherwise the valve will rust, or freeze crack.
The water pressure test must be carried out in winter, and the water must be blown clean after the pressure test.
Taboo 2
The pipeline system was not flushed carefully before completion, and the flow rate and speed could not meet the requirements of pipeline flushing. Even water pressure strength test drainage instead of flushing.
Consequence: water quality can not meet the requirements of pipeline system operation, often will cause pipeline section reduction or blockage.
Measures: wash with the maximum set flow rate of juice in the system or the flow rate should not be less than 3m/s. The color and transparency of discharge outlet should be consistent with that of inlet water visually.
Taboo 3
Sewage, rainwater, condensate pipes do not do closed water test will be concealed.
Consequences: May cause water leakage and loss of users.
Measures: closed water test work should be strictly in accordance with the standard inspection acceptance. Underground buried, suspended ceiling, pipe and other hidden sewage, rainwater, condensed water pipe to ensure that no leakage.
Taboo 4
In the water pressure strength test and tightness test of pipeline system, only the change of pressure value and water level is observed, and the inspection of leakage is not enough.
Consequence: Leakage occurred after the operation of the pipeline system, affecting the normal use.
Measures: when the pipeline system is tested according to the design requirements and construction specifications, in addition to recording the pressure value or water level change within the specified time, it is especially necessary to carefully check whether there is leakage.
Taboo 5
Butterfly valve flanges with ordinary valve flanges.
Consequences: butterfly valve flange and ordinary valve flange size is not the same, some flange diameter is small, and the butterfly valve disc is large, resulting in not open or hard to open the valve damage.
Measures: according to the actual size of the butterfly valve flange processing flange.
Taboo 6
There are no reserved holes and embedded parts in the construction of the building structure, or the size of reserved holes is too small and the embedded parts are not marked.
Consequence: in the construction of heating and sanitation project, chisel the building structure, or even cut off the reinforced steel, affecting the safety performance of the building.
Measures: carefully familiar with the construction drawings of heating and sanitation engineering, according to the needs of pipeline and support hanger installation, take the initiative to seriously cooperate with the construction of reserved holes and embedded parts of the building structure, with specific reference to the design requirements and construction specifications.
Taboo 7
When the pipe is welded, the wrong mouth of the opposite pipe is not on a Central Line, the opposite pipe does not leave gaps, the thick wall pipe does not shovel groove, and the width and height of the weld do not meet the requirements of the construction code.
Consequence: the pipe wrong mouth is not in a center line directly affects the welding quality and perception quality. There is no gap between the pair, the thick wall pipe does not shovel the groove, the width and height of the weld does not meet the requirements of welding strength requirements.
Measures: after welding pipe matching, the pipe can not be wrong mouth, to a center line; The counterpart should leave a gap; Thick wall pipe to shovel groove. In addition, the width and height of the weld shall be welded in accordance with the specification requirements.
Taboo 8
The pipe is directly buried in frozen soil and untreated loose soil, the distance and position of the pipe piers are improper, and even the form of dry code brick is adopted.
Consequence: The pipeline was damaged in the process of backfill compaction due to unstable support, resulting in rework and repair.
Measures: the pipeline shall not be buried in frozen soil and untreated loose soil, the pier spacing should meet the requirements of the construction code, the pad should be firm, especially the pipeline interface, should not bear shear force. Brick support pier to use cement mortar masonry, ensure integrity, firm.
Taboo 9
The expansion bolts used to fix pipe supports are of poor quality, the holes of the expansion bolts are too large, or the expansion bolts are installed on brick walls or even lightweight walls.
Consequence: the pipe bracket loosens, the pipe deforms, even falls off.
Measures: The expansion bolt must be selected qualified products, and the sample test should be carried out if necessary. The aperture of the expansion bolt should not be larger than the outer diameter of the expansion bolt 2mm, and the expansion bolt should be used in the concrete structure.
Taboo 10
Flange and gasket strength of pipeline connection is not enough, the connecting bolt is short or thin diameter. Heat pipe uses rubber pad, cold water pipe uses double pad or inclined pad, flange liner protruding into the pipe.
Consequences: flange joint is not tight, even damage, leakage phenomenon. The flange liner protrudes into the pipe and increases flow resistance.
Measures: flanges and gaskets for pipelines must meet the requirements of design working pressure of pipelines. For flange gaskets of heating and hot water supply pipes, rubber asbestos gaskets should be used; Rubber gaskets should be used for flange gaskets of water supply and drainage pipes. Flange gasket should not protrude into the pipe, its outer circle to the flange bolt hole is appropriate. No bevel pad or several gaskets shall be placed in the middle of the flange. The diameter of the bolt connecting the flange should be less than 2mm than the flange aperture, and the length of the bolt rod protecting nut should be 1/2 of the nut thickness.
Post time: Sep-03-2021