Taboos and Solutions of Valve Installation


A valve is a device in a fluid system for controlling the direction, pressure, and flow of a fluid. It is a device that allows the medium (liquid, gas, powder) in the piping and equipment to flow or stop and to control its flow. In the construction process, the valve installation will directly affect the normal operation of the future or not, this article will sum up the valve installation of some of the notes, I hope the reader will help.

Taboo 1: The main materials used in construction, equipment and products, the lack of national or ministerial standards in line with the existing technical quality certification documents or product certification.

Consequences: project quality unqualified, there are hidden dangers of accidents, can not be delivered on schedule, must rework repair; resulting in delays in construction, labor and material inputs.
Measures: The main materials, equipment and products used in the water supply and drainage and heating and air-conditioning projects shall have the technical quality appraisal documents or product certificates that meet the current standards issued by the State or the Ministry. The product names, models, specifications, national quality standards Code, date of manufacture, manufacturer name and location, factory inspection certificate or code.

Taboo 2: the valve is not required before the installation of the necessary quality inspection.

Consequences: the system is running the valve switch is not flexible, closed lax and the phenomenon of water leakage (steam), resulting in rework repair, and even affect the normal water supply (steam).
Measures: valve installation, should do pressure strength and tightness test. The test shall be spot-tested at 10% of each batch (same grade, same specification, same type) and not less than one. For installation in the trunk pipe cut off from the role of the closed-valve, one by one for the strength and tightness test. Valve strength and tightness test pressure should be consistent with "Building Water and Heating Engineering Construction Quality Acceptance" (GB 50242-2002) requirements.

Taboo 3: Installation of the valve specifications, models do not meet the design requirements. For example, the valve nominal pressure is less than the system test pressure; water branch pipe diameter less than or equal to 50mm when the use of gate valve; hot water heating stem, riser using cut-off valve; fire pump suction pipe butterfly valve.

Consequences: affect the normal opening and closing valves and adjust the resistance, pressure and other functions. Or even cause the system to run, the valve was forced to repair damage.
Measures: familiar with the application of various types of valves, according to the design requirements of the valve specifications and models. Valve nominal pressure to meet the system test pressure requirements. According to construction specifications: water supply pipe diameter is less than or equal to 50mm should be used cut-off valve; diameter greater than 50mm should be used gate valve. Hot water heating dry, stand control valve should be used gate valve, fire pump suction pipe should not use butterfly valve.

Taboo 4: The valve installation method is wrong. For example, check valve or check valve water (steam) and the signs of the contrary, the valve stem down installation, horizontal installation of the check valve to the vertical installation, open-gate valve or butterfly valve handle is not open, closed space, Do not look toward the door.

Consequences: Valve failure, switch maintenance difficulties, stem down often cause leakage.
Measures: Strictly according to the valve installation instructions for installation, open the stem valve to open the stem to open the opening height, butterfly valve fully consider the handle rotation space, a variety of valve rods can not be lower than the horizontal position, but not down. The concealed valve should not only be set to meet the needs of the valve opening and closing inspection doors, while the stem should be facing the inspection door.

Taboo 5: butterfly valve flanges with ordinary valve flange.

Consequences: Butterfly valve flange and the general size of different size valves, and some flange diameter is small, while the butterfly valve disc large, resulting in open or hard to open the valve Ershi damage.
Action: The flanges should be machined in accordance with the actual dimensions of the butterfly valve flange.

Taboo 6: the construction of the construction does not reserve holes and embedded parts, or reserved hole size is too small and embedded parts did not mark.

Consequences: warm-Wei construction, tick building structure, or even cut off the steel bars, affecting the safety performance of buildings.
Measures: Carefully familiar with the construction drawings of heating and ventilation works, according to the needs of pipe and support installation, take the initiative to seriously with the construction of construction holes and embedded parts reserved, the specific reference to design requirements and construction specifications.

Taboo 7: pipe welding, the mouth of the mouth is not the wrong mouth of a central line, not leaving the gap counterparts, thick-walled pipe does not shovel groove, weld width, height does not meet the construction specifications.

Consequence: the wrong pipe mouth is not a direct impact on the center line of the quality of the welding quality and perception. The mouth does not leave the gap, thick-walled pipe does not shovel groove, the width of the weld, height does not meet the requirements of less than the strength requirements of welding.
Measures: welding pipe counterparts, the tube can not be wrong mouth, in a center line, the counterpart should be left gap, thick-walled pipe to shovel groove, the other weld width and height should be in accordance with the requirements of welding specifications.

Taboo 8: pipe buried directly in the frozen soil and untreated loose soil, pipe support spacing and location of improper, or even dry code brick form.

Consequences: Pipeline due to the support is not stable, in the backfill compaction process damage, resulting in rework repair.
Measures: The pipeline shall not be buried in the frozen soil and untreated loose soil, the distance between the abutment to meet the construction specifications, support mat to be solid, especially the pipeline interface, should not be subjected to shear. Bricks supporting pier to use cement mortar masonry, to ensure integrity, solid.

Taboo 9: fixed pipe bracket expansion bolt of poor quality, installation of expansion bolt hole is too large or expansion bolts installed in the brick wall or even light on the wall.

Consequences: loose pipe support, pipe deformation, or even fall off.
Measures: expansion bolts must choose qualified products, if necessary, should be sampled for testing, installation of expansion bolts should not exceed the diameter of the expansion bolt diameter 2mm, expansion bolts used in concrete structures.

Taboo 10: pipe connection flange and gasket strength is not enough, connecting bolts short or small diameter. Heat pipes using rubber mats, cold water pipes using asbestos pads, as well as the use of double mats or inclined mats, flange gasket protruding tube.

Consequences: flange connection is not tight, or even damaged, there is leakage. Flange gasket into the tube, will increase the water resistance.
Measures: Pipeline flanges and gaskets must meet the requirements of the piping design working pressure. Heating and hot water supply pipe flange gasket, should adopt rubber asbestos pad; to the drain pipe flange gasket, should adopt rubber pad. The flange of the liner shall not protrude into the pipe, the outer circle to the flange bolt hole is appropriate. Flange should not be placed in the middle of the ramp pad or a few pads, connecting flange diameter of the flange diameter than the flange should be less than 2mm, the nut protruding nut length should be the thickness of the nut 1 /

Taboo 11: Pipeline system hydraulic strength test and tightness test, only to observe the pressure and water level changes, the leakage check is not enough.

Consequences: Piping system leakage occurs after the operation of the phenomenon, affecting the normal use.
Measures: Pipeline system in accordance with the design requirements and construction specifications for testing, in addition to recording the pressure within the specified time or water level changes, in particular, to carefully check whether there is leakage.

Contraindications 12: Sewage, rain, condensate pipes do not do water test will do hidden.

Consequences: May cause water leakage and cause loss to the user.
Measures: closed water test work should be strictly in accordance with the norms of inspection and acceptance. Underground buried, ceiling, pipes and other concealed sewage, rain, condensate pipes and other to ensure that impermeable does not leak.

Taboo 13: pipeline system is not completed before the flushing, flow and speed of pipe flushing requirements. Even with water pressure test instead of flushing water discharge.

Consequences: water quality can not meet the requirements of the pipeline system, often resulting in reduced or blocked pipe section.
Action: Flush the system with a maximum set flow rate or a flow rate of not less than 3 m / s. Should be to export the water color, transparency and water color, transparency, visual consistency is qualified.

Taboo 14: winter construction at a negative temperature for hydrostatic test.

Consequences: As the water pressure test tube quickly frozen, so that the tube frozen.
Measures: as far as possible in the winter before the water pressure test, and after the pressure test to blow water, especially in the water valve must be removed from the net, or the valve will crack. Works must be carried out in the winter water pressure test, to keep the room temperature is carried out after the pressure test to blow the net. When the hydrostatic test can not be carried out, the test can be carried out with compressed air.