19 taboos and measures for the construction of water supply and drainage valves and pipelines

Taboo 1: The main materials, equipment and products used in construction lack technical quality appraisal documents or product certificates that meet the current standards issued by the state or ministry.

Consequence: the quality of the project is unqualified, there is a hidden danger of accident, it cannot be delivered and used on schedule, and it must be reworked and repaired; This has caused delays in construction and increased labor and material inputs.

Measures: The main materials, equipment and products used in water supply and drainage and heating and sanitation projects shall have technical quality appraisal documents or product certificates that meet the current standards issued by the state or the ministry; The product name, model, specification, national quality standard code, factory date, manufacturer name and location, factory product inspection certificate or code should be indicated.

Taboo 2: Failure to carry out the necessary quality inspection according to the regulations before the valve is installed.

Consequences: The valve switch is inflexible in the operation of the system, the closing is not strict and the phenomenon of water leakage (steam) occurs, resulting in rework and repair, and even affecting the normal water supply (steam).

Measures: Before the valve is installed, the compressive strength and tightness test should be done. The test should be spot-checked at 10% of the quantity of each batch (same brand, same specification, same model), and not less than one. For the closed-circuit valves installed on the main pipe to play a cut-off role, the strength and tightness test should be carried out one by one. The valve strength and tightness test pressure should comply with the provisions of the Code for Construction Quality Acceptance of Building Water Supply and Drainage and Heating Engineering (GB 50242-2002).

Taboo 3: The specifications and models of the installation valve do not meet the design requirements. For example, the nominal pressure of the valve is less than the system test pressure; When the pipe diameter of the water supply branch pipe is less than or equal to 50mm, the gate valve is adopted; The dry and riser pipes of hot water heating adopt shut-off valves; The suction pipe of the fire pump adopts a butterfly valve.

Consequence: affect the normal opening and closing of the valve and adjust the resistance, pressure and other functions. Even during the operation of the system, the valve is damaged and forced to be repaired.

Measures: Familiar with the application range of various valves, and select the specifications and models of valves according to the design requirements. The nominal pressure of the valve should meet the requirements of the system test pressure. According to the requirements of the construction specifications: the shut-off valve should be used when the pipe diameter of the water supply branch pipe is less than or equal to 50mm; When the pipe diameter is greater than 50mm, the gate valve should be used. Hot water heating and drying, vertical control valve should use gate valve, fire pump suction pipe should not use butterfly valve.

Taboo 4: Wrong valve installation method. For example, the water (vapor) flow direction of the globe valve or check valve is opposite to the mark, the valve stem is installed downward, the horizontally installed check valve is installed vertically, the open rod gate valve or butterfly valve handle has no opening and closing space, and the stem of the concealed valve does not face the inspection door.

Consequence: Valve failure, difficult switch maintenance, stem downward often cause water leakage.

Measures: Install in strict accordance with the valve installation instructions, open rod gate valve leave enough to extend the opening height of the valve stem, butterfly valve fully consider the handle rotation space, all kinds of valve stems can not be lower than the horizontal position, let alone downward. The concealed valve should not only be provided with an inspection door that meets the needs of valve opening and closing, but also the stem should face the inspection door.

Taboo 5: Butterfly valve flange with ordinary valve flange.

Consequences: The size of the butterfly valve flange plate and the ordinary valve flange is different, some flanges have a small inner diameter, and the disc of the butterfly valve is large, resulting in failure to open or hard opening and damage to the valve.

Measures: The flange should be processed according to the actual size of the butterfly valve flange.

Taboo 6: There are no reserved holes and embedded parts in the construction of building structures, or the size of the reserved holes is too small and the embedded parts are not marked.

Consequences: During the construction of the heating and sanitation project, the building structure is chiseled and even the stressed steel bar is cut off, which affects the safety performance of the building.

Measures: Carefully familiar with the construction drawings of the heating and sanitation project, according to the needs of pipeline and support hanger installation, take the initiative to seriously cooperate with the construction of building structure reserved holes and embedded parts, specifically refer to the design requirements and construction specifications.

Taboo 7: When the pipe is welded, the wrong mouth of the pipe after the counterpart is not on a center line, the counterpart does not leave a gap, the thick-walled pipe does not shovel the groove, and the width and height of the weld do not meet the requirements of the construction specifications.

Consequence: The wrong mouth of the pipe is not in a centerline, which directly affects the quality of welding and the quality of the look. The counterpart does not leave a gap, the thick-walled pipe does not shovel the groove, and the width and height of the weld do not meet the requirements of the weld and cannot meet the strength requirements.

Measures: After welding the pipe to the mouth, the pipe can not be wrong, to be on a center line, the counterpart should leave a gap, the thick-walled pipe should be shoveled groove, and the width and height of the weld should be welded in accordance with the requirements of the specification.

Taboo 8: Pipelines are buried directly on frozen soil and untreated loose soil, improper spacing and position of pipe piers, and even in the form of dry yard bricks.

Consequence: The pipeline suffered damage during the backfill process due to unstable supports, resulting in rework and repair.

Measures: The pipeline shall not be buried on frozen soil and untreated loose soil, the spacing of the piers should meet the requirements of the construction specifications, and the support pad should be firm, especially at the interface of the pipeline, and should not bear shear force. The brick pier should be built with cement mortar to ensure that it is complete and firm.

Taboo 9: The expansion bolt fixing the pipe bracket is of poor material, the hole diameter of the expansion bolt is too large, or the expansion bolt is installed on a brick wall or even a lightweight wall.

Consequence: Loose pipe supports, deformation of pipes, or even falling off.

Measures: Expansion bolts must select qualified products, if necessary, sampling for test inspection, the aperture of the installation expansion bolt should not be greater than the outer diameter of the expansion bolt 2mm, expansion bolt applied to concrete structure.

Taboo 10: The strength of the flange and liner of the pipe connection is not enough, and the connecting bolt is short or the diameter is thin. Rubber pads are used for thermal pipes, asbestos pads are used for cold water pipes, and double-layer pads or beveled pads are used, and flange liners are used inside the pipes.

Consequence: The flange connection is not tight, or even damaged, and leakage occurs. The flange liner protrudes into the tube, increasing the resistance of the water flow.

Measures: The flange and liner for the pipeline must meet the requirements of the pipeline design working pressure. Flange liner for heating and hot water supply pipelines, rubber asbestos pads should be used; The flange liner of the water supply and drainage pipeline should be made of rubber pad. The gasket of the flange shall not protrude into the tube, and its outer circle should be to the flange bolt hole. Bevel pads or several liners shall not be placed in the middle of the flange, the diameter of the bolt connecting the flange should be less than 2mm than the diameter of the flange hole, and the length of the bolt rod protruding nut should be 1/2 of the thickness of the nut.

Taboo 11: During the hydraulic strength test and tightness test of the pipeline system, only the pressure value and water level change are observed, and the leakage inspection is not enough.

Consequence: Leakage occurs after the operation of the pipeline system, which affects the normal use.

Measures: When the piping 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 a leakage problem.

Taboo 12: Sewage, rainwater, condensate pipes are concealed without a closed water test.

Consequence: May cause water leakage and cause user loss.

Measures: The closed water test work should be strictly inspected and accepted in accordance with the specifications. Underground burial, ceiling, between pipes and other concealed sewage, rainwater, condensate pipes, etc. should be achieved to ensure that there is no seepage or leakage.

Taboo 13: The pipeline system is not flushed carefully before completion, and the flow rate and speed cannot meet the pipeline flushing requirements. Even water discharge is replaced by hydrostatic strength test.

Consequence: Water quality does not meet the operational requirements of the pipeline system, and often causes the pipeline section to be reduced or blocked.

Measures: Rinse with the maximum juice flow rate in the system or the water flow rate that should not be less than 3m/s. The color and transparency of the discharge outlet water should be consistent with the water color and transparency of the inlet water.

Taboo 14: Hydrostatic test at negative temperature for winter construction.

Consequence: Due to the rapid freezing of the tube during the hydrostatic test, the tube is frozen.

Measures: Try to carry out the water pressure test before winter application, and blow the water clean after the pressure test, especially the water in the valve must be removed, otherwise the valve will freeze crack. The project must be carried out at a positive indoor temperature when the water pressure test is carried out in winter, and the water should be blown clean after the pressure test. When the hydrostatic test cannot be carried out, the test can be carried out with compressed air.

Taboo 15: After testing the water in the pipeline in cold areas, the water accumulation in the pipeline is not drained in time in winter.

Consequences: Frozen damage to pipes and parts, resulting in water outages for repair, affecting normal production and domestic water.

Measures: In cold areas, water accumulation in the pipe should be removed in time.

Taboo 16: When the concealed project is not inspected or unqualified, the next process construction begins.

Consequence: Engineering legacy hazards often result in rework losses.

Measures: All parts buried or buried in concrete in the project, pipelines or equipment with thermal insulation requirements, as well as pipelines and accessories installed in pipe trenches, tube wells and equipment layers that cannot be accessed by people, should be inspected for concealed engineering in time, and the next process can be carried out only after qualifying.

Taboo 17: Rooms of the same type with the same plumbing do not make model rooms.

Consequence: The water pipes in the room are the same but the practice is different, the size of the throwing mouth is not uniform, resulting in rework.

Measures: For rooms of the same type with the same pipeline, such as toilet pipeline construction, you must first make a sample, check that the pipe is horizontal and vertical, and the size of the rejection mouth meets the requirements of the design drawings and the manufacturer's sample, to ensure that each pipeline practice of each worker is consistent, and the places that do not intersect with other majors should be corrected. Then, according to the model practice, large-scale pipeline construction was carried out.

Taboo 18: Install the pump without checking the strength of the pump foundation.

Consequence: During the operation of the pump, the foundation strength is not damaged enough.

Measures: Before the installation of the pump, not only its basic size, location and standard should be inspected, but also its strength should be checked to ensure that it meets the design requirements.

Taboo 19: Piping and valves at the inlet and outlet of the pump do not have fixed brackets.

Consequence: The weight of the pump piping and valve is directly borne by the pump interface, as well as the distortion of the flexible short pipe connecting the pump entry and exit door.

Measures: At the piping or valve of the pump, an independent fixed bracket should be provided, and at the same time ensure that the pump inlet and outlet are connected to the flexible short pipe axis, and the connection line between the two centers of the pipeline and the pump interface. In order to ensure accuracy, temporary fixation should be made during installation.

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