It's not easy to install a valve. There are 14 major taboos. Do you know? What will happen if you break these taboos? And how to solve it?

Taboo 1
Water pressure test under negative temperature in winter construction.
Consequence: due to the rapid freezing in the tube, the pipe is frozen.
Measures: as far as possible in the winter before the water pressure test and pressure test to blow away the water, especially in the valve water must be removed from net, otherwise the valve will be.
The project must be in winter water pressure test, to maintain the room temperature is positive, the pressure should be blown water. The compressed air can be used when the hydraulic test can not be carried out.
Taboo 2
The pipeline system is not carefully flushed before completion, and the flow and speed can not meet the requirements of pipeline flushing. Even water pressure test is used instead of flushing.
Consequences: water quality can not meet the operation requirements of the pipeline system, often lead to reduction or blockage of the pipe section.
Measures: use the maximum flow rate of the system or the water velocity not less than 3m / s to flush. The consistency of the water color, transparency and water color and transparency of the outlet water should be consistent.
Taboo 3

The sewage, rainwater and condensate pipe are concealed without closed water test.
Consequences: may cause leakage, and cause user losses.
Measures: closed water test work should be strictly checked and accepted according to the standard. Underground buried, ceiling, pipe and other dark sewage, rainwater, condensate pipe to ensure that no leakage.
Taboo 4
In the hydraulic strength test and tightness test of pipeline system, only the pressure value and water level change are observed, and the leakage check is not enough.
Consequences: leakage occurred after the operation of the pipeline system, affecting the normal use.
Measures: piping system according to design requirements and construction specifications for testing, in addition to recording the pressure value or water level changes within the specified time, especially to check whether there is leakage problem.
Taboo 5
Common valve flange for butterfly valve flange.
Consequences: butterfly valve flange and ordinary valve flange size is different, and some flange diameter is small, and butterfly valve big, causing open or hard open and make the valve damage.
Measures: according to the actual size of the butterfly flange processing flange.
Taboo 6

The building structure construction without reserved holes and embedded parts, or the hole size is too small and no embedded parts marking.
Consequence: during the construction of the warming and protecting project, the structure of the building is cut off, and even the steel bar is cut off, which affects the safety performance of the building.
Measures: to be familiar with the warm health project construction drawings, and according to the pipe hanger installation, active coordination construction for holes and embedded parts, with specific reference to the design and construction norms.
Taboo 7
When the pipe is welded, the pipe is not in a central line, the counterpart does not leave the gap, the thick wall pipe does not shovel the groove, the width and height of the welding line does not meet the requirements of the construction specification.
Consequence: the pipe misalignment is not in one central line, which directly affects the welding quality and impression quality. When the width and height of the welding seam do not meet the requirements, the welding can not reach the strength requirement.
Measures: after welding pipe alignment, the pipe can not be wrong mouth, should be in a central line, the counterpart should stay clearance, thick wall pipe to shovel groove, in addition, the width and height of welding seam should be welded according to the specification requirements. 　
Taboo 8
The pipeline is directly buried in the frozen soil and the untreated soil, and the spacing and location of the piers are improper, and even the form of dry brick is used.
Consequence: due to unstable support, the pipeline was damaged in the process of backfill compaction, resulting in rework repair.
Measures: the pipeline shall not be buried in the frozen soil and the soil without treatment, the spacing between the piers should meet the requirements of the construction specifications, and the supporting cushion should be firm, especially the pipe interface, which should not bear shear force. Brick piers to use cement mortar masonry, ensure a tight and complete.
Taboo 9

The expansion bolt of the fixed pipe bracket is poor in material, the aperture of the expansion bolt is too large, or the expansion bolt is installed on the brick wall or even the light wall.
Consequence: the pipe supports are loose, the pipes deform and even fall off.
Measures: the expansion bolt must choose the qualified product, if necessary, should be sampled for inspection, installation of expansion bolt aperture should not be larger than the expansion bolt diameter 2mm, expansion bolt applied to concrete structure.
Taboo 10
The flange and liner of the pipe are not strong enough and the connecting bolts are short or small in diameter. Heat pipes use rubber pads, cold water pipes use asbestos mats, and double deck or inclined pads are used. Flange gasket falls into the pipe.
Consequences: flange connection is not tight, and even damage, leakage phenomenon. The flange gasket penetrates into the pipe and increases the flow resistance.
Measures: the use of piping and gaskets must meet the requirements of piping design pressure.
Rubber gasket is suitable for the flange gasket of heating and hot water supply pipeline; rubber gasket should be adopted for the flange gasket of water supply and drainage pipeline.
The flange of the liner shall not into the tube, the outer circle flange bolt hole is appropriate. Flange should not be placed in the middle of the inclined pad or a few gasket, the flange bolt diameter than flange diameter should be less than 2mm, the bolt rod protruding nut length should be 1 / 2 of nut thickness.
Taboo 11
Valve installation method error.
For example, the cut-off valve or check valve water (steam) flow direction is opposite to the sign, the valve stem downward installation, horizontal installation check valve to take vertical installation, open rod gate valve or butterfly valve handle open and closed space, the valve does not touch the valve door.
Consequences: valve failure, switch repair difficult, stem down often cause leakage.
Measures: in strict accordance with the valve installation instructions for installation, clear shot valve opening height for stem elongation, fully consider the butterfly valve handle rotation space, all kinds of valve rod can not be lower than the horizontal position, not toUnder the. The concealed valve should not only set the inspection door which meets the need of valve opening and closing, but also the valve stem should be facing the check door.
Taboo 12

Installation of valve specifications, models do not meet the design requirements.
For example, the nominal pressure of the valve is less than the system test pressure; the branch pipe is used when the pipe diameter is less than or equal to 50mm; the dry and vertical pipes of hot water heating use cut-off valves; and the fire pump suction pipes adopt butterfly valves.
Consequences: affect the valve normal opening and closing and regulating resistance, pressure and other functions. Even cause system operation, valve damage is forced to repair.
Measures: familiar with the scope of application of various types of valves, according to the requirements of the design of valve specifications and models. The nominal pressure of the valve must meet the requirements of the system test pressure. According to the construction specification requirements: the water supply branch pipe diameter is less than or equal to 50mm should use the cut-off valve; when the pipe diameter is greater than 50mm, should use the gate valve. Hot water heating, dry and vertical control valve should use gate valve, fire pump suction pipe should not use butterfly valve.
Taboo 13
Before valve installation, the necessary quality inspection is not carried out according to the regulations.
Consequences: the system operation valve switch is not flexible, closed lax and leakage (steam) phenomenon, resulting in rework, repair, and even affect the normal water supply (steam).
Measures: should be done before the valve installation pressure strength and tightness test. The test should be carried out in 10% batches of each batch (the same grade, same specification, same type), and not less than one.
For closed circuit valves installed on main pipe, the strength and tightness test should be done one by one. Valve strength and tightness test pressure should comply with "building water supply and drainage and heating engineering construction quality acceptance specification" (GB 50242-2002) regulations.
Taboo 14
The main materials, equipment and products used in the construction are lack of technical quality appraisal documents or product certificates conforming to the current standards issued by the state or the ministry.
Consequences: the quality of the project is not qualified, there are potential accidents, can not be delivered on time, must rework repair, resulting in delays in the construction period, labor and material investment increased.
The main measures: materials, plumbing and heating and sanitary engineering the use of equipment and products, should comply with the technical quality of identification documents issued by the Ministry of state or the current standard or product qualification certificate; shall indicate the product name, type, specifications and quality standards of the state code, production date, manufacturer name and location, product inspection certificate or code.

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