14 Major Contraindications for electric actuator and valve Installation! Just be careful!
14 Major Contraindications for electric actuator and valve Installation! Just be careful!
Installing valves and electric actuators is not an easy thing to do. There are 14 taboos, you know? What would happen if these taboos were violated? How are we going to solve this problem? Today let QOTO valve editorial staff take you to have a look!
Taboo 1 The water pressure test was carried out under negative temperature in the winter construction.
Consequences: As the water pressure test, the tube freezes quickly.
Measures: Try to do water pressure test before the winter application, and after the test, the water must be cleaned, especially in the valve, otherwise the valve will freeze.
The water pressure test must be carried out in winter under normal indoor temperature, and the water must be blown out after the test. Compressed air may be used to test when a water pressure test cannot be carried out.
Taboo2 The pipe system is not properly flushed before completion, and the flow and speed can not meet the requirements of pipe flushing. Even the water pressure strength test is used instead of flushing.
Consequences: The quality of the water does not meet the operational requirements of the pipe system, often resulting in a reduction or blockage of the pipe cross-section.
Measures: Using the maximum juice flow rate in the system or not less than 3m/ s water flow rate for flushing. Shall be qualified as water color, transparency and the water color and transparency of the inlet water are in accordance with the visual measurement.
Taboo3 Sewage, rainwater, condensate pipe do not do closed water test to do covert.
Consequences: May cause leakage and loss to users.
Measures: The closed water test shall be inspected and accepted strictly according to the norms. Buried underground, suspended ceiling, pipe room and other hidden sewage, rainwater, condensate pipe, etc. shall be so as to ensure that no leakage.
Taboo4 Only pressure values and water level changes are observed in the hydraulic strength test and strictness test of pipeline system, and leakage inspection is not enough.
Consequence: Leakage happens after the pipeline system is in operation, which affects the normal use.
Measures: When testing in the pipeline system in accordance with the design requirements and construction specifications, in addition to recording pressure values or changes in water levels within a specified period of time, in particular to examine carefully the existence of leakage problems.
Taboo5 Butterfly valve flanges are ordinary valve flanges.
Consequences: The size of the butterfly valve flange is different from the size of the general valve flange. Some flanges have small inner diameter, while the disc of the butterfly valve is large, which can not be opened or hard to open and damage the valve.
Measures: The flange should be machined according to the actual size of the butterfly valve flange.
Taboo6 In the construction of building structure, there are no reserved holes and embedded parts, or the reserved holes are small in size and the embedded parts are not marked.
Consequences: In the construction of the CHP, the construction structure can be chiseled or even cut off the stress steel bar, which will affect the safety performance of the building.
Measures: Be familiar with the construction drawings of HVP, take the initiative to cooperate with the hole and embedded parts in the construction of building structure according to the requirements of pipe and hanger installation, and refer to the requirements of design and construction code for specific requirements.
Taboo7 The interface is not in a center line, there is no gap between the mouth and the thick wall pipe is not shoveled, the width and height of the weld are not in accordance with the requirements of the construction code.
Consequences: The pipe misalignment not in a central line directly affects the quality of welding and the quality of perception. The width and height of the weld are not up to the requirements of the strength when the gap is not kept, the thick-wall pipe is not shoveled, and the width and height of the weld are not up to the requirements.
Measures: When pipe is welded, the pipe after welding pipe to mouth, pipe should not be staggered, to a center line, should leave clearance, thick-wall pipe to shovel slope, and the width and height of weld should be welded according to the specifications.
Taboo8 The pipe is directly buried on frozen soil and untreated loose soil. The distance and position of the pipe buttress are improper, even in the form of dry-code bricks.
Consequence: The pipe is damaged in the course of backfill tamping due to the unstable support, causing rework-ing repair.
Measures: Pipelines shall not be buried on frozen soil and untreated loose soil, the spacing of piers shall meet the requirements of the construction code, the cushion shall be firm, especially at the pipe joint, and shall not be subjected to shear force. Brick piers to be built with water and sediment slurry to ensure integrity and firmness.
Taboo9 pipe supports are of inferior material, and the diameter of installing expansion bolts is too large or the expansion bolts are installed on brick walls or even light walls.
Consequence: The pipe support is loose, the pipe is deformed and even falls off.
Measures: The expansion bolt must be selected qualified products, and the sample should be inspected if necessary. The diameter of the expansion bolt should not be more than 2mm, and the expansion bolt should be applied to the concrete structure.
Taboo10 Flanges and gaskets for pipe connections are not strong enough, with short bolts or fine diameters. Heating pipes use rubber mats, cold water pipes use asbestos mats, and double or bevel gaskets, flanged gaskets projecting into the tubes.
Consequences: The flange connection is not tight, even damaged, and leakage occurs. The flange bushing thrusting into the tube will increase the flow resistance.
Measures: Flanges and gaskets for pipes must meet the requirements of pipe design work-ing pressure.
Flange gaskets for heating and hot water supply lines should be rubber asbestos gaskets. The flange gasket of water supply and drainage pipe should be rubber pad.
The gasket of the flange shall not go into the pipe, and its outer circle to the flange bolt hole is advisable. The flange should not be placed in the middle of the beveled gasket or several gaskets, the bolt diameter of the connecting flange should be less than 2mm than that of the flange plate, and the length of the bolt rod salient nut should be 1/2 of the thickness of the nut.
Taboo11 Wrong installation of valve and electric actuator.
For example cut-off or check valve water (vapor) flow direction and mark opposite, Stem mounted downwards, horizontal mounting check valves are vertical mounted, open stem gate valves or butterfly handles not open and closed, hidden valve stem not facing inspection doors.
Consequences: Valve failure, difficult switch repair, stem down often causes leakage.
Measures: strictly follow the valve installation instructions, keep the foot of the stem elongation open height, the butterfly valve takes full account of the handle rotation space, various stem can not be lower than the horizontal position, let alone downward. The hidden valve shall be provided not only with an inspection door that meets the needs of the valve opening and closing, but also with the stem facing the inspection door.
Taboo12 The specification and model of installation valve do not meet the design requirements.
For example, the nominal pressure of the valve is less than the system test pressure; A gate valve is used when the diameter of the water supply branch pipe is less than or equal to 50mm; The hot water heating dry, riser adopts the cut-off valve; The suction pipe of fire pump adopts butterfly valve.
Consequences: Affect the normal opening and closing of the valve and adjust the resistance, pressure and other functions. Even cause system operation, valve damage to be forced to repair.
Measures: Familiar with the application range of all kinds of valves, select the specification and model of valves according to the design requirements. The nominal pressure of the valve shall meet the requirements of system test pressure. According to the requirements of the construction code: the water supply branch pipe diameter is less than or equal to 50mm should use the cut-off valve; Gate valves should be used when the pipe diameter is more than 50mm. Hot water heating dry, vertical control valve should be used gate valve, fire pump suction pipe should not use butterfly valve.
Taboo13 Valve and electric actuator installation is not required to carry out the necessary quality inspection.
Consequences: system operation valve switch is not flexible, close not strict and leakage (steam) phenomenon, resulting in rework repair, and even affect the normal water supply (steam).
Measures : pressure strength and tightness test should be done before valve installation. The test shall be carried out in batches of 10 % and not less than one in each batch ( same brand, same specification, same type ).
For the closed circuit valve installed on the main pipe, the strength and tightness test shall be done one by one. Valve strength and tightness test pressure should be in line with the ” building water supply and drainage and heating engineering construction quality acceptance specification ” ( GB ) 50242-2002).
Taboo14 The main materials, equipment and products used in the construction are lack of technical quality appraisal documents or product qualification certificates that meet the current standards issued by the state or ministry.
Consequences: The project quality is unqualified, there is hidden danger of accident, can not be delivered and used on schedule, must rework repair; As a result, the construction period is delayed and the input of labor and materials is increased.
Measures: The main materials, equipment and products used in water supply, drainage and heating projects shall be provided with technical quality appraisal documents or product conformity certificates in accordance with the current standards issued by the State or the Ministry; The product name, model, specification, national quality standard code, date of departure, name and location of the manufacturer, inspection certificate or code of the factory shall be indicated.