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It’s important to keep these points in mind when it comes to valve installation.

It’s important to keep these points in mind when it comes to valve installation.

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When the valve body is cast, its surface should be smooth and smooth, without cracks, keyholes, tracholes, pores, burrs and other defects; When forging outside the valve body, the surface should be free of cracks, interlayers, heavy skin, spots and other defects. The quality certificate document must be checked before the valve is installed. The manufacturer’s nameplate should be on the valve, and the manufacturer’s name, valve model, nominal pressure, nominal diameter and other labels should be on the nameplate and valve body, and should comply with the provisions of the “General Valve Logo” GB12220. The valve must be visually inspected before installation
When the valve body is cast, its surface should be smooth and smooth, without cracks, keyholes, tracholes, pores, burrs and other defects; When forging outside the valve body, the surface should be free of cracks, interlayers, heavy skin, spots and other defects.
I. Document inspection
The quality certificate document must be checked before the valve is installed. The manufacturer’s nameplate should be on the valve, and the manufacturer’s name, valve model, nominal pressure, nominal diameter and other labels should be on the nameplate and valve body, and should comply with the provisions of the “General Valve Logo” GB12220.
Second, appearance inspection
The valve must be visually inspected before installation
1. The opening and closing position of the valve during transportation shall meet the following requirements
· Valves, globe valves, throttle valves, regulating valves, butterfly valves, bottom valves and other valves should be in the fully closed position
Plug valve, ball valve closing parts should be in the full open position
· The diaphragm valve should be in the closed position and not closed too tightly to prevent damage to the diaphragm
· The disc of the check valve shall be closed and secured
2, the valve shall not be damaged, missing parts, corrosion, nameplate off and other phenomena, and the valve body shall not be dirty
3. Both ends of the valve should be protected. Handle or hand wheel operation should be flexible and light, no stuck phenomenon
4. When the valve body is casting, its surface should be smooth and smooth, without cracks, keyholes, tracholes, pores, burrs and other defects; When forging outside the valve body, the surface should be free of cracks, interlayers, heavy skin, spots and other defects.
5, check valve disc or spool action is flexible and accurate, no eccentricity, displacement or skew phenomenon
6, spring type safety valve should have a lead seal, lever type safety valve should have a heavy hammer positioning device
7. The inner surface of the body lined with rubber, enamel and plastic should be smooth and smooth, the lining layer is firmly combined with the matrix, and there is no crack, bubble and other defects. The surface of the lining layer should be checked by high-frequency electric spark generator, and no breakdown of the lining layer (white flash phenomenon) is qualified
8, valve flange sealing surface should meet the requirements, and no radial scratches
It’s important to keep these points in mind about valve installation! (a) valve installation direction and position of many valves with directional, such as globe valve, throttle valve, pressure reducing valve, check valve, etc., if installed in reverse, it will affect the use of the effect and life (such as throttle valve), or simply do not work (such as pressure reducing valve), and even cause danger (such as check valve).
General valve, there is a direction mark on the valve body; If not, it should be correctly identified according to the principle of valve operation.
The valve chamber around the globe valve is asymmetrical, fluid to let it from the bottom to the top through the valve port, so the fluid resistance is small (determined by the shape), open labor-saving (due to the medium pressure up), closed after the medium pressure packing, easy to repair, this is why the globe valve can not install the truth.
Other valves have their own characteristics.
Import and domestic please click the valve installation position, must be convenient to operate: even if the installation is temporarily difficult, but also for the long-term work of the operator.
Valve handwheel and chest alignment (generally 1.2 meters from the operating floor), so that the opening and closing of the valve is less effort.
Floor valve handwheel should be facing up and not tilted to avoid awkward operation.
The valve of the wall machine depends on the equipment, and the operator should also be left standing room.
To avoid the operation of the sky, especially acid and alkali, toxic media, otherwise it is not safe.
The gate should not be inverted (that is, the handwheel is down), otherwise the medium will be retained in the cover space for a long time, easy to corrode the stem, and for some process requirements taboo.
It is extremely inconvenient to replace packing at the same time.
Open STEM GATE VALVES, DO NOT INSTALL underground, otherwise due to damp corrosion of the exposed stem.
Lift check valve, installation to ensure that the valve disc vertical, so that the lift flexible.
Swing check valve, when installed to ensure that the pin level, in order to swing flexible.
The pressure reducing valve shall be installed upright on the horizontal pipe, and shall not tilt in any direction.
(2) Valve installation construction work installation construction must be careful, do not hit the brittle material made of the valve.
Before INSTALLATION, THE VALVE SHOULD be INSPECTED TO check specifications AND models to identify any damage, especially for the stem.
Also rotate a few times to see if it is skewed, because during transportation, the valve stem is easy to hit crooked.
Also *** debris in the valve.
When LIFTING THE VALVE, THE ROPE SHOULD NOT BE TIED TO THE HANDWHEEL OR STEM TO AVOID DAMAGE TO THESE PARTS. It SHOULD BE TIED TO THE flange.
The line to which the valve is connected must be cleaned.
Compressed air can be used to blow iron oxide filings, sand, welding slag and other sundries.
These debris, not only easy to scratch the sealing surface of the valve, the large particles of debris (such as welding slag), but also can block the small valve, so that its failure.
When INSTALLING THE SCREW VALVE, THE SEALING PACKING (WIRE AND aluminum oil OR PTFE RAW material belt) should be wrapped on the pipe thread, do not get into the valve, so as to avoid the valve memory volume, affect the medium flow.
When installing flange valves, pay attention to tighten the bolts symmetrically and evenly.
The valve flange and the pipe flange must be parallel, the clearance is reasonable, lest the valve produces excessive pressure, even crack.
For brittle materials and not high strength of the valve, special attention should be paid.
The valve to be welded with the pipe shall be spot welded first, then the closed part shall be fully opened, and then welded dead.
(3) Valve protection measures some valves must also have external protection, which is heat preservation and cold preservation.
The insulation layer is sometimes mixed with hot steam lines.
What kind of valve should be heat or cold, according to the production requirements.
In principle, where the valve medium to reduce the temperature is too much, will affect the production efficiency or frozen valve, you need to keep warm, even mix heat; Where the valve is bare, adverse to production or cause frost and other adverse phenomena, you need to keep cold.
Insulation materials are asbestos, slag wool, glass wool, perlite, diatomite, vermiculite, etc.; The cooling materials are cork, perlite, foam, plastic and so on.
(4) Bypass and instrument some valves, in addition to the necessary protection facilities, but also have bypass and instrument.
A bypass is installed.
Easy to repair the trap.
Other valves, also installed bypass.
Bypass installation depends on valve condition, importance, and production requirements.
(five) packing to replace the stock valve, some packing has not been good, and some do not conform to the use of medium, which needs to replace the packing.
Valve factory can not consider the use of thousands of different types of media, packing box is always filled with ordinary root, but when used, must let the packing in the medium to adapt.
When replacing packing, press in round by round.
Each ring seam to 45 degrees is appropriate, ring and ring open 180 degrees.
The packing height should consider the leeway for the gland to continue pressing, and now it is necessary to let the lower part of the gland press the packing chamber to an appropriate depth, which can generally be 10-20% of the total depth of the packing chamber.
For demanding valves, the joint Angle is 30 degrees.
The seam between the ring and the ring is staggered 120 degrees.
In addition to the packing, but also according to the specific situation, the use of rubber O-ring (natural rubber resistant to 60 degrees Celsius weak alkali, butadiene rubber resistant to 80 degrees Celsius oil crystal, Fluorine rubber resistant to a variety of corrosive media below 150 degrees Celsius) three stacked polytetrafluoron ring (resistant to strong corrosive media below 200 degrees Celsius) nylon bowl ring (resistant to 120 degrees Celsius ammonia, alkali) and other forming filler.
A layer of TEflon raw material tape can improve the sealing effect and reduce the electrochemical corrosion of the valve stem.
When pressing the seasoning, turn the stem at the same time to keep all around evenly, and prevent too dead, tighten the gland to force evenly, can not tilt.


Post time: Sep-14-2022

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