Pipeline valve installation requirements how to deal with refrigeration equipment pipeline valve “run, run, drip, leak”?
What are the requirements for the installation of pipe valves? Is it necessary to meet certain installation requirements?
1. When installing, pay attention to the direction of the flow of the medium should be consistent with the direction of the arrow of the valve body.
2. Check valve shall be installed before the condensate enters the recovery main pipe after the trap to prevent the condensate from returning.
3, the rod valve can not be buried device, in case of stem corrosion. In the gutter with cover plate, the valve should be installed in the place where maintenance and inspection and operation are convenient.
4, some requirements close when the water strike impact is relatively small or no water strike pipeline, the best choice of slow closing butterfly check valve, slow closing swing check valve.
5. When installing threaded valves, it is necessary to ensure that the threads are intact, and coated with sealed packing according to different media. When tightening, it is necessary to force evenly to avoid damage to the valve and valve accessories.
6. When installing the socket type welding valve, the socket should have a gap of 12m to prevent the thermal stress during welding from expanding and cracking the weld.
7. When installed on the horizontal pipeline, the stem should be vertically upward or tilted to a certain Angle, and the stem is not allowed to be installed downward.
8, butt valve and pipeline connection weld bottom should use argon arc welding welding, welding should open the valve to prevent overheating deformation.
9, before installing the trap, be sure to use pressure steam to purge the pipeline, the debris in the pipeline.
10, steam trap do not install in series.
11, diaphragm type check valve is often used for easy to produce water strike on the pipeline, because the diaphragm can be very good to eliminate the medium countercurrent when the water strike, but limited by temperature and pressure, generally used in low pressure room temperature pipeline.
12, the trap should be installed before the filter, to ensure that the trap is not blocked by pipe debris, regularly clean the filter.
13. Valves connected with flanges and threads should be closed during installation.
14, condensate flow direction should be consistent with the trap installation arrow mark.
15, the trap should be installed in the lowest outlet of the equipment, timely discharge of condensed water, to avoid steam resistance pipeline.
16. When installing flanged valves, the two flange ends should be parallel and concentric.
17, before and after the trap to install the valve, convenient trap at any time to pick up repair.
18, mechanical trap to be installed horizontally.
19, found that the trap steam, to timely discharge and clean the filter, according to the actual use of frequent inspection, in case of fault repair at any time.
20, do not make the check valve bear weight in the pipeline, large check valve should be ** * supported, so that it is not affected by the pressure produced by the pipe system.
21. The condensate recovery main pipe after the trap cannot climb, which will increase the back pressure of the trap.
22. If the trap is not installed at the lowest part of the equipment, a reverse bend should be added at the lowest part of the water outlet, and the condensate level is raised before installing the trap to avoid steam resistance.
23, the drain pipe of the trap should not be immersed in water.
24. If there is condensate recovery after the trap, the drain pipe of the trap should be connected to the main pipe above the recovery main pipe to reduce back pressure and prevent reflux.
25. Each piece of equipment shall be equipped with its own trap.
30, lift type horizontal flap check valve should be installed in the horizontal pipeline.
31, installed in the steam pipe trap, the main pipe to set up a close to the radius of the main pipe condensate water collection well, and then lead to the trap with a small pipe.
32, if there is condensate recovery after the trap, it is necessary to separate the pipeline recovery of different levels of pressure.
33, lift type vertical flap check valve needs to be installed vertically.
34, mechanical trap is not used for a long time, need to remove the drain screw, the water inside the release, to prevent freezing.
35, thermostatic trap before the need for more than one meter of thermal insulation of the supercooled pipe, other forms of trap should be as close as possible to the equipment.
How to deal with refrigeration equipment pipeline valve “run, run, drop, leak”? The best way to deal with the “running, bubbling, dripping, leaking” of refrigeration pipe valves is to prevent them. How to find the problem and avoid the accident before the valve failure? Then, we must do the following:
The best way to deal with the “running, bubbling, dripping, leaking” of refrigeration pipe valves is to prevent them. How to find the problem and avoid the accident before the valve failure? Then, we must do the following:
1, prevent valve water leakage, steam leakage
All valves must be hydraulically tested in different grades after entering the factory.
Valves that need to be disassembled must be ground.
In the process of overrepair, it is necessary to carefully check whether the pan root is added and whether the pan root gland is tightened.
Valve before installation must check whether there is dust, sand, iron oxide and other sundries inside the valve. If any of the above sundries must be cleaned before installation.
All valves must be fitted with appropriate grade spacers before installation.
When installing the flange door, the fasteners must be tightened, and when tightening the flange bolts, they must be tightened in a symmetrical direction.
In THE PROCESS OF VALVE installation, ALL valves must be correctly installed according to the system and pressure, and random and mixed installation is strictly prohibited. For this purpose, all valves must be numbered and recorded according to the system before installation.
2. Prevent oil system leakage and oil running
The system with oil storage tank must be carefully checked and cleaned before installation.
Hydrostatic test must be carried out on equipment with oil cooler.
Hydrostatic test and pickling should also be done for the oil pipeline system.
All flanged joints or live connections with wire buckles must be fitted with oil-resistant rubber MATS or whetstone MATS during oil line installation.
The leakage points of the oil system are mainly concentrated in the flange and threaded live joints, so the bolts must be tightened evenly when installing the flange. Prevent leakage tight or not tight situation.
In the process of oil filtration, the construction personnel must stick to their jobs at all times, and it is forbidden to take off the post and string the post.
In the replacement of oil filter paper is necessary to stop the oil filter mechanism.
When installing the temporary oil filter connection pipe (** plastic transparent hose), the joint must be bound with lead wire firmly to prevent the phenomenon of jumping and running oil after the oil filter runs for a long time.
Deployment of responsible construction personnel to watch the work of the oil filter.
Before the oil circulation of the auxiliary engine oil system begins, the Engineering Department shall organize a detailed technical disclosure to the personnel in charge of the oil circulation of the auxiliary engine.
3, prevent equipment and pipe fitting joint surface bubble, bubbling, dripping, leakage
For flange gaskets above 2.5Mpa, metal winding gaskets are adopted.
1.0Mpa-2.5Mpa flange gasp, using asbestos gasp, and coated with black lead powder.
The flange gasket of the water pipeline below 1.0Mpa shall be rubber gasket and coated with black lead powder.
Water pump disc root are using PTFE fiber composite disc root.
For the sealed parts of smoke and air coal pipelines, the asbestos rope should be twisted and added to the joint surface smoothly at one time. It is strictly prohibited to add it forcefully after tightening the screws.
4. Prevent leakage of valve
Pipe installation construction, must establish a good quality awareness, consciously clean up the oxide iron sheet and pipe wall, do not leave sundries, ensure the pipe wall clean.
First of all, ensure that the valves entering the site must be 100% hydrostatic tested.
Valve GRINDING SHOULD BE CAREFULLY CARRIED OUT, ALL VALVES (EXCEPT IMPORTED VALVES) should BE SENT TO THE GRINDING TEAM FOR DISassembly inspection, grinding maintenance, and implementation of responsibility, SELF-consciously make records and marks, easy to trace. Important valves should be listed in detail for secondary acceptance, so that “stamping, printing, record” requirements.
The upper water gate and discharge gate of the boiler shall be determined in advance. Only these valves are allowed to be opened during the hydrostatic test. Other valves shall not be opened at will, so as to protect the valve core.
When the pipe is flushed, it should be opened and closed gently to prevent damage to the door core.
5, if the valve has leaked, how to do?
Find the reason, the right medicine!
Leakage of body and bonnet
The reason:
Cast iron casting quality is not high, the valve body and valve cover body has trachoma, loose organization, slag and other defects;
Day freezing crack;
Poor welding, slag inclusion, unwelded, stress cracks and other defects;
The cast iron valve was damaged by a heavy object.
Maintenance Methods:
To improve the casting quality, before installation in strict accordance with the provisions of the strength test;
The temperature of the valve at 0℃ and below 0℃, should be heat preservation or mixing, stop using the valve should be removed water;
The welding seam of the body and valve cover composed by welding shall be carried out according to the relevant welding operation rules, and the flaw detection and strength test shall be carried out after welding;
It IS FORBIDDEN TO PUSH AND PUT HEAVY OBJECTS ON THE VALVE. It is not allowed to hit the cast iron and non-metal valve with hammer. The installation of large diameter valve should be supported.
Leakage at packing
Valve leakage, packing accounted for a large proportion.
The reason:
Packing selection is wrong, not resistant to medium corrosion, not resistant to high pressure or vacuum valve, high temperature or low temperature use;
The packing is not installed correctly, there are some defects such as replacing the small with the large, the helix winding joint is not good, the upper tight and the lower loose.
The packing has aged and lost elasticity beyond the service life;
Valve stem accuracy is not high, bending, corrosion, wear and other defects;
The number of packing rings is insufficient, the gland is not pressed;
Gland, bolts, and other parts are damaged, so that the gland can not be compressed;
Improper operation, excessive force, etc.;
Gland skew, gland and stem gap is too small or too large, resulting in stem wear, packing damage.
Maintenance Methods:
The material and type of packing should be selected according to the working conditions;
According to the relevant provisions of the correct installation packing, the root of the pan should be placed and pressed round by turn, the joint should be 30℃ or 45℃;
The packing with too long service life, aging and damage should be replaced in time;
Valve stem bending, wear should be straightened, repair, serious damage should be replaced in time;
The packing should be installed according to the prescribed number of turns, the gland should be symmetrical and evenly tightened, the pressure sleeve should have more than 5mm pretightening gap;
The damaged gland, bolts and other parts should be repaired or replaced in time;
Should comply with the operating procedures, except the impact of the handwheel, with uniform speed normal force operation;
The gland bolt should be tightened evenly and symmetrically. If the gap between gland and valve stem is too small, the gap should be appropriately increased. If the gap between gland and stem is too large, it should be replaced.
Leakage of the sealing surface
The reason:
Sealing surface grinding uneven, can not form a close line;
The connection between the stem and the closing part is suspended, not straight or wear;
Valve stem bending or assembly is not correct, so that the closing part is skewed or not in the middle;
Improper selection of sealing surface material quality or not according to the working conditions of the valve selection.
The reason:
Poor operation, so that the closing piece is stuck or more than the dead point, the connection is damaged and broken;
Close the connection is not firm, loose and fall off;
The choice of connection material is not right, can not stand the corrosion of the medium and mechanical wear.
Maintenance Methods:
Correct operation, close the valve can not force too much, open the valve can not exceed the dead point, the valve is fully opened, the handwheel should reverse a little;
The connection between the closing part and the valve stem should be firm, and the thread connection should be a backstop part;
The fasteners used for connecting the closing parts and the valve stem shall withstand the corrosion of the medium and have certain mechanical strength and wear resistance.
Post time: Oct-28-2022
