Daily maintenance valve main technical performance

Daily maintenance valve main technical performance

Daily maintenance
1. Attention should be paid to the storage environment of the valve. It should be stored in a dry and ventilated room and blocked at both ends of the channel.
2, the valve should be checked regularly, and eliminate the dirt on it, smear anti-rust oil on its surface.
3. After the installation and application of the valve, it should be repaired regularly to ensure its normal work.
4. Check whether the sealing surface of the valve is worn and repair or replace it according to the situation.
5, check the trapezoidal thread wear of the stem and stem nut, whether the packing is outdated and invalid, and carry out the necessary replacement.
6, the sealing performance of the valve should be tested to ensure its performance.
7. The valve in operation should be intact, the bolts on the flange and bracket are complete, the threads are not damaged, and there is no loosening phenomenon.
8, if the hand wheel is lost, it should be ready in time, and can not be replaced by a adjustable wrench.
9. Packing gland is not allowed to be skewed or without preload clearance.
10, if the valve use environment is more bad, vulnerable to rain, snow, dust, sand and other dirt contamination, should be installed for the stem protective cover.
11, the valve on the scale should be kept complete, accurate, clear, valve seal, cap.
12, insulation jacket should not sag, crack.
13, in operation of the valve, avoid knocking on it, or support heavy objects, etc.
Cleaning steps
Valve parts must go through the following process before assembly:
1, according to the processing requirements, some parts need to do polishing treatment, the surface can not have processing burr, etc.;
2. All parts are degreased;
3, pickling passivation after degreasing, cleaning agent does not contain phosphorus;
4, pickling purified with pure water after washing, can not have drug residue, carbon steel parts omit this step;
5, one by one parts with non-woven cloth dry, can not retain wire wool parts surface, or with clean nitrogen dry;
6. Wipe the parts one by one with non-woven cloth or precision filter paper stained with pure alcohol until there is no dirty color.
The main technical performance of the valve valve sealing parts of the ability to prevent media leakage, it is the most important technical performance indicators of the valve. There are three sealing parts of the valve: the contact between the opening and closing parts and the valve seat two sealing surface; Packing and valve stem and packing box matching; Joint of body to bonnet. One of the former leakage is called internal leakage, which is usually said to be lax, it will affect the ability of the valve to cut off the medium.
Main technical performance of valve
First, valve sealing performance
Refers to the valve sealing parts of the ability to prevent media leakage, it is the most important technical performance indicators of the valve. There are three sealing parts of the valve: the contact between the opening and closing parts and the valve seat two sealing surface; Packing and valve stem and packing box matching; Joint of body to bonnet. One of the former leakage is called internal leakage, which is usually said to be lax, it will affect the ability of the valve to cut off the medium. For the block valve class, internal leakage is not allowed. The latter two leakage is called external leakage, that is, media leakage from the valve to the valve outside. Leakage will cause material loss, pollution of the environment, serious will also cause accidents. For flammable, explosive, toxic or radioactive media, leakage is not allowed, so the valve must have reliable sealing performance.
Two, the flow medium
The flow medium refers to the medium through the valve will produce pressure loss (pressure difference before and after the valve), that is, the valve has a certain resistance to the flow of the medium, medium to overcome the resistance of the valve will consume a certain amount of energy. From the consideration of energy saving, design and manufacture of valves to reduce the valve resistance to the flow medium as much as possible.
Three, opening and closing force and opening and closing moment
Opening and closing force and torque are the forces or torques that must be applied to open or close the valve. Close the valve, the need to make the open-close part and send a form a seal between the two sealing surface pressure, but also overcome between stem and packing, the valve stem and between threads of the nut, valve rod end bearing friction and other parts of the friction force, and therefore must exert closing force and close moment, in the process of opening and closing, the valve is required for opening and closing force and the open-close torque changes, Its maximum value is at the end of the closed moment or at the beginning of the open moment. Valves should be designed and manufactured to reduce closing force and closing torque.
Four, opening and closing speed
Opening and closing speed is expressed as the time required to complete an opening or closing action of the valve. General valve opening and closing speed is not strict requirements, but some conditions have special requirements for opening and closing speed, such as some requirements for rapid opening or closing, in case of accidents, some requirements for slow closing, in case of water strike, which should be considered when choosing the valve type.
Five, movement sensitivity and reliability
Action sensitivity and reliability refers to the valve for medium parameter changes, make the corresponding response to the degree of sensitivity. For throttle valve, pressure reducing valve, regulating valve and other valves used to adjust the parameters of the medium as well as safety valve, trap valve and other valves with specific functions, its functional sensitivity and reliability are very important technical performance indicators.
Six, service life
Service life refers to the durability of the valve, is an important performance index of the valve, and has great economic significance. Usually in order to ensure the sealing requirements of the number of times to express, can also be expressed by the use of time.