Preparation before valve installation
1. Check valve model and specifications
Confirm that valve material, pressure rating, connection method (flange, thread, welding, etc.) match the pipeline system.
Check whether the valve flow direction mark (such as arrow, text) is consistent with the flow direction of the medium (such as stop valve, pay attention to the inlet and outlet direction).
2. Cleaning and inspection
Remove debris and rust inside and outside the valve, check whether the valve seat and sealing surface are intact, and avoid impurities affecting the sealing.
Perform water pressure test or sealing test on new valves (according to specifications).
3. Installation tool preparation
Prepare tools such as wrenches, screwdrivers, raw tape/sealant, pipe supports, etc.
Welding valves need to be equipped with welding guns, oxygen cylinders and other equipment, and ensure that the valve is in a closed state before welding.
Valve installation steps
1. Positioning and fixing
Determine the valve position according to the pipeline design drawing to ensure that the valve is easy to operate and maintain after installation.
Use pipe supports or hangers to fix the valve to avoid leakage or damage caused by uneven force.
2. Connection method selection
Flange connection:
The flange surfaces must be parallel, and the bolts must be tightened symmetrically (tightened step by step in diagonal order) to avoid local stress concentration.
When adding gaskets, select materials that are resistant to medium corrosion (such as rubber gaskets for low-pressure water systems and metal gaskets for high temperature and high pressure).
Threaded connection:
The pipe end is processed with external threads, and the valve end is processed with internal threads. The direction of winding the raw tape is consistent with the direction of thread rotation (clockwise winding).
Avoid excessive tightening to cause thread stripping or valve body deformation.
Welding connection:
Close the valve before welding, and use argon arc welding to prime to avoid high temperature damage to the internal parts of the valve.
Perform heat treatment after welding (according to the valve material requirements).
3. Installation direction control
Stop valve/gate valve: The medium flow direction should be low in and high out (the valve stem is vertically upward for the open state).
Ball valve/butterfly valve: There is no strict direction requirement, but the handle/transmission mechanism must be easy to operate.
Check valve: When installing, pay attention to the direction of the arrow being consistent with the medium flow direction to prevent backflow.
4. Sealing treatment
Apply sealant or gaskets to flange interfaces and threaded joints to ensure no leakage.
Check whether the valve cover bolts are tightened to avoid loosening due to vibration during operation.
Precautions for valve use
1. Operation specifications
Open the valve slowly to avoid damage to the seal due to instantaneous high-pressure impact.
Tighten the valve thoroughly when closing it, but do not use excessive force (especially cast iron valves to prevent cracking).
2. Working condition monitoring
Check valve leakage regularly (especially flange gaskets and packing).
Monitor valve temperature changes to avoid material deformation or seal failure due to overheating.
3. Prohibited behavior
It is prohibited to hang heavy objects on the valve or use it as a support point.
Avoid the valve from being in a half-open and half-closed state for a long time to prevent medium erosion and wear.
Maintenance and troubleshooting
1. Daily maintenance
Check the appearance of the valve at least once a week to clean rust and dust.
Regularly lubricate moving parts (such as valve stems and gears) and use grease compatible with the medium.
2. Common troubleshooting
Leakage
Flange leakage: tighten bolts or replace gaskets.
Padding leakage: tighten gland or add packing.
Unable to open/close
Check if the valve stem is stuck, remove foreign matter or disassemble and clean.
Adjust the lubrication of the valve stem thread.
Abnormal sound
Check if there is cavitation or impurity accumulation, and disassemble and clean or replace the valve.
3. Regular maintenance
The overhaul cycle is generally 1-3 years, which can be extended or shortened according to the frequency of valve use and working conditions.
Replace key components such as valve seats and sealing rings that are severely worn.
Safety tips
Protective equipment (gloves, goggles) must be worn when operating high-pressure and high-temperature valves.
When the valve is not used in winter, drain the water in the valve to prevent freezing and cracking.
Valves for explosive media (such as ammonia) should be explosion-proof and kept away from fire.
