• Inspection and installation of valves (part three)

Services

Inspection and installation of valves (part three)

  • Nov 30, 2018
  • Hits: 16
The installation of Relief Valves
  1. Vertically installed relief valves at a feasible height along the wall or horizontally install them on permanent operating platform.
  2. Practical steel should be put into the wall outside two control valves(mostly globe valves) for forming as a bracket. Also, establish the by-pass pipe on the bracket evenly.
  3. Vertically mount the relief valve on the horizontal pipe without a slight incline. The arrow on the valve body should point to the flow direction of the medium.
  4. Globe valve, low and high pressure gauges should be set on two sides of the valve so that the pressure changes before and after valve can be directly viewed.
  5. The equalizing pipe of diaphragm reducing valve should be linked to the low pressure pipeline, which needs a safety valve for ensuring proper functioning of the system.
  6. For reducing the pressure of vapour, a water drain pipe has to be set. And a pipe system with a high-demanding purification requires a filter in front of the relief valve.
  7. After the installation, a test of pressure, cleaning, adjustment and an adjusted sign are needed based on the design requirements.
  8. When flushing the relief valve, turn off the inlet valve of the pressure reducer, and turn on the flush valve.

The installation of Safety Valves
Safety valve is normally off when disc is under external forces. It is a specific value that is used for preventing the medium pressure from being above the set value by discharging medium out of the system.

It can be categorized into automatic valves and used in boiler, pressure vessel,pipeline before pressure testing. The control pressure, for safety, should not exceed the set value.
  1. A scrutiny of product is needed before installation, which includes certificate of quality, default constant pressure checking, and reading manual. 
  2. Preferably, safety valve should be installed near the platform for inspection and maintenance.
  3. Vertically install the valve, ensure the verticality of the valve rod, let the medium flow upward.
  4. Generally, shut-off valves are not allowed to be installed in front or back of the safety valve, just to be on the safe side.
  5. Decompression of the safety valve: Liquid media are normally discharged into pipeline or closed system,while gas media are released to the air.
  6. Oil gas media can be discharged into the atmosphere when the exit of the atmospheric vent is three-meter higher than the highest building around.
  7. The diameters of the inlet pipe, and discharge pipe should not be less than these of valve's inlet and outlet respectively.The discharge pipe has to extend to the outdoor, with elbow pipe, toward safe zone.
  8. When the safety valves, devices, and pipes are connected by perforating and welding, the open hole caliber should be equal to the nominal diameter of the safety valve.

The inspection and maintenance of Common Valves
Due to the issues of valves' quality and abrasion, problems such as leakage and valve being unable to close entirely may occur during installation and using.

1. Leakages of valve bonnets
2. Failing to open, or bing unable to transfer water and gas
(1) Gate valves
(2) Globe valves
(3) Valves or pipe clogging
3. Being unable to close entirely
(1) Impurities or damage between the valve body and core
(2) Breaking the door when opening it with a great force