Cautions for use of bellows valves——HERO VALVE
Issuing time:2020-04-21 13:16Source:www.hero-valve.com
Cautions for use of bellows valves:
Bellows sealed valves are generally used in applications requiring zero leakage of media, such as steam systems, thermal oil systems, chemical industry systems, etc.
• Before installation, carefully check whether the valve type, pressure, and caliber meet the requirements. The direction of the arrow should be consistent with the flow direction of the pipeline medium, and it can be installed after confirmation. Before installation, make sure that the inner cavity and the sealing surface are clean. Check the sealing surface, bolt connection, packing compression, and whether the valve stem rotates freely.
• For a valve on a horizontal pipeline, the valve stem is best to be vertically upward, and it is not appropriate to install the valve stem downward; the valve stem is not only inconvenient to operate and maintain, but the valve is also easy to corrode.
• Valves installed on pipelines should have space for operation, maintenance and disassembly. The reserved space of handwheel should not be less than 100mm.
• For the valve with flange end structure, the user should select appropriate studs and gaskets according to the temperature, pressure and medium, and tighten the connecting bolts and nuts evenly and symmetrically.
• For valves with a butt-end structure, users should perform welding and heat treatment according to standard requirements. Welding should be performed by qualified personnel, and welding can only be carried out after the process is qualified.
• When the valve is opened or closed, pay attention to the position of the positioning piece. Do not open or close it simply and violently. Excessive use of the “F” wrench may easily cause damage to the internal parts of the valve.
• The valve must be in the fully closed or fully open position during the pressure test of the system or pipeline. It must not be partially opened for regulating flow or emergency discharge. The manufacturer is not responsible for any harm caused by such use.
• Usually bellows valves have no thermal insulation. When the medium is a high-temperature or low-temperature fluid, do not touch the surface of the valve to prevent burns or frostbite.
• The surface and moving parts of the valve, such as the trapezoidal thread of the stem and stem nut, the sliding parts of the valve nut and the bracket are easy to accumulate dust, oil and medium residue, which is easy to cause wear and corrosion and even frictional heat to the valve, which is burning Sex gases are very dangerous and should be cleaned frequently according to working conditions.
• If there is water in the valve cavity, at low temperature (such as liquid nitrogen), the switch is easy to cause damage to the bellows. Before installation, the water should be drained to avoid ice formation in the valve cavity.
• After the valve is used, regular in-service inspections should be carried out, frequently checking the sealing surface for sealing and wear, etc .; whether the packing is aging or invalid; whether the valve body is corroded. If the above situation is found, it should be repaired or replaced in time. It is recommended to overhaul the water and oil media every three months, and to repair the corrosive media every other month, or according to local regulations.
• The valve is reassembled and adjusted after being repaired. During this process, welding slag is not allowed to splash on the surface of the bellows or cause other mechanical damage to the bellows; in addition, it is strictly prohibited to adjust the pipeline by deforming the bellows. Installation deviation, so as not to affect the normal function of the bellows and reduce the service life. After assembly, conduct sealing performance test and make relevant records.
• The user can choose the appropriate size to replace the valve packing, gasket, bolt and nut. However, it is forbidden to open the bonnet or replace the bolts, nuts and packing when the valve is under pressure. After replacement, it should be used after passing the pressure test.
• The user can repair the sealing surface of the valve by himself, but the sealing performance should be ensured and used after passing the pressure test. Valve internals are generally replaced and repairs are not recommended.
• It is not recommended to repair the pressure-bearing parts of the valve. If the pressure-bearing parts are found to be too long to use and cause safety defects, the user should replace the new valve in time.