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Valve Selection

Correct selection of significance

Correct selection of valves to ensure plant safety, increased valve life, and meet the long term is vital. Many of the valves accidents mainly due to improper valve selection, such as cast iron valve used in cold areas, oil in the water accumulated in the valve body, winter icing is easy to frost-crack the valve. In pump body outlet valve that, for some reason, needed to process low pump power, often use small gate to regulate the flow of methods, local open due to valve plate, vibration, and accelerated wear of the gate and valve seat sealing surface, is likely to result in leakage of valves. In addition, the valve quality of use also has a great impact on production.

If a large chemical fertilizer plant explosion, the cause of the accident to identify, was caused by serious quality problems in the valve of the incidents. The cause of the blast was: two outlet valves withstand working pressure burst check valves failure, 0.75MPa of semi-water gas within the system quickly overflows, mixed with the ambient air to form an explosive gas space, gas chemical explosion. It is testing the valve has a number of indicators does not comply with the relevant national standards. In addition, both of these are to water, steam and valve for oil as the medium, non-flammable gas valves, design selection is wrong. Therefore, the correct choice for the production, security, long term operation, efficiency is very important.

The principle of selection of valve

Valves for petrochemical production installations should meet the following basic principles

Reliability

Petrochemical production requires continuous, stable, long term operation. Therefore, requires use of the valves should have a high reliability, safety factor, not because of a valve failure caused serious production safety and accident; meet the requirements of long term run, long-period of continuous production is effective; in addition, reduce or avoid caused by valve to "run, run, drip, leak", creating a clean and civilized factory, carrying out HSE management.

Meet the production requirements

Valves shall meet the medium, pressure, temperature and usage needs, this is the most basic valve selection requirements. Such as overpressure protective effect of valve, discharge the excess media, safety valves, relief valves should be used; the need to prevent the return of media during the operation, check valves should be used; requires automatic condensation of the steam piping and equipment in the water, air and other non-condensation of gases, at the same time prevents steam escaping, traps should be used. In addition, corrosion, corrosion-resistant materials for the valve body should be chosen.

Operation, easy installation, repair and maintenance

Safety valve after the valve should be able to enable the operator to correctly identify directions, opening signs, direction signals, allows for timely and decisive handling of emergency failure. Meanwhile, selected valves type structure should be as simple, easy installation and repair and maintenance.

Economy

Note save investment and reduce unit costs, cost of today's investments are tomorrow. For general application, domestic production can meet the requirements, should choose domestic valves; several were able to meet the requirements of different valve types, cheap, simple structure the valve should be used; common materials can meet use requirement, should not use a higher level of material, such as Babbitt and CR-MO steel, stainless steel.