The double-valve problem.
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O mighty seas and rivers, I seek help from all the experts out there. Dual-valve connection – is it possible to use a direct connection? Is it necessary to add a straight pipe section in the middle, and under what circumstances is it required? It is specified in which relevant standards.
Generally, it’s not possible, as a drain valve needs to be installed between the two valves of the main pipeline. If it’s for drainage purposes, then there’s no problem – the pipes can be connected directly
This post was last edited by CHANGBAISHI on 2018-12-13 08:51. If the purpose of installing a second valve is for backup use without affecting the operation of the valve, it can be connected directly. If it affects the switch, such as a butterfly valve, it cannot be connected directly. There are also wafer valves; those that affect the replacement of the second valve cannot be connected directly either.
Valves with a nominal diameter of less than DN50 should preferably not be connected directly to other valves, as the bolts cannot be removed. When valves are connected directly to each other, attention should be paid to the type of sealing surface of the valves
In the case of liquefied gases, to prevent pressure buildup, it is recommended to install a safety valve between the two valves. For ordinary liquids, options such as waste discharge can be considered; it depends on the specific medium involved.