Internal leakage problem of the valve
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Some of the gate valves in our factory have severe internal leakage, **which hinders maintenance and replacement work. I would like to ask here: are there any grades for internal leakage in valves? Are there any good valves available at the moment, such as imported valves or manual valves with a good internal leakage rating?
Serious issue: I replaced it several times before, but it still leaked; eventually I modified it with dual valves, and that gave slightly better results~~~
The quality of valves varies greatly; there’s no good choice available, so one can only rely on luck~~~
There are many internal leaks in hard-sealed versions. Valves with soft seals are much better, and factors such as selection and quality also play a role; improper operation and maintenance can also affect their performance.
Valve leakage levels are divided into six grades, with grade six being the highest. Some manufacturers also claim zero leakage.
It is possible to specify the leakage level at the design stage, but often the leakage increases over time.
Please tell me about the properties of your material and its temperature; perhaps the valve I recommend can meet your requirements. Valves with soft seals can withstand a pressure of 5 kilograms
Now that there are more companies manufacturing valves, the quality has declined
Valves that are completely leak-free are virtually non-existent; especially gate valves and globe valves tend to develop leaks after being used for some time. Ball valves are somewhat better in this regard. Search on Baidu for “Is leakage from check valves acceptable? What is the allowable amount of leakage?” – there you will find detailed answers
To prevent internal leakage and cross-contamination, important pipelines use a setup of two valves plus a check valve, which is equivalent to three valves in total
If it is to be used in liquid ammonia pipelines, it is recommended to use babbitt for sealing, as hard seals are prone to internal leakage.