Installation of steam purge valves for gas pipelines?
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How many valves are typically used for steam purging in the gas pipelines of coking plants, and are blind plates installed behind these valves? For a single valve, if it breaks it cannot be repaired; if two valves are used, is a blind plate still needed?
Generally, blind plates are required on both the upstream and downstream valves, and they are used during pressure testing.
For steam purging in the gas pipelines of typical coking plants, a single valve is sufficient. Under normal conditions, no blind plate is installed behind the valve; however, when steam supply is stopped for maintenance, especially when work is carried out on the steam pipelines, a blind plate must be placed behind the valve to prevent the pipelines from cooling down and becoming under pressure after the steam supply is stopped, which could allow gas to enter the steam pipelines. If there are two valves, blind flanges still need to be installed during hot work maintenance to ensure safety.
Generally, only one valve is used; no blind flanges are installed under normal conditions. Blind flanges are used to create a separation during hot work. Of course, using two blind flanges can reduce the number of repairs and replacements, but blind flanges must still be used during hot work.