For Class A/B fixed-roof storage tanks, can a dual-pipe vent valve be used to replace the nitrogen supply and discharge sealing device? ?
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A fixed-roof storage tank with a capacity of 15 m3, purchased and installed in 2008, is used to store flammable liquids of Class A and B. The Emergency Management Bureau invited experts for an on-site inspection and requested that nitrogen sealing devices be installed on the storage tanks; however, the following difficulties arose during the rectification work. 1. The original design for the filling port included 4 openings: a manhole, a feed hole, a fire-resistant vent, and a spare opening (which was used as an installation point for the radar level gauge) ； Not meeting the conditions for resuming flight operations ； 2. It is now planned to replace the fire-resistant breathing valve with a fire-retardant breathing valve equipped with dual pipes, the inlet connected to the nitrogen source and the outlet connected to the exhaust gas collection pipeline. Additionally, it is planned to use gas cylinders connected in parallel to supply nitrogen at reduced pressure. Does this piping design require additional facilities (such as explosion relief manholes, etc.)? Is it in violation of relevant regulations? How is the security when using it? I earnestly ask the expert to clarify this for me.
Dagongmen, please give some advice – it’s sinking! :'(
The main function of the explosion vent manhole is to serve as an emergency ventilation outlet in cases where the breather valve and nitrogen seal valve fail, or in situations where a fire occurs in the storage tank. Theoretically, pressure relief manholes need to be installed on storage tanks. The existing manholes can be modified into flip-top explosion vent manholes, which can be used as access points for people to enter and exit, as well as as explosion vents in emergency situations.