Why are some pipes equipped with flanged blind plugs for drainage, while others use plug-type closures?
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Why are some pipes equipped with flanged blind plugs for drainage, while others use plug-type closures? Are there any differences in the uses of these two types of downcomers? Thank you
The drain lines for process materials (chemicals) pipelines should be sealed using blind flanges; this way, if there are issues with the gaskets, they can be replaced, and the reliability of the seal can be ensured after replacement. If plug seals are used, there is a higher likelihood of chemical leakage if the threaded seal fails. For the drain pipes of utility (non-chemical) systems, plug valves are recommended for sealing, as this facilitates disassembly.
This is the difference between threaded valves and flanged valves: threaded valves can be fitted with a plug directly, or a double-threaded fitting can be installed followed by a pipe cap, while flanged valves can only be equipped with a blind plate. If high pressure ratings or strict leak prevention requirements are involved, flanged valves should be used. For threaded connections, it is generally required that the connection be welded in place before the first valve; otherwise, the system will not be reliable, and welding makes it difficult to replace the connection.
The answer above is correct; in projects, it’s common to see designers making confused choices regarding the valves used for drainage and venting. After asking them to follow SH3012 standards, they all installed double valves, which left me both amused and exasperated.
The reasoning was already explained upstairs. For inspection, maintenance, and special operations. What’s even more embarrassing are the flanged valves and welded valves on certain pipelines. Welded valves are used to reduce leakage points, but internal leakage creates even more problems.
In actual production, threaded valves are commonly used for backwashing, as this design makes it easier to empty the material; removing the pipe cap allows the use of a flexible metal hose, which facilitates operation. . . . Flange valves are used in situations where high pressure exists and it is necessary to drain the contents; however, such situations are not common, as high-pressure materials are usually liquefied hydrocarbons and toxic liquids, and in such cases double valves are employed along with underground lines and tanks to empty the contents. . .
There are many thread plugs on site, while flanges are few
Are there standards? Or just experience?
The term \"relative to thread plugs\" is likely used in contrast to flanges, as the cost is lower in that case