After installing dual safety valves, is it still necessary to add a bypass line?
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I thought that Sinopec’s regulations from 2001 meant it wasn’t necessary, but in practice, additional lines are often added. What are everyone’s thoughts on this? O(∩_∩)O Thank you
This post was last edited by ylb913 on 2015-12-30 at 12:35. The safety valve bypass is used for pressure relief under sealed conditions or for purging under sealed conditions. For the shutdown treatment of a single unit, it is impossible to carry out sealed pressure relief and purging without a bypass line. Furthermore, for toxic media such as acidic gases, a short bypass line should be installed as close as possible before and after the safety valve, in order to prevent overly long dead zones ahead of and behind the safety valve during steam displacement.
During maintenance, pressure can be released manually.
For dual safety valves, it depends on the situation: 1. When there are two identical safety valves, one is used while the other serves as a backup. At this point, it is not necessary to add a side line. 2. Sometimes, although it appears that two safety valves are installed in the area, these two valves serve different purposes and have different set pressures. A secondary line must be added at this time.
If no auxiliary lines are used, then how should exhaust be handled during the shutdown and purging process as mentioned by those upstairs?
In some of the projects I have worked on, many steps no longer involve shutdown purging. Two identical safety valves, one in use and one as a backup, are used for purging without interrupting operations. I’ve heard that in foreign countries, many devices operate for several years straight, with constant minor cleaning and maintenance tasks. In practice, for a project I worked on worth over 30 billion dollars, the safety valves were two identical ones, one in use and one as a backup; it’s likely for this very reason.
After the NX device has been in operation for a few years, it will also need a major overhaul
It may be possible to repair it in a few years, but safety valves in China are adjusted once a year.
Then how will it be emptied during maintenance?
Draining means releasing the contents after switching the circuit