Regulating valve stuffing box leakage standards

Valves should not leak; leakage is an abnormal condition. Even trace amounts of toxic, corrosive, flammable, or explosive substances are not allowed; operation must be stopped immediately for inspection and repair ； Leaks in ordinary media (such as water, nitrogen, compressed air) can be tolerated for 24 hours, but not beyond the second shift. This is our standard during operation; of course, for valves within the warranty period, a replacement is provided in case of leakage – it’s essential.

Are there any relevant authoritative standards and specifications?

Personally, I think the valves are already in use, so it’s not possible to conduct any tests. If the new valve packing gland is leaking, tighten it first; if that doesn’t work, packing needs to be added (during the warranty period, you can ask the manufacturer to send someone to handle it). In most cases, this is due to a quality issue with the valve manufacturing.

Just like the gas valve in your home, does it allow leaks? Is this standard used? :)

Flammable and explosive materials are definitely not acceptable. But having a standard guideline makes things easier to discuss. For example, I would like to put forward the following requirements to the supplier: During the warranty period of this project, the acceptance criteria for leakage in the valve stuffing boxes supplied (both dynamic and static conditions) shall be zero leakage under acidic and other liquid media ； Under steam medium conditions, there is zero leakage; even slight seepage does not result in leakage of water droplets or noise from steam leakage. But after all, this is just self-consistent and lacks a basis in court.

Oh, in that case, for ordinary valves, it’s likely difficult for the supplier to meet your requirements. It is advisable to take a look at previous contract templates. Those familiar with valve structures know that it is truly impossible to determine the lifespan of valves that are operated frequently versus those that remain stationary for long periods of time. It would be better to find out about the structure and material of the valves supplied by the vendor to determine whether they are suitable for your needs. For reference.

For us actual users, it shouldn’t leak. There is only the concept of a service life; the filler ensures no leakage for as long as it is used

1. According to SH 3518-2013 \"Rules for Inspection and Management of Petrochemical Valves\", clause 5.5.2b) specifies requirements regarding the temperature, pressure, and leakage amount for the leakage test of valve stem seals during factory inspection. As detailed below, my understanding is that no leakage is allowed; in other words, the valve must not have any external leaks. 2. During the warranty period, the leakage requirements for the valve stem seals (such as packing, bellows, etc.) should be equivalent to those specified in the factory inspection requirements, or as otherwise stipulated in the technical agreement ； 3. After all, the packing is a wear part; if there is a leak during operation, it can generally be resolved by tightening the packing manually ； If the leakage is severe, it is recommended to inspect and replace the packing; if it is still within the warranty period, the manufacturer should be contacted to address the issue of fault analysis and related costs ； 4. Additionally, in the identification of VOC pollution sources in the petrochemical industry, companies generally conduct LDAR tests; dynamic sealing points (such as the packing seals of control valves) are required to be tested once per quarter, and any concentration above 200 ppm necessitates repair. It can be considered a requirement during operation, after all, it’s not possible to conduct inspections every day, nor is it possible to check everything without exception.