Are there any regulations requiring that the air supply ball valve of the automatic valves in a DCS system be marked with a \"Do Not Close\" indication or secured using tie straps?
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Some experts say that on DCS systems, a \"Do Not Close\" sign or a seal should be placed on the air supply ball valves of all pneumatic valves to prevent accidental operation. Are there any regulatory requirements in this regard?
Yes, in accordance with general industrial operating procedures, the air supply ball valves used to control pneumatic valves in DCS systems do indeed need to be fitted with \"Do Not Close\" signs or secured properly to prevent accidental operation. This is done primarily to ensure the proper operation of the pneumatic valves as well as the safety and stability of the system. The specific regulatory details may vary across different industries, but the basic principles remain the same. .
According to 10.3.6.8 of SHT3005-2016, a manual valve should be able to be installed on the air circuit of the pneumatic actuator; operating this manual valve on-site can close the valve, and it should be protected with a seal.
Yes, the internal RC department will require you to set it to always on/always off or lock/unlock mode; basically, the three inspections and four fixations processes will involve checking this
It is recommended to set this up, but it is advised to use a locked air source ball valve (instrument air manual valve). In accordance with 10.3.6.8 of SHT3005-2016, a manual valve should be able to be installed on the air circuit of the pneumatic actuator; operating this manual valve on-site can close the valve, and it should be protected by a lead seal. Purpose: In actual production, contact, clothing straps, or accidental operations may cause the air supply ball valve to not be in the fully open or fully closed position, resulting in delayed operation or complete failure of the control valve to function. The “manual valve” mentioned in the guidelines refers to the instrument air manual valve associated with the pneumatic actuator. Literally speaking, it is necessary to apply a “seal” to the instrument air manual valve of each pneumatic valve in order to prevent accidental operation of these valves. In addition to the sealing method specified in the guidelines, the following three methods can also effectively prevent accidental operation of the instrument air manual valves. The main methods are: 1) Remove the handle of the air supply manual valve and place it in an easily accessible location; reinstall the handle only when it is time to operate the air supply manual valve ； Image 2) Fix the handle of the air supply manual valve to the corresponding instrument air pipeline using a hose clamp/tie wire/wire, etc., and remove the tie wire when it is time to operate the air supply manual valve ； Image 3) Seal the valve with a lead seal (CSO). 4) Use a pneumatic hand valve equipped with a locking device, as shown in the figure below. The image specifications are primarily aimed at preventing accidental operation of the gas supply ball valve; therefore, from the perspectives of emergency handling, cost-effectiveness, ease of operation, and aesthetic appearance at the site, the fourth solution is the most suitable. However, for already installed devices, it is recommended to give priority to the second or first option.