Definition of safety accessories on the pressure vessel body
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1. Requirement of Section 3.1.4.1 of the Fixed Volume Code: The design documents shall include calculations for the safe discharge volume, the discharge capacity of the safety valve, and the discharge area of the rupture disc. 2. However, on regular design drawings, the technical requirements state that \"safety accessories shall be considered uniformly by the user within the system,\" so the calculation documents do not include any calculations related to safety accessories. 3. According to Regulation 1.6 on the scope of pressure vessels, paragraph 1.6.2 stipulates that the safety accessories of pressure vessels include safety valves that are directly connected to the pressure vessels... 4. As per Regulation 9.1.2 regarding the requirements for installing overpressure relief devices, it states that “when the pressure source is external to the pressure vessel and is under reliable control, the overpressure relief device does not need to be installed directly on the pressure vessel.” In summary, there are differences in our organization’s understanding of the above regulations. There is a drawing of the chlorine buffer tank, and no safety valve ports are shown on it; the drawing states that the user should take that into account. Therefore, no calculations related to the safety attachments were carried out either. The disagreement is: 1. Does the safety valve installed on the pipeline count as part of that pressure vessel? 2. The drawing indicates whether the user has taken that statement into account; is it still necessary to perform calculations related to safety accessories? 3. If a calculation is done, it is only for the safety accessories of that individual device, not for the entire system. Then, is the calculation of these safety accessories useful as a reference for calculating the safety accessories of the whole system?
Decisions regarding whether to install overpressure relief devices, where to install them, and where to direct the released gas are made by the chemical process engineering team; the equipment engineering team is responsible only for the design of the individual equipment units and has no authority in these matters. If you are the manufacturing unit, it is sufficient to indicate on the drawings that \"the user should consider integrating this into the system.\" 1. The interface standards for pressure vessels are also clearly stated. 2. If it is not required of you to use safety attachments, such calculations are meaningless.
I saw the original poster say that the safety valve is installed on the pipeline – does that mean it’s installed on the process pipeline far away from the buffer tank? If that is the case, it is unsafe; the safety valve should be as close as possible to the buffer tank being protected.
If the installation direction of the safety valve is not vertically upward, approval from the equipment manufacturer must be obtained.
Another reason why equipment manufacturers do not install safety valves is the fear of leaks resulting from valve failures; after all, chlorine is a toxic gas, and there is concern about taking responsibility in such cases
1. It’s definitely written that way on the drawings in order to avoid liability. The point of disagreement is that the other party believes that the safety accessories have been taken into account in the design of that single device; if the user does not consider them, then they are also avoiding their responsibilities. 2. We have only been responsible for the design and manufacturing of that single device. The user has not provided us with the parameters for their entire pipeline system. 3. Since the user did not request us to install a safety valve, and considering that this device is merely a buffer tank rather than a storage tank, we decided that it is acceptable not to install a safety valve, leaving that decision to the user. If it is a storage tank, then the calculation of safety accessories will definitely be taken into consideration.
I agree with your view. Our team designed and manufactured this equipment; the design requirements specified by the user were clear regarding the operating pressure, temperature, and medium of this equipment, but no parameters related to the piping system were provided. For toxic substances like chlorine, there must be devices such as relief tanks in the system. And such a device is definitely connected to the piping system, rather than just to this single piece of equipment. So my view is that the pipeline manufacturer took into account the drainage of the entire system, which is why they provided us with the specific operating pressure for this individual device. Furthermore, I believe this device is merely a buffer tank rather than a storage tank; if it were a storage tank, then safety accessories would need to be considered.
I agree with your view. Our team designed and manufactured this equipment; the design requirements specified by the user were clear regarding the operating pressure, temperature, and medium of this equipment, but no parameters related to the piping system were provided. For toxic substances like chlorine, there must be devices such as relief tanks in the system. And such a device is definitely connected to the piping system, rather than just to this single piece of equipment. So my view is that the pipeline manufacturer took into account the drainage of the entire system, which is why they provided us with the specific operating pressure for this individual device. Furthermore, I believe this device is merely a buffer tank rather than a storage tank; if it were a storage tank, then safety accessories would need to be considered.
It has nothing to do with whether it’s a storage tank or not; you’re only responsible for manufacturing it and ensuring that its mechanical aspects are compliant and functional. The safety valve is something he needs to take care of on his own. If he wants you to handle it, then ask him for the necessary money as well as the dimensions and model specifications
Our approach in the equipment engineering field is as follows: safety devices such as safety valves that are directly connected to the equipment are evaluated by the equipment engineering team and fall under the scope of equipment design; everything else falls within the responsibility of the process engineering team. Therefore, there is no need to calculate the discharge area of the safety valve for this device.
Here’s a suggestion: specify the safety valve in the calculation documents, indicating in the drawings the model, specifications, set pressure, etc., of the safety valve that should be installed on the inlet pipeline; meanwhile, show no safety valve on the equipment drawings.