What aspects should be considered in the design of PX containers?
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Hello, everyone! I have a container containing mixed xylene (PX) as the medium; according to online information, this medium is flammable, moderately toxic, and harmful to the environment (leaks must be avoided). I would like to ask the experienced colleagues: what requirements need to be met in terms of material selection and testing for the containers of such media? Parameters: Shell (DN1000) Q345R, Flange: 16Mn ； Operating/design pressure: 2.38/3.62 MPa (FV@175℃) ； Operating/design temperature: 175°C/195°C; I have some questions I’d like to ask: 1. I found online that the boiling point of this medium is around 140°C, but the owner’s data sheet states it is in liquid form. 2. Is it necessary to conduct a gas-tightness test on this device? (Presently it is only RT100%); 3. Can reinforcement rings be used to strengthen this device when holes are made in it? 4. Is a Grade III forging required for the flange? 5. Is heat treatment necessary?
No heat treatment is required; reinforcement rings can be used, and a leak test can be performed. I can use grade II forgings
The normal pressure boiling point is probably 140, and it increases when pressure is applied.
1. The value obtained from lz is likely the standard boiling point, not the boiling point under operating conditions. The boiling point is directly proportional to pressure; the higher the pressure, the higher the boiling point. 2. As LZ yourself said, the medium is harmful to the environment, so leaks are not allowed. Nowadays, people’s awareness of environmental protection is growing stronger, and I personally believe it is necessary to conduct airtightness tests. 3. If necessary, reinforcement rings can be used. The design parameters of this LZ device do not fall within the scope of “overall reinforcement” (HG20583, P-315). 4. The forging grade of this equipment can be grade III; in my opinion, it is not necessary. For cases where a forging grade of III or IV is required, one can refer to the Tolerances Specification, as well as other relevant standards. 5. Heat treatment depends on specific conditions, such as the thickness of the plate and the head forming process.
There’s really no need to worry about this medium; neither heat treatment nor test plates are required. Furthermore, in GB150-2011, whether reinforcement rings are used for reinforcement has no direct relation to the medium; rather, it depends on whether the area of the opening allows for the application of the equal-area reinforcement method.
Of these 5 requirements, only the airtightness test is related to the medium – no leaks are allowed, which is why an airtightness test is specified. The other requirements can be met in accordance with GB150 and relevant container standards, based on factors such as pressure and container type. Personal opinion.