Can a manhole with an inner diameter of 800 be used for one with an inner diameter of 400?
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Can a manhole with an inner diameter of 800 be used for one with an inner diameter of 400? Including the corrosion margin, the opening diameter will be greater than 400, which does not fall within the range specified for openings in GB150. Is it possible to use the pressure-area method to calculate opening reinforcement? I think it’s possible, because in strength calculation software, it can be calculated, though the pressure-area method is used. This pressure area method appears in HG20582, but it does not conform to GB150. Is it approved by the Standardization Technical Committee for Pressure Vessels? Paragraph 1.4 of GB150 permits the use of the following methods for designing compressed components for which the structural dimensions cannot be determined using this standard, provided that such methods are approved by the National Technical Committee for Pressure Vessel Standardization. -Stress analysis, including the finite element method ； -Difficulty-proving experimental analysis (such as experimental stress analysis, verification hydrostatic tests) ； -Empirical design is carried out by comparing with comparable structures that are already in use. Does it belong to the first one? -Stress analysis, including the finite element method ； If it does not fall under that category, what procedures must be followed? Or simply write down the standard number HG20582 directly. But why doesn’t GB150 include reinforcement for large openings in its standards? Moreover, the code also specifies that for values greater than 500 and less than or equal to 1000, a manhole with a diameter of 400 must be installed. Exceeding half of the diameter no longer complies with GB150. Don’t we always design according to GB150? Why the contradiction? How do people solve such problems?
The reinforcement calculation for HG20582 with large openings is feasible. di=0.85Di.
Because there are standards set by the Ministry of Chemical Industry for reinforcing large openings; GB is another set of standards. The Ministry of Chemical Industry faces many issues related to large openings, which is why such specific standards were established. However, GB is still another set of standards. If all the standards from various industries were included in GB, then GB150 could end up being tens of thousands of pages long. It’s impossible to master all the knowledge in China just by studying GB150! ! So, OP, it’s necessary to give the HG department special treatment.
I also think HG’s equal-area method can be used; after all, using stress analysis or experimental verification methods is too costly. But couldn’t the original poster replace the manhole with an additional equipment flange? That would be more economical and convenient.
Do we have to open the manhole? I think it can be carried out in accordance with the regulations of HG20582
According to GB150, openings are not allowed, but such issues often arise in actual chemical production; the standards set by the HG department can be adopted. The inner diameter of the sulfuric acid drying tower in our plant is 800; it is a packed tower. There are four manholes on the equipment body – three of them are used for filling the packing, while the one at the bottom serves as a manhole for the support structure. Reinforcement openings are provided at each manhole.
It can be driven. The scope specified in GB150 is too narrow; HG20582 has been tested in practice, but special provisions should be noted for large openings.
Why must an access hole be opened? Increasing the options for equipment flanges is also a good idea. The GB standard is certainly stricter than the HG standard; although using larger holes for reinforcement is actually applied in practice and is also permitted under HG, it’s best to avoid it whenever possible. It’s troublesome to explain when applying for a renewal audit for the design certificate
Thank you all for your responses. In fact, I later followed Article 46 of the regulations and did not install manholes, thereby avoiding this problem. But it was avoided this time, but next time it might not be possible to avoid it; I still have doubts, and the issue hasn’t been resolved yet. I might encounter this issue again during the design process, and I would like everyone’s help in resolving it. Does it really mean that operations cannot be carried out if GB150 applies? (If a large opening cannot be made, two handholes can be created.) There are many solutions); it is also possible to not follow GB150 and simply use the pressure area method instead. No procedures are needed either? I still don’t understand.
If it has to be used, there’s no problem with that; just design it in accordance with JB4732－95~~~
It’s not allowed according to GB150; it’s fine according to JB4732.
It’s usually fine, but it’s better not to use it; if you must use it, go with an elliptical shape
When this topic was first posted, a search was conducted using a diameter of 800 only; just now, many similar issues were found using the term “large opening”. I understand a lot, but there are still issues. The pressure area method is also a type of stress analysis, but it is not finite element analysis. It shall be designed in accordance with the JB4732 method. But stress analysis isn’t something that ordinary pressure vessel designers know either; a certification is required, and only qualified individuals can carry out such design work, right? Article 40 of the code stipulates that, for certain pressurized components with special structures for which strength calculations cannot be carried out using conventional standards, analysis and calculation may locally be conducted in accordance with the methods specified in JB4732, and such approaches must be approved by the person responsible for pressure vessel design. The unit that conducts analysis and calculations of the pressure-bearing components of pressure vessels in accordance with the JB4732 standard locally may not require qualification for stress analysis design projects. “ Can this sentence be understood as meaning that people without a stress analysis certification can carry out design work? People who don’t have a stress analysis certification generally can’t do it; they can only use the results from strength calculation software, and those limits are also accepted, right? Are there any other special requirements?
Using the pressure area method for calculation poses no issues at all
I personally think it’s possible, because the standards set by the Ministry of Chemical Industry are definitely higher than the national standards