For manhole designs that exceed the standard specifications, should they be designed using pipe flanges or vessel flanges?
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I would like to ask everyone: when designing manholes that exceed the standard specifications, should the manhole flanges be selected according to pipe flange standards or container flange standards? I am currently faced with a manhole with a design pressure of 6.0 MPa, a temperature of 70 degrees, and a medium of converted gas, with a diameter of DN450; I need to determine which type of flange to use for this application； 1. The 6.4 MPa, DN450 flange specified in JB/T4703 for container flanges can be used ； 2. HG20615-97 or WN450-11.0 FM flanges can be chosen; let’s discuss which one is more appropriate, or consider alternative flange sizes. In the existing manhole standards, should flanges be selected as pipe flanges or vessel flanges? This post was last edited by tulongshao on 2008-2-1 08:20]
As far as I know, the current manholes are selected based on pipe flanges! This post was last edited by zh0075 on 2008-4-4 21:00.]
Suggestion: For non-standard designs, there is a wide range of options when it comes to pipe flanges; European and American standard systems are available, and ready-made steel pipes can be used for the DN450 manhole stubs. But it does not emphasize that it is “necessary””
It doesn’t matter which one is chosen, as long as the strength is sufficient and people can enter and exit without problems. As long as these two points are taken into account, any option will work; it’s also fine to design the dimensions yourself
I agree with the comment above; manhole flanges designed according to the connection flanges (HG20592 or HG20615) are heavier than those designed according to the equipment flanges (JB/T4703). During the design process, it is necessary to check the maximum allowable pressure of the flange material at that temperature in accordance with the relevant flange standards, based on the selected pressure level and temperature. This post was last edited by hhhxh5712 on 2008-4-4 18:17.]
Actually, I think the so-called “pipe” flanges and “equipment” flanges are just there for the sake of easy classification! There isn’t really that much difference; they can be used interchangeably
For the design of pipe flanges, existing manhole construction drawings can be used as a reference. To avoid recalculating the data. Of course, if reinforcement proves difficult to implement, the use of reinforcement stubs could be considered.
While meeting the strength requirements and access needs for people, the lowest possible cost should be considered
Based on the conditions provided by the poster – a design pressure of 6.0 MPa, a temperature of 70 degrees, and a medium of converted gas for a DN450 manhole – the standard manholes specified in HG/T21518-2005 \"Swing-type cover with necked butt-welded flange manholes\" can be used; the male-female mating surface (MFM), the tenon-groove surface (TG), and the ring joint surface (RJ) all meet the required specifications.
Anything that can be accessed by people can be called a manhole; therefore, any standard can be chosen, as long as you select the appropriate pressure rating and material for the flange based on the process requirements.
Under normal circumstances, I think pipe flanges should be considered first
It is possible to calculate the strength of the flange; as long as the strength is sufficient, it works regardless of the standards used, even for custom-designed flanges
Standard manholes should be given priority; non-standard ones should only be considered if necessary.
For simplicity, choose a standard manhole; the flange for such manholes is selected according to pipe flange standards. It is also possible to use a manhole flange, but in that case strength calculations are required, as well as calculations related to the manhole cover. Generally, the flange for a manhole differs from the flange used on pipes.
The manhole standards are based on the coupling flange, in accordance with European standards. For flanges under 500, the pipe flange should have a larger diameter than the equipment flange; you can compare HG20615 and JB/T4703 for this purpose. Therefore, from an economic perspective, the equipment flange is more cost-effective. In other words, the design should not be too rigid; it is necessary to give designers the freedom to use their creativity. Even if they design the flanges themselves, as long as the strength and stiffness requirements are met, that’s sufficient.
Pipe flanges are used, complete with flange covers. Fasteners can also be selected directly according to standards. If device flanges are used, the cover becomes non-standard, and the cover calculated in this case may be thicker than a standard pipe flange cover. The flange in manhole standards is a pipe flange.
If it’s possible to choose, do so; if not, design it yourself as long as it meets the design requirements~~~
As long as the calculated strength is sufficient, any standard can be used; there is no need to impose a specific standard. Many flanges are designed in this way.
Besides meeting strength requirements and allowing people to pass through, are there any requirements regarding the diameter of manholes?
Refer to page P440 of HG/T20583 for the specifications regarding manholes