Are there any standards for gaskets used on tower manholes?
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This post was last edited by brainandrain on 2009-5-19 09:19. Before repairing the unit tower, winding-type inner and outer gaskets were used according to the values specified in the drawings – DN800, PN2.5. However, after opening the manhole, it was found that these gaskets were not suitable; the original drawings did not provide any standards, so custom gaskets had to be made using values determined on our own, and it’s not clear whether they will work or not. The sealing surface is 25 mm wide, and the internal positioning ring is 10 mm wide.
It depends on the type of sealing surface and dimensions of the manhole flange. First, check the drawing of the manhole flange, and then select the gasket based on the results
There are standards; according to the gasket standards specified in the manhole standards, the material of the gaskets is selected based on the operating pressure, temperature, and properties of the medium in the tower equipment
This post was last edited by brainandrain on 2009-5-19 09:20. There were too many ads, so I couldn’t see the details below. According to the data given in the drawings, DN800 PN2.5 required wound-type inner and outer gaskets; however, after opening the manhole, it turned out that the gaskets used were not suitable. The original drawings did not specify any standards, so I had to determine the appropriate parameters myself and use non-standard gaskets – I’m not sure if this will work. The sealing surface is 25 mm wide, and the internal positioning ring is 10 mm wide. The manhole is of DN800 size – is it really necessary to have it this large? Were the flanges selected according to JB/T4703–2000? If so, were the gasket specifications based on JB/T4705–2000? If the flange is selected in accordance with HG20595－97, the gasket shall be in accordance with HG20610－97
4# Happy Man is actually this big!
Based on the data measured by the poster himself, there should be no problems with installation. Manufacturers of manholes for containers with low pressure levels may not provide standard specifications, so it’s necessary to measure the gaskets oneself and keep them ready in advance for use before disassembling the container again.
Manhole flange gaskets are mostly PTFE-coated asbestos gaskets. These gaskets are inexpensive, but they have low elasticity and poor sealing reliability; they are only suitable for equipment with a design pressure of 0.25 MPa or less, where high sealing reliability is not required. For equipment with high design pressures and high requirements for sealing reliability, gaskets with corrugated steel inserted inside or fluororubber-asbestos gaskets should be used
First of all, the standards for gaskets in ordinary holes should be the same as those for ordinary flanges. This is not a standard manhole; it should be a custom-made piece. On-site measurement is required.
1. Standards have been established: our company offers manholes in only two sizes – 600 mm; for smaller equipment, there is also a 500 mm size. That’s all; in other words, these are the so-called 20-inch and 24-inch manholes. Special specifications require separate registration, with at least three spare units to be kept on hand. 2. Keep spare parts: Create a table for the gaskets of all important company equipment, manage them separately, and replenish them as soon as they are used up. This way, there will be no chaos.
If your manhole flange features a necked butt weld, and its pressure rating is 2.5, then the flange standard should be HG/T21521, while the gasket standard should be 20610. If this is not the case, please check the type of manhole flange. If the pressure rating is not one of the common values such as 2.0, 5.0, 11.0, etc., then it’s not a flange standard but rather a manhole flange standard.
The gasket material is selected according to requirements. However, the size of the gasket needs to be determined by cutting it according to the actual size of the manhole