Flange waterline
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HG/T20592-2009 no longer mentions the water line on the upper flange, whereas flanges according to the previous standard did have such a line; was the water line removed because it is ineffective for improving sealing?
Are these concentric circles the waterline?
This is the standard for version 97; it specifies requirements regarding the waterline, while version 09 does not clearly state any such requirements
For reference: Container flange water ripple lines https://bbs.hcbbs.com/thread-1953006-1-1.html (Source: Haichuan Chemical Industry Forum)
For reference: Waterline of the RF flange surface https://bbs.hcbbs.com/thread-2135109-1-1.html (Source: Haichuan Chemical Industry Forum)
GB/T9124-2010 Technical requirements for steel pipe flanges – Requirements for the water line of the sealing surface
No, the waterline has been removed from the standards, but there are clear requirements regarding roughness as well as specific manufacturing processes for achieving that level of roughness; the end result is the same in either case, which is to ensure proper sealing.
Yes. The old standard used to be two or three turns of waterline, and ship flanges still use this same waterline standard today. The new standard features fine ribbed water lines, rather than the traditional two or three rings. The purpose in all cases is to ensure sealing performance.
Whether it’s necessary depends on the gasket used; these days, for safety reasons, people often use metal wound gaskets right away, and they can last for many years! So, water ripple lines are no longer necessary. This is my understanding
This should also change as the material of gaskets evolves, and so does the form of water lines. In the past, asbestos gaskets were commonly used; however, due to concerns related to environmental protection and occupational diseases, Europe has banned their use, and China is now following Europe’s lead. Asbestos gaskets are becoming increasingly rare these days.
The experts upstairs have explained it very clearly; it is necessary to follow the standard waterline. Not all flange surfaces require a water line; trapezoidal groove and hard gasket flange surfaces do not need one.