On the protection of flange sealing surfaces during galvanizing
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Experts, in construction projects, we often need to use galvanized steel pipes and flanges (including hot-dip galvanized ones). But when galvanizing (hot-dip galvanizing), is it necessary to protect the flange sealing surface? Are there any regulatory requirements? The structures I’ve seen are sometimes protected, and sometimes the sealing surfaces are also coated with zinc – is there any standard that mandates this?
We are also facing this problem now. The temperature in the hot-dip galvanizing tank is said to be 300 degrees, while the melting point of zinc is 419.5 degrees. If we need to protect the flange sealing surface, what can be used for protection? The requirement we are facing now is that if the sealing surface is galvanized, the flange water line must be machined again.
Just slap on some paint to cover it up – a couple of flanges aren’t a big deal; P
What about the standards? What are the requirements? Providing the standard name or standard number is also acceptable. . .
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I don’t think there are any special requirements; we just shape it together. Last time, we used a brush for that, I think
For this, direct hot-dip zinc plating is sufficient without any additional protection. Flanges that are galvanized are generally used for medium and low pressure applications; they are not suitable for high-pressure use. The purpose of such plating is simply to prevent rust
Upon investigation, there are no clear regulatory requirements for galvanizing the sealing surface; as long as it meets the standards for flanges, whether it is galvanized or not is considered irrelevant.
It can be done using flange rubber patches
Personally, I think it is necessary; the flange sealing surface has specific requirements regarding roughness, and if this roughness does not meet the required standards after galvanizing, it will affect the sealing performance.