29f

Flange support

In your standard piping support drawings, you might find standard pipe support shown on the figure below. Please note that the connection plate is fairly large and it is tighten with many bolts to the flange. This type of support cannot be used for every piping system and for all pipe size. So, let’s see where we can use this type of support.
1-support-at-flange
This type of support can be used on a metallic piping up to 6″ pipe size. If we have a metallic pipe larger than 6″, normally, we use the support shown on the figure below. Please note that this type of support will provide free rotations for the flange.
2-support-at-flange
In the case of very large metallic pipe (more than 12″) which is very often case in mining industry, good option is to support valve directly, providing free rotations for the flanges having less stress on the flange and valve casing. Please see the figure below.
3-valve-support
Reason why we do not directly support flanges for large pipe is that the flanges are the most stress part in piping system. However, a small size pipes are more flexible and even if we restrain the flange by support, the rest of the pipe will be easily bent. A large pipe size, on the other hand, is more rigid and that will result in creating very high stress on the flanges which might result in flange leakage. Supporting flange directly is desirable option if we have a connection between metallic and plastic (GRP) piping. Please see the figure below.
4-support-at-flange-steel-hdpe
Since plastic (or GRP) pipe is very flexible and restraining metallic flange (in a vertical position) will result in having tight connection between the flanges and therefore less chance of flange leakage. In fire water design, very often, you will find type of support shown on the figure below.
5-waterworks-flange-support
This type of support can be used and reason is that the connection plate is not big in size and will provide flange free rotation. Of course, some restrain will be imposed on the flange, but it is a generally small.