Backing Rings for Fiberglass Pipe Flanges?
Backing Rings for Fiberglass Pipe Flanges?
(OP)
At one time, backing rings were recommended for frp pipe flanges.
Large frp manufacturers such as Ameron and Fibercast have told me that backing rings are not necessary because of the better quality in flange production.
Can provide me with the reason why they are not used anymore? Also, I'm curious why the backing rings were recommended in the past? Were there problems with failure in the flanges, etc.???
Thanks
Large frp manufacturers such as Ameron and Fibercast have told me that backing rings are not necessary because of the better quality in flange production.
Can provide me with the reason why they are not used anymore? Also, I'm curious why the backing rings were recommended in the past? Were there problems with failure in the flanges, etc.???
Thanks





RE: Backing Rings for Fiberglass Pipe Flanges?
1) You can get cracking in the fillet radius on back of flange. It's often cosmetic and not a structural concern.
2) Check mating flange faces for flatness. Over-tightening flange bolts to stop a leak can fracture the flange. I suspect that backing rings were used to try to seal a flange that was too light or not flat.
Choose a good FRP fabricator.
RE: Backing Rings for Fiberglass Pipe Flanges?
RE: Backing Rings for Fiberglass Pipe Flanges?
1) Improves installation time to compensate for poor alignment of valves etc. Especially when retrofitting into metallic pipelines.
2) Is usually cheaper than full face flanges especially when dealing with 400NB and above even more so at 16bar+
3) It negates bending effects especially when connecting to raised face flanges.
I would like to think that poor manufacturing techniques have been irradicated, but there are better and more cost effective jointing techniques for pipe-pipe connections and that stub flanges with backing rings should typically be used for those installations where drilling detail is subject to change or alignment can be less than ideal.