ABS or uPVC flange 3

[rcooper]

Are ABS or uPVC suitable materials to make half face flanges from, or is the material too brittle? A look at the Durapipe catalogue shows they do not offer plastic half face flanges. To achieve a half face flange a GMS backing ring is used.

The reason for the query - a contractor has installed a half face plastic flange with a plastic backing ring. The plastic backing ring has cracked.

Thanks,

rcooper

 

[Zapster]

What is a half-faced-flange?

This is a term that I am unfamiliar with, and as such, I am curious about what this thing looks like and what it does.

 

[rcooper]

Zapster,

Also called a raised face flange. There is a raised area of the flange within the bolt circle which forms the sealing area, as apposed to a full face flange, which has a flat flange face and the whole of the face of the flange forms the sealing area.

Half face may be a colloquialism

 

[moltenmetal]

CPVC flanges are usually flat faced and used with full face rubber gaskets (EPDM etc.) And yes, you'd be worried about breakage mating it to a raised face flange.

 

[rcooper]

Thanks moltenmetal.

 

[rconner]

Flanged joints, at least as employed with some legacy materials, have been used for hundreds of years; nevertheless, when even using the strongest available materials the performance of flanged joints requires proper selection of the many components and then is additionally labor intensive and reliant (due to the required straight alignment/support and bolting nature). Attempted employment of much weaker and additionally viscoelastic (e.g. extrememly low material moduli and also prone to "creep" etc.) plastic materials in such applications may not make this job any easier.

 

[stanier]

ABS to AS 3518 has an ABS stub flange with a galvanised carbion steel or a stainless steel backing flange. I am on the SAA committee for this material and have used it for over 30 years and have never seen a backing flange in plastic.

By their nature ABS stub ends with backing flanges are raised face. Small diamter full face fittings are available up to DN100 but even these are may be used with a backing flange. In some locations the backing flange may be split in two to retro fit same.

An alternative source of ABS is from Eurapipe (Tyco Australia). This is being sold in the UK now. It is available up to DN800.

http://www.tycowater.com/plastic_pipeline_systems/Overview/plastic_products