Glass and PTFE lined pipe flange assembly 1

[iangineer]

I can find very little information for glass-lined and PTFE-lined pipe flanges. I have reviewed my plant's procedures, but they do not reference any standards outside of the company. Do any of you have any experience with assembling glass/PTFE lined flanges, and/or know of any standards that provide guidance on such? I'm working on improving the procedures and apparently these types of flanges are the ones with the most leak problems.

Thank you!

 

[LittleInch]

A diagram always helps, but I assume you mean that the sealing surfaces are faced with glass flake epoxy? or PTFE?.

Neither is really good for that duty and you won't find any standards about it.

PTFE creeps over time when subjected to constant stress of the level experienced at a flange sealing surface so it just won't stay sealed. Its inherent int he properties of the material.

"Glass" is too vague, but mostly it is too brittle / uneven and again doesn't like long term compressive stress.

Usually you need face the flange with inconel or similar and then joint the inner lining material to the flange outside the flange face.

Title liner use a metal ring which I think in reality acts as the sealing surface once the inner PE faces have relaxed. Additionally I guess it stops the inner flanges faces from creeping outwards and so prevents the loss of sealing force which you would otherwise get as the PE / PTFE slowly squashes itself and the edge gets bigger. Some combination of the two I reckon.

https://unitedpipeline.com/prefit-tite-liner-system

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[EdStainless]

The people that make glass lined equipment (Pfaudler or Dedrietrich) know a lot about this.
Ask them.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[iangineer]

Thanks y'all. I wasn't sure if there was any general guidance like there is for FRP flanges. I'll contact those two manufacturers and see if they have any additional information.

 

[shvet]

I had been worked on a process unit with PTFE and glass piping. We had multiple flange connection of these piping and no problems were reported. Bolts on glass flanges had springs to avoid overstress. No a special "standard" was required as all elements were "standard".

Actually your question is not clear, I can not understand your question. You should rephrase what standard you are looking for.