Paddle Spacer - maximum thickness

[dfsantos]

We currently have an installed 6" CL300 piping which has 20mm gap between two flanges. We want to fit up avoiding rework on spools and one idea is to install a paddle spacer to fill the gap. Checking ASME B16.48 the spacer standard thickness for this size is 15.7mm, so I would like to know if it is possible to use a thicker spacer in order to bolt it up. I know that we can calculate the minimum thickness, but I could not find anything related to maximum thickness.

Thanks!

 

[LittleInch]

In short Yes, but don't forget to make the bolts at least 20mm longer....

And don't forget the thickness of two gaskets. As such the standard spacer might well be good if gaskets are 3mm thick?

It's just those spacers may be off the shelf as opposed to getting one specially made. That's all.

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[dfsantos]

Thanks LittleInch! Just to know, is there a calculation for maximum thickness?

 

[LittleInch]

It's called pipe design.

Well not strictly true as you now have a high compressive stress as it's caught between two flanges.

I think most people would start to get nervous once the thickness exceeded half the OD.

Look up "bleed rings" or "vent rings". Basically what you want to do with the addition of a valve stuck in the middle.

I sure wouldn't want to go much thicker than those.

E.g.

http://www.wermac.org/flanges/flanges_bleed-ring_drip-ring.html

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