Gasket Discussion, Comparison PTFE vs Viton vs Polysteel vs Solid PTFE or Envelope ?

[Humpi]

I read somewhere not to use High Pressure Bolt Clamps for ptfe gaskets? is this true that I have to change clamps if I make the change to PTFE gaskets? THanks

 

[Dab Strudel]

I read somewhere not to use High Pressure Bolt Clamps for ptfe gaskets? is this true that I have to change clamps if I make the change to PTFE gaskets? THanks

High pressure bolt clamps are especially needed for PTFE gaskets broham

 

[GratefulOne]

This is the second place I have seen a recommendation against PTFE gaskets used with two bolt clamps. It seems envelope gaskets are a good direction to head.

If you are not suppose to use pure PTFE gaskets with two bolt clamps I have have no idea when they should be used. The two bolt clamp provides better spread of clamping force.

http://gfistainless.com/GFI CATALOG/WCB SANITARY FITTINGS & CLAMPS.pdf
Quote from link:
Note: Pressure ratings are based on the following parameters:
Nominal wall thickness (.065 1.5"-3", .083 4"), use of elastomer
type gasket*, weld ferrules, properly aligned and assembled
joints (nuts torqued to 20 ft. lb.) and the absence of water
hammer or shock loads.
Remember, use the Clamped Union pressure rating above for
safe, correct pipeline design. Pressure ratings of the clamp alone
are generally higher yet do not take into account the full clamped
assembly with gasket.
PTFE gaskets are not recommended for use with 13MHP clamps.
Consult factory for Solid PTFE and PTFE Envelope Gasket
information.
Higher pressure ratings for the clamp alone are available upon
request.
End Quote



Also note Swagelok calls for 25 ft. lbs. of tourque- the most I have seen.
http://infracom.kylos.pl/profil_tech_katalog/a/11/11_01_(02150).pdf

AJC13HP-HIGH PRESSURE CLAMP
(With wing nut tightened to 25 ft lb of torque)
Clamps are tested hydrostatically using Standard-Molded
Buna-M material gaskets. All ratings shown are dependent upon
related components in the system, absence of shock pressure,
proper expansion of ferrules, assembly of joints, and installation.
For temperatures above 250˚F/121.1˚C we recommend only
AJC13HP clamps be used.

 

[dabdynasty]

I am in transition to purge all viton from my system. The worst part is ptfe screen gaskets costing over 100 dollars each. To mitigate that cost I have designed a rebuildable ss304 filter pack that only uses ptfe and stainless mesh. It could be done with 2"x1.5" endcap to ferule reducers.

The other problem with ptfe gaskets is the cold flow (no memory after being squished) but I was directed to check out ptfe envelope gaskets and am very glad I did. They wrap standard gasket material (viton/epdm) in ptfe so the core has memory but doesnt touch the inside of the joint. Only the ptfe does. I've also picked up some Tuf-steel gaskets (PTFE mixed with stainless steel). Gonna try them out.
I've been told that soaking the older solid ptfe gaskets in boiling water brings them back to life after they stop sealing properly. I have not tried it yet though.

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Roji what are you using for the center insert?

 

[kronus]

where can we buy these envelope gaskets?? need a 10 incher

plz help?? also a silicone heat map wrap thing for a 4x36 colum and 6x36 ??

 

[pharmco]

If you search "envelope gaskets fkm ptfe" the third result is Austenitex, and the first two are rubberfab on Amazon, which Austenitex sells. You should spend some time looking through their offerings, and determine what you need.

The silicone heating mats are made by keenovo, I advise you to read the heating mat threads, and posts by Skyhighler, who explains in detail how to use these heating mats PROPERLY.

 

[BrainChild]

Austenitex is a great company. One stop shop for high quality clamps, gaskets and lots of other stuff. I've been using their heavy duty 3 segment clamps http://www.austenitex.com/shop_by_category/Tri-Clamps/Three-Segment-Clamps with their FKM/PTFE envelope gaskets (at my frequently changed 1.5" connections) and they work great together. These clamps make regular single pin clamps seem pretty jank, and are much easier to take on and off vs the bolted kind. Also, I've bought gaskets from glacier, terpp, best value vacs, brewery gaskets, and the rubberfab gaskets that austenitex sells are the best. The viton I got from them had no smell, no black residue when cleaning and are perfectly molded.

 

[GratefulOne]

Rubberfab are first quality products made in the US. The other sources Brain mentions are generic Chinese junk.

 

[Dab Strudel]

Austenitex only goes up to 6" for the Tuf Flex envelope gaskets. And the price can fly a kite. Im reaching out to the Gylon gaskets and seeing whats what with that.

 

[GratefulOne]

Gylon should also be good gaskets. The prices for anything of high quality will be high compared to Chinese crap. You can pay $200-$300 for a good quality 12" gasket.

 

[pharmco]

Rubberfab are first quality products made in the US. The other sources Brain mentions are generic Chinese junk.

I have had no issue with my Glacier Viton, differing vastly from Roji's apparently Cinnamon flavored viton. Mine never smudged either.
I do acknowledge that it is chinese, but it has served me well for 1.5 years, until I purchased my FKM/PTFE envelopes.

 

[Dab Strudel]

I can vouch for cinnamon viton, i was even told by brewers hardware that "...if it doesnt smell like cinnamon then its not viton."

 

[Gray Wolf]

I can vouch for cinnamon viton, i was even told by brewers hardware that "...if it doesnt smell like cinnamon then its not viton."

Viton is available cinnamon flavored, but it isn't standard.

 

[SkyHighLer]

Viton is available cinnamon flavored, but it isn't standard.

"Cinnamon Scented -- If Requested"
http://thermodyn.com/100fkm

Lot of info at that site,
http://thermodyn.com/products/gasket-materials

 

[pharmco]

Goes to show, even in "FKM" there is a fair degree of variation in formulation and quality control. There are 2-4 distinct crowds, those with cinnamon smelling viton/FKM that may/may not smear black, and those with unscented FKM that may/may not smear black.
Not really the ideal for something we want as a wetted gasket material.

I'm loving my envelope gaskets. The PTFE has been resiliant to deformation, and the FKM interior maintains a good elasticity, making for easy seals even with single pin clamps.

 

[Roji]

Roji what are you using for the center insert?

Its a 1.5" ptfe gasket with the ridges shaved off.

 

[Dab Strudel]

I was uncomfortable just setting my wrench to 25 ft lbs and going off on it, and im glad i was. i set it to 10 ft lbs and without it clicking I couldnt bare torquing it down any further. seems like a lot

 

[Dab Strudel]

Garlock is a no go for subzero. the Bio Pro envelope gasket only goes down to 60~*f

 

[pictureguy]

Theres not alot of feedback in this thread, so i wanted to give my 2 cents.

I just upgraded my gaskets to ptfe with epdm inserts and I bought the ptfe 40 mesh screens from Cole parmer. Gonna see how well these work, and how long they last

 

[Towelie Rules]

The gasket used is really going to depend on how you run your system. If super cold, I'd recommend the tuff steel. I may have missed it being mentioned with envelope gaskets, but they are only rated to the lowest spec material used. So if you were using a ptfe gasket that had a buna interior, the gasket temp ratings would normally be only as good as the buna.

Always buy from a reputable supplier like rubberfab, Newman, or some of the ones GW has mentioned. I know glacier gets theirs from china and the quality is hit or miss. Same with brewerygaskets.com. I think sanitarysteel is from newman and rubberfab, but I'd ask them.

I'll sometimes use filter stacks to get the screening levels I need without resorting to using screened gaskets