Metal jacketed vs Spiral wound gaskets for Heat Exchangers 4

[EngTal]

Why metal jacketed gaskets are used in Heat exchanger's' head covers instead of spiral wound gaskets. What is the advantage of double jacketed gaskets over spiral wound in heat exchangers?

 

[Krausen]

The big problem with spiral-wounds is you'll need a inner ring to prevent the windings from buckling. The outer ring on spiral-wounds also prevents winding buckling, but this is typically not need if your exchanger flanges are a confined type, which serves the same purpose for a spiral-wound gasket. If you're dealing with floating head covers on a straight tube bundle, you'll need a larger floating head to accommodate a spiral-wound gasket with inner ring, which increases overall cost & may require your shell cover to be built larger as well. If you have existing double-jacketed gaskets in any exchanger girth flanges or floating head flanges, I'd recommend upgrading them to kammpro gaskets

 

[r6155]

See TEMA 11ed 2023

Regards

 

[A8yssUK]

Also while you are looking at that, check out Flexitallics Change gasket, its sort of a best of both worlds. Basically a spiral wound gasket with extra thick windings that don't buckle as easily and impart more resilience. They are really good... but I am slightly biased because I did a large chunk of the R&D on it.
I'll point out however that I had nothing to do with the stupid name...

 

[Christine74]

Good question. What Krausen mentioned above is correct, all else being the same you would need your shell to be 0.5 inches larger in diameter if you specified Spiral Wound gaskets in a floating head exchanger due to the inner ring. But it's still quite rare to see Spiral Wound gaskets used with Fixed Tubesheet or U-tube designs where the gasket inner ring doesn't typically affect the required shell diameter.

I think what happened is that Double Jacketed gaskets became the industry standard before custom-made Spiral Wound gaskets became readily available, and when custom diameter Spiral Wound gaskets did become available they offered no real advantages over Double Jacketed gaskets. It's also possible that Double Jacketed gaskets are cheaper and/or easier to fabricate with pass partition ribs.

As an aside whenever I see Double Jacketed gaskets specified on an exchanger data sheet I wonder if the designer has been living in a cave for the past 30 years. Almost no one in the petrochemical industry is using them any more as much better gasket types are available these days (corrugated metal graphite covered, grooved metal graphite covered, etc.).

-Christine

 

[r6155]

Metal gasket is better for external pressure (shell side pressure).

Regards

 

[ShabsRBI]

I have not seen a Spiral wound gasket in Heat Exchanger services as all the Spiral wound gaskets are now changed to kamprofile gaskets with thinner width. Kamprofile gasket seems to accommodate more seating stresses as they are used for seating stresses of 10ksi-40 ksi with a optimum of 25ksi. On Steam reboiler with very high Shell side pressure kamprofile gaskets are found working successfully at stress of around 32ksi.