Gasket Spiral Wound or Ring Joint for rating 900# above 1

[Weko]

On pressure rating class 900#, 1500# and 2500#. When do we use Ring Joint and When do we use Spiralwound?

Since most of the oil and gas company prefer Ring Joint gasket for 900# and above.

But some also allows spiral wound on 900#. The vendors also proposed SPWD since it would be more cheaper.

 

[BigInch]

Offshore, toxic products, high temperatures and anywhere that extra assurance against flange leakage is wanted, my gas company experience says RTJ. In other areas, you might use RF, but be prepared for a leak.

Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso

 

[Weko]

the service is natural gas... so RTJ is chioce... thanks

 

[Duwe6]

At Class 900, I am ameniable to either a spiral-wound or an RTJ. At Class 1500 and up, RTJ is the only thing I recommend. They just seem to work better and make up easier.

 

[TGS4]

There are more options than just these two. There are a whole host of other gasket types (Kammprofile, for example) that can be used on raised-face flanges. RTJs have their own unique issues that must be managed - cracking in the groove happens frequently, so you need to know that so that you can plan to weld-repair them after breaking them apart.

There are other types of non-welded connections, too, that are well-suited for high pressure applications.

 

[Weko]

for RTJ, which type is prefered, octogonal or oval type?

 

[Duwe6]

All I've seen used is octagonal. It doesn't seem to matter much. The main issue is hardness. Especially on stainless flanges, make sure that the ring is softer than the flange.

 

[TechThreads]

Duwe6 is right about hardness. Make sure you call out the exact material type of the RTJ gasket, especially in SS or alloys (i.e. 304 and 347 have different hardnesses). The flange can crack the gasket or even vice-versa if the hardnesses are incorrect.

As to the issue of which RTJ type, from Lamons:

"The octagonal cross section has a higher sealing efficiency than the oval and would be the preferred gasket. However, only the oval cross section can be used in the old type round bottom groove. The newer flat bottom groove design will accept either the oval or the octagonal cross section."