Tubing vs hard pipe in very high pressure applications

[maraisjo]

Good day Eng-Tippers

I searched the forums, but could not find a relevant thread.

What are your experiences with the use of tubing vs hard piping for instrument connections in very high pressure applications (Cl 1500 & Cl 1500)?

We're currently considering both options, and would like to get an idea of 'industry standard'.

Regards,

maraisjo

 

[JGard1985]

Stainless steel tubing. So much easier to make up connections to transmitters and pressure taps. Used to use A213, 0.065 wall tubing for instrument lines at Nuclear Power Plant. Line spec had materials good for 2084psi @ 800F

Jeff
Pipe Stress Analysis Engineer

http://www.xceed-eng.com

 

[moltenmetal]

Class 1500 isn't actually all that high pressure for stainless steel tubing. It is well within the limits of ordinary 2-ferrule compression fittings. Hard pipe is a disaster for instrument impulse lines because it is so inflexible to change. Some end user clients use it on large lines and vessels. I can see the benefit for root line sizes say 12" and larger, and vessels greater than say 8' in diameter, but the benefit for line sizes and vessels smaller than that is specious at best in my opinion.

"High pressure" to us is beyond 2500# class. Then you're into either pipe with Grayloc type closures, or tubing with cone and thread closures. Such "tubing" is basically pipe, just with a different method of end connection, and it typically has a wall thickness which approaches its ID.