EN 13480 Test Pressure Above Flange Rating 1

[jmr1992]

Hi All,

Hopefully someone can point me in the right direction with this. Apologies if this has been asked before, I have tried searching the forum already but to no avail.

My question concerns the hydrostatic test pressure of a system to EN 13480 where the test pressure will be above the flange rating.

For example PN 10 flange rated for 10bar at 20deg. Design pressure is lets say 9bar. Test pressure would be 1.43x Design giving 12.87 bar.

I am a little unfamiliar with EN code, however I am almost certain that this would be acceptable but was hoping someone could point me to a specific paragraph in the code where it states this is allowed, something like per para 2.6 of ASME B16.5.

Thanks in advance.

 

[LittleInch]

A flange is simply regarded as part of the system being tested. So as long as the flange max WORKING pressure (design) is above or equal to he design pressure of the system you are good to go. Sometimes codes don't spell this out as they assume everyone knows it....

There is a general understanding that flanges are good for 1.5 times their MAWP.

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

 

[GBTorpenhow]

PN10 flange should be good for a pressure test of 1.43 x design pressure up to 10 bar design pressure. i.e. max test pressure of 14.3 bar.

thread378-502263

 

[jmr1992]

Thanks to you both for the help

 

[XL83NL]

An indirect to this is provided in EN 13480-3, where it (indirectly) details how the factor 1.43 was born. Refer to para 5.2. For testing it uses 95% yield max, and for other than test conditions it has a factor of 1.5 over yield (at temp.). This 1.5 times 0.95 equals 1.43.

What you would be looking for (and what I have looked for in the past), is a para similar to B16.5 para 2.6 in EN 1092-1. That doesn't exist. I've asked this question to the applicable CEN/TC committee too, but to no avail.

My approx is that for piping spec, we always hydrotest to 1.5 times the ambient flange rating. Both for class-rated and PN-rated flanges. I have never found a para that allows the latter, but as long as my flanges don't yield, Im OK. They've never yield, and we've tested hundreds. That now has become my substantiation.

Huub
- You never get what you expect, you only get what you inspect.

 

[Krausen]

Typical practice is to hydrotest your system to 1.5 x Flange Rating (at ambient), as stated above by others. B16.5 flanges have proven themselves to be able to handle higher hydrotests pressures than this though, but I’ve never been able to quantify how much higher beyond 1.5 x Rating one may go to. Would be curious of forum’s experience with this question?

 

[LittleInch]

At 1.5 x I think just about everything is close to yield. Flange, bolts, gasket.

So you might be able to maintain tightness at 2x, but your flange will be permanently bent and your bolts a bit longer than they were before you started.

So something will start to yield enough to start leaking.

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