EN 13480 vs ASME B31.3 1

[don1980]

Does EN 13480 allow short-term pressure excursions similar to those allowed by ASME B31.3? Specifically, I’m referring paragraph 302.2.4 in ASME B31.3 which conditionally allows excursion up to 120% and 133% of design pressure, for a limited number of hours per occurrence and per year. This allows one to set a thermal relief valve at 120% of the pipe's design pressure. I'm searching to determine whether EN 13480 allows similar short-term pressure excursions.

I’m hoping the answer is yes, because that means we don’t have to have separate thermal relief guidance for facilities in EU countries.

 

[XL83NL]

Interesting question. Afaik: no. I’ll dig through 13480 next week when I’m at the office again, and post when I found the opposite is true.

On a side note; what is preventing you from doing what you stated in the last paragraph of your first post?
If the scope of your work is subject to the PED, have you checked if your wish is allowed under EN 764-7?

 

[don1980]

Thanks for your assistance XL83NL!

Your side question has caused me to re-think an old assumption, which is based on my ASME bias (I'm in the US). ASME has different pressure protection rules for pressure vessels (Sec VIII) and for process piping (B31.3). Since that is my "norm" I assumed that the same is true for the harmonized PED standards (ISO 4126 & EN 764-7). Prior to now, I just assumed that was true and hadn't given a thought to whether that was indeed true. For example, I assumed that ISO 4126 and EN 764-7 were only applicable to pressure vessels, just as ASME sec VIII is only applicable to pressure vessels. Now that I've gone back and read the scope of ISO 4126 and EN 764-7, it appears that both of these standards are applicable to systems that are: (1) piping only, (2) pressure vessels only, and (3) combinations of pressure vessels and piping. If that's true, then my question isn't relevant. If the EU pressure protection standards don't distinguish between piping and vessels, then the rules are the same. And that means that one can't use a PSV, set at 120% the design pressure, to protect EN 13480 piping.

Please confirm whether you agree with what I've stated in the previous paragraph. And, thanks for spot-lighting this long-held erroneous assumption that I've carried around for all these years!

 

[XL83NL]

For EU work, in the end all you need to do is satisfy the PED and it's ESR's (Essential Safety Requirements), provided theyre applicable (P>0.5 barg, and category > 0).
Using the EN 764 series will make it easy to show compliance with the PED, especially for assemblies, because thats where EN 764(-7) kicks in.

We design & build plants for the chemical, (bio-)pharmaceutical, oil&gas, polymers, synfuels, bio-energy & -fuels, etc. industry. The scope of our work is 90% subject to PED. We buy all items with CE, and assemble them into a plant. That assmebly introduces (potential new) hazards, which we need to evaluate as we need to apply CE on the assembly for a multitude of directives (usually PED and Machine directive, quite often also ATEX, LVD, EMC). Such potential hazards are overpressure.

The EN 764 series, esp. part 7, is useful to us since our systems contain a large number of safety systems and accessories. Vessels and piping in our plants are built under all tpyes of design codes, sometimes 'mixed'. We can have ASME VIII-1, EN 13445, AD2000 (all vessel codes) and B31.3 (for piping) together in 1 plant. We dont use EN 13480 quite often since the code is still too prone to errors, making it difficult to use. The overpressure protection we have on our PSV's, and the design of our PSV's, are however set to 1 set of rules.

Our PSV's dont necessarily need to be to ISO 4126 (rules for design pressure design). However we have the experience that being able to show that when you satisfy EN 764-7 and you're allowed to mention this on your EU DoC (EU Declaration of Conformity), things become a whole lot easier with the NoBo. Recently we had a discussion with our NoBo about our overpressure protection philosophy, and the cases we identify for these scenario's. At the end of the discussion, we changed our protection philosophy to be more in line with EN 764-7 (whereas in the past we used to be more on the API 520/521 side).

To sum up your reply;

And that means that one can't use a PSV, set at 120% the design pressure, to protect EN 13480 piping.

Not necessarily; as long as you satisfy the PED and it's ESR's, that would not be a problem per se. However, see PED annex I 7.3, which specifies the max surge above MAP.


If you like more info, I can talk with our engineer in charge for the company design docs for overpressure protection (i.e. relief valves, busting discs, etc.)

 

[don1980]

Thanks again XL83NL for your well informed comments. They have been very helpful.

 

[KevinNZ]

"This allows one to set a thermal relief valve at 120% of the pipe's design pressure" Is this correct?

I have never seen pressure safety valves or disks set above the piping design pressure. After lift the pressure is allowed to rise 10 or 16%.