Flange Hydrotest pressure (EN1092-1) 1

[pingmi]

Hello,

I referred to EN 1092-1-2007 standard for hydrostatic test pressures & test duration of PN designated flanges. However I could not find any such reference in that standard.

If I recall correctly old versions of applicable DIN standards for steel flanges used to mention minimum test presure equal to 1.5 x maximum working pressure of flange at 20°C as per P/T rating.

Can anyone help me with this?

Thanks in advance.

 

[Raaden]

You are right, 1092-1 doesn't mention anything about hydrotesting.
In ASME B16.5 regular flanges doesn't need hydrotesting, but flanged fittings do and I think it works the same way in the EN world.

 

[pingmi]

Thanks Raaden for your reply. I need to have a basis / reference from EN standard to justify the hydro test pressures & test duration of a PN rated flanged fitting or valve. Very often such references are required to convince the local inspection authorities.

Would you be able to help me further with this?
Thanks.

 

[Raaden]

Well a flanged valve is tested according to EN 12266-1 with the following pressure:
"The test pressure (see A.1.6) shall be a minimum of 1,5 times the allowable pressure at room temperature."

 

[OSIRIS7]

Annex E.3.2.1 gives you insight in the calculation method for some flange types.

"-at assembly and testing 200 MPa (Ptest = 1,43 × PN)."

So it seems you should use a higher PN-rate when your pressure testing becomes higher that 1,34xPN.

Kelly

 

[Raaden]

Kelly, can you elaborate on your statement about 1,34xPN?

The 1,43PN is taken directly from the PED and that pressure will create a stress in the material that can be up to 95% of the yield strength of the material, which also happens to be what most EN standards specify as their max allowed stress at test condition. So I would say that you only need to worry about the test pressure when it gets higher than 1,43PN.

 

[pingmi]

Raaden,

Referring to the statement:-
The test pressure (see A.1.6) shall be a minimum of 1,5 times the allowable pressure at room temperature."

I was wondering if there is any limit specified in standards on the maximum allowable hydrotest pressure.

Please comment.

 

[Raaden]

The only limiting factor for the test pressure is that the membrane stress in the part shall not go above 95% of the yield stress (90% in ASME) during testing.

 

[OSIRIS7]

Sorry, the 1,34 is a typo. Should be 1,43.