Hydrotest & Pneumatic Test

Absolutely correct GA

Excellent!

It also justifies doing the hydro test to the higher multiplier BEFORE carrying out the pneumatic test at the lower one.

Where in hell did you get those ideas?

(I'll stand corrected if you provide valid references.)

Oil is sometime used as the hydro test medium, as when trace moisture would be undesirable in a vessel or piping. The required pressure isn't changed.

Dear Mr Life is adventure,

"Some of the posters here simply read wiki pages and misinterpret what they read, or the pages are incorrect (as they are written by anyone who chooses to write on them and regulated by people who are not engineers)"

I feel, in this forum your above statement is highly objectionable, particularly after the only post from Tornado followed by two appreciations, which is an excellent answer for the question. After going through the first para of your post many engineers can judge that your above statement applies perfectly to yourself.

Although "Life Is an Enerventure" has contributed some meritorious answers, for the most part he is a recognizable nutcase, who seems to read stuff from whatever random and unidentified source, and just regurgitates it. (As anyone can see from cruising his posts.)

I was surprised by your description of both hydro and pneumo tests being equal at 1.43 x design pressure. Do you know why 1.43 rather than some other number?

Many years ago, the Crane Valve Company published a hardbound orange catalog that was a virtual Bible of piping, valve, air compression, steam, and heat exchanger information. Those guys had an underground bunker in which they destructively tested vessels and piping/valve assemblies. They also had a fancy layout floor for bending large pipe formations.

In the PC and FEA world of today, I suspect that some historical value is being lost.

I have studied many standards and codes about hydraulic and pneumatic test pessure. Mostly I found 1.5 and 1.1 times the design pressure respectively. Only in Europian standard this value is mentioned. I also got surprised. May kindlly refer BS EN 13480-5 in support of it.

Unless it is on line, I don't have that standard available to me. Can you quote it?

Pressure test is conducted as an adequete proof to satisfactory perform at designe pressure. 50% higher than the design pressure is considered to be adequete. But the same logic is not applied for pneumatic test, because in case of failure it is dangerous due to possibility of reclining effect and air comming out at higher velocity.

However, if you refer BS EN 13480-5, test pressure is same both for hydraulic as well as pneumatic test. That is 1.43 times the design pressure OR

1.25 * design pressure * ratio of nominal stress at test temp. & design temp.

In reference to the extra safety precautions needed in Pneumatic Tests, I often see Compressors and/or their casings tested in a water filled tank that is shielded during pressure ramp-up.

After dwell time, VT is than conducted.