Air diffusing into water during hydrotest
Air diffusing into water during hydrotest
(OP)
I have read several forums on the problem with air trapped in a hydro test. I know in fresh water typically water diffuses into water at 1200psi.
Our issue is thus, what is the lowest pressure that air will start to diffuse into water and to add another factor not fresh water but into produced water. I don't have the salt content available at this time.
The pipeline we are testing has been in service since 2004 and is a OD-112.5mm WT-7.4 Star 2000 fibreglass line 380m in length
any and all help greatly appriciated
Our issue is thus, what is the lowest pressure that air will start to diffuse into water and to add another factor not fresh water but into produced water. I don't have the salt content available at this time.
The pipeline we are testing has been in service since 2004 and is a OD-112.5mm WT-7.4 Star 2000 fibreglass line 380m in length
any and all help greatly appriciated





RE: Air diffusing into water during hydrotest
Rate of solution (for nitrogen and oxygen) into static (non-sprayed, no waves, no "bubbling brooks" of splashing water) room-temperature water will be proportional to area of the water, will increase slightly as temperature goes down (and will be zero when the water is boiling), and will increase with air pressure (more collisions of air molecules O2 and N2 with the water surface per unit area.
RE: Air diffusing into water during hydrotest
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Air diffusing into water during hydrotest
The volume of trapped air in a hydrotest is important to minimize - to eliminate completely if in ANY way possible! - but the dissolved gasses in the water in a hydrotest? I have never seen that be a problem in any systems flush or hydrotest or operational test.
Dissolved gasses affects water chemistry of course, but that is an operation issue settled over time well after the initial fill and flushes and hydro.
RE: Air diffusing into water during hydrotest
As the others have indicated, you are creating an issue where there isn't one.
RE: Air diffusing into water during hydrotest
RE: Air diffusing into water during hydrotest
Agreed that the trapped air could pose a problem (maintaing pressure and safety related) but not its diffusion into the water. This is 122 mm (4") diameter FRP pipe. It should be no real problem in filling & venting.
RE: Air diffusing into water during hydrotest