hydrotesting using water

[local324]

I have a question we are working in a Hydrogen unit tying into existing CS piping and the ITP calls for water, should we be using bottled water with a PH between 6.5-8.5 instead of water from a plant hydrant? The concern I have is if all the water is not drained out and the water is left behind in the process piping could it cause cracking or possible explosion is chlorides are left in the piping?

 

[cloa]

Why would bottled water necessarily have low chloride content? For you to be worried about cracking there would need to be usually stainless steels under significant stress say 80% of yield.

 

[Metalguy]

Is a stainless steel involved here? If so, and it's something like 304L/316L and is welded, make sure you use a biocide to kill bacteria. There are many cases of thru-wall pitting in SS caused by hydrotest water that wasn't completely drained and dried.

Also, the HAZs next to welds are usually right at the yield strength of the material if left as-welded.

"You see, wire telegraph is like a very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? Radio operates the same way: You send signals here, they receive them there. The only difference is there is no cat." A. Einstein

 

[EdStainless]

regardless of the water source there needs to be a plan to quickly drain and dry the system after testing. You can get a lot of corrosion in a few weeks or even days from stagnant hydro water.

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[blacksmith37]

If your location permits , blow inert gas (dry flue gas -N and CO2) through it. Alternatively, N blanket, bottled N is pretty dry and will absorb a small amount of water.