can some of you experienced individ 4

I imagine that the requirements would be the same, and for the same reasons.

What do you mean by "flushing" exactly? This implies there was something in the pipe that you want o remove by introducing water, but in a new pipe what is that?

Stl Stl doesn't like chlorides in any form and it is best avoided.

Can't see hay anything different from hydrotest wouldn't apply.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

Did you use seawater to do the hydrotest?

no it is brand new installation, never been in the service and flushing is "normal" for project realm to clean all debris and trash before bringing service medium whatever that may be. I agree with LittleInch about not having anything different than hydrotest, however only problem is amount of fluid needed for flushing is lot and cost of maintaining hydrotest spec on flushing fluid be considerable for whoever performing flushing. I am end user but wanted to make sure it will be done with code compliance and/or considering longevity of the equipment/piping post flushing, especially Aust SS in high temp service. I was given eference pH to be between 6.8 and 8 while chloride content less than 200 ppm but seen some discussion on this site that someone listed chloride not be more than 50 ppm for Aust SS piping per API 570 BUT that was in reference to hydrotest, Not flushing.

And no, we never use seawater to hydro on pipe spool at the fab shop. no hydro has ever performed at site to date, not there yet.

What is more important than the chloride level in the water is the duration of the flushing or hydrotest activity.

Since 200 mg/L (304SS), 2,000 mg/L (316SS) and 5,000 mg/L (904LSS) chloride levels are acceptable for avoiding pitting & crevice corrosion are for extended use in critical service, use of water somewhat above these levels should not cause problems at the short times used in hydrotesting and flushing. Obviously, this requires the hydrotesting and flushing times to be kept short, and the equipment to be drained and dried after hydrotesting and flushing.

Disinfection of the water is also essential to remove the risk of MIC. Disinfection can be carried out by a variety of methods, some of which also carry risks of making the water more aggressive for other forms of corrosion. Potable water from properly conditioned municipal supplies do not generally require further disinfection. Potable waters seldom have more than 100 mg/L of chlorides.

Refer to the attachment.


API 570: Piping & Inspection Code, American Petroleum Institute.
Piping fabricated of or having components of 300 series stainless steel should be hydrotested with a solution made up of potable water (see note) or steam condensate. After testing is completed, the piping should be thoroughly drained (all high-point vents should be opened during draining), air blown, or otherwise dried. If potable water is not available or if immediate draining and drying is not possible, water having a very low chloride level, higher pH (>10), and an inhibitor addition may be considered to reduce the risk of pitting and Microbiologically Induced Corrosion (MIC).

Note: Potable = ‘suitable for drinking’. Potable water in this context follows US practice, with 250 ppm maximum chloride, sanitized with chlorine or ozone.

For SS lines, use only low chloride inhibited RO water, suitably doped with biocide and oxygen scavenger, whatever the service may be. For long term storage, drain out all inhibited water, dry out and blanket with N2 before capping off the line.

thank you all for taking time to share your thought and experience. I am truly thankful to you all

bimr made the best argument there. Potable water is usually more than adequate. Our potable water varies between 20 and 30 mg/L Cl- and no AI or client rep has had a problem with us using it for hydrotesting or flushing lines. If you are storing the lines with water for a long, ling period, then going to the extreme recommended by George MIGHT be necessary. The biggest issue, though, is NOT allowing substantial water pockets to evaporate to dryness, concentrating all their residue of evaporation into a single very strong brine at the very lowest point. That is a no-no.

I have never seen a 316 pipe line that would tolerate 2,000ppm Cl, 200 ppm is more like it.
And today finding 304 pipe that will survive long in 100ppm is a gamble.
I would like see potable water used, <50ppm Cl, pH above 7 (stainless does not care if it is 10), and a biocide added.
MIC will destroy a pipe in a few days once it starts growing.

George is also correct in pointing out that unless the line is going straight into service you need to drain and dry it. Standing pools or water invite both Cl pitting and MIC. If a 1l puddle evaporates to 10ml the Cl content has just gone up 100x.

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P.E. Metallurgy, Plymouth Tube