Water Quality for Hydrotesting 6

[Frank Burns]

All,

I have been tasked with meeting a specification for hydrotest water purity that seems a little "stringent". Usually DI water was sufficient at other sites, however, now I have a new specification to meet with water purity as follows:
Chlorides 50 ppm max (SS) 100 ppm max (CS)
pH 6.5-9
Sulfate 42 ppm
Fatty Acids 14 ppm
Ammonium 3 ppm (max)
Bacteria(SRB ,APB ,etc.) insignificant or "very low" activity
Total Suspended Solids 30 ppm
Turbidity <1 Nephelometric Turbidity Unit
Total Organic Compound 4 ppm
Temperature < 120°F

I have exhausted my resources trying to find a lab that can test for "all" of the list and can't seem to find a vendor who can deliver water "pre-tested" and certified to meet all of the requirements above. I am reaching out to anyone with water purity experience for advice, vendors, etc. that can aid in what I am trying to meet. (Keep in mind, I am a mechanical guy and not a chemist), so any comments are welcome.

 

[Frank Burns]

It's all over the pipe, however it is more aggressive in the HAZ and areas of stagnant flow. It just so happens that the leaks are rearing their ugly heads at the HAZ's first. I'm not a metallurgist, just relaying what the lab reported.....

 

[brimmer]

The issue is the way the system operates, not so much the hydrotest water (if those sections were dewaterd and dried properly, yes obviously on the chlorides you need to limit that). But why on earth are they leaving water stagnant for 6 months? Of course you're going to get MIC problems. If they are doing this they should inhibit the system with biocide and/or other corrosion inhibitor compatable with stainless. Seems like they're doomed to failure operating like this and hydrotest water can be a small part of many different problems. You should be able to treat water before the test as far as bacteria, I wuold find it hard to believe municipal DW would have ammonia and fatty acids to begin with? No basic specs available from the source on this?

 

[Frank Burns]

Brimmer,

[/You ask very good questions. I am not an operator and really do not have an answer as to why they leave the water stagnant for so long within the pipe. The water is, however, allegedly de-ionized water that should be very low on all counts (chlorides, TSS, ETC.). I really have no explanation as to why deionized water would have these types of issues other than leaving any type of moisture, in a stagnant phase over a period of time would create such issues. I may be way off base, however I am at as much of a loss on the reason for the detected damage mechanisms as I am with the water quality requirements.​