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.

 

[0707]

For SS 50 PPM chlorides (demineralized water) shall be respected ,

For CS drinking water is ok.

 

[DekDee]

Is this requirement for a hydrotest or for the Client to bathe in ?

 

[LittleInch]

A decent chemical testing lab should be able to do all those things, but the difficulty is probably time and sampling of a large amount which needs to be stored in potable water tankers.

What sort of volume are you looking at?

Can't you just sample the mains water?

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

 

[Frank Burns]

Unfortunately the water supplied to the site does not even come close to the requirements for this specification, as I am on the weekly mailing list from the municipal water district for their reporting. In addition, they do not test for everything listed. I agree that chlorides of 50 ppm is standard for stainless however the site wants 100 ppm for CS. As far as volume, this will be an on-going thing for fabrication of spool pieces requiring hydrotesting, so we could be talking about a 2 ft. 1" diameter spool piece or 300 ft. of 18 inch pipe (it is going to vary). I have tried several labs and showed them the specifications, but the standard response is "we can test for some of it, but the other tests will need to be sent to other labs several states away from your site". We have the option of pneumatic testing, however, for safety concerns, I prefer the hydro method. UGH !!!

 

[LittleInch]

Could you use something like mineral oil instead?

Or you need to get some sort of UV steriliser to get rid of the bacteria etc.

Can you realistically save lots of the test water and then filter it and test it on regular basis in a storage tank?

All looks a bit OTT to me.

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

 

[Frank Burns]

Unfortunately, no and no to (littleinch). There is a specific paragraph in the specification for no oils and no re-use of water previously used in testing (even if it is re-filtered). I think I have hit the "brick wall" with this one. I really don't see the need to use "nuclear surgical grade" water for hydrotesting, especially when the part is going to be immediately dried afterwards and then put "who knows what" through the pipe after testing. I may be off base with this and there might be a simple explanation, but after talking with several labs and actual chemists/lab techs, it seems that there is a lot of head scratching going on, on both sides.....

 

[LittleInch]

I don't normally encourage double posting, but maybe you could try a similar worded (but not identical) post and link to this one in the water treatment and distribution forum.

There are people there who are much more "water based"

Add how much you need and where you are based otherwise you'll just get asked that question...

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

 

[Frank Burns]

I'm a "newbie to this forum, this is my first post. Any direction on how to repost and link ? Thank You in advance. I appreciate the help.

 

[LittleInch]

Well don't actually copy the same post, you'll just get it red flagged....

And just copy and paste in the address.

And I said the water forum, but the chemical process one....

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

 

[Dhurjati Sen]

Suggest the client that you would go for 100% RT as well as LPI of the root (if SMAW) or root and hot pass (if GTAW).

Keep your fingers crossed if this gets you a hydro-test waiver.

DHURJATI SEN
Kolkata, India

 

[MintJulep]

Looks like someone at your company signed a contract without understanding it well enough.

That's what change orders are for.

 

[mk3223]

IMO, why and where is the water per "Client" spec as posted having Sulfate, Fatty Acids, Ammonium, etc.? Or, are these contents typically in the testing water in your shop for the fabricated pipe spools?

Alternatively, you may present the water quality from your shop used for "successfully" testing the pipes in the pass.

 

[Frank Burns]

So, here is the deal. The previous systems were hydrotested by the contractor of the units using demineralized water. A few months later, water started leaking from the heat affected zone of alloy welds. That being said, the welds were sent to the lab and found to be water related. So...... long story short, DI water is no longer a viable water source for hydrotesting unless it meets all of the requirements listed above. Keep in mind, the oldest unit is less than 5 years old. This is an Owner corporate policy and one that was put into place after the owner accepted turnover from the contractor and started having all of these water related issues. So, now we are stuck with trying to meet this specification. Alternate forms of NDE is not an option at our site, as the Owner wants everything capable of being pressure tested, to be pressure tested, whether it be pneumatic or hydro. I prefer the latter, for safety reasons. So, if anyone on here has dealt with sulfates, fatty acids, etc. which utterly make no sense to me, I'd love to hear from you.

Regards

 

[0707]

- ASME PCC2 2018

The use of salt or brackish water should be avoided.

Test water should be free from sediment and corrosive substances.

The test water should be verified to be free of microbes. If the water contains an unacceptable level of microbes, it should be disinfected.

Test water used for austenitic steel vessels or piping systems, or for components clad or overlaid with austenitic stainless steel, should be condensate, demineralized, or of potable quality, with a verified chloride content of less than 50 ppm.

Test liquid should be drained immediately after completion of the hydrostatic test.

Care should be exercised to provide proper venting to prevent the creation of internal negative pressure (vacuum) during draining.

Pressure vessels and/or piping systems that will hold the test water for more than 10 days, whether or not the test liquid is pressurized, should be treated with a corrosion inhibitor and biocide.

A corrosion engineer should be consulted.

If further drying is necessary, the use of hot air or hot nitrogen should be considered.

If complete drainage of austenitic stainless steel vessels and/or piping systems is not possible, the components should be flushed with low-chloride (less than 5 ppm)

Regards

luis

 

[DekDee]

Go with pneumatic - Yes, it is possibly more dangerous than hydrostatic but I have been involved with numerous pneumatic tests on various LNG sites and never an issue.
Requires a large exclusion zone but as long as scheduling is planned well there is very little impact on production downtime.

 

[LittleInch]

I would really like to know how they came to the conclusion that demineralised water caused a failure in a system with water in it, but guess that's for another time.

fatty acids and sulphate sounds like waste water to me.

Perhaps suggest other fluids - one listed seem to be propylene glycol, potassium acetate, methanol (not one on my list tbh) or this stuff someone else makes..

https://www.novamen.ca/products/hydro-testing-products-services/ecotest-400/

Probably costs multiples what the water does, but if it gets you out of the holes you're in then??

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

 

[r6155]

The problem is in the weld, not in the water.

Regards

 

[Frank Burns]

To r6155,

I should have responded to the question posed above as to how the lab determined that the failures were induced by water.
The welds that formed leaks are associated with an RO water service that is intermittently used. It can remain stagnant for up to 6 months before flow is established in the line. The lab concluded that one of the damage mechanisms were due to MIC and the other was due to Chloride stress corrosion cracking. The welds in question are 316 ss, sch. 10, and less than 3 years in age. I do not believe the welding is the issue in this instance.​

 

[r6155]

If the leak is in the weld and HAZ and not in another section of pipe, then the problem is in the weld.
My opinion only.

Regards