non-standard water for hydro test 2

[vrezazadelimagmail.com]

Dear All;

recently our manufacturer has tested a vessel of A 537 class 1 with non standard water. after delivery at site some area was suspected to corrosion. our site man announced that the total corrosion in some areas were up to 3mm equal to our C.A. however with thickness guaging showed that the thickness is remained fixed and equal drawing thickness requirement.but steel there is some argument which says that have lost our C.A. how we can be sure about it? and is 3 mm of corrosion after 3 months in humid atmosphere possible at all?

in another case a 316 l vessel had been tested with non standard water ,i mean chlorine at least 60 ppm, what will happen for our vessel later and how we can prevent any failure?

 

(1) You were cheated on vessel thickness or your constructor somehow forgot to factor in the corrosion allowance, because perfectly uniform general corrosion exactly equal to the CA is totally implausible. While you're at it I would have the vessel plates tested to ensure they are actually A537 Cl 1.
(2) Hydrotest water quality is usually specified in the purchase specification, and then sampled and tested by your guy in the field (you do have a guy in the field?)
(3) Someone will need to do a 100% visual examination on the 316L vessel. I am doubtful that is possible.
(4) You may need the services of a good lawyer.
(5) Never ever go back to this constructor.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[EdStainless]

Where the water pools and slowly evaporates in the 316 vessel you will reach high Cl and you will get some localized pitting attack.
You have problems.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[mk3223]

You may need to have third party to perform an full inspection the vessel and prepare a report. And, you may involve the Engineering and Procurement together to negotiate with the Mfr for the material issue and possible solutions.

 

[metengr]

Excellent advice from ironic metallurgist.

 

[DekDee]

Basically you get what you paid for - hopefully.
If you (or your bosses) thought it was a waste of time and/or money to have surveillance performed on these vessels whilst being fabricated then you only have yourselves to blame for the end results.

 

[LittleInch]

vre,

It isn't clear exactly what your issue is.

If you can use actual thicknesses then we might understand what's going on.

Can you explain what this sentence means - "however with thickness guaging showed that the thickness is remained fixed and equal drawing thickness requirement"

What thickness is fixed and what is "drawing thickness"??

3mm of corrosion is easily possible if there is water, heat and supply of oxygen, and is increased if the water contains bacterial and microbes or is "dirty"

What is meant by "non standard water"??



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

 

[KevinNZ]

I have seem pipe stored outside for a few weeks form a thick corrosion layer. This layer can be quite thick but the actual lost material from the pipe wall is much less. May be you site man has seen the corrosion layer, but the actual measured thickness has not reduced by much.

 

[chicopee]

With 3mm of CA gone, I would expect to see scale. Did your field guy see that? Show us pictures too! Was the non standard water sea water?

 

[racookpe1978]

3 mm of (uniform general or specific pitting) corrosion loss is very, very hard to believe in a stainless steel PV filled for a static pressure test with any kind of water (other than high saline or acid) after new construction, then drained.

Something else is very, very wrong. You need that tank audited as-now, with UT (??) checks for ALL accessible sources. Also, audit the fabricator for that company's material cert's.