hydro test with fresh water

[jaykidd]

Good Day to All!

sirs/ma'am,

We conducted hydro test using fresh water in tank truck and passed. but after filled with gasoline/diesel,leaks happened.

possible? causes?


Thanks in advance to all of you sir!!!

 

[EdStainless]

How was the water disinfected?
How long was it in the tank?
How was the tank dried after testing?
My guess is MIC.

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P.E. Metallurgy, Plymouth Tube

 

[jaykidd]

good day!
edstainless,

thanks for your reply!!

How was the water disinfected?
no disinfection of water occur! water was come from faucet.

How long was it in the tank?
hydro test time duration was 1.5hrs to 2hrs.

How was the tank dried after testing?
water was drained and filled with gasoline/diesel after


thanks!

 

[metengr]

Where exactly did the leaks occur? More information is needed. What was the time duration after hydrotesting and before gas/diesel was added?

 

[zeusfaber]

Hopefully a silly question, but how well do you trust the people who made the tank?

Are they the kind of people who might have sealed known leaks with silicone gunge so it would get through the hydrotest and they could get paid?

Not that any of my contractors would behave like that.

A.

 

[chicopee]

To be of any help, you'll have to tell us everything about the tank and the procedure of the hydrostatic test.

 

[jaykidd]

Good Day to All!!


sorry for the late reply..

#metengr
#zeusfaber
#chicopee

my apology for the incomplete information...all procedures(as per code/standards) and personnel were certified/qualified. Our hydro test were passed but after hydro test and gasoline/diesel filled in the tank(lorry) leaks were occured! can this be possible/happened? and can you support your answer sir?

I need some of your ideas for this failure!!

Thanks in Advance sirs!!!

 

[r6155]

jaykidd: Revise all procedures and change personnel certified.

Regards
r6155

 

[EdStainless]

How did you dry it before fuel was added?
What is the coating inside?
There may still be a pool of water in the bottom.

But, if it started leaking right away then the hydro was not done correctly and the leak was there before the fuel was added.

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

 

[chicopee]

With diesel fuel, there could be weeping at threaded connection. So are active were those leaks?

 

[chicopee]

Also about showing some pictures of the leaking areas.

 

[r6155]

Fuel act as penetrant oil testing. See API 650

Regards
r6155

 

[abangbikerz]

Diesel fuel molecule vs water molecule. Which one is smaller? I dont know which one is smaller,but if diesel molecule is smaller than it may get pass through all the small hole that water cant.

 

[weldstan]

Was the hydro test done after a repair to an existing tank or was the tank new? A truck mounted tank is governed by DOT regulations regarding repairs and general operation. Were leaks located at the tank bottom?

 

[berkshire]

As a matter of information we used to fabricate metal fresh water tanks, to leak test these, we painted the insides of the seams with kerosene with a developer powder on the outside seams of the tank. Only after it passed that test did we fill the tank with water.
B.E.

You are judged not by what you know, but by what you can do.

 

[cloa]

The minimum size for a water drop is larger than drop of diesel due to hydrogen bonding and its related water surface tension- hundreds of molecules whereas a drop of diesel only dozens due to weak bonds. The minium size of drop doesn't matter since its impossible to have a hole in order of nanometres- metal metal contact rebonds as those scales.

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[moltenmetal]

The size of the molecule doesn't matter in this case because we're dealing with liquids rather than gases so diffusivity isn't the issue. cloa should mention surface tension, which results from the hydrogen bonding. Diesel is an excellent penetrant because it has low surface tension.

All of this depends greatly on a) how high the hydrotest pressure was and b) where the leaks occurred. The OP needs to tell us these things for us to be of further help.

 

[jaykidd]

Good Day!

sirs,
thank you for all your responsed and given information...

yes sirs all were followed. tank was subject for annual inspection(out of service inspection).

 

[cneberly]

Is it possible that the tank is leaking through gaskets which might be incompatible with the fuel?

Chris Eberly, PE

http://www.parkusa.com

 

[weldstan]

Being that the tank was not new, how old was it and where were leaks found? Surface tension of the water in conjunction with probable prior surface contamination by remnants of fuel oil could account for why leaks were not discovered during hydro yet occurred after filling with fuel oil.