Winter Hydrotest

[code1]

Hi all,

I will have a vessel (75m^3) coming up for hydrotest in the winter (-4 deg. C ambient).

The material is A516 Gr70 with thickness of 15mm. The MDMT for design is 5 deg. C.

My contractor has explained it is okay to test in the winter without any additional measures.

We are aware that the ASME VIII Code states temperature is recommended to be 17 deg. C higher than the MDMT selected to reduce any chances of brittle failure, hence our concerns.

Should we revise the MDMT to take care of this case?
The contractor may not have heating facilities at the workshop, so what other options are available to us?

(I have also read similar threads here, but none was specific to this)

Thanks all

 

[Unotec]

Heat up the water? Is this an insulated vessel?

<<A good friend will bail you out of jail, but a true friend
will be sitting beside you saying ” Damn that was fun!” - Unknown>>

 

[MJCronin]

1) Aim a bunch of rental torpedos at the tank/piping and preheat the vessels

2) Fill the tanks with heated water.

3) Test (quickly)

4) Drain (quickly)

DONE

-MJC

 

[eliebl]

A couple things.

I am picky when it comes to material specifications. You are likely using SA-516 Gr 70 (may be an ASTM equivalent recertified by the fabricator) and that material at 15 mm would be good for -30C even if it has not been normalized. The MDMT I would have used for the design would be -20F or -29C so that we don't run into problems with things like hydrotesting at a high enough temperature.

Secondly, check this and other forums for low temperature hydrotesting. It has been discussed more than once. If the ambient is -4C then I wouldn't be too concerned with anything freezing. Where I am located truck mounted or mobile boilers are common place. Get one and fill the vessel with warm water. It will take a long time to cool down to a point where freezing would be a concern.

My opinion only.

EJL

 

[gr2vessels]

For low (lower?) temperatures the ASME SA 516 requires the 15 mm plate to be normalised, that will ensure the suitability for hydrotesting at -4 deg C. As for the water, use some antifreeze additives, because you need time to equalize the shell and water temperature as per the Code requirements (I assume that you'd use water, not ice to fill the vessel, hence the water temperature must be above 0 deg C- typically the tap water would be at around 8 deg C).
cheers,
gr2vessels

 

[code1]

Hi all,

Agreed and thank you for the above comments and suggestions.

The question of the MDMT was picked up by my Inspector because the design was specified for 5 deg. C only. And due to some delayed in schedule the tests are now approaching winter time. So this is why the MDMT was not considered to be lower at the point in time. And if the actual MDMT stated in drwing and calculation is 5 deg. C this is the vaule that should be used for evaluation.

Interestingly upon detailed checking the mill certs it was only hot rolled without normalizing.

In anycase, I was told that typically in the colder region workshop in the country in Asia, two situations can be present:
1. use of preheated water as described
2. conduct the tests in a heated portion of the shop where the ambient air will be high enough.

THanks and best regards all.