UAN32 Storage Tank - Urea Ammonia Nitrate

[lpfaustini]

Dear forum fellows,

A client ask me to design a UAN32 Storage Tank for his facilities. I'm a tank designer, but, as I never did one before, I had to do some research. I found out that UAN32 is extremely corrosive. Although the use of corrosion inhibitors reduces the problem, tank liner and epoxy internal coating are also needed. The tank designer must think about a recirculation header too (to avoid slug deposit) and be careful about how much of ammonia is going to the atmosphere (unpleasant odor). I wonder if I put all this solutions together, wouldn't be too much? I am curious to know what do you usually recommend.

Thank in advance,
Luiz

 

[MJCronin]

Uuuummmm .......... "I'm a tank designer, but, as I never did one before....."

Sadly, it seems that many of the recent posts on these fora are only from engineers/designers in title only....

MJCronin
Sr. Process Engineer

 

[lpfaustini]

MJCronin,

You misunderstood, but I confess I was not clear. I'm a tank designer since 2012, but never did an UAN32 tank before.

 

[robsalv]

I don't think I understand that question.

In my jurisdiction, the EPA guidelines would spell out the ammonia vapour restrictions.

You would give the client a range of options from lined carbon steel to intrinsically corrosion resistant materials and costs. An indication of the life cycle costs of each option would help make their decision.

Is the recycle header intrinsic with the tank? Are you offering a turnkey design and installation? Would the recirculation header be part of external piping done by others? Hasn't your client provided an approved set of control of change design documents? Is this just a scope study exercise?

I think I'm with MJcronin on this one - weird post.

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"Life! No one get's out of it alive."
"The trick is to grow up without growing old..."

 

[JStephen]

Normally, it would be the purchaser's responsibility to specify what materials, coatings, and features are required in order to be compatible with their particular product.

 

[lpfaustini]

Robsalv, JStephen

Thank you for your kind support.

This is no case study, this is for real. I work in Brazil doing tank design for people who knows nothing about tanks where only a few professionals know something. This is why I am in this forum, because there's nothing related to storage tanks in Brazil. Our national standard is outdated since 1983.

About my case:

The problem is I cannot use stainless steel material for the shell. My client said it would be too expensive and he can't afford it. So I stay with carbon steel.

As I said, my client doesnt know anything about UAN32 tanks and put the responsability on my shoulders. My best choice is to suggest epoxy internal coating, although I read that epoxy itself is not enough and a tank liner is also recommended.

I'm just curious to know what kind of solutions do you usually recommend to your clients.

Kind regards,

 

[MJCronin]

These people seem to have completed a similar project.

Their storage tanks seem to carbon steel, double containment.

http://www.matrixservice.com/images/Orascom project summary.pdf

MJCronin
Sr. Process Engineer

 

[robsalv]

An old engineer once told me, "Rob, your job as a technical expert in the organisation is to give the technically correct answer. Let the managers worry about the money". That's still a motto I live by today.

I don't know much about UAN, but I understand that when it is not properly cared for or properly stored, it rapidly chews through CS. A lined CS tank could cost as much as a stainless tank and almost certainly cost more in life cycle costs when you factor in the need for inspections and lining maintenance.

If your client is genuinely ignorant, then it's up to you to hold their hand and advise them of all the options and the associated risks. Just be aware, if Brazil has a duty of care obligation on designers such as yourself, this advice may follow you for the rest of your career.

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"Life! No one get's out of it alive."
"The trick is to grow up without growing old..."