Material to use with Urea 99% at 140 Deg, 20 Bar for flowmeter

[HoumanK]

Hello.

I have been assigned to choose a mass flowmeter to measure 99% urea at 140 Deg C and 20 bar.

I have been checking Endress+Hauser and Krohne documents,and:

E+H recommends only Ti tube for temp < 100 Deg

Krohne recommends either SS 316 or Ti for temp < 90 Deg.

However, beside that this will require the flow to be cooled; it also required to completely change the flow as I believe 99% urea flow will crystallize at temp < 135 deg or so.

I am at a loss currently as I can't find enough data on corrosivity of a rather pure urea flow. Is it even corrosive to being with?

Thanks for the help.

 

[EdStainless]

The Outokumpu corrosion guide lists the following data.
This suggests that 317L or 904L would be suitable at higher temps as would Ti.
I would be leery of 316L in these conditions.

Urea
CO(NH2)2
Temp. °C: 180

4438 : 0
4439 : 0
904L : 0
Ti : 0




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Plymouth Tube

 

[HoumanK]

Thank you!

May I ask if the table is referring to the pure melted Urea?

Also, what does the 0 numbers in from of the materials stand for?

 

[cloa]

Zero or close to zero corrosion.

 

[HoumanK]

thx, but won't that be in contradiction with both E+H and Krohne's suggestion for temp. < 100 for Titanium?

 

[EdStainless]

http://www.outokumpu.com/applications/corrosion/corrstart.asp

since they don't give a concentration I presume that it is 100%. This is their normal practice.

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Plymouth Tube

 

[HoumanK]

WOW!

Thanks a lot for the link, I didn't know they provide their tables online!

Based on their tables, corrosion for Standard Cr-Ni-Mo is also '0'.

I believe 316l, which is the normal stainless steel material for flowmeters tube, falls under this category?

 

[EdStainless]

I wouldn't. The old European 316 ran higher chemistry than is typical in the US today.
I would step up.

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Plymouth Tube