HEAT TREATMENT (NH3 - ANHYDROUS - GAS) 2

[JACKSTAN]

Hi,
I have a tank made from carbon steel type SA516 Gr. 60 with thk. = 10 mm (0,4 inch). The question is, heat treatment for welds of the tank shall be applied or not?

 

[unclesyd]

What are your pressures and temperature?

 

[MJCronin]

JACKSTAN....

Annealing of carbon steel pressure vessels in anhydrous ammonia service is recommended to mitigate the long term effects of SCC..

An ANSI "K" series standard(ANSI K61.1)exists for pressure vessels in anhydrous ammonia service.

You should be aware of and follow the current ANSI-K61.1 Standard, “Safety Requirements for the Storage and . Handling of Anhydrous Ammonia”, or applicable Ammonia Manufacturing.


Alos see these links:

http://www.springerlink.com/content/w22606142k137h72/

http://www.hghouston.com/dcforum/DCForumID2/78.html

http://books.google.com/books?id=oX...hl=en&sa=X&oi=book_result&resnum=10&ct=result

http://www.terraindustries.com/getdoc/41ad7408-1347-4642-aa4d-37bb58601013/anhydrous_ammonia.aspx

http://www.tannerind.com/sto-anh-ammonia.html

Please complete this thread and let us know about your final design...

-MJC

 

[JACKSTAN]

Hi,
I have following conditions: MAWP = 12 bar (174 psi), and MAWT = 50°C (122 F).

 

[JACKSTAN]

Hi All,

For parameters as were sent last time for anhydrous ammonia (NH3) and after read your comments I think that PWHT is not required. But, I am not sure for 100%.

 

[Shmulik]

Further to the issue of SCC avoidance, I would strongly suggest you be aware of laws & regulations at location of installation of your vessel.
In case destination's law requires you consider Ammonia as a lethal substance, thus, you fall into UW-2 Service Restrictions who require you PWHT regardless to SCC considerations.
You may find further useful info (not only for PWHT) at the Handbook of Compressed Gasses (CGA Inc.):

http://books.google.co.il/books?id=...a=X&oi=book_result&resnum=9&ct=result#PPP1,M1