Jump to content

  • Log in with Facebook Log In with Google      Sign In   
  • Create Account


ChExpress Blog - 7/9/14

Read the latest news from the chemical industry in Christa's blog.

Featured Articles

Check out the latest featured articles.

File Library

Check out the latest downloads available in the File Library.

New Article

Product Viscosity vs. Shear

Featured File

Air Vessel Sizing for Water Hammer Prevention

Thermal Inbreathing Requirements As Per Api 2000 / Iso 28300:2008

api 2000

This topic has been archived. This means that you cannot reply to this topic.
3 replies to this topic
Share this topic:

#1 benoyjohn

benoyjohn

    Gold Member

  • Members
  • 70 posts

Posted 18 September 2011 - 03:13 AM

Hello,

The API STANDARD 2000 SIXTH EDITION, NOVEMBER 2009 indicates method for calculation of thermal inbreathing by formula.

Vit = C * Vtk ^0.7 * Ri (Sec 4.3.2.3.3)

For a case where volume of tank is 300 m3, located @ latitude 23 deg, operating at 30 deg C, the C factor for hexane fluid is 6.5.

Thus the thermal inbreathing requirement for a uninsulated tank works out to be 352 Nm3/hr.

However Annexure A which gives an alternative calculation method gives 50.4 Nm3/hr as the inbreathing requirement based on Table A.3.

Appreciate if someone could clarify this huge apparent discrepancy in the standard.

Thanks and regards,

Benoy

#2 ankur2061

ankur2061

    Gold Member

  • Forum Moderator
  • 2,253 posts

Posted 18 September 2011 - 03:22 AM

Benoy,

I would recommend that you go throught the following link carefully. The last post has a comparison between the old and the new API in the form of a powerpoint presentation where the importance of Annex A of the latest API 2000 is also discussed.Here is the link:

http://www.cheresour...g-requirements/

Regards,
Ankur.

#3 proinwv

proinwv

    Gold Member

  • ChE Plus Subscriber
  • 343 posts

Posted 18 September 2011 - 10:02 AM

Ankur's suggestion is very good.

Also, I can add that I attended a presentation on the 6th edition before its publication and this was mentioned by the presenter.

We were told that the new values were established based upon good science and testing. I cannot validate that statement. However, I have always believed that it was better to err on the side of larger vents than to undersize which can lead to an accident.

Further, to protect the tank from sudden drops in pressure due to a large vent opening under a small demand, the engineer should use multiple vents, staged to open at slightly different set points.

#4 fallah

fallah

    Gold Member

  • ChE Plus Subscriber
  • 3,066 posts

Posted 19 September 2011 - 03:34 AM

benoyjohn,

My response in brief:

For normal tank venting;
Tanks that meet the criteria in Annex A (section A. 1. 2) can have tank vents designed using the method shown in Annex A.
Tanks that don’t meet the Annex A criteria, then the general method in 4.3.2 should be used.

Thus you should check the conditions as per mentioned criteria and then use one of above methods accordingly.

Fallah

Edited by fallah, 19 September 2011 - 03:59 AM.





Similar Topics