Using LOPA for Sil Assignment: A Tale of Two Plants

Global Congress on Process Safety
2011 Global Congress on Process Safety
Global Congress on Process Safety
March 13, 2011 - 8:00pm

Two plants operated by the same company have ?identical? ammonium nitrate (AN) solution pump installations. Yet the LOPA teams concluded that the safety instrumented functions to protect those pumps needed different safety integrity levels (SILs). Despite the similarity of the installations, the teams discovered legitimate differences that warranted different conclusions about what SIL assignment should be. For those with a specific interest in AN, this paper reviews the consequences of AN pump hazards, their initiating causes, and the types of independent layers of protection (IPL) that can be brought to bear. Of more general interest will be the discussion of the impact of risk tolerance criteria, frequency modifiers, and IPLs on final SIL assignment, and why dictating a fixed SIL assignment to certain types of hazards or installations is inappropriate, especially in the development of industry standards or government regulations.
Professional Development Hours
0.5 PDHs
You will be able to download and print a certificate for these PDH credits once the content has been viewed. If you have already viewed this content, please click here to login.

Would you like to access this content?

No problem. You just have to complete the following steps.

You have completed 0 of 2 steps.

  1. Log in

    You must be logged in to view this content. Log in now.

  2. Purchase Technical Presentation

    You must purchase this technical presentation using one of the options below.
    If you already purchased this content recently, please click here to refresh the system's record of ownerships.


Credits 0.5 Use credits
List Price $25.00 Buy now
AIChE Members $15.00 Buy now
AIChE Undergraduate Student Members Free Free access
AIChE Graduate Student Members $15.00 Buy now