Academy Offers

AIChE members receive complimentary, unlimited access to live and on-demand AIChE webinars by purchasing them with their newly increased number of credits. See more resources.

Notice: AIChE Customer Service telephone lines have been temporarily impacted by Tropical Storm Isaias. Most calls will reach a representative, however, if you have an issue please email and we will respond as soon as possible. We apologize for any inconvenience.

Calculating Facility Siting Study Leak Sizes - Applications of the Maximum Design Leak (MDL) Approach

  • Type:
    Conference Presentation
  • Conference Type:
    AIChE Spring Meeting and Global Congress on Process Safety
  • Presentation Date:
    April 28, 2015
  • Duration:
    30 minutes
  • Skill Level:
  • PDHs:

Share This Post:

Consequence-based Facility Siting Studies (FSSs) typically requires the user assume a credible leak size to use in the evaluation of potential releases, which is often up to a 2” diameter leak. Many facilities tend to be less complex in comparison to large refineries or petrochemical plants, leading operators at the less complex facilities to ask why they should assume the same leak sizes as more complex facilities. Other facilities have unique processes with safety systems and factors they would like to quantify in a FSS. One solution would be to perform a Quantitative Risk Assessment (QRA) to capture the risks from all potential release locations and release sizes. However, many companies have not defined risk tolerance criteria and are resistant to do so for various reasons or do not want to invest in a QRA, which are more costly than a consequence-based study. A unique approach developed by ABS Consulting and first presented in 2011 is called the Maximum Design Leak approach [1]. This approach calculates frequency-based leak sizes and then applies the leak size that exceeds a frequency criterion (events/year) in a consequence-based FSS instead of assuming a given leak size as credible. This avoids having to establish risk criteria in terms of fatalities/year and having to model a plethora of scenarios yet takes advantage of many features in a QRA. This paper presents case studies as examples of how the MDL has been applied to several situations.

[1] The Maximum Design Leak (MDL) Approach to Leak Size Selection, G.A. Fitzgerald, M.W. Stahl, D.J. Campbell, F. Nouri, R.L. Montgomery, presented at the 2011 Mary Kay O’Connor Process Safety Center International Symposium, October 25, 2011.

Once the content has been viewed and you have attested to it, you will be able to download and print a certificate for PDH credits. If you have already viewed this content, please click here to login.



Do you already own this?



AIChE Member Credits 0.5
AIChE Members $15.00
AIChE Graduate Student Members Free
AIChE Undergraduate Student Members Free
Non-Members $25.00