Worst Credible Process Fire: Experiences from the Norwegian Petroleum Industry
(2019) VRSM01 20191Risk Management and Safety Engineering (M.Sc.Eng.)
Division of Risk Management and Societal Safety
- Abstract
- The term Worst Credible Process Fire (WCPF) was introduced to the Norwegian Petroleum Industry as a complement to the probabilistic approach to define design loads for offshore facilities. Currently there are mainly two documents about the WCPF being the SINTEF report (2017) and the definition in NORSOK S-001 (2018). The WCPF concept have only been used within the industry for a few years and combined with the limited literature there might be some challenges that need to be considered. To investigate this, interviews were held with safety experts from various actors within the industry. With these interviews it was possible to address what the challenges are and if the perspectives vary within the industry. Similar concepts such as... (More)
- The term Worst Credible Process Fire (WCPF) was introduced to the Norwegian Petroleum Industry as a complement to the probabilistic approach to define design loads for offshore facilities. Currently there are mainly two documents about the WCPF being the SINTEF report (2017) and the definition in NORSOK S-001 (2018). The WCPF concept have only been used within the industry for a few years and combined with the limited literature there might be some challenges that need to be considered. To investigate this, interviews were held with safety experts from various actors within the industry. With these interviews it was possible to address what the challenges are and if the perspectives vary within the industry. Similar concepts such as worst-case scenarios, maximum credible scenarios and worst maximum credible scenarios were also studied as a complement to the interview study. The thesis found that some of the main challenges were subjectivity in scenario selection, lack of probability perspective and limited documentation for heat loads, temperatures and fire duration.
The thesis concluded that the view of the WCPF was not unified as the PSA is asking what is done and the industry how it is done. New companies did not seem to be unfairly affected by the limited literature in comparison to older companies. There were also some disagreements within the industry on how to approach the analysis. Variations within the industry could be approached in three separate ways, being transparency, standard methods and further clarification of the WCPF. Currently the literature surrounding WCPF could be considered enough but could be improved with additional clarifications. Lastly, the way barriers are credited in the WCPF could be improved and more justifiable with a higher focus on barrier management. (Less) - Popular Abstract
- The definition is clearer and encourage more robust designs, but the industry and the Petroleum Safety Authority have different focuses and subjectivity is still seemingly an issue. What can be concluded from the experiences within the industry?
The thesis investigated the Norwegian petroleum industry and its use of the term Worst Credible Process Fire (WCPF). It is a tool to design offshore facilities in a safe and robust way by using a representative scenario. The literature surrounding WCPF is quite limited and the term itself is relatively new. It assumes the worst fire with some credited (assumed to be to be working) safety systems. So now a few years after its introduction, what can the experiences from the industry tell us? What... (More) - The definition is clearer and encourage more robust designs, but the industry and the Petroleum Safety Authority have different focuses and subjectivity is still seemingly an issue. What can be concluded from the experiences within the industry?
The thesis investigated the Norwegian petroleum industry and its use of the term Worst Credible Process Fire (WCPF). It is a tool to design offshore facilities in a safe and robust way by using a representative scenario. The literature surrounding WCPF is quite limited and the term itself is relatively new. It assumes the worst fire with some credited (assumed to be to be working) safety systems. So now a few years after its introduction, what can the experiences from the industry tell us? What about the future?
It seems like the industry is more unified in its approach to the WCPF now than a couple of years ago. In fact, the industry manages quite well with the current definition. There are still some differences and difficulties though. The Petroleum Safety Authority focuses on what is done, and the industry on how it is done. It also seems like the WCPF definition is clear on what to do but the how is more subjective. This is where variation starts. This can be seen in everything from the word credible itself to simulation, to scenario selection. Subjectivity is – and has always been – a risk assessment challenge. To limit subjectivity and variation further, the thesis proposes the following strategies:
• Further specifications and instructions,
• Standard methods,
• and Transparency.
It is not possible to completely erase variation. In fact it can’t be erased since different facilities have different designs and needs. This means that the design loads will never be the same for different facilities. But these design loads can be decided with a standardized method to lower subjectivity.
There were the concern that smaller and newer operators might be affected by the limited documentation disproportionately in comparison to older operators. This did not however seem to be the case as the operators normally hire consultancies for risk assessments and calculations. By extension, this also means that it is mainly the consultancies that are in charge of the implementation of the WCPF. If the WCPF should be investigated further, consultancies should there get more attention.
Worst Credible Process Fire is meant to be independent of frequency, but the word credible itself and the crediting of safety systems does cover frequency, but only indirectly. However, some safety systems can be credited but others not. In terms of emergency shut down and depressurisation, both of which you can credit, there seems not to be many concerns. The drain system can also be credited. According to the industry maintenance and the state of the drain can vary for different facilities. It works well if maintained properly but if not it can have problems with clogging which can affect the availability of the system. The fire water system also works well if maintained properly but this system cannot be credited. Not including the effect of firewater for integrity estimates is actually part of the Regulations. But why credit the drain but not the fire water system? To not credit the fire water system promotes more robust designs, that’s why. Passive fire protection can be credited but isn’t tested for the high temperatures the WCPF can reach. This begs the question… Could the facility fall apart at these temperatures? We do not know that for sure until more temperature tests have been done. So, should systems that might not work be credited? Maybe not. So most importantly moving forward, when assuming a safety system works, make sure it works! (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/8995159
- author
- Tengvall, Linnéa LU
- supervisor
- organization
- course
- VRSM01 20191
- year
- 2019
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- Worst Credible Process Fire, Norwegian offshore industry, offshore fire safety, offshore process safety, offshore design
- language
- English
- id
- 8995159
- date added to LUP
- 2019-09-18 09:25:18
- date last changed
- 2020-12-03 14:26:14
@misc{8995159,
abstract = {{The term Worst Credible Process Fire (WCPF) was introduced to the Norwegian Petroleum Industry as a complement to the probabilistic approach to define design loads for offshore facilities. Currently there are mainly two documents about the WCPF being the SINTEF report (2017) and the definition in NORSOK S-001 (2018). The WCPF concept have only been used within the industry for a few years and combined with the limited literature there might be some challenges that need to be considered. To investigate this, interviews were held with safety experts from various actors within the industry. With these interviews it was possible to address what the challenges are and if the perspectives vary within the industry. Similar concepts such as worst-case scenarios, maximum credible scenarios and worst maximum credible scenarios were also studied as a complement to the interview study. The thesis found that some of the main challenges were subjectivity in scenario selection, lack of probability perspective and limited documentation for heat loads, temperatures and fire duration.
The thesis concluded that the view of the WCPF was not unified as the PSA is asking what is done and the industry how it is done. New companies did not seem to be unfairly affected by the limited literature in comparison to older companies. There were also some disagreements within the industry on how to approach the analysis. Variations within the industry could be approached in three separate ways, being transparency, standard methods and further clarification of the WCPF. Currently the literature surrounding WCPF could be considered enough but could be improved with additional clarifications. Lastly, the way barriers are credited in the WCPF could be improved and more justifiable with a higher focus on barrier management.}},
author = {{Tengvall, Linnéa}},
language = {{eng}},
note = {{Student Paper}},
title = {{Worst Credible Process Fire: Experiences from the Norwegian Petroleum Industry}},
year = {{2019}},
}