A review of the applicability of the jet fire resistance test of passive fire protection materials to a range of release scenarios
Introduction
Jet fires are recognised as severe hazard scenarios that require a test method capable of simulating both the high thermal and mechanical loads placed on passive fire protection (PFP) materials during direct jet-fire impingement. Following the Piper Alpha disaster and recommendations from the public enquiry (Cullen, 1990), a working group with members from the U.K., Norway and the U.S.A. developed an interim jet fire test method (HSE, 1993) (HSE, 1995), which then formed the basis of the international standard ISO 22899-1: 2007 (International Standardisation Organisation, ISO 22899-1, 2007). The ISO jet fire resistance test (JFRT) is currently the most widespread test method used to demonstrate PFP material resilience in jet-fire scenarios.
Recent years have seen an increase in concerns being raised by parties across industry that the current ISO jet fire resistance test (JFRT) is not representative of more severe jet fire scenarios. Such concerns have almost entirely been related to the heat flux values the specimen is exposed to during a test (Fire and Blast Information Group, 2018). Alternative methods of test, often referred to as “high heat flux tests”, have been developed by individual test laboratories, and are being increasingly requested by PFP manufacturers, engineers and operators. Such alternative methods of test are unpublished and without validation studies.
The growth of ad-hoc test methods is generating confusion within industry, leading some to call into question whether the JFRT is applicable to any jet fire scenario. There is a clear desire within industry for clarity on the applicability of the current JFRT and, if the test is not applicable to a given scenario, clarity on how a PFP system can then be tested to demonstrate resilience.
In early 2017 the U.K. Health and Safety Executive commissioned a literature review of large-scale jet fire tests (Health and Safety Executive, 2017) to address the situation. The primary aims were to assess the applicability of the JFRT to a range of jet-fire release scenarios, discuss whether further test method development is justified, and propose a plan for test development if deemed necessary. The literature review will be published as report MH/17/27 (hereafter referred to as the report).
Section snippets
Jet fire characterisation
The nature of jet fires has been studied in some detail (Lowesmith and Hankinson, 2007) (FABIG, 2014) (Chamberlain, 2002). Unlike furnace-based tests, jet fires produce highly non-uniform conditions and PFP system failure is far more likely to be localised, sudden and complete. Predicting the response of a PFP material in a jet fire is not trivial. The severity of a jet fire comes from a combination of thermal and mechanical loads when it impinges on an object, and the peak values of each are
Validation of the JFRT
Having stated the importance of characterising a jet fire through an appropriate description of the release and environment, and the importance of assessing the severity in terms of the thermal and mechanical loads applied, attention must be given to the large-scale releases characterised around the time of the JFRT development in the early 1990s. Although the quantity of large-scale jet fire test evidence was limited compared with that available today, the working group had access to detailed
Methodology
To the knowledge of the authors, there have been no tests performed that seek to characterise PFP material response in large-scale jet fires other than the 3 kg/s natural gas validation studies described above and a study of PFP performance on LPG tanks (HSL, 1996). In the absence of direct test evidence, an assessment of the applicability of the JFRT to alternative scenarios can be performed through consideration of the test aspects that affect PFP material response, and comparison of the
Conclusions
In this article the applicability of the JFRT to alternative release scenarios has been assessed by comparison of the conditions within the alternative scenarios to those within the 3 kg/s sonic natural gas release (referred to herein as the benchmark test).
This benchmark test, and by extension the JFRT, is concluded to be representative of unconfined and partially confined flashing liquid releases, or gaseous releases of similar flow rates and reservoir pressures (60 bar).
It is concluded that
Disclaimer
The paper's contents, including any opinions and/or conclusions expressed, are those of the authors alone and do not necessarily reflect HSE policy.
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A Review of the Applicability of the Jet Fire Resistance Test of Passive Fire Protection Materials to Severe Release Scenarios MH/17/27
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Jet fires involving releases of gas and solid particle
2021, Process Safety and Environmental ProtectionCitation Excerpt :In comparison, the sand and soil were observed to enter the high-pressure hydrogen jet fires in a field test, and the intensity of thermal radiation was found to increase (Acton et al., 2010), but the correlation is still unclear between solid particle entrainment and thermal radiation enhancement. In addition, the jet fire resistance test of passive fire protection materials only involves the release scenarios of gas, flashing liquid, crude-oil and gas-liquid mixture (Bradley et al., 2019). In short, the gas-solid jet fire seems to lack of consideration in terms of the thermal hazards and the reliability of protection barrier in process industry.