Lagging fires pose a significant safety risk in industrial systems where organic contaminants interact with lagging (insulation) materials. This study used isothermal calorimetry to investigate factors influencing the self-heating and ignition propensity of various C18-based substances and rapeseed oil, as contaminants in the lagging. The contaminant and lagging under investigation were added to glass ampoules, and pentane was used as a solvent to distribute the contaminant on the lagging. The factors studied were lagging materials, molecular functionalities, and metal contaminants. It was found that substances with non-conjugated double bonds, particularly those containing bis-allylic hydrogen, gave rise to the greatest peak thermal powers. Noteworthy, all tested substances exhibited some level of reactivity, suggesting no substance can be considered completely safe without system-specific analysis. To evaluate different lagging materials, rapeseed oil was used. Greater peak thermal powers were observed with glass wool and stone wool treated at temperatures ≥500 °C, likely due to the degradation of the binder materials, as supported by TGA, SEM, and EDS analyses. Furthermore, it was found that metal salts (Mn, Fe, and Cu) and copper shavings significantly increased the reactivity, while stainless steel shavings had no significant effect. Mixtures of reactive substances behaved as single entities, and their peak thermal power could be estimated as a weighted average of the pure components’ peak thermal powers. The findings have practical implications for system design, material selection, and experimental protocols, aiding engineers in evaluating fire risks and developing safer insulation systems under realistic operating conditions. © 2025 The Authors

ABSTRACT The transition to fluorine-free firefighting foams has revealed that per- and polyfluoroalkyl substances (PFAS) can remain adsorbed on material surfaces and undergo slow desorption over time. This phenomenon results in the unintended contamination of fluorine-free replacement foams, continuing the environmental spreading of PFAS. Through an extensive review of peer-reviewed literature and supplementary data from direct contacts, this study consolidates current knowledge on the issue, representing one of the most comprehensive analyses to date. Existing research consistently identifies this as a significant challenge requiring attention. This review synthesizes findings from various studies, highlighting that certain cleaning agents and methodologies tend to demonstrate greater efficacy in removing PFAS residues compared to water. Proprietary products and available performance data were also evaluated; however, the range of such products remains limited, and for several, no conclusive evidence supports some of them to be superior to water. The most promising decontamination strategies involve a combination of water and co-solvents, potentially augmented by extreme pH conditions. To accurately assess the effectiveness of PFAS decontamination methods, a multi-faceted analytical approach is recommended. This should include PFAS target analysis, total oxidizable precursor (TOP) assays, and total organic fluorine (TOF) measurements. Additionally, comparisons of surface deposition estimates derived from diverse data sources emphasize the critical need for thorough PFAS decontamination before the implementation of fluorine-free replacement foams. Environmental Implication Per- and polyfluoroalkyl substances (PFAS) are pollutants of significant concern. Studies have linked PFAS exposure to a range of adverse health outcomes, including developmental, reproductive, hepatic, and immunological effects, as well as tumorigenesis in animal studies. Firefighting foams is one of the largest contributors to PFAS in the environment. When transition to fluorine free firefighting foams, PFAS remains adsorbed to the PFAS-exposed equipment and contaminates the product intended to be fluorine free. Effective decontamination protocols are needed to reduce the PFAS-rebound to a minimum. This paper synthesis knowledge from different studies to find trends improving the cleaning.

Current state of knowledge regarding PFAS-contaminated fire-fighting equipment   Since the discovery of per- and polyfluoroalkyl substances (PFAS), these have been a common additive in fire-fighting foam concentrates. This is because PFAS add properties that improve extinguishing performance, particularly against pool fires. PFAS constitute a group of substances, several of which have been shown to have negative health effects; furthermore, PFAS do not break down in nature (or do so only very slowly or to a limited extent). In addition to the negative health effects, increasingly strict legal requirements are gradually forcing a transition to PFAS-free fire-fighting foam. Today, there are PFAS-free fire-fighting foams developed for pool fires with sufficiently good performance, and there is normally no reason not to switch to PFAS-free foams. Several studies have highlighted challenges with this transition – despite cleaning equipment, PFAS remain on the surfaces of fire-fighting equipment materials, and residual PFAS will slowly leach over time and contaminate the product that is intended to be PFAS-free (so-called PFAS rebound). This report provides a summary of the legal requirements as well as an overview of the tests that have been conducted to clean equipment and limit PFAS rebound. Factors that appear to improve the cleaning effect include elevated temperature, scrubbing/high-pressure washing, and the addition of solvents (e.g., methanol, ethanol, and butyl carbitol). pH is also noted to influence cleaning, and it may be necessary to combine washes with both high and low pH. Furthermore, the report concludes that cleaning is needed to meet the levels proposed in the requirements, and that complete cleaning is not considered possible based on current knowledge.

This investigation delves into the extraction dynamics of 22 per- and polyfluoroalkyl substances from PFAS contaminated firefighting materials. Two distinct test sets were executed: one contrasting a commercial product with water following an elaborate decontamination procedure, and the other assessing seven washing agents on materials from firefighting installations, with one agent examined at 22 °C and 50 °C. A general tendency for improved desorption at the higher temperature was observed. Furthermore, a discernible influence of the cleaning agent's pH on the extraction of specific PFAS species was observed, elucidating the role of chemical environment in the extraction process. PFAS rebound was studied for a period of up to 157 days, this unveiled a gradual escalation in PFAS22 levels, indicative of a protracted desorption mechanism. Intriguingly, PFAS with abbreviated carbon chains (C4–C6) exhibit superior desorption efficiency compared to their elongated congeners, suggesting a chain-length-dependent decontamination potential. A comparative scrutiny between a commercially available cleaning product, featuring multiple washing and flushing steps, and a water-only treatment regimen underscores the potential efficacy of the former. This exhaustive investigation furnishes nuanced insights into PFAS extraction complexities, offering a foundation for informed decontamination strategies

In recent years, fire accidents on Ro-Ro ships have led to numerous fatalities and significant economic losses. The response of the crew and the ship's protection systems are crucial in managing these incidents and mitigating their consequences. To assess fire safety improvements, this study has focused on developing and quantifying a risk model that captures the dynamics of a fire starting in a Ro-Ro space. Various risk modelling techniques were reviewed to construct the model, which was then quantified using historical data, simulations, and expert judgments. A Delphi-based, fully digital approach to expert elicitation was introduced, utilizing Microsoft Teams and Microsoft Excel-based questionnaires. This method ensured full anonymity for the experts, reducing the risk of group bias and eliminating the need for travel. To enhance understanding and verify the results, uncertainty and sensitivity analyses were performed. They revealed that the potential loss of life deviated, with 90% confidence, from the calculated mean value by less than 26%. Overall, the questionnaire-based method proved effective for expert elicitation and for quantifying nodes in the risk model, demonstrating its utility in the risk assessment process.

Reducing the environmental and climate impact of shipping propelled by liquefied natural gas (LNG) requires the introduction of alternative fuels such as liquid biogas/biomethane (LBG) (Jivén et al., 2022). Today, only a small part of the biomethane produced in Sweden is liquefied into LBG and an even smaller part is used as fuel for shipping. The price and availability of biogas is governed by supply and demand in an international market where shipping, industry and heavy trucks demand biogas. The biogas then needs to be processed into upgraded biogas (biomethane) or LBG quality in order to be transported and used in the respective sectors inside and outside of Sweden. The trend is for a larger proportion of biogas to be liquefied into LBG. The market has thus gone from a local market, where biogas was produced in the city's wastewater treatment plant and the city buses ran on biogas, to an international market where biogas often is transported in the same way as fossil gas and marketed using the fossil gas together with certificates. The project "Renewable liquid biogas (LBG) for shipping in practice" was carried out by IVL Swedish Environmental Research Institute and RISE in 2023 together with stakeholders from the shipping sector, ports and industry organizations for biogas. The project has studied the conditions required to make LBG available to shipping in practice at Swedish ports. The study shows that the major obstacles to an established use of LBG in the shipping sector in Sweden today are pricing/willingness to pay that is affected by international market prices, lack of suitable logistical solutions as well as the absence of the piece of the puzzle that is the business model and cooperation needed to make available the large volumes of biogas that shipping may demand. The stakeholders in the project estimate their total need of biogas to 3 TWh in a short term, and 10 TWh in a longer term. The project has identified a number of conclusions and recommendations for future work, including that the potential for biogas is large and untapped, but that new solutions for the distribution and logistics of LBG are needed. There is a clear interest from maritime actors as they see biogas as a strategic solution and the dialog between actors in the industry remains important. A change in the tax system could be needed so that more actors can use the green gas principle for LBG. In addition, a functioning "marketplace" is needed, which simplifies for sellers and buyers of LBG, and agreements/contracts are needed that are longterm and to a greater extent based on the costs of producing and providing LBG.

Lagging fires, also known as insulation fires, pose significant risks in the process industry, arising from the self-heating of leaked combustible liquids within insulation materials. These fires typically initiate through oxidation, leading to smouldering that can escalate into larger fires or serve as ignition sources for other flammable materials. Statistics from the Swedish Contingency Agency was collected for a period of ten years an revealed an average of ten fires per year. Following discussions with six industries, this is likely an underestimation. A small-scale test method, based on isothermal calorimetry, has been developed to estimate a system’s self-ignition temperature. The small-scale test method resulted in apparent heat generation rates, which were used to model lagging on a DN50 pipe. To find an ignition criterion, real-scale tests were conducted. A system comprised of rapeseed oil and industrial lagging was used. The small-scale method was used to study and compare the reactivity of different C18-substances. It was found that substances with conjugated double bonds are more prone to self-heat than substances with a single double bond, whin in turn are more reactive than substances lacking a double bond. Thermal power from rapeseed oil mixed with either mineral wool, glass wool, or mineral wool treated at 500 °C were studied with isothermal calorimetry. One of the materials, as well as the heat-treated mineral wool were found to increase the maximal thermal power. This highlights that different laggings, or elevated temperatures, may affect the risk of a lagging fire. It was also found that copper catalyses the autoxidation and thus increases the risk of a lagging fire. 

Lagging fires, also known as insulation fires, pose significant risks in the process industry, arising from the self-heating of leaked combustible liquids within insulation materials. These fires typically initiate through oxidation, leading to smouldering that can escalate into larger fires or serve as ignition sources for other flammable materials. Statistics from the Swedish Contingency Agency was collected for a period of ten years an revealed an average of ten fires per year. Following discussions with six industries, this is likely an underestimation. A small-scale test method, based on isothermal calorimetry, has been developed to estimate a system’s self-ignition temperature. The small-scale test method resulted in apparent heat generation rates, which were used to model lagging on a DN50 pipe. To find an ignition criterion, real-scale tests were conducted. A system comprised of rapeseed oil and industrial lagging was used. The small-scale method was used to study and compare the reactivity of different C18-substances. It was found that substances with conjugated double bonds are more prone to self-heat than substances with a single double bond, whin in turn are more reactive than substances lacking a double bond. Thermal power from rapeseed oil mixed with either mineral wool, glass wool, or mineral wool treated at 500 °C were studied with isothermal calorimetry. One of the materials, as well as the heat-treated mineral wool were found to increase the maximal thermal power. This highlights that different laggings, or elevated temperatures, may affect the risk of a lagging fire. It was also found that copper catalyses the autoxidation and thus increases the risk of a lagging fire.

Lagging fires, also known as insulation fires, pose significant risks in the process industry, arising from the self-heating of leaked combustible liquids within insulation materials. These fires typically initiate through oxidation, leading to smouldering that can escalate into larger fires or serve as ignition sources for other flammable materials. Statistics from the Swedish Contingency Agency was collected for a period of ten years an revealed an average of ten fires per year. Following discussions with six industries, this is likely an underestimation. A small-scale test method, based on isothermal calorimetry, has been developed to estimate a system’s self-ignition temperature. The small-scale test method resulted in apparent heat generation rates, which were used to model lagging on a DN50 pipe. To find an ignition criterion, real-scale tests were conducted. A system comprised of rapeseed oil and industrial lagging was used. The small-scale method was used to study and compare the reactivity of different C18-substances. It was found that substances with conjugated double bonds are more prone to self-heat than substances with a single double bond, whin in turn are more reactive than substances lacking a double bond. Thermal power from rapeseed oil mixed with either mineral wool, glass wool, or mineral wool treated at 500 °C were studied with isothermal calorimetry. One of the materials, as well as the heat-treated mineral wool were found to increase the maximal thermal power. This highlights that different laggings, or elevated temperatures, may affect the risk of a lagging fire. It was also found that copper catalyses the autoxidation and thus increases the risk of a lagging fire.