Third party certification
that a structure can retain and resist collapse. Furthermore, by modelling, a full structure can be investigated where the cost of performing a full scale test is prohibitive. This complication is further increased
when we consider the fact that LNG is stored under atmospheric pressure conditions and transported via pressurised pipe networks. A leak from a pressurised vessel, or even the base of a large tank, may initially lead to the liquid jetting, followed by a pool formation. Worsening the case, two different fire types can form from this release – pool and jet fire – and each has its own characteristics and effects on the protection or structure. Furthermore, classical analysis methods in engineering are based on assumptions of continuum behaviour, which means that the material properties can be averaged on a large scale and thus allow hand calculations to be carried out, or widely used engineering software to be implemented. However, this becomes inadequate when
low carbon ferritic steel structure (widely used in the oil and gas industry) is cooled to cryogenic temperatures. In these cases, we have to consider the impact of small cracks and defects inside the material, whose properties can no longer be averaged, as they start to behave as non uniformities in the structure. Analysing them and predicting their growth and reduction in the strength of the structure are critical to ensure that collapse does not occur during cold temperature exposure, and that the fire resistance is not compromised.
Damage control
The extent of damage can be significantly controlled by the application of cold spill and fire protection materials, and the computer analysis tools can aid in the design stage. However, it forms part of the weakest link model – ie the manufacturing of such protection – its installation, and inspection should be carried out accordingly to ensure that the product will perform as expected from the experimental stage. A failure of one system will trigger a systematic error in the ability of the protection to operate as expected, thus highlighting the importance of the certification process and the adoption of a risk management system. In order to ensure that a hydrocarbon fire
safety system remains relevant to the needs of the oil and gas industry, the characteristics of integral fire safety need careful consideration. Central to good fire protection in engineering or safety specification is the use of genuine and appropriate product testing, assessment and certification. Robust testing within the overall production of industrial structures will ensure that they remain fit for purpose, that their fire safety elements are installed correctly and that they are managed and maintained well over their lifetime
Dr Nikola Stoyanov is certification engineer and Jifeng Yuan is chief engineer and industrial supervisor at Exova Warringtonfire. For more information, view page 5
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www.frmjournal.com MARCH 2018
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