PROTECTION OF STORAGE TANKS FROM 2-PHASE FLOW DUE TO FIRE EXPOSURE

Various approaches are presented to protect storage tanks from fire ex posure. Design techniques for emergency relief devices flowing vapor o r two-phase vapor-liquid flow are discussed The effects of maximum des ign pressure versus emergency relief device set pressure, fire exposur e insulation and water spray protection fire exposure duration, relief device flow characterization and inlet pipe pressure drop and dischar ge pipe back pressure must all be considered when designing to prefect storage tanks. This paper discusses some aspects of pressure relief d esign for low pressure storage tanks. The concepts and techniques disc ussed here can be modified to include design guidance/recommended desi gn parameters from specific standards. Even if not used for pressure r elief design, the concepts/calculations presented should be useful for Process Hazard Analysis studies to determine the relative ranking of credible scenarios. The reader is cautioned that no attempt was made t o cover every design situation or conform to any design standard/recom mended practice. There ale too many specific scenarios and too many (u nnecessary) conflicts between standards/recommended practices. Instead , the reader is cautioned to ensure that all prescribed federal, state and local as well as company design standards are followed when manda ted.