Methodology for Inherent Safety Assessment of Heat Exchangers in Early Design Stages
Abstract
Shell and tube heat exchangers are used extensively in the process industry; they are a part of every process and make up for significant part of the capital cost investment. Due to high number of heat exchangers present in plant, their frequent failure is also a continuous problem. The heat exchanger failures can lead to lower production, unplanned shutdown and in some cases injury or loss of life. Insufficient safety analysis and lack of risk assessment followed by inherent safety considerations in the initial phases of design are the primary reason behind frequent failure of these exchangers. Investigations of previous incidents indicate that the failures could have been avoided, if appropriate safety assessment of the equipment was carried out in the basic engineering phase.
This study focuses on underlying reason behind frequent failure of shell & tube heat exchangers and develops a methodology for inherent safety quantification of these exchangers in early design stage. The current practice is to use QRA for safety assessment of heat exchangers, which can only be done at later stages in project development, and by this time the opportunity to implement inherent safety principles is minimum and expensive. In this work, an index has been developed which incorporates the safety aspect of metallurgy selected and possible interaction between the material of construction and selected process chemical. Additionally, a framework has been proposed which provides systematic evaluation method for equipment safety along with process safety in the basic design phase of the project.
The developed methodology was applied to a fire and explosion which occurred at Tesoro’s, Anacortes refinery due to catastrophic rupture of heat exchanger and resulted in seven fatalities.
An important conclusion that can be drawn from this work is that inherent safety principles can be applied to metallurgy selection process of equipment, which is typically during pre-design and basic engineering phase of the project. Then utilizing the information available inherent safety level assessment of both process and equipment can be carried out in the early design stage.
Subject
Shell and Tube Heat ExchangersInherently Safer Design
Metallurgy interaction
Heat Exchanger Safety Index
Equipment Safety Index
Collections
Citation
Sarkar, Richa (2018). Methodology for Inherent Safety Assessment of Heat Exchangers in Early Design Stages. Master's thesis, Texas A & M University. Available electronically from https : / /hdl .handle .net /1969 .1 /173358.