Many storage tanks currently in use in the chemical and related industries are designated as "atmospheric" storage vessels. Experience with the design of pressure relief systems on such vessels has shown that the design and basis of safety for pressure relief of atmospheric tanks is often misunderstood leading to situations where the tank may be subjected to pressures outside of the design limitations. This paper provides a summary of the design requirements for low-pressure storage tanks especially relating to the design and sizing of pressure relief systems. The various pressure relief cases applicable to storage tanks are considered and the appropriate sizing calculations discussed in order to provide safe venting of the system. Various types of pressure relief arrangements are described and their application to differing process conditions and materials is discussed. The key differences between the various types of pressure relief devices and systems are highlighted in terms of the relevance to the storage of flammable and toxic materials. The design and use of nitrogen purging and padding and flame arresters on vents is also examined.
展开▼
