Shell Deer Park Olefins Plant Explosion

Shell Deer Park Olefins Plant Explosion 

On June 22, 1997, an explosion and fire destroyed an olefin plant at the Shell Deer Park, Texas chemical complex. Thirty workers received minor injuries and extensive damage resulted to both the plant and adjacent community. The incident was caused by the sudden failure of a pneumatic check valve in a 300-psig gas compressor discharge line that led to a large release of propylene vapor. A few minutes after the release, the gas ignited causing a vapor cloud explosion and flash fire. 

Before the incident, the facility had experienced a power failure that led to the shutdown of an olefins unit. For several hours, a restart had been attempted and the compressor had tripped on high vibration at low speed. This caused the check valve to close, which placed additional stresses on the valve shaft. Failure to execute a smooth planned start-up was a key contributor to the timing of this incident. However, given the design defects inherent in the valve, an ultimate failure was inevitable. 

The investigation revealed that the valve design did not recognize or compensate for the forces experienced in normal operation at 300 psig. Alternatively, the design did not specify the correct hardware for the service conditions. Use of nonstandard hardware should be avoided until such time that its operation is well understood and documented. There are certain hazards and risks associated with the use of specialty hardware and these are magnified when large size equipment is used. 

Apart from the technical details of this incident, there were some organizational issues worthy of note. Shell operates refineries and chemical plants in many locations around the world. Before the incident at Deer Park, a similar failure had occurred in a pneumatic valve manufactured by the same supplier at another Shell refinery in the Middle East. A company-wide bulletin had been issued warning of the potential for failure with this type of valve, but no follow-up action appeared to have been taken. 

---

Shell Deer Park Olefins Plant Explosion... 

---