The review concentrated on the risk to operators within the enclosure by studying fuel leaks and their ignition. Natural gas is the primary fuel at the Teeside plant, with naptha and propane used as the secondary fuels. Fuel is supplied at 25 bar gauge and reduced to 15 bar gauge before being sent to the nozzles. The PHR quantified small leaks as holes smaller than 1.5 millimeters, medium leaks as holes 1.5 to 6 mm in size, and large leaks as holes more than 6 mm. Ignition sources identified by PHR included faults in electrical equipment, gas turbine hot spots, fuel discharges that can cause static electricity, and the mechanical failure of rotating equipment.
Couplings protect turbines by limiting surges in torque.
The fault trees included data collected as detailed from the causes of leaks, likelihood of a flammable mixture formation, ventilation reliability, detection system ignition probability, and the probability of an operator being present. This approach enabled the analysts to compare the quantified level of risk against acceptable target criteria and highlighted those areas that contributed most to the risk. This application of a quantified approach is commonly used in the chemical and petrochemical industry, he added. Improving Maintenance Procedures Eutech made a number of recommendations to Enron to improve safety at Teeside. He said all of these hardware changes were implemented by Enron on a single turbine for study and refining before they are retrofit to all eight turbine enclosures at Teeside.