Under fire -
Fire Safe Valves Withstand Explosions and Blazes.
Demand is Growing
Danger lurks everywhere. Fires are a daily risk in the oil and gas industry. Valves must cope with extremes in the case of emergency. Components thus need to be fire safe if they are to withstand threatening situations. Everything else would be playing with fire. No wonder demand is increasing for fire safe valves.
Losses can be devastating in a case of emergency; therefore, safety is just as high a priority for valves as high quality, and a long life cycle. "Fire safe valves are mainly used in the oil and gas industry, as risk of fire is high," explains product manager Stefan Keller, AS Schneider. Fire hazards lurk in each step of the process - ranging from oil and gas production to transport, as well as in refineries and storage. The consequences could "understandably be substantial," emphasises Keller.
Danger for man and material
Explosions in refineries or on oil rigs are a threat to man and material. A defective blowout preventer with safety valves played a major role in the devastating catastrophe on the oil rig "Deepwater Horizon", in the Gulf of Mexico. The valves malfunctioned, 780 million litres of crude oil flowed uncontrolled into the ocean, and caused several billion dollars in damages. Even more, eleven men died and 600,000 birds perished.
Other sectors also place their trust in fire safe valves. Petrochemistry, for instance, where "filling processes of inflammable substances in tank farms" are usual, explains Vetec Ventiltechnik. In a critical situation, fire safe valves have to stand the test in real conditions, particularly in view of having to handle fast filling times. Vetec developed a rotary plug valve with a double excentric plug design, which ensures that there is no contact between plug and seat while rotating. No particles can adhere in between. "The housing is basically free of dead space, so no troublesome soot deposits can occur," states Vetec.
Operating with highly flammable materials
Fire safe valves also provide the chemical industry with much needed security. Ethylene oxide becomes highly flammable in contact with oxygen, reports Vetec. In an emergency, fire safe valves go through hell to keep the plant safe. Valves should not only have a fire safe design, but also be certified as fire safe. Here, fire safe testing facilities come into play.
Specialised testing facilities leave nothing to chance and put valves through their paces. Take Amtec, for example. The company developed a new fire safe test rig to test valves according to DIN EN ISO 10497, API 607, API 6FA or API 6FB. "With this test rig, all important type acceptance tests for fire resistance can be conducted," says Manfred Schaaf, Amtec Advanced Measurement. Not only that: if needed, client-defined testing procedures can also be performed. This allows individual applications to be tested.
Automated ignition process
Amtec's test rig allows automated test procedures without manual intervention during firing and pressurising - for instance for regulating temperature and pressure. Ignition is automated, as well as the burner shutdown after the end of the firing period. Valve manufacturers are promised an improved repeat accuracy, a lower variation of temperature curves between tests and full compliance with norms. User-defined procedures are configured. And all of this with an increased level of safety, states Amtec: housing and burning chamber with window are closed, the flame is controlled, a pressure relief valve adds a further level of security. The housing temperature is controlled, including the automatic cooling system. The test rig is equipped with an emergency shut off function, turning off the burner and pump.
Under fire for 30 minutes
The stresses a valve must withstand in the test rig also depend on the test standard. There are important main criteria: the valve must be able to resist interior pressure - depending on norm, valve size and type. Water is used as a medium. Firing lasts 30 minutes, the flame reaches a temperature of up to 1000 °C, and the housing temperature 600 °C. After the firing period, water is used to cool down the valve to 100 °C, over a period of ten minutes. Depending on norm, cooling can also take place using air. It is essential for the "leakage rate to comply with the specific norm," emphasises Manfred Schaaf, Amtec. Packaging, housing seal and seat are viewed as critical. If a valve fulfils the leakage criteria set in a norm, the product receives a certificate: tested fire safe!