There are three valve-related accidents have taken place in the past month. Valve in oxygen cylinder the culprit in 747 explosion 
In July 29, 2008, a valve from an oxygen cylinder blasted a hole at least 20 centimeters in diameter in the floor of the passenger cabin of the Qantas 747 stricken in mid-air emergency. On QF30, the 346 passengers and 19 crew, all uninjured, reported hearing a loud bang before the plane suddenly depressurized. The hole in the cabin floor was at the galley area between business and economy sections, according to John Westcott, a commercial aircraft captain who was a passenger. Broken Valve Leaves Part Of Port Columbus Without Water COLUMBUS, Ohio — A portion of Port Columbus International Airport was without water after a 12-inch water line broke Friday night. A broken valve sent water gushing onto International Gateway, 10TV News reported. A boil alert was issued for business and homes in the surrounding area. People should boil water for at least 60 seconds before drinking or cooking. Small valve leak found on nuclear sub 
A small radioactive leak aboard the fast-attack submarine Houston was confirmed during testing July 24, prompting submarine officials to notify federal authorities, according to a Navy spokesman. The boat was in dry dock for scheduled maintenance when the leak was discovered, said Lt. Cmdr. One of the shut valves associated with the boat’s propulsion system was “weeping” water at a rate higher than design specifications, he said. As we know a valve is a device that regulates the flow of substances (either gases, fluidized solids, slurries, or liquids) by opening, closing, or partially obstructing various passageways. The development of valves is closely related to the development of industry. And now they are used in a variety of applications including industrial, military, commercial, residential, transportation. Plumbing valves are the most obvious in everyday life, but many more are used. In a word valves are playing an important role in our life. And you can not fell the importance of valves until the accidents taken place. In much time the broken of valves will bring serious damage. So what can we do to avoid the accidents caused by valves? The fist thing many people will think out is that we should make new valves. The new ones must be more stable. In fact the development of valves has never stopped. On the one hand many new kinds of materials are used in valves and the structure of valves is also improved. On the other hand by combing computer technology with valves they have became more precise. But there is another thing many people forget. No matter how well a machine is, it still needs to be manipulated by people. In many times accidents are not caused by machines but by people. So we still need to improve the responsibility of the people who operate valves while we improve the quality of valves.