Accidents hoses

The strength of the hose was determined through a set of ten tension-to-failure experiments performed on miniature tension specimens cut from the accident hose. The experiments were performed both at room temperature and at 100°C (Fig. 11.9). 

Safety Showers. Safety showers and eyewash fountains or hoses should be installed where corrosive or toxic materials are handled. A large-volume, low velocity discharge from directly overhead should effect continuous drenching, ie, a minimum flow of 20 L/min (50 gal /min). Water to outside showers may be heated to a maximum temperature of 27°C by an electric heating cable. The valves for all safety showers should be at the same height and relative position to the shower head, and they should operate in the same way and direction. The shower station should be identified by paint of a bright, contrasting color. In areas where chemicals harmful to the eyes may be encountered, an eyewash fountain or spray should be available in case of splash accidents. 

The hazards of water hammer are described in Section 9,1,5 and the hazards of ice formation in Section 9,1,1, This section describes some accidents that have occurred as the result of the sudden vaporization of water, incidents known as boilovers, slopovers, foamovers, frothovers, or puking, Boilover is used if the tank is on fire and hot residues from the burning travel down to the water layer, Slopover is often used if water from fire hoses vaporizes as it enters a burning tank. Sections 9,1.1 and 12.4.5 describe incidents in which vessels burst because water that had... 

The most recent major expln in a US TNT plant occurred in May 1974 at the Radford Army Ammunition Plant. The accident completely destroyed one of the three continuous nitration lines at the plant. According to the AMC News, Sept 1974, the investigation board reported that an operator inadvertently introduced a 5 to 6-foot rubber hose to clean out unwanted material that had collected in a transfer line leading to the nitrator, when the hose was pulled from his hands into the nitrator. This resulted in a rapid temp rise and subsequent explosion. The hose was commonly used in this manner . The material causing the blockage in the transfer line was believed to be an oxidation product of TNT, 2,2 -dicarboxy-3,3, 5,5,-tetra-nitroazoxybenzene, also referred to as White Compound. The introduction of the rubber hose caused a rapid, exothermic oxidation reaction between the hose material and the mixed acid present. The heat generated by this reaction caused a local acceleration of the normal nitration/oxidation reactions which occur in the nitrator until a critical temp was reached, at which point rapid oxidation of DNT/TNT proceeded as a runaway reaction, igniting the material present in the vessel. 

The foreman recognized a possible hazard from flammable vapor escaping from the vent pipe and igniting on the sparks from the welding operation. He connected a hose to the vent at the top of the tank and ran the hose down to the ground. Because the flammable vapors were water soluble, he stuck the end of the hose in a drum full of water. During a subsequent operation that involved emptying the tank, an accident occurred. Can you explain what happened and how ... 

The accident investigation indicated that the explosion was caused by a static spark that jumped from the steel nozzle to the tank car. The nozzle was not bonded to the tank car to prevent static accumulation. The use of a nonmetallic hose probably also contributed. 

More than two years later a similar accident occurred in the same company, again the pump bearing overheated but on this occasion it was not the pump which exploded but a tanker refilling at a storage tank. The explosive decomposition had not been stopped by the cold transportation hose, as in 1999, which allowed it to enter the vehicle s tank and explode. The explosion caused injury to 11 people and severe damage to the immediate surroundings. 

On the night of the accident, operators heard a screeching noise from the relief valve on one of the tanks. Unfortunately, the closed blowdown system had been taken out of service for maintenance. It was later established that while operators were on their shift change or on a break, someone disconnected a pressure gauge from the cover plate on one of the tanks and attached a water hose. A quantity of water estimated between 450 and 900 kg entered the tank and caused a severe upset and release of MIC vapor. With no means of notifying the public and evacuating the community, thousands were exposed to the vapor cloud, resulting in the deaths and injuries. 

After discussion on this block has been completed, other blocks are subject to a similar examination. The loading of the tanker will be interesting, and will raise issues of possible overfilling, containment of spillages, drive-away accidents (when the tanker drives off before proper disconnection of hoses) and failure of plant operating procedures, as well as many of the fire scenarios dealt with previously. 

The District Engineering Inspectors Report confirmed that the machine was completely isolated and the ammonia system was not protected by a safety valve or any type of pressure-relief device. The cause of the accident was the presence of the steam hose underneath the equipment to melt the ice on the drain valve or to help evacuate the system. The inspectors report could not determine if these preparations were intentional or accidental. [5]... 

After the explosion, investigators confirmed that the 8-inch DEMCO block valve was open at the time of the accident. Furthermore, tests showed that the compressed air hoses were improperly connected in a reversed position. This unauthorized step during maintenance... 

The procedure was to clear the transfer fine of the waxy material with compressed air supply just before the transfer fine was put in service. On the evening of the accident, an operator connected an air hose to a 90 psig (6 bar) supply to clear the entire 200 meters (600 ft.) of feed line. The operator then walked to the elevated tank to determine if air could be heard rushing out of the tank vent. He heard nothing. The operator spoke to two maintenance employees working near the end of the 20-m3 (700 ft3 or 5,300 gallon) tank and left the area to find his supervisor. Shortly after that, one end of the tank blew off, and the two maintenance mechanics plunged some 40 ft. (12 m) to their deaths. [7]... 

Compressors, hoses, and pumps are very common, vital pieces of equipment in chemical plants, petroleum refineries, and terminals. Each of these pieces of equipment regularly conveys chemicals from one location to another in a safe manner. Each element serves the industry very well, but each must be properly specified, correctly installed, and maintained. Some accidents involving these industrial components are detailed below. 

Some of the most tragic and well-remembered accidents also had a start with a mini-modification made with a hose connection. The Bhopal Tragedy, the Three-Mile Island Incident, and the Flixborough Disaster were initiated by the improper use of hoses. 

Accident Involving Compressors, Hoses, and Pumps 153 Hoses Used to Warm Equipment... 

Van Pelt, Stephen, Choosing Hose Assemblies for Safety s Sake—Saving Money, Reducing Accidents, Chemical Processing, April 2002, pp. 29, 30. 

The procedure was to clear the transfer line of the waxy material with a compressed air supply just before the transfer line was put in service. On the evening of the accident, an operator connected an air hose to a 90 psig (6 bar) supply to clear the entire 200 meters (600 ft.) of feed line. The operator then walked to the elevated tank to determine if air... 

Hoses are essential within chemical plants. They are often necessary to purge vessels to wash vessels and to load and unload trucks, rail cars, barges, and ships. Hoses help to compensate for unavailable equipment, to prepare for maintenance, to safety-vent systems, and similar tasks. When hoses are misused, many unpleasant things can occur— including some of the world s worst chemical plant accidents. 

Full details of this accident can be found in several major reports. This brief review is focused on the utility hose and the one-minute modification aspects of the accident. Reportedly the trouble started when one of the parallel paths used to treat the secondary water system started plugging. When this resin polisher system, which is designed to remove trace impurities, started to plug, an operator decided to clear the blockage with instrument air. [9]... 

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