January 29, 2021
January 25, 2021
TEG SOAKED INSULATION FIRE INCIDENT
A fire on an offshore installation has highlighted the risk of low temperature spontaneous combustion from TEG soaked insulation. An investigation has shown that spontaneous combustion of TEG soaked into fibrous materials can occur at relatively low temperatures (70oC). Therefore, specific precautions are required for stripping and disposal, to avoid unexpected ignition and fire.
The incident occurred on the process deck and involved removal of the aluminium cladding and TEG soaked insulation (Kaowool Ceramic) from dehydration system pipework following a small leak of hot TEG from a flange. The materials were temporarily stored, with rags used to mop up excess TEG from the deck, in a plastic sack. Spontaneous combustion subsequently caused a fire, which consumed the sack and contents.
The TEG soaked insulation was at, or near, the pipework temperature when it was placed in the plastic sack. The process of stripping the insulation allowed air to be absorbed into the insulation. In addition, dry hot insulation could have come into contact with TEG soaked insulation after being removed from the pipework.
As the insulation cooled it was possible for an oxidation process to have begun in the centre of the waste in the plastic sack, which eventually gave rise to spontaneous ignition and combustion.
This incident is an example of a well-recognised phenomenon more often observed in oil soaked rags in workshops and insulation soaked in mineral oil. It is less common in relation to TEG but can occur in the following circumstances: For spontaneous combustion to occur, TEG must be absorbed into an insulating material which has sufficient void spaces for air to be absorbed. The temperature will rise if the temperature of the insulation is relatively high and the volume sufficient to allow heat generated by an oxidation process at its centre to be retained. The larger the volume of the insulation, the greater the amount of heat retained and the lower the temperature at which spontaneous combustion of the TEG will begin. High temperatures can develop that could lead to a fire. If the bulk of TEG soaked insulation is large enough, spontaneous combustion could occur even if the insulation starts from cold. However, the time taken before the initiation of the rapid heating process would be much longer. TEG soaked rags are much less reactive than insulation, but could still present a hazard. TEG dehydration systems can run at temperatures up to 200oC and pipework is often insulated with fibrous rock wool type material. This material has a structure suited to the absorption of air into the void spaces. In normal circumstances the insulation will be clad with aluminium plate, which holds the insulation in a compressed state and prevents the ingress of air. When cladding is removed and the insulation stripped from the pipework, air will be absorbed into the insulation. If the TEG and insulation are hot from the process pipework and collected in bulk, the conditions within the stripped material can be susceptible to spontaneous combustion.
SOURCE:IOGP
January 21, 2021
January 17, 2021
January 13, 2021
INCIDENT DUE TO BLOCKING OF ISOLATION VALVE
In 2008, facility workers in the US closed an isolation valve between the heat exchanger shell and a relief valve to replace a burst rupture disk. Maintenance workers replaced the rupture disk on the day, however, they forgot to reopen the isolation valve. The next day, other facility workers closed a block valve to isolate the pressure control valve from the heat exchange so that they could connect a steam line to the process line to clean the piping. The steam flowed through the heat exchanger tubes, heated the liquid in the exchanger shell, and increased the pressure in the shell. The closed isolation and block valves prevented the increasing pressure from safely venting through either the pressure control valve or the rupture disk and relief valve. The pressure in the heat exchanger shell increased until it violently ruptured.
January 9, 2021
MY ARTICLE IN CEP ISSUE JANUARY 2021
My fourth article "Understand Process Hazards to Safely manage Change" has been published in the January 2021 issue of the CEP magazine of the American Institute of Chemical Engineers. Read it after logging in in this link https://www.aiche.org/publications/cep
You have to be a member of AIChE to read it.
January 5, 2021
January 2, 2021
Tank explosion due to a chemical reaction
The accident occurred when nitric acid delivered to a factory by a tank truck was unloaded into the wrong tank. The tank exploded due to a chemical reaction within the tank.Around 5:30 in the afternoon on the day of the accident, the driver of the tank truck carrying nitric acid arrived at the factory, handed over a delivery slip to the employee inc harge of accepting deliveries, and connected the hose of the tank truck to the flange(for unloading).As this was the first time for the driver to make deliveries to this factory, his co-worker who has delivered to this factory before told him that the flange for nitric acid was the second from the left. However, as the second flange from the left was made of vinyl chloride and the driver did not think that this could be the pipe for nitric acid, the driver connected the hose to the second flange from the right, which was made of stainless steel.After the connection of the hose, the employee in charge of accepting deliveries opened the electromagnetic valve, and the driver started the discharge. As the liquid surface of the nitric acid tank did not rise, however, the driver checked the label of the tank and found that he was unloading nitric acid into the tank for triethanolamine.The driver informed the employee in charge of accepting deliveries of the mistake,connected the hose to the correct flange for the nitric acid tank, and completed the unloading in about 20 minutes. When the driver was going out from the front gate, he noticed white smoke being emitted from the tank. Around 6:25 in the afternoon, the sub-tank and main tank for triethanolamine that were wrongly charged exploded,releasing a chemical spill in the area.No injuries or fatalities were caused by this accident.
Causes
The following can be considered as the causes of this accident.The hose of the truck delivering nitric acid was mistakenly connected to the pipe for the wrong chemical. The contact and coordination procedures for chemical delivery work were insufficient.Safety and health education for workers was insufficient.
Source: tamu.edu