The explosion in Tianjin, China, August 12, 2015

The explosion in Tianjin, China has been shocking to all of us in the process safety community. Outstanding firsthand videos and information have appeared on the Internet. A few sources are provided below as a reference to this article [1–3]. At the time of this writing, the investigation was continuing. The video demonstrates the difference between a deflagration and a detonation [3]. The big flash that occurs about 20 s into the video is most likely due to an ammonium nitrate explosion, or a related explosive, that contains both the reducing agent and oxidizing agent at the molecular level separated only by a single bond. The magnitude of this explosion ranks second in nonwarfare type of explosions. The first, was an explosion that occurred in Fauld, England in 1944, when an underground munitions storage facility blew up and left a 0.5mile-diameter hole and roughly at a depth of 100 ft [4]. A farm above was completely destroyed and all evidence of its existence disappeared. A crater remains today, and can be seen when hiking a short distance from the village. Looking at the overviews of the Tianjin explosion, we see a similar crater that has been created from the explosion (see the cover photo). One hundred and sixty-four people have been reported killed as of October 3, 2015. Concerning the location, it is a miracle that it was not higher. The storage facility was surrounded by inhabitants. It is reported that China had strict laws regarding the placement of hazardous materials relative to local populations. This facility overlooked regulations or became grandfathered in as the area developed around it. Storage of explosives is generally subject to the highest level of government regulation. Within the United States, for example, storage nonmilitary bulk explosives fall under the Alcohol Tobacco and Firearms regulatory agency. Remote storage is always a requirement. Another “history repeats itself” is related to the chemical itself. Ammonium nitrate can be explosive. It is a challenge to be in the explosive range because a small amount of moisture will move ammonium nitrate out of the explosive range. We must be vigilant when large quantities of ammonium nitrate are being stored. Are the storage piles/quantities above the critical diameter? Can moisture be removed because of excessive warming when sitting inside a closed building that is exposed to the sun? Fortunately, the munitions storage facility in 1944 was located in a very rural area of England. Tianjin is an example of how not to store highly hazardous chemicals—near highly populated areas. What about your hazard chemicals? Are they isolated from the surrounding population should something go wrong? Do you need all of that inventory at any one time? Thoughts to ponder as you read the links below and the reports provided by experts from China below. We are thankful to Ping Huang and Jingyuan Zhang, State Key Laboratory of Explosion Science, Beijing, and Byron Sun, AIChE-CCPS Shanghai, for contributing these articles under short notice and with the ongoing investigations continuing at the time.