Cause of Caribbean Petroleum Tank Farm Fire was faulty level indications says CSB

Industrial Accidents

Here’s an update on the the Caribbean Tank Farm Fire from the CSB (US Chemical Safety Board).

Bayamon, PR, November 17, 2009 – The U.S. Chemical Safety Board (CSB) today announced that it will be conducting a full investigation of the October 23, 2009 explosion and fire at Caribbean Petroleum Refining. CSB investigators continue to examine the events and circumstances surrounding the catastrophic tank explosion and fire.

At 12:23 a.m. on October 23, a large vapor cloud ignited at the Caribbean Petroleum facility near San Juan, Puerto Rico. The blast damaged homes and businesses over a mile from the facility. Investigators from the U.S. Chemical Safety Board arrived in Puerto Rico that evening. Over the past few weeks the five-person investigation team has conducted numerous interviews, requested hundreds of pages of documents and catalogued key pieces of evidence.

CSB Board Member William Wright said, “The CSB will conduct a thorough and comprehensive investigation of this accident; our team will uncover exactly what events led to an explosion of this magnitude. Our goal is to determine not only what happened, but why it happened.”

At the time of the incident a tank was being filled with gasoline from a ship docked in San Juan harbor. Investigators have determined that a likely scenario leading to the release was an accidental overfilling of the tank. Gasoline spilled from the tank without detection; as the material spilled it vaporized and spread across the facility. CSB investigators estimate that the vapor cloud spread to a 2000 foot diameter until it reached an ignition source in the northwest section of the facility.

The CSB found that on the evening of the incident, the liquid level in the tank could not be determined because the facility’s computerized level monitoring system was not fully operational. In order to monitor the level in the tank, operators used a mechanical gauge on the tank’s exterior wall. Therefore as the gasoline , employees located in the facility’s control room were unaware of the emergency.

“The filling of a tank without a functioning monitoring system is the type of activity the CSB will be examining very closely,” said Investigator-in-Charge Jeffrey Wanko, P.E. CSP. “The CSB’s investigation will examine operations particular to Caribbean Petroleum, but will also look at the regulations and best practices surrounding the industry as a whole in an effort to improve safety practices at similar facilities.”

So once again the same old story about poor level monitoring and overfill protection systems continues….the last such level monitoring failure was at Buncefield in the UK, where a malfunctioning level indicator caused overfilling and a massive explosion and fire. (Read more about it on this bog by typing Buncefield in the Search box)

On a side note: To prevent accidents and such undesirable events, it is not only essential that your plant or facility have the necessary instruments and systems, but also your staff needs to have training in how to use them. An example would be the excellent training course on hazardous area instrumentation here and another one on gas monitors here.