On January 13, 2022, workers inside the company’s fabrication shop performed a "wet test" on a newly built tank truck to check for leakage. This entailed running diesel test fuel through different tank compartments and other truck components. This was a routine operation at the workplace. Workers knew never to use gasoline, and the company had a standard operating procedure that prohibited gasoline or any tanker truck containing gasoline from entering the fabrication shop. The diesel test fuel was stored in a tank outdoors.

The day before, another worker had used diesel test fuel to "wet test" a newly built tank truck OUTDOORS. They left the diesel test fuel in the truck to calibrate the diesel meter. At some point, more fuel was added to the truck.  On January 13, a worker pumped the diesel test fuel from the truck OUTSIDE into the truck inside the fabrication shop. That afternoon, flammable liquid vapors in the vicinity of the truck inside the shop ignited, causing one explosion followed by a second larger explosion. Seven (7) workers were injured, six fatally and one critically as a result.

Following the explosions and fire, several fuel storage tanks at the workplace were tested for contamination. Gasoline was identified as a contaminant in several diesel tanks, and diesel was identified as a contaminant in a gasoline tank.

An Ontario Fire Marshall investigation found that the gasoline involved in the explosion resulted from the use of CONTAMINATED diesel test fuel in the "wet test."

I have written several articles on the topic of when we store our flammable liquids BELOW their flash points with the aid of refrigeration and how that makes our "refrigeration/chiller" a critical utility if we wish to take credit for storing the flammable below its FP.  I have also discussed processing a Class IIIB/Cat 4 flammable liquid within 30 degrees of its FP.  However, this article is about a "utility process" used for heating a process, and the heat transfer fluid (HTF) is heated above its FP. 

This process and analyzing its hazards can be tricky. When we look at the Safety Data Sheets and the Technical Datasheets, these fluids are almost always listed as "Non-Flammable" as their FPs are well over 200F.  So at standard temperature and pressure (i.e., 68°F and 14.7 psi), the solution is indeed NOT flammable; however, we will be heating the solution to above its FP.  This is a recognized hazard by OSHA, Insurance Providers, and NFPA; which insurance and NFPA 30 provide the user(s) some excellent DESIGN features to help PREVENT a LOPC event and PROTECTION and MITIGATION layers when the LOPC event occurs.

First and foremost, codes and standards manage these hazards by setting a tolerance against operating up to 30 degrees within the solutions FP.

Are "safety cans" created equally?  Nope, and which UL standard they meet will dictate how much "safety they provide."

OSHA's 1910.106 defines a "safety can" as

Safety can shall mean an approved container, of not more than 5 gallons capacity, having a spring-closing lid and spout cover and so designed that it will safely relieve internal pressure when subjected to fire exposure.

 

NFPA has a slightly different definition:

Have you ever walked up to a atmopsheric storage tank and seen the paint bubbling and the hazard signs/placards faded/peeling off?  Look up and you will most likely see the atmopsheric vent line on that side of the tank.  What are these indicators of?  The tank being over filled, which is a serious event and is certainly a Loss of Primary Containment (LOPC) event.  But these days, these events should be a thing of the past, as the IFC and most state Fire Codes now require these flammable liquid Storage Tanks to have "Overfill" safety systems.

(emphasis and revised structure by me)

DOT tank vehicles and tank cars are NOT allowed to be used as flammable liquid storage tanksAlthough it is done often, most state Fire Codes PROHIBIT the use of DOT tank vehicles and tank cars as "Flammable Liquid Storage Tanks."  We call this "dropping trailers," and my 2014 Article "Dropping Trailers of Flammable Liquids" got quite the debate going.  But trust me, there are sound engineering reasons why we can not and should not use DOT shipping containers as "flammable liquid" storage tanks. In this article, I provide those sound engineering reasons. Hint: Materials of Construction!

NOTE: this unsafe practice can also have an impact on PSM/RMP coverage!

Here is the OH Fire Code language (mimics the IFC)

(emphasis by me)

This is another opportunity for facility sitting to apply specific metrics to the exercise. Just as the distances for Tank Truck and Rail Car Unloading/Loading facilities are intended to protect our bulk storage tanks, this is intended to prevent BLEVE(s) that could impact the above-ground storage tank.

(emphasis by me)

1910.106(b)(2)(ii)(f) The MINIMUM SEPARATION between a liquefied petroleum gas (LPG) container and a flammable liquid storage tank shall be 20'...

SUITABLE MEANS shall be taken to PREVENT the accumulation of flammable liquids under adjacent LPG containers such as by diversion curbs or grading.

When flammable liquid storage tanks are within a diked area, the LPG containers shall be outside the diked area and at least 10 feet away from the centerline of the wall of the diked area.

 

SAFTENG members can download the image depicting this requirement

 

LPG and Flammable Liq Tanks WM

 
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