Can Propane-LPG Tanks (Gas Cylinders) Explode - Propane-LPG Gas Tank Explosion - LPG Explosion
A gas cylinder can explode if it heats up and the pressure builds at a rate that overcomes the pressure relief valve. The result could be a BLEVE - Boiling Liquid Expanding Vapour Explosion – a gas cylinder explosion, which is a rare event.
However, that is a very unlikely and uncommon scenario. Propane-LPG gas tank explosions (gas cylinder explosions) do not happen with any frequency. An Propane-LPG gas tank explosion is actually quite rare. Propane tanks-LPG gas cylinders can explode but not easily or often. Even trying to cause a Propane-LPG gas tank explosion intentionally is very challenging.
Now, you may be thinking that I am only saying this because I work for an LPG company.
How can what I say be true when you see reports of “Propane-LPG tank explosion” in the news with some frequency?
The issue lies with the erroneous reporting of the LPG explosion facts…
Propane-LPG Gas Tank Explosion vs LPG Explosion - Can Propane Tanks Explode
A BLEVE - Boiling Liquid Expanding Vapour Explosion – which is an LPG gas tank explosion, can occur if it heats up and the pressure builds at a rate that overcomes the pressure relief valve.
It is extremely difficult to get a propane tank to explode or LPG gas tank to explode, even trying intentionally. A Propane-LPG gas tank explosion (gas cylinder explosion) is a very rare event. What is usually taking place is an LPG explosion that does not directly involve the gas bottle(s).
Propane tanks can explode but it is also rare.
The real issue lies with poor reporting. Reporters have a habit of saying any LPG explosion that involves bottled gas is a "Propane-LPG tank explosion" or “propane tanks explode”.
The typical scenario is an LPG gas leak explosion from a gas appliance, connection or fitting.
Gas from the leak accumulates within a confined space and that is what catches fire or an LPG explosion.
Because home LPG bottles are normally stored outside, the gas bottles or LPG tanks themselves are frequently untouched by the LPG gas leak explosion or fire.
For example, there was a tragic accident a few years ago involving an LPG explosion and fire.
The newspaper headline read “Propane-LPG Tank Explosion” but the accompanying picture (see below) showed the LPG tanks still standing there, next to the gutted house.
Ironically, the LPG tanks (green arrows) were just about the only thing left intact.
Even the intense heat of the adjacent fire didn't make the propane tanks explode.
BLEVE - Boiling Liquid Expanding Vapour Explosion
A boiling liquid expanding vapor explosion – BLEVE (blĕ-vē)- is an explosion initiated by the breach of a vessel containing a pressurised liquid that has reached a temperature above its boiling point.
If a pressurised gas bottle or vessel ruptures when the contents are above their boiling point, it is referred to as a BLEVE. A BLEVE does not necessarily involve fire. A prime example of this is a steam boiler explosion.
LPG cylinders and LPG tanks rarely BLEVE because of the Pressure Relief Valve that releases the excess pressure, preventing a Propane-LPG tank explosion.
A Propane-LPG tank explosion (LPG explosion) is sometimes referred to as a BLEVE (blĕ-vē). BLEVE is the acronym abbreviation for Boiling Liquid Expanding Vapour Explosion.
Shaking Gas Cylinder - Does Shaking LPG Gas Cylinder Cause it to Explode - Propane-LPG Tank Explosion
Shaking an gas cylinder does not cause a Propane-LPG tank explosion (gas cylinder explosion). The only result from shaking a gas cylinder is getting tired arms, but it will not cause a Propane-LPG tank explosion (LPG explosion).
Evidently there is a fake video showing the shaking of a gas cylinder causing a Propane-LPG tank explosion, but it is just a hoax.
LPG vs Natural Gas Leak Explosion
An LPG explosion is almost always caused by the accumulation of gas leak in an enclosed space combined with an ignition source, not a Propane-LPG tank explosion (gas cylinder explosion). The leak can be from the gas appliance or other source not involving the bottle. In many cases, when a gas leak LPG explosion occurs, the gas bottles are not even involved.
Leaking gas in a house or other structure could be either natural gas or LPG. Either scenario could result in a gas leak explosion and fire.
If there is a problem with an appliance or fitting, within the house, leaking gas can accumulate, causing a potential gas leak explosion.
Regardless of the type of gas, the results would be the same.
This is one reason why you should have regular maintenance on gas appliances.
BBQ Gas Fire vs LPG Tank Explosion
BBQ gas fires very rarely cause a Propane-LPG tank explosion (gas cylinder explosion). Faulty barbecues can cause gas fires, as gas BBQ maintenance is often overlooked.
This neglect results in hoses perishing, O-rings getting damaged or lost, old regulators leaking or gas knob valves starting to leak.
Gas leaks from poor connections, faulty gas regulators and damaged hoses are the most common causes.
Homeowners should regularly check for leaks with the soapy water leak test.
Preventing BBQ fires with good BBQ maintenance should be the focus.
The gas leak is rarely from the gas bottle itself and an actual gas cylinder explosion or Propane-LPG tank explosion, resulting from a BBQ fire, would be very unusual.
The fire will self-extinguish when the gas cylinder runs dry, as barbecues should always be placed safely away from other flammable materials.
The gas bottle may have some scorch marks on it, but it is intact.
In my many years in the LPG industry, I have seen many BBQ fire investigation reports and photos.
In all that time, I have not once seen a homeowner’s BBQ gas cylinder explode or a Propane-LPG gas tank explosion.
Not once. Never. That is how rare an event it is.
Reason for Gas Cylinder Blast
The typical reason for a gas cylinder blast is a gas leak from the cylinder, regulator or fittings. The gas leak mixes with air at proportions within the limits of flammability. Add an ignition source to this and you have a gas cylinder blast or explosion.
However, what is described above is a gas leak explosion and not really a gas cylinder blast.
Gas Leak Explosion: What Causes Cooking Gas Explosion - LPG Explosion
Cooking gas explosions are caused by a gas leak mixed with a source of ignition. Cooking gas explosions can be natural gas or LPG, but the LPG gas bottles are usually not directly involved in the explosion.
A cooking gas explosion (gas leak explosion) occurs when there is a gas leak and an accumulated mix of gas and air (within its flammability limits) combined with a source of ignition. The cooking gas leak explosion could be a natural gas (methane), LPG - propane or butane - or CNG (methane) gas explosion.
What causes a cooking gas explosion is almost always the accumulation of a gas leak in an enclosed space, combined with air and an ignition source. A gas leak explosion could be caused by various explosive gases, including natural gas (methane), LPG (propane or butane) or a welding gas, like acetylene left by a tradesperson.
A cooking gas explosion involving propane tank or LPG gas bottle explosion (gas cylinder explosion) would be very rare. So, a cooking gas explosion is typically a gas leak explosion. The gas leak explosion can be from the cooking gas appliance or other source not involving the gas bottle. In most cases, when an LPG explosion occurs, the gas bottles are not even involved.
A cooking gas explosion (gas leak explosion) is preventable. The important thing is to make sure the flame is lit, so that there is no accumulation of gas.
There are built in safety devices, such as a flame failure device, which is designed to stop gas going to the burner of a gas appliance if the flame is extinguished. These safety devices helps prevent a dangerous buildup of gas within the stove and a cooking gas leak explosion.
Some stoves also have auto re-ignition, that can relight the burner if it goes out, helping prevent a gas leak explosion.
There are also timers built into some of the starters, that cut-off the gas if it doesn’t ignite within a very few seconds, preventing the accumulation of gas and any possible cooking gas explosion.
A gas leak explosion only happens if the safety devices fail and the stove is unattended, as you would smell the gas.
No gas accumulation equals cooking gas explosion.
The gas involved in a gas leak explosion may also be welding gas or other non-LPG gas.
There must be an ignition source for a cooking gas explosion to occur.
Tradespeople Incidents with Other Gases
Gas cylinder explosions involving tradespeople, and welding in particular, are almost certainly not an LPG explosion.
Acetylene gas used in oxy acetylene welding, which is very volatile, is frequently the culprit.
Pictures of a completely destroyed plumber’s truck are almost assuredly acetylene related.
Pictured above is the result of an acetylene gas cylinder explosion in a tradie's van.
However, the media just reports “gas cylinder explosion” without specifying the gas.
The result is that many people falsely assume it was a Propane-LPG tank explosion.
The Media Just Loves to Report Gas Cylinders Explode or Propane-LPG Tank Explosion
It should come as no surprise that the media is fond of reporting “gas cylinders explode”, even if an LPG explosion did not actually occur. It just sounds so much more exciting and dramatic than “BBQ fire”.
Most of us have heard the news media expression: “If it bleeds, it leads!”
And it would not be an exaggeration to say that the media likes to sensationalise the news.
After all, that’s one way they keep their audience interested.
Pressure Relief Valves Prevent Propane-LPG Tank Explosions
So, why are gas cylinder or Propane-LPG tank explosions (LPG explosions) so rare?
Gas bottles have been around for about 100 years.
Over that time, the gas industry has had a lot of time to perfect the safety features of gas bottles and valves.
Arguably, the single most important safety feature of a gas bottle is the Pressure Relief Valve.
It’s actually a valve within a valve.
The Pressure Relief Valve is incorporated into the main gas valve on the bottle, as shown in the accompanying picture.
If the pressure of the gas inside the bottle increases, as the result of a fire or other heat source, the pressure relief valve releases some of the gas to relieve the pressure.
The typical cylinder would probably only burst with pressures over 6895 kPa or 1,000 PSIG.
That's about 5x the normal pressure.
The typical pressure relief valve setting is 2585 kPa or 375 PSIG.
So, the cylinder would never actually go above this, as the valve would open and lets some gas escape, limiting the pressure inside the cylinder.
Even at 54°C (130°F), the pressure would only be 1794 kPa (257 PSIG).
So, not only wouldn’t it approach bursting pressure (≈ 1,000 PSIG) but, under normal circumstances, it would never even reach the 375 PSIG required to trigger the pressure relief valve.
No pressure build up means no risk of a Propane-LPG tank explosion (gas cylinder explosion).
Pressure Relief Valves Writ Large
All LPG vessels have pressure relief valves, even the very large ones.
A recent accident showed the wisdom of this inclusion.
A B-double LPG road tanker, full with 63,000 litres of LPG, was involved in a crash with a car.
The car crossed the centre divider and hit the tanker head on.
This ruptured the diesel tanks of the truck resulting in a massive fire.
The prime mover (tractor) section of the truck was destroyed. It even melted the tyres. See image above.
However, the tanker trailers remained intact, even though the exteriors were scorched (they were originally white) but there was no LPG tank explosion.
The contents were safely removed after the fire was extinguished.
This is a testimony to the design safety incorporated into all LPG vessels.
The Exception - Sub-Standard Gas Cylinders Can Explode
In some countries, there are problems when substandard gas cylinders explode because they do not meet the manufacturing and safety requirements.
The typical problem is an insufficient regulatory mechanism and/or a lack of enforcement. For example, both India and Pakistan have struggled with this issue in recent years.
Be sure to only buy gas cylinders from reputable suppliers. If the deal is too good to be true, there is probably a reason. Steer clear of any gas cylinder that is odd looking or non-standard in any way.
The problem can be even worse with CNG - Compressed Natural Gas. CNG cylinders for vehicles have a much higher operating pressure so any cylinder with substandard manufacturing is more likely to fail.
Whilst one should always take care when using gas, there is no reason for an irrational fear of a gas cylinder explosion or LPG explosion.
Gas bottles, with their Pressure Relief Vales, have a very effective safety system.
The result is that Propane-LPG tank explosions are extremely uncommon in most countries.
The real concern should be the proper maintenance of gas appliances and fittings.
Comments, questions or feedback?
The information in this article is derived from various sources and is believed to be correct at the time of publication. However, the information may not be error free and may not be applicable in all circumstances.