# Do pressurised cans still pose a risk to bursting in normal conditions, but after being exposed to heat?

We're planning on shipping some items from the US to Australia as you cannot get them here, that being:

https://www.chewy.com/sentry-stop-that-noise-pheromone-dog/dp/56486

I have been in contact with a freight forwarder who can ship them to Australia, but obviously they will need to be shipped as a hazmat item and go inside a particular sized box and be shipped by FedEx or DHL.

Now, as I understand it, the reason these are classified as hazmat is because of the chance of bursting as well as being flammable.

As per the link above:

Contents under pressure. Do not puncture or incinerate container. Do not set on stove or radiator, expose to heat or store at temperatures above 120°F (49°C), as container may burst.

I have no idea, but I assume they wouldn't be exposed to high temperatures such as that during shipping, but my question is...

Assuming we got them ok and they didn't burst, do pressurised cans such as these still pose a risk to bursting in "normal" conditions AFTER they have been exposed to high heat? Such as if they had been exposed to high heat during shipping, but we got them ok, would they still pose a risk to us with the possibility of bursting?

The manufacturer provides a Material Safety Data Sheet on their website, which you have to email them or register to get it sent to you, but if it's of any interest you can download it here from MediaFire.

Alternatively you can find instructions to download it via their site - see under "PRODUCT SAFETY INFORMATION".

If you don't want to download anything then you can see screenshots of the document I uploaded to an Imgur gallery here: https://imgur.com/a/gXKxVeE

Note though, the above data sheet was provided via their site that shows their old packaging, the link from Chewy above shows their new packaging, as far as I know the packaging is the only thing that has changed.

Assume that high temperature causes no chemical reactions in the contents or between the contents and the can.

High temperature will increase the pressure in the can. Assume the can is fully unaffected in its mechanical integrity up to the point that it fails.

With all of the above, when you get the can back at room temperature, it will have no change in its potential to fail or not.

One weak link will be the potential for increased fatigue at the seams on the can as the contents go to high pressure and back to lower pressure. Another weak link will be in the potential for over-stress on the plastic cap seal on the top of the container.

When the contents react at high temperature and that temperature is exceeded, all bets are off.

In summary, this system affords no absolute guarantee that it will have no increased probability to fail when temperature cycles to a high value and returns to room temperature. The biggest uncertainty is what exactly is meant by high temperature (i.e. 100 °C or 500 °C) and for how long (i.e. immediately or for a few minutes or for a few days). The practical issue is whether and to what extent your shipment will reach the bounds.

Based on what is stated on the Website, the failure seems to be immediate at a point at or just above 50 °C. I would have to say that whatever company is ready to accept these cans knows that they have to keep them below that temperature during shipping. But, what you might want to know is whether they were at a high temperature just below that for an extended time,

I might suggest to mark the cans before shipment with a paint or dye or wax that changes color irreversibly when a certain temperature is exceeded. Or include a temperature probe with the shipment that tracks temperature with time over the entire shipment. Then, you can decide at the receiving end of the shipment whether the cans where shipped to your satisfaction.

• Putting a data logging thermometer in the box is something I've done before - works well! – Jonathan R Swift Nov 30 '19 at 8:51
• @Jeffrey: Tip of the day: You can use HTML entities &Omega;, &mu;, &deg;, &times;, &pm;, etc. as well as <sup>...</sup> and <sub>...</sub> in the posts (but they don't work in the comments). – Transistor Dec 1 '19 at 18:50
• Thanks a lot; and great idea about putting in a temp. probe. :) Do you think something like this or this which has an external sensor will do? – Brett Dec 3 '19 at 12:44
• Either sensor looks reasonable. Glad to help out. – Jeffrey J Weimer Dec 3 '19 at 15:37