Treat Plastic Cartons as Expanded Encapsulated?

2/22/2023

I have (2) different storage scenarios with the same product. They are empty 5 liter HDPE containers from 2 different manufactures and packaging slightly different but both having cardboard dividers and on wood pallets.

I am leaning towards exposed expanded encapsulated Group "A" on the pallet load without cardboard sides due to the row of containers enclosed in plastic bags.

The pallet load with the cardboard partial sides and full cardboard top would be the same due to having only partial sides.

Any help would be greatly appreciated.

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9 Comments

Dan Wilder

2/22/2023 07:34:13 am

I've done a couple of these for the half gallon/ 1 gallon size containers and went the same route.

Couple items I ran into:

This biggest issue we had was clearance/excessive clearance due to the temp nature and movement of the commodity within the building (post MFG/extruding, staging warehouse, transportation warehouse). This created a couple situations with exceeding maximum clearances (forcing specific storage configuratins) or we had to add additional in rack protection for partially loaded racks. They also like to stack to the maximum height and not provide the minimum clearances (the 3rd picture).

We found some of the bundles were encapsulated (the pallets on the ground in the 4th picture)

The solid piles with collapse potential stacked up to 18', and sometimes a little higher with the pallet heights and containers combined. Each pallet measured over 6' tall so 1 high vs 2 high vs 3 high all had different criteria.

Dan

2/22/2023 11:21:10 am

Referencing Appendix A.20.4.5.1 13-22 Ed.

Empty Containers Rigid plastic (not including PET), up to 32 oz (1 L) Nonexpanded
Rigid plastic (not including PET), greater than 32 oz (1 L) Expanded

Dan Wilder

2/22/2023 11:34:38 am

We have not had good luck trying to explain the difference in PET vs non-PET bottles with their characteristics being so similar.

Table A.20.4(b) 13-22' Ed
PET, bottles or jars Class IV
Rigid plastic (not including PET), up to 32 oz. (1 L) Group A Nonexpanded

Pete H

3/3/2023 12:51:59 pm

The best shot you can have (in my opinion) is if you can find an MSDS or manufacturer sheet referring to the bottles as PET or polyethylene terephthalate and then you can rely on the code to do the heavy lifting for you. But most AHJ's will want some confirmation or substantiation that you specifically have PET plastic as the commodity if you're trying to use the more relaxed coverage allowed for PET plastic.

Franck

3/7/2023 12:59:25 am

PE (or HDPE) is unfortunately not to be considered as PET. Different chemical formula and different behavior.
This is why NFPA introduced the concept of Class A, B and C plastics.

Just like meat.
Chicken and beef are both meat, but they definitely don’t taste the same in my plate ;)

Jesse

2/22/2023 10:17:29 am

I don't see that as "expanded". Expanded Group A Plastic is a foam-like material with quantities of microscopic air-pockets dispersed through the mass. Think acoustical foam, packing peanuts, mattress foam, etc. Expanded Group A is created by a chemical reaction which is exothermal in most cases.

These bottles are likely blow-molded.

Franck

2/22/2023 12:18:47 pm

Plastic material categorization is quite difficult as very different fire behaviors are associated to each plastic.
Some of them are considered expanded (such as big recipients) because the fire behavior is as for expanded plastic, caused by the amount of air around the plastic.
You can make the analogy with wood. Wood is normally a class III commodity, but wooden pallets is a category of its own because it burns like hell very fast. You need a much higher sprinkler density.

With encapsulation, it is also another phenomenon: you don’t wet adjacent products, because it’s encapsulated, and it will then burn more easily. Take the example of cardboard. Non burning cardboard adjacent to the fire area will be wetted by the sprinklers and will be more difficult to ignite. If encapsulated, it won’t be wet and burn quicker and easier. Thus the increase of commodity when encapsulated.
But encapsulated plastic does not make a difference… It is still plastic.

To come back to plastic materials, Polyethylene does not burn the same way as PET because it has a different chemical organization. Same with PVC. PVC creates problems because of the release of toxic fumes but does not burn as easily as other plastics.
This is why some plastics are classified as Group B or C and are equivalent to class IV or even III commodity.
Group A plastic are by far the worst (they behave like a flammable liquid when they burn), and when exposed you don’t have the wetting effect to the packaging to limit the speed of fire spread.
Worst case is obviously expanded (lot of air for quicker combustion), exposed (no wetted barrier), group A plastic !

Franck

2/23/2023 01:17:00 am

As a complement, a little bit of chemistry… that sometimes helps to understand how things burn…

A fire is nothing else than a very quick oxidation reaction (with some rare exceptions). This means that the material is oxydized by consumming oxygen and releasing carbon dioxide (CO2), water vapor (H2O) and other subproducts (CO in poor oxygen condition, No, NO2…).
This is why air (oxygen in reality) is one of the key element of the fire tetrahedron.
This being said, polyethylene is the simplest plastic compound with a chain of carbon and hydrogen. This is why it is prone to burn (oxydize) so easily, producing carbon dioxide and water vapor (and some CO because of poor combustion reaction).
With PVC, you have chlorine (Cl) which is s very reactive chemical that will come in competition with oxygen and react with hydrogen (H) to make hydrogen chloride (HCl), thus limiting the combustion process…

Gasoline, coming from crude oil, is also made of carbon chain. And burn easily because easier to vaporize from the liquid form (need less energy). Propane is even worse because it is already in tha gas form.

Wood is also composed of carbon and hydrogen, plus other compounds. It burns well, but less than PE.
Carboard, as paper, is coming from wood but has a higher moisture content than paper and burns less easily (except some coated paper, because of the coating).

Everything is chemistry!

I am pretty sure you won’t see fires the sane way anymore ;)

Chris

3/6/2023 05:06:50 pm

I was thinking expanded because of the amount of air within the load after reading Franck's comments on an earlier posts.

Whether or not it is actually considered PET is another great question. The MSDS clearly states they are HDPE jugs, the only place I believe I have seen HDPE come up in NFPA 13 is with plastic pallets.

Treat Plastic Cartons as Expanded Encapsulated?

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