New truck tray rusting away after 4 months? Quality issue?

[MJTaylor]

Good day people,

I have a question for the learned regarding a steel truck tray. The truck and tray were purchased brand new two years ago. After 4 months the tray had started to scale / rust quite badly in the bottom of the tray where the paint was scratched. The tray has been used to carry trees and landscaping supplies, no acids or nasty chemicals. The supplier of the tray claims that some chemical must have damaged the tray and caused it to rust. As such the owner and the tray supplier are now in arbitration (it is now 2 years since the tray was purchased). The rust is now so bad that large pieces of steel are flaking off and in some places the tray is almost holed through.

My question is can this possibly be the fault of the owner, or is it more likely the material / manufacturing of the tray has led to the excessively short time it took for the tray to rust this badly? What could cause the tray to rust so quickly? Is there a standard for the material and / or manufacturing process that covers this area? I am in Australia.

Thanks!

 

[Carburize]

For clarification - what exactly do you mean by "truck tray"?

 

[MJTaylor]

Oh, sorry, should have clarified, I am talking about the tray off the back of a tipper truck. Like a tray on the back of a ute, but a bit bigger.

 

[Metalguy]

Assuming the "tray" is the bed/bottom of a tilting dump truck, it is most likely made from easy-to-weld low carbon steel. With the exception of steels which have a little Cu in them, most low carbon steels have approx. similar rates of corrosion, and the supplier/builder really has no control over the end use/user.

If a user stores wet grass/dirt, etc. for long periods in his truck, he will soon find that the worst corr. is under the thickest areas--assuming no differences in dirt composition. The corr. is driven by oxygen, and while it seems backwards, the worst corr. takes place where the O is lowest.

I suspect the owner didn't wash his truck bed frequently to clean off deposits and possible chemicals which can greatly accelerate corr--esp. nitrates. He also should allow it to dry well after he cleans it.

 

[rnd2]

I agree with Metalguy. The nitrates (ammonium nitrate as well as other salt compounds)he is referring to will undoubtably have come from fertiliser which will be part of the 'garden mix' the user delivers, along with super phosphate which always contain traces of sulphuric acid. In addition rotting leaves are acidic and eat straight through roof gutters which are made of galvanised mild steel if left with puddles of water.
Bit like shutting the stable door after the horse has bolted but the owner would have been wise to tilt the tray at wash down, if he ever bothered to do that.

 

[EdStainless]

Of course if there was a bad prime and cure job on the paint then it would absorb moisture and accelerate the rusting.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[MJTaylor]

Thanks guys,

After talking to the truck owner and explaining teh above points to him I have some additional information that makes things a little less clear. Seems after 4 months he had the worst section of rust cut out of the tray, and a new piece of steel welded in (approx 400 x 400mm section). The interesting thing is now, 2 years later, the rest of the original tray is still badly rusting as described in my first post, but the new section of steel that was welded in has not rusted anywhere near as badly.

The second piece of information that he told me is he owns 6 trucsks, all in exactly the same service, all used to carry the same fertilizers, soil, garden waste, etc. The other 5 trays have not rusted anything at all like the truck in question, and they are all older. Only the new truck is being rapidly eaten away. The other trays came from differnt suppliers, hence his concern that a somehow "inferior" grade of steel was used in the new tray that is making it more suceptable to rusting away?

Can anyone suggest if there are any tests we coudl have done on the material to identify if this is the case, or companies in Australia that do such testing?

 

[rnd2]

Assuming the information given you is correct, only under completely independent supervision, and this would have to be verifiable legally, material from the rusting and non-rusting trucks would have to be removed and comparison tested for resistance to various corrosion mechanisms. If it was established irrefutably there was significant difference in rate of corrosion between the materials there may be something to legally pursue.
Frankly I doubt it is worth pursuing.
The fabricator would have purchased his steel from the steel supplier in good faith and constructed the truck
tray in good faith.
The steel supplier in turn would have purchased the steel from the manufacturer in good faith with a requirement the steel would meet his minimum specifications.
As I see it, it is well known carbon steel rusts so the actual rusting is not an issue. Therefore unless there is a clause in the purchase contract that specifically covered the corrosion issue, another clause that covered the actual grade and/or manufacturer of the steel and sheeted that to the responsibility of the fabricator then with the lack of any other evidence to the contrary it will fall back the responsibility of the owner. Caveat Emptor.