Question: “Could you tell me the service life of an ISO tank? Do you know if tank companies keep a record of the services and repairs performed on the tanks??”
Tank Guru: The first question is one I get asked a lot, and unfortunately the answer is not simple because it depends on too many factors – and it depends also one what type of tank you are referring to… T11’s? T50’s? T75’s?
We have refurbished some of the first ISO tanks ever built from the late 1960’s (liquid products, not gas products) and lots of units from the 1970’s and 1980’s, and they left our shop ready for another 40 or 50 years of service.
For liquid tanks, the stainless steel was just better back then (many older tanks were built from 316LN or 316Ti instead of 316L) and the tank shells were a little thicker. Newer tanks are built with the thinnest possible 316L material and very little corrosion allowance, in order to minimize the amount of stainless used – which keeps tare weights low and new tank prices down as cheap as they are.
On the contrary, we’ve also seen brand new tanks that were declared a total loss before their first 2.5-year test, due to being loaded with a corrosive product in tanks without an interior lining.
The service environment also matters. Tanks operating in the Caribbean (or other saltwater areas) that don’t get regular exterior washes will have frame corrosion problems early on, whereas tanks operating strictly on land don’t experience that same corrosion.
With T50 tank barrels made of carbon steel instead of stainless steel, it makes a huge difference whether the interiors are always kept dry (free from moisture) by maintaining an inert environment, or not.
The second question is much easier. All of the large leasing companies and tank operators have very sophisticated computer systems that can track work that was done on their equipment. One of our customers bases their decisions about disposal of old equipment based exclusively on how much they’ve spent on M&R feach asset, rather than the age of the asset.
