Question: “Is there anything in CFR about pressure-testing lined tanks?”
Tank Guru: Not that I’m aware of. All tanks have to be pressure tested, regardless of whether they are lined. Additionally, the lining should be inspected visually as you would perform an interior inspection at the 2.5 and 5-year periodic anyway; and if the visual raises cause for concern then a spark test (or other type of additional inspection) may be warranted.
There is the IMDG language about waiver of the interior inspection during 2.5 year test for tanks in dedicated service (as I suppose that many lined tanks are), but as a tank owner you certainly wouldn’t want to skip something so important as a chance to ensure that your lining is holding up against the cargo!
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Hello Tank Guru
Firstly would like to apologize for posting this question here as i was unable to find a question posting option anywhere here.
I am from a Indian ISO tank operating company, having both owned and leased tanks.
Probably you would find my question stupid but what is the total internal area of a typical 20′ ISO tank (24KL or 23KL capacity).
I am asking this because i have a survey report stating that there is 200 sq ft of superficial pitting and as the tank reached destination have a 80% pitting in the tank now.
Now i think in a 20′ container the internal area is some 608 sq ft without floor board, but this is cylindrical!!!
So what was the % of total area affected before cargo loading and % of area affected after destuffing.
Please let me know if this isn’t too stupid a question.
Hello, and thanks for your question! There is a saying here in the States, “There’s no such thing as a stupid question.” How can we learn if we don’t ask, right?
As a rule of thumb, figure on approximately 600 ft2 total for the tank barrel and heads on a 23/24KL tank. This is comprised of roughly 494 ft2 for the shell, and 53 ft2 for each tank head (106 ft2 for both). So 494 + 106 = 600 ft2.
If there is 200 ft2 of superficial pitting out of 600 ft2 total surface area for shell and heads, then the tank would have pitting covering about 1/3 of the total surface. If the survey report came with photos, check to see if the tank appears to be pitted over 1/3 of the interior. And if not, perhaps the surveyor can provide some more detailed measurements.