AST Aboveground Storage Tank Forum RSS Welcome the aboveground storage tank forum, a bulletin board dedicated to tanks, fuel tanks, plastic tanks, fuel storage tanks, and above ground storage tanks for engineers, tank operators, maintenance personnel, and technicians who work on or around these aboveground storage tanks (AST) and chemical plastic tanks. 10/23/2017 5:35:28 AM Earl at AST Aboveground Storage Tank Forum RSS 180 150 Re: UT in lieu of RT - By: Tankee [235] Thanks David, I knew you would come through. Thats what I thought and said, but I had others saying the other way, which wouldnt make sense to have that option and then limit it. Sat, 21 Oct 2017 09:35:00 -0300 Re: UT in lieu of RT - By: [39] Is this a reference to section 8.1 - Radiographic Method which says<br /><br />For the purposes of this paragraph, plates shall be considered of the same thickness when the difference in their specified or design thickness does not exceed 3 mm 1/8 in.. Thu, 19 Oct 2017 22:40:00 -0300 UT in lieu of RT - By: Tankee [235] In Annex U of API 650, when considering performing UT instead of RT, it states in U.1.2, line a: when adjacent plates may be regarded as the same thickness. Does that mean that both plates have to be the same thickness, or that the examiner regards them as the same thickness, as in calibrating to either the thinner or the thicker of the plates? I can see it both ways, but do not have a clear understanding of either way that API may mean.<br /> Thu, 19 Oct 2017 13:31:00 -0300 Re: Aluminum IFR or CS IFR - By: Laurent [78] Hi DavidR,<br /><br />Have you step ahead on this new product. If yes, I would be really interested to know more about it.<br />Could you drop me an Email with some docs :<br />Thanks in advance &amp; best regards Mon, 9 Oct 2017 05:58:00 -0300 Re: Secondary Seal Wiper Tip For IFR Tank - By: [39] A seal that weighs 3,000 Kg for a 24 Meter tank weighs about 40 Kg per Meter or about 12 pounds per foot. This is a very heavy seal and not suitable for an AIFR. Thu, 5 Oct 2017 08:24:00 -0300 Re: Secondary Seal Wiper Tip For IFR Tank - By: Dunedin [37] If you install a good quality primary seal then there could be an argument that a secondary seal is not necessary on an internal floating roof. The majority of the sealing comes from the primary seal and the secondary seal is there to protect it from the elements, however since this is an internal floating roof the primary seal is already protected by the tank roof. On this basis, spend as much money as you can on a good quality primary seal and what is left use for a secondary seal if you are so inclined. Thu, 5 Oct 2017 05:54:00 -0300 Secondary Seal Wiper Tip For IFR Tank - By: Kumaran [1861] I have been experienced with poly ethylene or poly urethane secondary wiper seal only, But i heard few days back about secondary seal wiper tip. this kind of sealing method is possible on aluminium internal floating roof. because normally they are using GI or SS plate for compression the seal tip depending on shell vertical to achieve the proper sealing through out IFR travel. The wiper seal is light weight and cheaper than wiper seal tip. If we installed secondary seal wiper tip what kind of precaution to be taken .<br /><br />Now we are going for primary mechanical shoe seal &amp; secondary seal wiper tip. The sealing weight will be approximately 3000 kg for 24 m diameter tank. We need some advise for the same please. Thu, 5 Oct 2017 03:25:00 -0300 Re: IFR Deck Drain - By: Dunedin [37] Key words in above statement should be However as you well know accidents happen when the unusual happens! 1 IFR do not always travel horizontally 2 when IFR is landed on the legs and not floating are just two examples of a circumstance where vapour could build up under the IFR and be released through the drains.. Thu, 5 Oct 2017 01:35:00 -0300 Re: IFR Deck Drain - By: BABRTs973 [53] When you say expose do you mean explosive atmosphere? <br />The drains are liquid mounted, meaning the dip tubes are or should be submerged in liquid to minimize the vapor loss. With circulation in the tank it would be hard to accumulate enough gas on top of the roof for any ignition or explosion. And a ignition source would be needed.<br />If this was a issue, IFRs would be blowing up and burning all over the world. Wed, 4 Oct 2017 17:44:00 -0300 Re: IFR Deck Drain - By: [39] I think the US EPA number is 7.9 pound-moles per year per drain. Unless the drain is sealed, it will still leak vapors at the same rate. Vapors are small and any small opening is enough for them all to get out. Even an overlapped and bolted deck seam leaks vapors, and drain seals are no where near as tight. I have yet to see a drain seal that can stop vapors in a meaningful manner and still function as a drain especially when there is a small amount of liquid on top. I have never seen testing that supports the contention that anything short of a screwed plug can stop vapors from drains. Yes, a drain plug, ball or cover will reduce any wind effect but an internal floating roof experiences zero wind speed anyway, so where is the benefit? In order to reduce emissions, some would advocate fewer drains but how do you make sure they are where the liquid will be? Putting a screwed plug means you dont have drains. If I saw a 140 foot cover with four drains with screwed plugs, I would call this a flagrant example of not meeting the intent of the standard and certainly not justifying designing to only 5 psf. The only solution is to not have drains. Only one aluminum IFR that I know of does this and they design for the higher live load 12.5 psf.<br /> <br />If you need drains because the deck is designed for only 5 psf then I think you need enough drains to protect the entire cover and they have to be fully functional, and I have yet to see a drain cover that seals and drains.<br /> <br />My opinion only ! Tue, 3 Oct 2017 09:07:00 -0300 Re: IFR Deck Drain - By: Dunedin [37] Yes very much so! In fact there will be a number of drains on an IFR and each one has the potential to allow hydrocarbon vapour to pass into atmosphere. However some manufacturers do supply a sealed drain which is normaly closed and only opens when product needs to drain from the IFR - I would recommend going for something like that. Tue, 3 Oct 2017 07:40:00 -0300 IFR Deck Drain - By: Kumaran [1861] As per aluminium IFR design the supplier providing deck drain pipe 12 mm dia ID pipe of 300 mm long. around 150 mm dip into product. my question is there any vapour expose is possible during tank operation through this deck drain pipe. Tue, 3 Oct 2017 03:12:00 -0300 Re: Hydro after tank moving - By: [39] API 653 defines tank jacking as a major repair and requires hydrotesting after all major repairs. The fact that you did no other work on the tank does not change the classificiation of the work as a major repair. See section 3.20.<br /> <br /> <br />3.20<br />major alteration/or major repair<br />An alteration or repair that includes any of the following:<br />...<br />h jacking a tank shell. Fri, 22 Sep 2017 16:51:00 -0300 Hydro after tank moving - By: Scott [1874] We are moving a 120 diameter tank 5 feet after recent hurricane moved it off its foundation. Best practices aside, what does the code require as it pertains to a hydrotest? Looking though 653, it deals with major repair and shell jacking but we are not doing any repairs. The entire tank is being jacked by a professional company experienced with doing this but now we are trying to decide if a hydro is required by code or not. I believe we should hydro the tank as a best practice but am looking for code interpretation on the subject. Fri, 22 Sep 2017 12:49:00 -0300 Re: Tender Documents example for Tank rehabilitation - By: ITS [1678] ...and that goes without saying. But if you do not get a response it is not because of my answer. Just remember it is an archaic and vague expression, but hopefully someone will give what they expect in the document package. Wed, 20 Sep 2017 11:11:00 -0300 Re: Tender Documents example for Tank rehabilitation - By: Jeroen [1873] I understand what you mean but was just curious to see how others fellow engineers setup their tender documents and maybe I could learn from theirs. Wed, 20 Sep 2017 08:25:00 -0300 Re: Tender Documents example for Tank rehabilitation - By: ITS [1678] I have found over the years this term or phase Tender Document very subjective and elitist, for it means get a document packet together that supports all the work that is claimed and was done for a tank rehabilitation in accordance to API 650 and EEMUA publication 159.<br /><br /> Sun, 17 Sep 2017 06:54:00 -0300 Tender Documents example for Tank rehabilitation - By: Jeroen [1873] Hi everybody. Can someone help me out with an example of a Tender Document for a tank rehabilitation. The tank inspection was done by a third party already according to the API 650 and EEMUA publication 159. Thanks! Wed, 13 Sep 2017 13:40:00 -0300 Re: Aluminium Geodesic Dome Roof - By: Dunedin [37] The gap beteween the shell and the last node points will be much greater than 50 mm - probably nearer to 400 mm. At 50 mm you would be in danger of jaming the roof even if the tank is within the dimensional tolerances of API 650, and it will not pass the curb angle. Winches are a good method but the dome manufacturer must give you the pre-tension dimensions before you start to lift. The dome is tensioned or pulled in to ensure that it will pass freely up the tank and passed the curb angle. This is a VERY specialist operation and it would be best to at least have to dome manufactuers representative on site for the complete lifting operation. Thu, 31 Aug 2017 03:56:00 -0300 Aluminium Geodesic Dome Roof - By: Kumaran [1861] What is the minimum gap required between shell and dome node plate. Dome is erecting inside the tank on EFR and dome will be lifting by mechanical winch. if 50 mm gap is there between shell and node plate then how do you lift the dome.<br /><br />We have an option for lifting the dome by mechanical winch only. please give me some advice. Thu, 31 Aug 2017 03:30:00 -0300