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. 2/24/2017 10:12:55 AM Earl at AST Aboveground Storage Tank Forum RSS 180 150 Re: Intersting AST Analysis - By: ITS [1678] AST or Aboveground Storage Tanks are built or designed on the basis of the thin membrane stress theory as opposed to a ASME B&amp;PV Code which is not. API650 tanks are very flexible under extreme conditions and behave like a bladder. Dont know about the flying pickup truck or 380 mph winds. Fri, 17 Feb 2017 15:34:00 -0300 Intersting AST Analysis - By: JGardiner [1848] Greetings all,<br /><br />New to the forum but have been working with API-650 tanks, mostly in the commercial nuclear industry. Wanted to share an interesting project!<br /><br />In the nuclear industry ASTs are used to store water essential for the cooling of the reactor. We used finite element analysis to evaluate the tank subjected to winds of 360 mph and struck by a tornado missile. In this case an airborne pickup truck going 80 miles per hour. Its amazing how a thin metal tank and its energy-absorbing contents can withstand the impact and maintain its integrity..Definitely not an API-650 code case!<br /><br />Project Description<br />-<br /><br />Impact Video<br />-<br /><br />Look forward to great discussions on this forum!<br /><br />Jeff! Fri, 17 Feb 2017 08:21:00 -0300 Re: TANK JACKING SYSTEM - By: Dunedin [37] In my view Option 2 is the only viable method but best consult with specialist jacking contractor. Tue, 7 Feb 2017 01:37:00 -0300 TANK JACKING SYSTEM - By: KRISHNASWAMY [1139] A 54 M DIA COLUMN SUPPORTED ROOF TANK IS TO BE ERECTED USING TANK JACKING SYSTEM<br /><br />IT HAS 1 CENTRAL COLUMN AND 24 OUTER COLUMNS.<br /><br />WHAT US THE BEST METHOD FOR THE JACKING SYSTEM TO BE ADOPTED.AS SUGGESTED BELOW.<br /><br />1. ERECT ALL THE COLUMNS FIRST<br /><br />2 START ERECTING THE SHELL USING THE JACKING METHOD<br /><br />3 AFTER REACHING FULL HEIGHT, ERECT THE ROOF PLATES FROM SHELL TO COLUMN AND COMPLETE .<br /><br />ALTERNATIVELY<br /><br />1 ERECT THE TOP 2 SHELL COURSES.<br /><br />2. ERECT THE CENTRAL COLUMN AND THE SUPPORT COLUMNS EQUAL TO THE TOTAL HEIGHT OF THE SHELL ERECTED,<br /><br />3 COMPLETE THE ROOF PLATES ERECTION AND WELDING.<br /><br />4 INSTALL THE JACKS ON THE SHELL AND FOR EACH COLUMN AS PER TANK STABILITY CALCULATIONS.<br /><br />5. NOW LIFT/JACK UP THE TANK TOTALLY ALONG WITH THE COLUMNS TO REQUIRED HEIGHT FOR PLACING THE NEXT SHELL COURSE PLATE.<br /><br />6. ERECT THE SHELL PLATES AND COLUMNS OF EQUAL SECTIONS OF SHELL PLATES AND COMPLETE THE WELDING.<br /><br />7. REPEAT THE PROCESS TILL ALL THE SHELL PLATES ARE ERECTED <br /><br />EXPERTS ADVISE WELCOME <br /><br />THANKS IN ADVANCE.<br /><br />REGARDS Mon, 6 Feb 2017 09:30:00 -0300 Re: INSPECTION INTERVALS - By: ITS2 [1678] Longterm corrosion rate is critical, but so is short term corrosion rate of a tank floor. The next internal inspection and measurement of the tank floor is projected from those numbers. Problem with probable methodology is a level of confidence verses risk. A 100 percent measurement is best. A five year is typically associated with external inspection or in service inspection of tank. Thu, 2 Feb 2017 19:26:00 -0300 Re: INSPECTION INTERVALS - By: ITS [1678] Dont know if this can be answered to your satisfaction concerning aboveground storage tank inspection intervals. But my impression is the inspection interval review at 5 years is a generic inspection interval that is broadly based on AST inspection experience of the committee members, so no one falls between the cracks as reasonably as possible. As far as the consequences, the locale of the tank or jurisdiction the tank is located determines the consequences if any. Not all locales have laws or regulations and rules concerning this important tank inspection interval. Mon, 30 Jan 2017 13:27:00 -0300 INSPECTION INTERVALS - By: ADI HAR-SHOSHAN [93] 1. Api-653 Paragraph 6.4.2 : Can somebody please clarify why the review should take place within 5 years from january 2012? and if not what is the consiquence ?<br />2. Tank that their initial recorded internal inspection was 50 years after construction and the floor was inspected in probabillstic method , can the next internal inspection be determind on the basis of this long term corrosion rate? Fri, 27 Jan 2017 10:02:00 -0300 Re: Sarc for settlement point B. - By: MIKE [696] Hi<br /><br />I have same problem with a tank in my factory and I am trying to interpretate API 653 about settlement problems. How do you get the optimum cosene curve? By a computer? Thank you Fri, 27 Jan 2017 06:36:00 -0300 Re: Doorsheet Reinforcement - By: Tankee [235] I have done it, and seen it performed with or without stiffening. I prefer stiffening, but the end result is the weld sequencing and keyplate usage and knowing how to use them during welding the doorsheet back in. As usual, knowledge and experience is key when welding doorsheets into place. Thu, 19 Jan 2017 08:24:00 -0300 Re: Doorsheet Reinforcement - By: [39] It may be worth noting that during construction, it is fairly common to leave out a two-ring doorsheet for crane access especially or larger tanks or where site access around the tank is limited. The crane is used from the inside to pick and place upper ring steel and stays there for most of the cone roof structure. At or near the end of the job the crane moves out and those two shell plates are installed. These openings are often not braced and do not hinder the erector from maintaining API tolerances on the tank construction. Wed, 18 Jan 2017 07:37:00 -0300 Re: Doorsheet Reinforcement - By: ITS [1678] Well, there is no escaping the reinforcement of an opening 2 inches or greater. A door sheet is of course much larger. Regardless of the shell course, a large opening will weaken the area around the opening and would be evident in a 45 degree ripple, so it needs to be stiffened.<br /><br />On the buckling issue of the shell I would refer to API Bulletin 2U, which I think was last updated in 2004. The root or basis of this rule of thumb on buckling stress is based on one-third or 1/3 of yield stress which means anything over that is fair game to a wrinkle or buckle in the shell. <br /><br />Hope other have more insight... Tue, 17 Jan 2017 15:59:00 -0300 Doorsheet Reinforcement - By: JES [1841] Is there a rule of thumb re: width of doorsheet opening in a tank vs. tank diameter. I would expect that first shell course thickness will increase with tank diameter and, subsequently, the width of a doorsheet not requiring reinforcement.<br /><br />Can anyone comment on this?<br />What analysis procedure would one use to evaluate likelihood of shell buckling?<br /><br />Thanks. Tue, 17 Jan 2017 11:26:00 -0300 Re: FOUNDATION CONTAMINATED BY PRODUCT - CRUDE OIL - By: ITS [1678] Well to answer your first question, I think you are already inspecting the foundation concrete annular ring. Your crude oil, which I presume is thick and out of the ground thick, will find the path of least resistance which is seeping out from under the steel bottom because of the floor lap plates. As the crude oil cools from its pour point temperature then it should thicken nicely. What has entered the ground will plug the soil or as we say - the soil sizing factor will determine the amount of soaking depth until is cools, then it will go no where.<br /><br />If the concrete is in reasonable condition the crude oil will not effect the strength of the concrete ring follows what I consider a reasonably good design. You may end up core drilling the concrete ring to draw seepage if any and possibly place a slight vacuum on the soil, but this needs a professional opinion.<br /><br />When repairing the floor of the AST, you may remove the plate or plates and access the soil, but I think you will find that very little saturation in the soil to any appreciable depth will be evident. Shovel it out. Sure you can get a hydrocarbon sniffer but that may not be practical or an application of good common sense until the entire tank farm is remediated if ever.<br /><br />I am not sure my help represents you site conditions, but maybe someone else can assist too. Fri, 13 Jan 2017 14:51:00 -0300 FOUNDATION CONTAMINATED BY PRODUCT - CRUDE OIL - By: CE [1592] Dear Tank Experts,<br /><br />A happy new year wish to you all.<br /><br />Case:<br />I have a situation with one of my jobs. It is a crude oil storage tank. Had its Single deck floating roof collapse that punctured the bottom plates and the product have seeped through the punctures. During inspection, we noticed oil weeps from underneath the annular plates from the tank external.<br />Questions:<br />1. How can the foundation be inspected.<br />2. What code do we refer for detailed tank foundation issues?<br />3. Oil contamination on foundation, what does it cause?<br />4. If confirmed contaminated by any code/standard, what is the repair/remedy procedure?<br /><br />I appreciate your usual assistance with these.<br /><br />Also any other useful infor will be appreciated.<br />I have just completed hydrocutting the roof and discovered the holes on the bottom plates.<br /><br />Thanks,<br /> Wed, 11 Jan 2017 14:06:00 -0300 Re: EFRT pontoon entry - By: Dunedin [37] The honest answer is NO it is not safe. Thu, 29 Dec 2016 08:44:00 -0300 Seasons Greetings - By: Earl To all our friends,<br /><br />Merry Christmas.<br /><br />Your Friend,<br />Earl Sun, 25 Dec 2016 00:00:00 -0300 Merry Christmas - By: ITS [1678] Merry Christmas to all my fellow fossil fuel storage folks. Sat, 24 Dec 2016 19:16:00 -0300 Re: Storage tanks of water for fire extinguishing - By: [39] Per NFPA 22 Standard for Water Tanks for Private Fire Protection<br />From the 2008 Edition:<br />Section 4.13.1: All tanks shall have roofs<br />Section A.4.13.1: Rules for slopes can be found in 5.4.3 of AWWA D100.<br /><br />Check NFPA 25 chapter 9 for maintenance of water tanks used in fire protection systems.<br /> Sun, 18 Dec 2016 22:41:00 -0300 Re: EFRT pontoon entry - By: [39] It might be safe if you are highly experienced are a keen observer and know what to look for and the situation is right. Reading an industry or regulatory guideline or two and thinking you are qualified is a quick recipe for death. Find a qualified and experienced person or contractor, carefully evaluate all aspects of this entry and employ all manner of safety precautions. Spend enough time with the entire team developing a plan so everyone knows the dangers and risks. Beat your brain looking for concerns, issues, what-ifs, how-tos, whys / why nots etc. Certainly it can be easy and go just fine, but it can also turn bad quickly. It is vital to have thought through every possibility, real or imagined, and have plans and backup plans for everything. Then figure the unexpected happens. Sun, 18 Dec 2016 22:20:00 -0300 Re: EFRT pontoon entry - By: ADI HAR-SHOSHAN [93] Use the guidelines of API-RP-2026 for pontoon EFRT entry Fri, 16 Dec 2016 00:51:00 -0300