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. 7/17/2018 11:00:40 AM Earl at AST Aboveground Storage Tank Forum RSS 180 150 Re: PRIMARY TUBE SEAL - By: Dunedin [1843] I suspect this is just an additional piece of abrasion resistant material to help prolong the life of the tube. Sat, 14 Jul 2018 06:33:00 -0300 PRIMARY TUBE SEAL - By: ADI HAR-SHOSHAN [93] What is the purpose of the ribbon surface texture of the scuff band that cone in contact with the inner surface of the tank shell? Sat, 14 Jul 2018 05:00:00 -0300 Re: Flash Losses - By: BABRTs973 [53] You need larger or multiple equipment. The flash gas goes into the wet gas sales line. The Vapor Recovery Units do a good job but are high maintenance. The new API 12 F will allow higher pressures to be held in the tank up to 16 ounces with a 24 ounce upset pressure. You may want to investigate having low pressure tanks built that can hold 2.5 psi. But the pipeline company or who ever is buying the oil may not allow it or you may have to take a big hickey on the RVP and Gravity.<br /><br />Figuring what equipment will get the TVP down before you get it in the sales tank is very complicated. Driving around the field and seeing what other producers are doing and asking the pumpers what works and does not can give you ideas. <br /><br />If you have the sales line to do it with, the flash towers seem to be the easiest way to drop the TVP but that puts a lot of low value product into the gas sales lines. I am not familiar with the tricks some use on the knockouts to lower the VP but some seem to have luck with it. Fri, 13 Jul 2018 10:43:00 -0300 Re: Flash Losses - By: Dunedin [1843] OK now we are getting close. If you use flash towers or knockout drums what happens to the vapors released into them? Also, the flash towers and knockout drums that I have found on the internet seem to be quite small and only suitable for a very small production well. What happens in large wells with large volumes of crude needing processed before taking to the large EFRT? Thu, 12 Jul 2018 11:00:00 -0300 Re: Flash Losses - By: BABRTs973 [53] Correct. If the TVP is above 11.1 storage in atmospheric ASTs is not recommended/allowed.<br />Using Flash towers or modified knockouts can lower the TVP before putting the liquid in the tank. These are the more common ways of lowering TVPs. Splitters can do it but are high volume and capital intensive.<br />Some try blending, but you need more than two truck drivers at a Coriolis meter manipulating the sample pot.<br /> Thu, 12 Jul 2018 08:22:00 -0300 Re: Flash Losses - By: Dunedin [1843] Thanks for the very detailed response, however it is my understanding that all the equipment you mention are only effective if the TVP of the liquid is low as these tanks and the equipment operate at atmospheric pressure. Thu, 12 Jul 2018 07:45:00 -0300 Re: Flash Losses - By: BABRTs973 [53] Table 2A and 2B from the API Manual of Petroleum Measurement Standards Chapter 19-2 Evaporative Loss from Floating-Roof Tanks gives the improvement of various deck appliances for floating roof emission control devices. Thu, 12 Jul 2018 07:45:00 -0300 Re: Flash Losses - By: BABRTs973 [53] When you are talking flash losses is this upstream in 12F production storage tanks<br />These can be controlled using vapor recovery units, pressure relief devices such as gauge hatches and stack valves on the vent lines. <br />On floating roof tanks, both IFR and EFR you have the floating roof itself, a liquid mounted primary seal and on EFRs or jurisdictional regulated IFRs a secondary seal, a gauge pole sleeve in slotted gauge poles and a gasketed gauge pole well cover and gasketed gauge pole seal. In addition a gauge pole cover in conjunction with a gasketed gauge pole float may be necessary. The roof legs need either socks or covers. <br />In short, if there is a visible gap, greater than 1/8 inch, it needs some form of control. Look up Federal Register/Vol. 65, No. 10/Friday. January 14, 2000/rules regulations Environmental Protection Agency 40 CFR Part 60 FRL-6518-2<br /><br />If you are being asked to offer suggestions I have some other information you may find useful such as the percent of emissions of roof appliances. After the rim space on floating roofs being the largest emitter, a slotted gauge pole without a sleeve, gasket and gasketed gauge pole well cover is the second largest emitter. But in offering this advice I make sure the air emissions person is very clear, I am NOT a engineer nor regardless of my experience a expert. The use or not of any emission appliance is up to the engineer and the company official, or designated inmate, who signs off on the emission calculations for the facility air permit. <br />Thanks to some really helpful people who have and do help me with this I am somewhat smarter than the average bear on AST emissions and encourage inspectors to get familiar with emission controls and regulations as this is going to be a good revenue source in the future. Thu, 12 Jul 2018 07:39:00 -0300 Flash Losses - By: Dunedin [1843] Can anyone explain to me how Flash Losses are controlled when crude oil is dumped into a Fixed Roof Tanks and b External Floating Roof Tanks? I find information on the internet about how to calculate the losses but so far not so much on how to control them. I assumed this would be carried out before the crude is put into the tank but all the calculation do not seem to support this! Tue, 10 Jul 2018 03:50:00 -0300 Re: repair on shell plate- stairway - By: test [15] test Fri, 6 Jul 2018 10:50:00 -0300 Re: repair on shell plate- stairway - By: ITS [1678] That is what I would have considered. Welding a lap plate under the ladder or stairway stringers after cleanup of the steel shell plate and ladder stairway seems reasonable. Thu, 5 Jul 2018 10:12:00 -0300 Re: repair on shell plate- stairway - By: [1940] How have you solved this problem?<br />Have you welded a lapped patch repais plate?<br /><br />responding to post from May 17 2010 Wed, 4 Jul 2018 09:11:00 -0300 Re: Where has everyone gone - By: ITS [1678] Seems that way. Fri, 29 Jun 2018 11:53:00 -0300 Where has everyone gone - By: Dunedin [1843] Is it correct that the last posting on AST was four weeks ago? Fri, 29 Jun 2018 00:57:00 -0300 Re: Internal Floating Roofs - By: Dunedin [1843] Thanks Sun, 3 Jun 2018 01:29:00 -0300 Re: Internal Floating Roofs - By: [39] Per NFPA-11 section 5.4.2 rim-protection is suitable for steel double deck, steel pontoon, full liquid-surface, metallic sandwich panel conforming to API 650 H and full liquid surface contact composite sandwich roof / seal system designed in accordance with several requirements Ill leave to you to read. All others required full-surface protection. this means more foam. On the other hand, per full-surface systems do not need to have separately valve laterals for each foam discharge location. In other words, full-surface systems can have a single pipe coming into the dike with a ring pipe around the tank leading to individual riser pipes to each foam discharge while a rim-protection system needs separate valves and pipes outside the dike for each foam chamber. Sat, 2 Jun 2018 10:57:00 -0300 Re: Internal Floating Roofs - By: Dunedin [1843] Thanks David Could you just expand on Item 6 which I assume relates to NFPA11? Is the regulations concerned with the seal or IFR surface protection? Sat, 2 Jun 2018 07:33:00 -0300 Re: Internal Floating Roofs - By: [39] The following is my opinion only, I am not totally unbiased and you are reading this on the internet! Non-contact are cheaper and can fit into the tank through a shell manhole The US EPA does not distinguish between full- and non- contact seam losses! Honeycomb full-contact typically have their top skin only about 1 1/2 inches above the liquid vs 4 inches or more for non-contact. That said, because there is no vapor space under the deck full-contact should have the following advantages: 1 lower corrosion, 2 increased safety, and 3 lower emissions also 4 they can be and some are made much stronger than non-contact, 5 at least one vendor makes them without drains lowest emissions and designs their supports and connections to the same strength as steel floating roofs so at least that one is additionally safer to walk on, 6 some honeycomb full-contact qualify for rim fire protection vs full-surface foam protection systems. Sat, 2 Jun 2018 06:49:00 -0300 Re: SS-Aluminum hybrid IFR - By: [39] In theory it is possible to get honeycomb with SS skins and then weld SS closures all around but I have not heard of anyone doing it. If there was a real and sizable demand it might happen but I would not hold your breath for this one. Sat, 2 Jun 2018 06:33:00 -0300 Internal Floating Roofs - By: Dunedin [1843] Full Contact v/s Pontoon IFR - which type is best, and why? Is anyone up to the challenge? Sat, 2 Jun 2018 00:33:00 -0300