API 650 TANK

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Anonymous Poster	API 650 TANK 01/22/2008 5:38 AM
	Dear All, we are facing problem in vertical field erected tank Dia # 16m& height 25m,API 650 code is used for fab.&erec. tank shell is distorted from curb angle to the top shell around 3m in the width & around 7m in periphery(in 12m partition plate area),it happened due to the partition plate welding from inside. in peaking & banding we are getting minimum 19mm & maximum 37mm,which is not acceptable according to code.Please any one can give the solution to resolve this matter without replacing the shell plate (behalf of design criteria). regards.
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nick name Guru Join Date: Mar 2007 Location: City of Light Posts: 3943 Good Answers: 183	#1 Re: API 650 TANK 01/22/2008 7:35 AM
	It is only a suggestion since i do not know neither if it is allowed by the code. nor if it is an economis approach. If the distortion is toward the interior you could use two circular profiles and hydraulic rams in between to counter deform and come in the tolerance field accepted by the code. One profile should have the same radius as the tank wall (inside) and the other should be slightly less and be narrower as the first. The second is used to form the wall where it is out of tolerances.
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Abdel Halim Galala Guru Join Date: Feb 2007 Location: Cairo, Egypt Posts: 1733 Good Answers: 248	#2 Re: API 650 TANK 01/23/2008 4:36 AM
	According to API 560: Para. 5.5.3 Roundness : For tank diameter 12 m - 45 m, the radii measured at 0.3 m (1 ft) above the bottom corner weld shall not exceed the following tolerances: ± 19 mm. Para. 5.5.4 Local Deviations: Local deviations from the theoretical shape (for example, weld discontinuities and flat spots) shall be limited as follows: a. Deviations (peaking) at vertical weld joints shall not exceed 13 mm (1/2 in.). Peaking at vertical weld joints shall be determined using a horizontal sweep board 900 mm (36 in.) long. The sweep board shall be made to the nominal radius of the tank. b. Deviations (banding) at horizontal weld joints shall not exceed 13 mm (1/2 in.). Banding at horizontal weld joints shall be determined using a straight edge vertical sweep board 900 mm (36 in.) long. c. Flat spots measured in the vertical plane shall not exceed the appropriate plate flatness and waviness requirements given in 5.5.2. So, you are requested to modify all dimensions to be within the specified tolerances of the code. __________________ It is better to be defeated on principles, than to win on lies!
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EnviroMan Guru Join Date: Nov 2007 Location: Gone to Alabama with my banjo on my knee... Posts: 5595 Good Answers: 20	#3 In reply to #2 Re: API 650 TANK 01/23/2008 12:31 PM
	Not just a whole lot of wiggle room in those tolerances, is there? I guess the right thing to do is shell replacement, at least partial, eh? Plus maybe a training program for their welders... __________________ Veni, vidi, video - I came, I saw, I got it on film.
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Anonymous Poster	#4 Re: API 650 TANK 01/23/2008 6:44 PM
	What material of the tank ? Is it stainless steel or carbon steel . The distortion is too much... You can follow the practice of repair in API 653 . API 650 is a code for new tank construction and API 653 is for repair and inspection for in-service tank . Would like you can give some sketches of the distorted area of the tank . May be I could help you . You can reply me at e-mail : pandan121@yahoo.com. regards .
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