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Description
Flow balancing orifice (FBO) are used in ITER Toroidal Field coil to uniform flow rate of the cooling gas in the side double pancakes which have a different length of the conductor of 99 m and 305 m,respectively.FBO consist of straight parts, elbows which are produced from 316L,tube 21.34 x 2.11 mm and orifices which are machined from the 316L rod. Each of right and left FBO contains 6 orifices, straight FBOs contain 4 and 6 orifices.Before manufacturing of qualification samples,JSC NIIEFA proposed to IO ITER new approach to provide the seamless connection between tube and plate therefore the most critical weld between orifice with 1mm thickness and tube was removed from the final design of FBOs. Since the proposed diameter of orifice is 4.5 mm which is three times less than the minimum requirement of the ISO 5167, therefore has been tasked to define correctness of calculation flow characteristic at room temperature and compare with experimental data. In 2015, the qualification samples of flow balancing orifices were produced and tested. The results of experimental data shown, that the deviation of calculated data less than 7%. Based on this result and other tests IO ITER approved design of FBO,which made it possible to start the serial production.In 2016 JSC “NIIEFA” delivered 50 FBOs to the IO ITER, i.e. 24 left side, 24 right side and 2 straight FBOs.To define the quality of FBOs has been prepared the test facility in NIIEFA.The helium tightness test at 10-9 m3·Pa/s under the pressure up to 3 MPa,the measuring of flow rate at the various pressure drops, the non-destructive tests of orifices and weld seams(ISO 5817,class B).Also other tests such as check dimensions and thermo cycling 300 - 80 - 300 K were carried out for each FBO.
