I need your helps. For Hydrogen Bullets some designers designed with Multilayered Vessel i.e. with a shell inside plate of 12 mm ( called Liner Plate) and 7 number of 6 mm each plate welded in a common groove for longitudinal and circ. seams. Q1. What could be the design basis of such type of construction for hydrogen bullets ? Q2. How to do Angle Beam Shear Wave UT inspection in this case as in the plate skip zone plate-to-plate interface will create false echoes and will not allow the beam to pass on to weld side wall ? Q3. Any other comments? regards DM

Debasis Q1: Design basis for multilayer - is the same as for other pressure vessels . ASME Sec VIII Div rules shall apply. Multi layer or multi coil technique - as it is called - is cheaper alternative compared to heavy wall forgings or heavy wall thickness plates. Technology for this was developed 50 years back by Mitsubhishi Heave Vessels Japan. Later many European / US heavy pressure vessel manufacturers developed the technology. China developed its own heavy wall muti-coil technology, similar to Mitsubhishi coil technology, for ammonia and urea reactors 35 years back. For your Hydrogen bullet , inner shell of 12 mm + 7 coil layer of 6 mm = total = 54 mm thickness with common axis long and circ weld seams. Q2: UT Shear wave : there will be plate to plate interference as 6 mm thickness itself requires a lot of standard calibration reference for sound interpretation. Yes false interpretation from echos definitely will confuse even a very experienced UT operator. This requires lot of sampling and reference defect from the same material right from the manufacturing stage for both UT operator and for the Third Party Inspector to diagnoze the real defect probability. If you have ordered or taken a sample reference of the same material and kept a standard reference block for UT flaw check for this bullet, at the time of ordering the bullet, then it may give better quality interpretation. It is not a high improbability for establishing a UT flaw detection by shear wave technique even for this 54 mm thick mult layer vessel plates. Without that, David Henderix is quite right that UT flaw will not work to get the inner 12 mm plate to get meaningful interpretative result by UT shear wave application. Trust this answers your querry C.V.Srinivasan Nishi Engineers Pvt Ltd India Sept 30,2005 E-mail: nishi@vsnl.com >I need your helps. > >For Hydrogen Bullets some designers designed with >Multilayered Vessel i.e. with a shell inside plate of 12 mm >( called Liner Plate) and 7 number of 6 mm each plate welded >in a common groove for longitudinal and circ. seams. > >Q1. What could be the design basis of such type of >construction for hydrogen bullets ? > >Q2. How to do Angle Beam Shear Wave UT inspection in this >case as in the plate skip zone plate-to-plate interface will >create false echoes and will not allow the beam to pass on >to weld side wall ? > >Q3. Any other comments? >regards >DM

Fakhor Is your urea reactor (MHI multi layer vessel) lined with S.S 316 L or Ti or Zr ? Did you experience any leak in the Carbon Steel shell from operation since 1976? How often do you inspect the S.S 316 L (Urea grade) or Ti or Zr liner? If you have not experienced any leak through internal liner welds or liner then, internal inspection can be done to assess the condition of the liner. If you have experienced any leak through liner welds and repaired the carbon steel and also the liner then inspection has to be done to assess the carbon steel shell as well as the internal liner. We have inspected some reactors - S.S 316 L lined as well Ti or Zr lined for a couple of times during the last 12 years. We have assessed urea reactor internal liner conditions for urea manufacturing plants / companies in India. Trust this is of help to you C.V.Srinivasan Nishi Engineers Pvt Ltd India Sept 95, 2006 E-mail: nishi@vsnl.com >We are a urea manufacturer and wish to establish integrity >of our multilayerered Urea autoclave pressure resisting CS >shell. The reactor was supplied by MHI in 1976. Can some one >point to an inspection agency / technique which we can use >for this purpose