1.6 Reinforcement of Vessel Openings

  • Openings in the vessels are made first by making holes in the vessel. Nozzles are then welded around these holes. Holes cause a discontinuity in the vessel wall. Due to pressure or other loads a stress concentration is created near the holes, the maximum value of the stress being at the edge of the holes.

  • The stress concentration at the hole can be reduced by increasing the thickness of the vessel in the vicinity of the nozzle. This can be done either by providing additional thickness to the vessel wall itself near the nozzle or by use of a separate reinforcing plate attached to the vessel wall covering an area surrounding the hole.

  • All openings up to 5 cm in size can be left uncompensated. See Fig.(10) for details of reinforcing a nozzle opening.

  • The purpose of the hole (called as tell-tale hole) on the reinforcing pad around a nozzle is to allow the attachment of the pad without having any trapped gases or pressure build-up between the pad and the tank wall.