Basic features wall thickness

Third, sinks are not only the result of the causes listed above but also can occur whenever supporting or reinforcing ribs, flanges, or similar features are used in an attempt to provide functional service without changing the basic wall thickness of a product. If the appearance of a sink on the surface is objectionable, the ribs and transition radius should be proportioned so that their contribution to the sink is minimal. Sinks can usually be eliminated by changing the process controls that usually results in the unwanted longer cycle times. 

Fig. 4.3-1. Basic features of the thick-walled vessels (adopted from Lewin et. al. [1]). A welded, with cover and closed-end B welded, with two covers...

One of the other basic questions given above was What size of defects in thick-walled metal pressure vessels can be detected reliably by non-destructive examination (NDE) The answer to this question will depend on the NDE method used (dye-penetration, magnetic particle, X-ray or ultrasonic), the skill and experience of the NDE technician, and the geometry of the crack within the steel (e.g., surface or non-surface penetrating, flat steel plate or near other features, and shape of defect). 

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