Machining or grinding

(1) Machining can be performed by a high speed rotaiy burr cutter and has the advantages of producing a more precise radius definition, leaving marks parallel to the stress direction and gaining access to corners. Alternatively a disk grinder may be used if access permits, see Figure E.2.1. In both cases the radius of the cutting tip or edge must be correctly chosen.

(2) To ensure the removal of intrusions etc. burr machining has to be extended to a depth of minimum 0.5mm below the bottom of any visible undercut etc., but should not exceed 2mm or 5% of the plate thickness, whichever is the less see Figure E.2.2. The slight reduction in plate thickness and corresponding increase in nominal stress is insignificant for thickness of 10mm or larger. In the case of multipass welds at least two weld toes must be treated. Care should also be taken to ensure that the required throat size is maintained.

a) Burr machining b) Disk grinding

Figure E.2.1 Machining/grinding Geometries techniques

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