FABRICATION OF FLANGE CUTS BASIC INFORMATION


The reduced beam section shall be made using thermal cutting to produce a smooth curve. The maximum surface roughness of the thermally cut surface shall be 500 microinches (13 microns) in accordance with ANSI B46.1, as measured using AWS C4.1–77 Sample 4 or similar visual comparator.

All transitions between the reduced beam section and the unmodified beam flange shall be rounded in the direction of the flange length to minimize notch effects due to abrupt transitions. Corners between the reduced section surface and the top and bottom of the flanges shall be ground to remove sharp edges, but a minimum chamfer or radius is not required.

Thermal cutting tolerances shall be plus or minus 1/4 in. (6 mm) from the theoretical cut line. The beam effective flange width at any section shall have a tolerance of plus or minus 3/8 in. (10 mm).

Gouges and notches that occur in the thermally cut RBS surface may be repaired by grinding if not more than 1/4 in. (6 mm) deep. The gouged or notched area shall be faired by grinding so that a smooth transition exists, and the total length of the area ground for the transition shall be no less than five times the depth of the removed gouge on each side of the gouge.

If a sharp notch exists, the area shall be inspected by MT after grinding to ensure that the entire depth of notch has been removed. Grinding that increases the depth of the RBS cut more than 1/4 in. (6 mm) beyond the specified depth of cut is not permitted.

Gouges and notches that exceed 1/4 in. (6 mm) in depth, but not to exceed 1/2 in. (12 mm) in depth, and those notches and gouges where repair by grinding would increase the effective depth of the RBS cut beyond tolerance, may be repaired by welding. The notch or gouge shall be removed and ground to provide a smooth radius of not less than 1/4 in. in preparation for welding.

The repair area shall be preheated to a temperature of 150o F or the value specified in AWS D1.1 Table 3.2, whichever is greater, measured at the location of the weld repair. Notches and gouges exceeding 1/2 in. (12 mm) in depth shall be repaired only with a method approved by the engineer of record.

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