SECTION B - Derry City Council

with anti-corrosive treatments.
Light angle sections may be cut by cropping providing the ends are
dressed flush and burrs removed.
Flame cutting (thermal cutting) of steel will be permitted only for the
wall ends of beams, filler joists, or the like.
Flame cutting of plates is permitted provided that properly prepared
templates or guides are used and all gas cuts are dressed up free
from oxidised metal to a bright metal finish.
All holes generally shall be drilled with a maximum of 2 mm
clearance for black bolts up to 24 mm diameter and 3 mm maximum
clearance for bolts over 24 mm diameter.
Punching of holes is acceptable only for secondary structural
members such as sheeting rails and light bracing angles and all
arises or burrs shall be removed prior to final assembly. Holes for
high strength friction grip bolts shall not be punched.
Unless adequate weld metal is provided to transmit forces, bearing
stiffeners shall be accurately ground over their full bearing faces to
fit tightly the angle or section stiffened.
For fabrication in Structural Hollow Sections, the ends of members
may be prepared for welding by sawing, machining, or by hand
flame cutting using properly prepared templates or by automatic
flame cutting or other approved methods.
The correct fusion bevel for the welding of sections or plates may
be achieved by flame cutting and/or grinding or machining. A
smooth contour, free from irregularities is essential. Surfaces
should also be free of any deleterious matter likely to affect the
ease of welding and the efficiency of the connection.
The edges of all plates etc cut by flame, which will be subject to
dynamic or fatigue loading or liable to brittle fracture, shall be further
machined to remove excessive face hardness. The amount of
metal to be removed shall be to the satisfaction of the Engineer.
Vent holes must be provided in Structural Hollow Section
fabrications which are subsequently to be hot-dip galvanised. After
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