UPN's 1:10 flange taper enhances load distribution but requires three substitution adjustments:
Bracket Design: Slotted bolt holes (10 mm longer) accommodate the taper, ensuring full contact between UPN and brackets. For example, a UPN 100's tapered flange (56 mm width at web, 50 mm at edge) needs slotted holes to align bolts with the narrower flange edge.
Load Calculation: UPN's taper increases the section modulus-e.g., UPN 200 (158 cm³) vs. GB C200x75x7 (144 cm³). Use this higher value to reduce channel size (e.g., UPN 180 instead of UPN 200) for cost savings.
Welding: Tapered flanges require slightly longer welds (10–15% more length) to maintain contact. Use GMAW with 0.8 mm wire (same as GB) and adjust travel speed to 300 mm/min for consistent bead quality.
These adjustments are straightforward, and UPN's taper provides a performance boost, making it a preferred substitute for heavy-load GB applications.