ISWB (Indian Standard Wide Flange Beam)

ISWB (Indian Standard Wide-Flange Beam) is a family of hot-rolled steel I-sections with wider flanges than ISMB at the same depth. Per IS 808:1989 + IS 2062:2011, ISWB provides better lateral stability and higher section modulus per kg of steel than ISMB — useful for laterally-unsupported beams and major structural members. ISWB designations: ISWB <depth>, e.g., ISWB 300 (300 mm depth, 50.0 kg/m vs ISMB 300's 44.2 kg/m).

Key ISWB sizes: ISWB 150 (17.0 kg/m, Ixx = 720 cm⁴), ISWB 200 (28.8 kg/m, Ixx = 2540 cm⁴), ISWB 225 (33.9 kg/m, Ixx = 3640 cm⁴), ISWB 250 (40.9 kg/m, Ixx = 5520 cm⁴), ISWB 300 (50.0 kg/m, Ixx = 9820 cm⁴), ISWB 350 (62.3 kg/m, Ixx = 16,250 cm⁴), ISWB 400 (75.6 kg/m, Ixx = 25,750 cm⁴), ISWB 500 (102.7 kg/m, Ixx = 55,000 cm⁴), ISWB 600 (137.0 kg/m, Ixx = 100,000 cm⁴). Compared to ISMB at same depth: ISWB has 12-20% higher Ixx (better moment capacity) and 25-50% wider flange (better lateral stability). Used for: laterally-unsupported beams, major floor beams in steel buildings, columns where biaxial bending matters, transfer beams in steel-frame construction.