Heavy transverse frame, larger than ordinary frames, providing structural support typically every 3–5 frame spaces.
Regulatory detail & full definition
Heavier transverse frame in a longitudinally framed hull, fabricated as a deep T or built-up plate girder rather than a rolled section. Web frames are typically spaced every three to five ordinary frame spaces and define the primary transverse strength rings of the hull — supporting longitudinal stiffeners, bulkheads, and decks. IACS Common Structural Rules size them by section modulus and shear area against still-water and wave bending moments. They are key inspection items at renewal survey because their cropped flanges and lug details concentrate fatigue stress.