F.H.Brundle stocks tube clamp fittings to suit five standard outside diameters: A-tube 26.9mm OD (¾” nominal bore), B-tube 33.7mm OD (1″ NB), C-tube 42.4mm OD (1½” NB), D-tube 48.3mm OD (1¾” NB) and E-tube 60.3mm OD (21⁄3″ NB). The most widely used size for handrails is C-tube 42.4mm OD, as it satisfies the DDA and Part M smooth-continuous-handrail requirement. Reducing fittings are available to combine different tube diameters within a single structure.
