purchase of cast iron manhole frames and covers of various sizes required for main sewer sections purchase of cast iron manhole frames and covers of various sizes required for main sewer sections under che s o department , manhole covers / frames , c.i. circular manhole cover 600 mm dia. , c.i. circular manhole frame 600 mm dia. , c.i. circular manhole covers with frame 600 mm dia. , c.i. rectangular manhole covers 900 x 450 mm , c.i. rectangular manhole covers 914 x 457 mm , c.i. rectangular manhole covers with frame 900 x 450 mm , c.i. rectangular manhole covers with frame 914 x 457 mm , c.i. rectangular manhole covers 900 x 600 mm , c.i. rectangular manhole covers with frame 900 x 600 mm , c.i. rectangular scrapper manhole covers 900 x 1200 mm , c.i. rectangular scrapper manhole covers with frame 900 x 1200 mm