Multiple steel covers recessed for concrete installation guide

Remove the covers from the frame and set them aside in such a way that they can be refitted to the frame in the same positions and orientations as delivered. This is particularly important in the case of locking covers.

Frame cross members (usually beams, channels or box sections) can either be removed or remain in position when placing the frame, this being dependent on the equipment available for lifting (Fig 2). On larger units, the beams will be bolted in place to help stabilise the frame. Note: Care should be taken when handling beams, their weight can exceed 40kg per metre.

Position the frame in the rebate or on the cover slab, ensuring that the clear opening of the frame aligns with the chamber opening, note that overhanging, unsupported framework can cause premature cover failure.

The top edge of the frame needs to be set level and at the correct finished floor height, achieve this by using hard shim material between the frame and the cover slab. (Fig. 3). Also ensure that the frame is square and that the sides are straight, spacing and packing where necessary, bolt the frame in position using M12 anchors through the 13 mm diameter holes provided in the frame flange (Do not overtighten as this can distort the frame).

If the support beams have been removed for handling purposes replace them now, fitting the full-length beams first followed by the shorter transverse beams.

Replace the covers as a trial fit, ensure that the covers do not rock and that they sit neatly with even gaps, making any necessary adjustments to the frame to achieve this. Note: It is critical to achieve a good fit at this stage, it cannot be improved once the frame is cast in.

When satisfied with the fit carefully remove the covers again, setting aside as necessary to enable them to be refitted in the same positions and orientation on completion.

The base of the frame must be fully supported on a mortar bed either by hand packing or pourable grout.

The outside of the frame should be encased in mortar, either within the rebate or cast into the floor slab.

Once the frame is secure the fabricated pockets supporting the cross beams need to be fixed to the chamber wall with M12 anchor bolts, and shim any gaps between the pocket and the chamber wall to avoid distortion of the frame.

Clear any debris and loose material from inside the frame and cross beams.

Refit the covers, keeping the same positions and orientations as previously.

If the covers are locking the bolts should now be replaced, check that the threads are clean prior to use. It is recommended that the threads are greased to aid future removal.

Finally, fill the cover recesses with concrete, to achieve design loads all covers should be fully filled with grade C30 concrete. Where the final finish is to be tarmacadam deep recessed covers (100 mm minimum) should be used, with 2/3 filled with C30 concrete and the top 1/3 with blacktop. Tape over cover edges, keyholes and locking bolts to avoid blockage by surplus fill material.