Ductile iron grates & access covers

What they are

Ductile iron – also called spheroidal graphite or nodular iron – is a cast iron in which the graphite forms small spheres rather than flakes. This gives the casting strength and a degree of ductility, so it can carry heavy wheel loads without the brittle cracking associated with grey iron. Ductile iron is the usual material for sewer and utility access covers and for many stormwater grates, because a cast lid can be shaped with ribs, seating faces, hinges and locking points in one piece.

World Steel does not cast iron. Ductile iron grates, covers and cast frames are produced by specialist foundries and are supplied by World Steel as part of a project drainage package. What we add is coordination: we schedule covers by pit, check that the selected product suits the class and opening on the drawings, fabricate any steel frames, surrounds, adaptor rings or support steel in our plant, inspect and pack everything together. Where a project mixes cast items with our fabricated steel drainage grates, trench covers and pit covers, the client deals with one supplier.

Types and options

For large or non-standard openings, cast lids can be combined with steel support beams in a multi-part cover system. For lightweight or non-conductive needs, compare composite access covers.

Design, approvals and compliance

The load class is set by the designer: AS 3996-2019 classes A to G in Australia, the EN 124 series (A15 to F900) in Europe, and AASHTO H-20 / HS-20 or HL-93 loads in the US. Typical ductile iron material grades are EN-GJS-500-7 to EN 1563 or ASTM A536 grades in the US; grey iron to ASTM A48 is still used for some lighter castings. Class compliance and any load test evidence come from the foundry for the specific product.

Water and sewer authorities often keep their own lists of accepted products – for example, appraisal under the WSAA product scheme in Australia. Acceptance is product-specific and belongs to the manufacturer. Tell us which authority list applies and we will only offer products that meet it; World Steel holds no product approvals for castings.

What World Steel fabricates and supplies

• Selection support: matching foundry products to the class, clear opening and authority list.
• Steel frames, adaptor frames and surrounds where a cast frame does not suit the opening or slab.
• Support beams and bearers for multi-part covers, galvanised to AS/NZS 4680, ASTM A123 or EN ISO 1461.
• Incoming inspection of castings for marking, fit and visible defects against the order.
• Consolidated packing and shipping with the steel package; see export supply.

Installation and selection notes

Cast frames must be fully bedded on mortar or concrete to the manufacturer's instructions; uneven bedding is the main cause of rocking covers. Check marking of class and standard on each cover before installation, and keep covers closed during paving. When requesting a quotation, give the pit schedule, clear openings, load class, authority list, sealing and locking needs and the frame setting detail. See also foundation interfaces.