Embed plates and cast-in items

What it is

Cast-in items are the steel parts set into concrete before it is poured so that steelwork, equipment, facades and services can be connected later. The most common are embed plates (a steel plate with headed studs or deformed bar anchors welded to the back), anchor bolt assemblies for column bases, cast-in edge angles for slab edges and pits, and channel or angle frames for trench covers. They are small items, but if one is missing or in the wrong place, the steel erection programme stops.

World Steel fabricates embeds and anchor assemblies for its own structural steel and PEB packages and as stand-alone misc. metals supplies. Background on the foundation interface is in anchor bolts and embeds and foundations interface.

Types and options

Plates can include threaded studs, tapped holes, slotted holes, shear lugs or weld-on brackets. Anchor rods are supplied straight, hooked or headed, with single or double nuts and leveling nuts as detailed.

Design and compliance

Anchorage to concrete is designed by the engineer of record: in the US to ACI 318 Chapter 17, in Australia to AS 5216 with AS 3600, and in Europe to EN 1992-4. The fabricator's job is to supply exactly the stud diameter, length, spacing, plate thickness and material shown, and to prove the stud welds. Headed studs are typically ASTM A108 material welded to AWS D1.1; Australian work follows AS/NZS 1554.2, and European work uses studs to EN ISO 13918 welded to EN ISO 14555. Anchor rods in the US are commonly ASTM F1554 Grade 36, 55 or 105.

Production stud welding is checked with pre-production bend tests and visual inspection of the weld collar on every stud, plus bend testing of samples as required by the welding standard. Where embed plates connect to structural steel under EN 1090, they are part of the execution class of the structure; under AS/NZS 5131 they follow the construction category set by the designer.

Fabrication and finishing at World Steel

Plates are CNC-cut and drilled from approved shop drawings, studs are welded with drawn-arc stud welding equipment, and rebar anchors are welded by qualified welders using approved procedures. Each item is hard-stamped or tagged with its piece mark and grid location. Anchor bolt sets are packed with their templates, nuts and washers so site crews receive complete assemblies.

Finishes are usually black (uncoated) for fully embedded items, or hot-dip galvanized by qualified galvanizers to ASTM A123 / AS/NZS 4680 / EN ISO 1461 for exposed faces; threaded parts are galvanized to ASTM A153 or the regional equivalent. Stainless steel embeds can be supplied for aggressive environments. See base plates and anchor bolts for coating guidance at the interface.

Installation and site notes

• Embeds and anchor sets are shipped first, separately from the main steel, and listed by pour.
• Items are fixed to formwork or templates and tied to reinforcement so they do not move during the pour.
• Threads are protected with tape or sleeves; plate faces are kept flush with the concrete surface.
• Positions are surveyed after the pour and checked against the erection tolerances before steel arrives; see erection tolerances.

Selecting and specifying

Send the embed schedule with plate sizes, stud or anchor details, material grades and quantities per pour. Define the finish for each item, whether a stud welding procedure qualification or sample testing is required, and the delivery sequence. Embeds supporting canopies, shelf angles or equipment can be coordinated in the same model as the steel they carry.