What is a lifting anchor?

Here's an explanation of lifting anchors, broken down into common construction site terms:

1. What's it used for?

A concrete "lifting ring": A metal component embedded in concrete structures (wall panels, stairs, beams). Hooks or bolts are screwed directly onto it for lifting.
Key to safe load-bearing: It supports tens of tons of weight; the crane's wire rope is attached here.

2. What do they commonly look like?

Type | Features | Uses
Internal Threaded Sleeve | A steel sleeve embedded in concrete, with threads in the middle. | Floor slabs, wall panels (flat surface, no protrusions)
Exposed Lifting Ring | Reinforcing steel bent into a U-shape, the ring end exposed after concrete pouring. | Temporary lifting (cut off after formwork removal)
Folding Anchor | Can be folded up when needed, flattened against the surface when not in use. | Exterior wall panels (to prevent damage during transport)
Bolt Anchoring | High-strength bolts screwed into embedded parts. | Large beams and columns (can be repeatedly disassembled and reassembled)

3. How is it installed?

Pre-embedding before pouring: ① Fix anchor point position when tying reinforcing bars (error ≤ 5mm) ② Weld sleeves/U-rings to main reinforcing bars to prevent displacement ③ Avoid anchor points during concrete vibration to prevent grouting
Post-installation (rarely used): Drilling → Injecting adhesive → Screwing in expansion bolts (only suitable for small and lightweight components)

4. What to keep a close eye on during use?

Don't get the direction wrong: Horizontal anchor points (such as floor slabs) can only be lifted vertically. Diagonal pulling may crack the concrete!
Rust prevention is crucial: Regularly apply oil to exposed threads to prevent them from rusting and becoming impossible to tighten.
Scrap signs: Deformation, cracks, stripped threads—replace immediately; continuing to use them will lead to serious problems.

5. Pitfalls encountered

Helping hook detachment: Threads not tightened, anchor point pulled out during lifting.
Concrete corner chipping: Anchor point too close to the edge, tearing the edge under stress.
Hook accidents: Exposed hooks trip workers; now concealed hooks are more common.