Drop-In Anchors, 303 Stainless Steel, Simpson Strong-Tie

What a Drop-In Anchor Does

A drop-in anchor is a female anchor: it sits flush in the concrete and gives you a threaded socket rather than a projecting stud. That makes it the usual choice for overhead work — hanging threaded rod for pipe, conduit, strut, sprinkler mains and equipment supports — and for anywhere a fixture needs to come off and go back on. Unlike a wedge anchor, nothing protrudes when the fixture is removed.

Sizes and Setting Tools

Each anchor size takes its own setting tool. The tool is what expands the anchor in the hole, and a tool of the wrong size will not seat the anchor correctly.

About 303 Stainless

303 is a free-machining austenitic stainless. Sulfur is added to the alloy so it can be machined cleanly into a threaded body like this one, and that sulfur is also what makes its corrosion resistance lower than 304 or 316. These anchors are well suited to interior work, mechanical rooms, parking structures and general concrete anchoring. They are not a marine-grade fastener. For direct salt spray, splash zones or chloride-heavy exposure, use a 316 stainless Titen HD® screw anchor instead.

How to Install a Drop-In Anchor

1. Drill the hole to the diameter and depth specified for the anchor size, using a carbide bit. Drill slightly deeper than the anchor length so the anchor can seat fully.
2. Blow the hole clean with compressed air. Dust under the anchor prevents it from seating flush.
3. Drop the anchor into the hole, lip end up, until it sits flush with the surface.
4. Insert the matching setting tool and strike it with a hammer until the tool shoulder bottoms against the anchor lip. That expansion is what locks the anchor into the concrete.
5. Thread the bolt or rod in by hand, then tighten. Do not overtighten — the holding power comes from the expansion already set, not from torque on the bolt.

Frequently Asked Questions

Do I need the setting tool?

Yes. The anchor does not expand on its own and does not expand from tightening the bolt — it has to be set with the tool before the bolt goes in. An unset anchor will pull straight back out. The tool is reusable across as many anchors of that size as you need, so one per size is usually enough.

Can I remove the bolt later?

Yes, and that is the main reason to choose this anchor. The bolt or rod threads out and back in as often as you need. The anchor body itself stays permanently in the concrete once set.

How is this different from a wedge anchor?

A wedge anchor is a male anchor — a stud that projects from the concrete and stays projecting whether or not anything is attached. A drop-in is female and sits flush, so the surface is clear when the fixture comes off. Wedge anchors are generally the higher-capacity option; drop-ins win on serviceability and on overhead work where a projecting stud is in the way.

Are these good for coastal or marine work?

No. 303 stainless is not a marine-grade alloy. For coastal, marine and chloride-exposed anchoring, choose a 316 stainless anchor.