Threaded galvanized steel conduit for bulk electrical orders
Threaded IMC lengths, couplings and elbows cover trade sizes from 1/2 to 4 in. The hot-dip galvanized steel range suits conduit runs that require threaded joints, with each fitting matched to the selected trade size.
| Product | Steel intermediate metal conduit (IMC) |
|---|---|
| Surface | Hot-dip galvanized exterior; corrosion-resistant interior |
| Size series | ANSI C80.6 / UL 1242 IMC dimensions |
| Lengths | Nominal 10 ft / 3.05 m, measured with the coupling |
| Ends | Tapered external threads on both ends |
| Coupling options | Matching threaded steel couplings, 1/2–4 in. |
| Additional fittings | Threaded couplings, 45° and 90° elbows, locknuts and bushings |
Find a trade size, outside diameter or thread pitch.
| Trade size (in.) | OD (in.) | OD (mm) | Nominal wall (in.) | Nominal wall (mm) | Threads per inch |
|---|---|---|---|---|---|
| 1/2 | 0.815 | 20.70 | 0.078 | 1.97 | 14 |
| 3/4 | 1.029 | 26.14 | 0.083 | 2.10 | 14 |
| 1 | 1.290 | 32.77 | 0.093 | 2.35 | 11.5 |
| 1-1/4 | 1.638 | 41.59 | 0.095 | 2.41 | 11.5 |
| 1-1/2 | 1.883 | 47.82 | 0.100 | 2.54 | 11.5 |
| 2 | 2.360 | 59.93 | 0.105 | 2.67 | 11.5 |
| 2-1/2 | 2.857 | 72.57 | 0.150 | 3.81 | 8 |
| 3 | 3.476 | 88.29 | 0.150 | 3.81 | 8 |
| 3-1/2 | 3.971 | 100.86 | 0.150 | 3.81 | 8 |
| 4 | 4.466 | 113.44 | 0.150 | 3.81 | 8 |
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Nominal dimensions for steel IMC. Tapered conduit threads use a 1:16 taper; thread pitch changes with the trade-size group.
IMC is quoted to its ANSI C80.6 size series, separately from rigid conduit and pressure pipe.
UL 1242 covers steel IMC. The dimensions on this page do not establish a product listing. For a listing-required order, our offer names the proposed manufacturer, listing file and covered sizes, with the corresponding submittal supplied before acceptance.
Submittal requirements are reviewed with the material schedule. The agreed package identifies the product specification, required certification records, sizes and packing references.
Both ends carry tapered male threads. A threaded coupling joins the next straight length; the bore remains clear for the conductor pull.
Spare couplings support cut sections, field changes and distributor stock. Each matches the conduit trade size.
Factory-formed threaded elbows are selected by angle and trade size, with the required centerline radius.
Threaded hubs, locknuts and bushings are priced for the specified enclosure entry and trade size.
Threaded fittings identified for both RMC and IMC use the matching trade-size connection. EMT-only set-screw or compression fittings belong to a different connection system.
Conduit lengths with fitted couplings and loose accessories are counted separately. This distinguishes the coupling supplied on a length from additional stock for field work.
A size-by-size stock order can combine straight IMC with the faster-moving coupling and elbow sizes. Separate accessory counts make it easier to receive and resell the full range.
IMC provides a threaded steel raceway for routes specified for mechanical protection. The circuit design determines conduit fill, supports and the fittings needed at each equipment connection.
Exterior runs require a complete conduit and fitting system suited to the location. Include the exposure conditions and required fitting ratings in the project schedule.
Our EMT and IMC outdoor-run comparison covers the exposure and fitting questions to resolve before choosing the conduit type.
Replacement sections retain the specified IMC type, trade size and threaded connection, with the required bends and enclosure entries.
Thread checks cover taper, damaged crests and coupling engagement. Clean end threads allow the mating fitting to start correctly without cross-threading.
Outside diameter and wall are checked against the selected IMC size. The 2-1/2 in. size has a nominal 2.857 in. OD, distinct from the 2.875 in. RMC diameter.
The hot-dip galvanized finish protects the outside steel surface. Handling checks identify coating damage before the lengths are bundled.
Interior protection and clean end openings matter along the conductor path. The bore is checked for obstructions and the cut edge for sharp burrs.
Prices per nominal foot and per length use the same 10 ft basis. Extra fittings are priced by piece, separately from the conduit lengths.
Exposed threads receive end protection for handling. Straight lengths are supported and strapped in size-separated bundles, with the trade size, length and piece count matched to the packing list.
Couplings and elbows are boxed by trade size beside the conduit bundles. Minimum batches and dispatch dates depend on the selected size mix.
At the same nominal 1 in. trade size, IMC has a heavier wall than EMT and a lighter wall than steel RMC.
| 1 in. conduit type | OD (in. / mm) | Nominal wall (in. / mm) | Connection |
|---|---|---|---|
| EMT | 1.163 / 29.54 | 0.057 / 1.45 | Plain ends; EMT fittings |
| IMC | 1.290 / 32.77 | 0.093 / 2.35 | Threaded ends; IMC/RMC fittings |
| RMC (steel) | 1.315 / 33.40 | 0.126 / 3.20 | Threaded ends; RMC/IMC fittings |
IMC and RMC share threaded fitting sizes, but the conduit dimensions differ. A change of conduit type still needs to match the project specification.
View our plain-end EMT rangeThe minimum is reviewed for each trade size and shown on that quote line. A mixed-size order keeps the conduit and accessory quantities separate.
Yes. Our factory catalog includes threaded and unthreaded end options. Plain-end IMC is quoted separately from the threaded supply shown on this page, with the intended connection stated on the order.
We quote samples and shipping separately. State the sizes and mating fittings you plan to evaluate so the sample request covers the actual threaded connection, as well as the tube dimensions.
Yes. The agreed label layout can include your item numbers alongside the trade size, length and bundle count, matching each bundle to the purchase-order line.
They belong to the plain-end EMT connection system. Threaded IMC uses the matching threaded fitting identified for IMC or IMC/RMC use, in the required trade size.
Send your IMC size schedule and destination. We will quote the conduit lengths, couplings, additional fittings and shipment terms together.