Unistrut clamps secure pipe, conduit, tubing, or a structural beam to a run of strut channel, and because they slide and lock anywhere along the channel’s slot, installers can place a support exactly where a load needs it instead of drilling a fixed hole. With several distinct clamp families on the market, though, picking the wrong one can mean a loose connection, unnecessary corrosion, or a support that cannot handle the load in front of it.
This guide breaks down the types of Unistrut clamps you are most likely to encounter, explains the job each one handles, and walks through how to match a clamp to your specific pipe, conduit, or structural connection.
What Do Unistrut Clamps Do?
At a basic level, a Unistrut clamp wraps around a pipe, conduit run, or beam flange, then bolts into a channel nut seated in the strut channel slot. Because the channel nut can slide to any position along the channel before it locks, installers gain flexibility that a fixed drilled hole never offers.
Beyond simply holding an item in place, clamps also distribute load across the channel rather than concentrating stress at a single point, which matters most on long horizontal pipe runs or heavily loaded vertical risers. The right clamp also protects the item it holds, since a poorly matched clamp can crush soft tubing, scuff a finished pipe surface, or trap moisture against a metal line.
The Main Types of Unistrut Clamps
Although manufacturers sell dozens of individual part numbers, nearly every Unistrut clamp belongs to one of the families below.
Beam Clamps
Beam clamps attach strut channel directly to the flange of a structural steel beam without drilling or welding into the beam itself. Because building codes often restrict field welding or drilling on structural steel, beam clamps are the standard way to hang a channel run from overhead steel in a warehouse, plant, or commercial building.
Pipe Clamps
Pipe clamps hold round pipe or tubing against or below the channel. They typically come in one-piece and two-piece styles: one-piece clamps thread over the pipe before installation, while two-piece clamps open to wrap around pipe that is already in place, which makes retrofits considerably easier.
Cushion Clamps
Cushion clamps add a rubber, foam, or synthetic liner inside the clamp body, which separates the pipe from the bare metal clamp. Installers reach for cushion clamps on insulated lines, refrigeration piping, and any application where metal-to-metal contact would cause vibration noise, abrasion, or condensation-driven corrosion over time.
Conduit Clamps
Conduit clamps fit electrical conduit specifically, rather than plumbing or mechanical pipe, and they typically hold a tighter tolerance to keep conduit from shifting or rotating. Electrical contractors use these on both rigid metal conduit and, with the correct size, PVC conduit runs.
U-Bolts and Riser Clamps
U-bolts wrap fully around a pipe and thread into a plate or channel on both ends, which gives an especially secure hold on vertical risers or lines subject to vibration. Riser clamps serve a related purpose on vertical pipe runs, transferring the pipe’s weight to the surrounding structure at each floor penetration.
The table below compares these clamp families at a glance.
| Clamp Type | What It Holds | Key Feature | Best Use Case |
|---|---|---|---|
| Beam Clamp | Channel to structural steel beam | No drilling or welding into the beam | Overhead channel runs from structural steel |
| Pipe Clamp | Round pipe or tubing | One-piece or two-piece styles | General pipe support along channel |
| Cushion Clamp | Insulated or bare pipe | Rubber or foam liner | Refrigeration, insulated, or vibration-sensitive lines |
| Conduit Clamp | Electrical conduit | Tighter tolerance, rotation resistant | Rigid metal or PVC conduit runs |
| U-Bolt / Riser Clamp | Pipe on vertical runs | Full wraparound grip | Vertical risers and vibration-prone lines |
How to Choose the Right Clamp for Your Application
Because each clamp family solves a different problem, work through the following questions before you order:
- What are you supporting? Structural steel calls for a beam clamp, round pipe calls for a pipe or cushion clamp, and electrical runs call for a conduit clamp.
- Does the line need insulation from the clamp itself? If condensation, vibration noise, or galvanic corrosion is a concern, choose a cushion clamp over a standard pipe clamp.
- Is the run horizontal or vertical? Long horizontal runs typically use standard pipe or cushion clamps at regular intervals, while vertical risers often need U-bolts or riser clamps to carry the full weight of the line.
- Will you install the clamp before or after the pipe is in place? Two-piece clamps make far more sense for a retrofit than one-piece styles that must slide over an open pipe end.
- What is the exposure environment? Outdoor, washdown, or high-humidity settings call for a different finish than a dry mechanical room, which the next section covers.
Clamp Sizing and Channel Compatibility
Beyond picking a clamp family, you also need to match the clamp to two separate measurements: the diameter of the pipe or conduit it holds, and the width of the channel it bolts to. Because these are independent specs, a clamp sized correctly for a 2-inch pipe still will not seat properly on the wrong channel width, and vice versa.
Most manufacturers stamp both dimensions directly on the clamp or list them in the same catalog entry, so check both figures against your project specs rather than assuming a clamp that fits your pipe will automatically fit your channel. If you are ordering clamps alongside new channel, confirming the pairing before the order ships saves a return trip and a delayed installation.
Material and Finish Considerations
Like other Unistrut components, clamps come in a handful of standard finishes, and matching finish to environment protects the connection over the long run.
- Electro-galvanized (EG): A cost-effective option for dry indoor environments.
- Hot-dip galvanized (HG): A thicker coating suited to outdoor or washdown conditions.
- Stainless steel: The right choice for food-grade, chemical, or coastal environments where corrosion resistance is a top priority.
Whenever a clamp holds a dissimilar metal, such as a copper line against a steel clamp, a cushion or insulated liner also helps prevent galvanic corrosion at the contact point, not just physical wear.
Installation Tips
A few practical habits go a long way toward a clamp installation that holds up over time:
- Support horizontal pipe runs at regular intervals rather than relying on widely spaced clamps to carry the full span.
- Seat the channel nut fully before tightening the clamp bolt, since a partially seated nut will not develop full holding strength.
- Choose a cushion clamp whenever a line will expand and contract with temperature changes, since rigid clamps can wear through pipe insulation over repeated cycles.
- Recheck clamp torque periodically in vibration-heavy environments, as fasteners can work loose faster than they would in a static installation.
Frequently Asked Questions
What is the difference between a pipe clamp and a cushion clamp? A standard pipe clamp holds bare metal against metal, while a cushion clamp adds a rubber or foam liner between the clamp and the pipe. Cushion clamps typically go on insulated, refrigeration, or vibration-sensitive lines where direct metal contact would cause damage or noise over time.
Can I install a beam clamp without drilling into the beam? Yes, and that is the main reason contractors choose them. A beam clamp grips the beam flange mechanically, which avoids the structural and code concerns that come with field-drilling or welding into load-bearing steel.
Do I need different clamps for horizontal and vertical pipe runs? Not always, but vertical risers often benefit from U-bolts or riser clamps because they need to carry the pipe’s full weight at each support point, while horizontal runs can typically use standard pipe or cushion clamps spaced at regular intervals.
How do I know if I need a one-piece or two-piece clamp? Choose a two-piece clamp whenever you retrofit an existing pipe run, since it opens to wrap around pipe that’s already in place. One-piece clamps work well on new installations, where the clamp can slide over the open pipe end before final placement.
Are Unistrut clamps compatible with all channel sizes? No. Like brackets and other fittings, manufacturers build clamps to match a specific channel width, so confirm your channel size (1-5/8″, 1-1/4″, or 13/16″) before ordering clamps for a project.
Get the Right Clamp the First Time
Matching the correct clamp type to your pipe, conduit, or beam connection protects both the installation and whatever it is holding in place. Steinco Industrial Solutions has supplied Unistrut clamps and framing components for more than 30 years, and as a GSA Multiple Award Schedule contract holder, we also support federal and defense facility projects directly. We pre-assemble clamp and channel packages, cut channel to length, and handle custom fabrication so your support system shows up ready to install.
Contact our team with your pipe size, load, and environment details, and we will help you select the right clamp type for the job.
