Attaching pipe, conduit, or cable tray support directly to structural steel without drilling or welding comes down to one component: the beam clamp. Unistrut beam clamps bolt onto the flange of a wide-flange beam, channel, or angle and give you an instant, load-rated attachment point for Unistrut channel, threaded rod, or hangers without ever touching the beam itself.

Below is a breakdown of the beam clamp types Steinco stocks, how to size one correctly, and how they compare to welding for structural attachment.

What Is a Unistrut Beam Clamp and How Does It Work?

A beam clamp is a two-piece (or hinged) fitting that grips the top or bottom flange of a structural steel beam using a set screw, cup point, or serrated jaw. Once torqued down, it creates a fixed or adjustable attachment point that accepts threaded rod, channel, or a direct bolt connection — no drilling, no welding, and no loss of the beam’s fireproofing or structural rating.

Because the clamp distributes load across the flange rather than concentrating it at a drilled hole, beam clamps are the standard method specified for suspending mechanical, electrical, and plumbing systems from structural steel in commercial and industrial construction.

What Types of Unistrut Beam Clamps Are Available?

Top Beam Clamps (C-Clamps)

The most common style, installed from the top of the flange with a single set screw. Steinco stocks these across multiple load ratings, including the P2867 beam clamp and P2868 beam clamp series.

Wide-Throat / Universal Beam Clamps

Built with an extended throat depth to fit oversized or non-standard flanges. The P2898 universal beam clamp series covers 3/8″ through 7/8″ rod sizes in a single adjustable body.

Purlin Beam Clamps

Designed specifically for the thinner flange profile of roof purlins rather than structural beams. See the P2784 purlin beam clamp for rooftop mechanical and conduit support.

FM-Approved Beam Clamps

Required on fire sprinkler and life-safety piping. The P2897 FM-approved beam clamp meets NFPA 13 hanger requirements for fire protection contractors.

Flange Clamps

A lighter-duty alternative for smaller flange widths and lighter loads, such as the PFL2 beam clamp and the PFL037 series.

The full stocked range — 27 SKUs across load ratings and rod sizes — is organized on the 1-5/8″ Beam Clamps category page. Steinco also stocks a 13/16″ beam clamp and tubing clip line for lighter framing systems and a Flex-Strut beam clamp line for FRP and corrosive-environment applications.

How Do You Choose the Right Beam Clamp Load Rating?

  • Confirm the flange width and thickness of the beam — undersized clamps won’t seat correctly and oversized clamps lose clamping force.
  • Match the rod size the clamp accepts (typically 3/8″ to 7/8″) to your hanger or channel drop.
  • Check the manufacturer’s rated working load and apply the project’s required safety factor — do not rely on the clamp’s ultimate load rating alone.
  • For seismic zones, confirm the clamp is rated for lateral load and paired with appropriate bracing; see Steinco’s 

seismic support system overview and the Seismic Support Pipe and Beam Clamps line for pre-rated hardware.

  • For fire protection piping, confirm FM approval and NFPA 13 compliance before specifying.

How Are Unistrut Beam Clamps Installed?

  • Position the clamp over the flange and hand-tighten the set screw or jaw bolt to seat it against the flange face.
  • Torque to the manufacturer’s specified value — under-torquing is the most common cause of beam clamp slippage under load.
  • Thread the rod or channel connector into the clamp body and verify it’s plumb before final load transfer.
  • Re-check torque after the system is loaded, particularly on vibration-prone mechanical and HVAC runs.

Beam Clamps vs. Welding: Which Is Better for Structural Attachment?

Welding a hanger directly to structural steel voids the beam’s fireproofing rating in most jurisdictions and requires a certified welder, hot work permit, and fire watch. A beam clamp achieves the same load-rated attachment point in minutes, requires no hot work, and can be relocated or removed without damaging the beam — which is why beam clamps are the default method specified in mechanical and electrical hanger schedules unless a project specifically calls for welded connections.

What Applications Use Unistrut Beam Clamps?

  • HVAC and mechanical piping support hung from structural steel
  • Electrical conduit and cable tray runs in warehouses and plants
  • Fire sprinkler branch line and main support (FM-approved clamps)
  • Rooftop equipment and purlin-mounted supports
  • Seismic bracing attachment points in retrofit and new construction

Frequently Asked Questions About Unistrut Beam Clamps

Do beam clamps damage the beam or void its fire rating? No. Unlike welding or drilling, a properly torqued beam clamp doesn’t penetrate the steel or its fireproofing coating, which is why it’s the preferred method on rated structural members.

What size rod do Unistrut beam clamps accept? Most of Steinco’s stocked line accepts 3/8″ through 7/8″ threaded rod, with the universal P2898 series covering that full range in one body.

Can beam clamps be used on wide-flange (W-shape) beams? Yes — top beam clamps and universal beam clamps are designed for standard W-shape flange profiles. Purlin clamps are a separate style for the thinner Z- and C-purlin profiles used on roofs.

Are FM-approved beam clamps required for all fire sprinkler work? Most fire protection specifications and NFPA 13 require FM-approved or UL-listed hangers on sprinkler piping specifically — confirm with your local AHJ and project specification before substituting a standard beam clamp.

What’s the difference between a beam clamp and a flange clamp? They serve the same purpose; “flange clamp” typically refers to the lighter-duty end of the range for smaller flange widths and lower loads, while “beam clamp” covers the full range including heavy structural applications.

Order Unistrut Beam Clamps from Steinco Industrial Solutions

Steinco stocks the full Unistrut beam clamp line — top, universal, purlin, FM-approved, and flange styles — across every standard rod size, alongside the full Unistrut clamps line and Unistrut brackets for a complete support system. Contact Steinco for wholesale pricing and project-specific specification support, or browse the full Unistrut product line.