Strut Channel Clamps: Beam Clamps, Pipe Clamps & EMT Clamps
Strut clamps — also called C-channel clamps, for the C-shaped channel they mount to — fall into three groups: beam clamps that hang channel or threaded rod from structural steel, rigid-conduit pipe clamps sized by pipe O.D., and EMT clamps for thin-wall conduit. Find the part number by size below, then check its published design load.
This page sizes a strut clamp: beam clamps by rod diameter, rigid conduit and EMT clamps by trade size, each with the part number and the load the manufacturer publishes against it.
Straight to the numbers: full specification table
Building a pipe support? Every layer of a strut trapeze, part number by part number
Go straight to the clamp tables and read the row. The search box in the header takes a part number on any page.
B-Line, Superstrut, Power-Strut or Haydon. The cross-reference table prints what each published document lists opposite it, with the source named on every cell.
Rod or channel, steel or conduit, plumb or angled. Four questions pick the family before you pick a number.
Reading the design loads
Published clamp loads are working loads, not failure loads — the manufacturer applies the safety factor before printing the number (a minimum factor of 4 on the P2897, for example). Three rules keep the numbers honest in the field. First, loads assume static service; add generous margin for anything that vibrates or cycles. Second, angle kills capacity: any clamp loaded off-vertical must use its derated figure, and if none is published, assume the clamp is not rated for angular loading at all. Third, the clamp is only one link — the rod, the channel nut and the channel itself each carry their own rating, and the assembly is only as strong as the weakest of them. For anything structural or life-safety, verify against the manufacturer’s current specification and applicable code with a qualified engineer.
Choosing between clamp families
Hanging rod from steel: P2898 by rod size, or P2899 when the flange is thick. Hanging channel from steel: P2784 matched to your channel series. Rod that cannot hang plumb: P2676. Attaching conduit or pipe to channel: P1109-series for rigid, P1425-series for EMT — matched by trade size, never by tape measurement, because trade size and actual O.D. differ by design. When a job mixes rigid and EMT below 2-1/2 in., keep the two clamp series separated in the parts bin; they look alike and do not interchange. Clamp loads assume the channel itself is rated for the span — see the channel size and load chart. For bolted channel-to-channel joints rather than clamped ones, see the strut fitting identification guide.
Full specification table
Beam clamps
A beam clamp grips the flange of an I-beam, bar joist or purlin and gives you an attachment point without drilling or welding structural steel. The three questions that pick the part are: what are you hanging (threaded rod or channel), what rod diameter, and does the load hang straight down. Every clamp below publishes a maximum load with the safety factor already applied — and every rating assumes a clean, square grip on the flange.
Universal beam clamps — P2898 series (UL listed, FM approved)
The workhorse for suspending threaded rod from steel. Rated to 450 °F, which is why the series shows up in fire-sprinkler work. Capacity scales with rod size:
| Part | Rod size | Max load |
|---|---|---|
| P2898-37 | 3/8" | 400 lbs |
| P2898-50 | 1/2" | 500 lbs |
| P2898-62 | 5/8" | 600 lbs |
| P2898-75 | 3/4" | 800 lbs |
| P2898-87 | 7/8" | 1200 lbs |
Catalog rating for the reference part, not for parts we supply.
Wide-throat top beam clamps — P2899 series (UL, FM)
Same job as the P2898 but with a deeper throat that reaches over thick flanges and deck edges, clamping from the top:
Show the table — 4 rows
| Part | Rod size | Max load |
|---|---|---|
| P2899-37 | 3/8" | 500 lbs |
| P2899-50 | 1/2" | 500 lbs |
| P2899-62 | 5/8" | 600 lbs |
| P2899-75 | 3/4" | 800 lbs |
Catalog rating for the reference part, not for parts we supply.
Channel-to-beam saddle — P2784 series
Instead of rod, this one saddles a run of strut channel directly onto a beam flange and clamps it — the fastest way to build a trapeze rack off structural steel. Pick the variant by the channel you are carrying:
Show the table — 3 rows
| Part | For channel | Load |
|---|---|---|
| P2784-1 | P1000/P1100/P2000 | 1200 lbs |
| P2784-2 | P1001/P1101/P2001 | 1200 lbs |
| P2784-3 | P5001/P5501 | 1200 lbs |
Catalog rating for the reference part, not for parts we supply.
C-clamps and swing clamps — P2897, P2675, P2676
The P2897 (FM approved) hangs 3/8 in. rod and is rated lower once the pull is more than 25° off vertical. The light-duty P2675 is rated by orientation, strong and weak, and is formed from .105 in. steel. The P2676 is the one to reach for when the rod cannot hang plumb: it accepts up to 1/2 in. rod with a built-in 15° swivel in all directions, and is also rated by orientation.
| Part | Rod size | Max load |
|---|---|---|
| P2897 | 3/8" | 550 lbs within 25° of vertical; 330 lbs out to 45° |
| P2675 | up to 3/8" | 250 lbs strong orientation; 150 lbs weak |
| P2676 | up to 1/2" | 300–500 lbs by orientation |
Catalog rating for the reference part, not for parts we supply.
Source: Unistrut® General Engineering Catalog no. 17, p. 122–123, 139 · Verified 2026-07-20
Pipe clamps for rigid steel conduit — P1109 thru P1126
Two-piece strap clamps — often called channel pipe clamps — that bolt a run of rigid conduit or pipe to the open face of 1-5/8 in. channel. Order by conduit trade size — the table gives the true outside diameter each clamp is formed for, the steel gauge, and the published design load. Slotted hex screw and nut are included; standard finish is electro-galvanized.
Show the table — 14 rows
| Part | Trade size | O.D. (in) | Steel | Design load |
|---|---|---|---|---|
| P1109 | 3/8" | 0.675 | 16 ga | 400 lbs |
| P1111 | 1/2" | 0.840 | 16 ga | 400 lbs |
| P1112 | 3/4" | 1.050 | 14 ga | 600 lbs |
| P1113 | 1" | 1.315 | 14 ga | 600 lbs |
| P1114 | 1-1/4" | 1.660 | 14 ga | 600 lbs |
| P1115 | 1-1/2" | 1.900 | 12 ga | 800 lbs |
| P1117 | 2" | 2.375 | 12 ga | 800 lbs |
| P1118 | 2-1/2" | 2.875 | 12 ga | 800 lbs |
| P1119 | 3" | 3.500 | 12 ga | 800 lbs |
| P1120 | 3-1/2" | 4.000 | 11 ga | 1000 lbs |
| P1121 | 4" | 4.500 | 11 ga | 1000 lbs |
| P1123 | 5" | 5.563 | 11 ga | 1000 lbs |
| P1124 | 6" | 6.625 | 10 ga | 1000 lbs |
| P1126 | 8" | 8.625 | 10 ga | 1000 lbs |
Catalog rating for the reference part, not for parts we supply.
Source: Unistrut® General Engineering Catalog no. 17, p. 122–123, 139 · Verified 2026-07-20
Pipe clamps for EMT (thin-wall conduit) — P1425 thru P1431
EMT runs smaller than rigid conduit at the same trade size, so it gets its own clamp series through 2 in. From 2-1/2 in. upward the O.D. converges and the rigid-conduit clamps P1118–P1121 do double duty.
Show the table — 7 rows
| Part | Trade size | O.D. (in) | Steel | Design load |
|---|---|---|---|---|
| P1425 | 3/8" | 0.577 | 16 ga | 400 lbs |
| P1426 | 1/2" | 0.706 | 16 ga | 400 lbs |
| P1427 | 3/4" | 0.922 | 16 ga | 400 lbs |
| P1428 | 1" | 1.163 | 14 ga | 600 lbs |
| P1429 | 1-1/4" | 1.510 | 14 ga | 600 lbs |
| P1430 | 1-1/2" | 1.740 | 12 ga | 800 lbs |
| P1431 | 2" | 2.197 | 12 ga | 800 lbs |
Catalog rating for the reference part, not for parts we supply.
Source: Unistrut® General Engineering Catalog no. 17, p. 122–123, 139 · Verified 2026-07-20
Where it is used
- Pipe and conduit
- Page 137 states that pipe clamps, pipe hangers, brackets and rollers are designed for the support of electrical and mechanical services.
- Rigid conduit
- Page 139 heads the P1109 thru P1126 range “Pipe Clamps for Rigid Steel Conduit”, listed by the pipe’s outside diameter, with the slotted hex head screw and nut included.
- Rod suspension
- Page 122 gives P2675 as a light duty rod suspension clamp, usable with a P3016-1024 or P3016-1420 nut for mounting insulators; p. 123 gives P2676 where the rod needs a free swing of up to 15°.
- Sprinkler work
- Pages 131 and 132 mark certain beam clamps FM approved when used for sprinkler systems only.
Source: Unistrut® General Engineering Catalog no. 17, p. 122–123, 131–132, 137, 139 · Verified 2026-09-19
Made to order
What we quote against a clamp number is a candidate substitute made to order by a contract manufacturer, not an original-manufacturer part.
- Catalog vs. ours
- Material figures in the catalog belong to the reference part: .105 in. (2.7 mm) steel for P2675 on p. 122, 1/8 in. (3.2 mm) for P2676 on p. 123, malleable iron for some beam clamps on p. 132. The steel and thickness we supply are quoted on their own line and never merged into that column.
- Hardware
- Catalog rigid and EMT clamps ship with the slotted hex head screw and nut in electro-galvanized finish (p. 139); say whether you want that hardware quoted in the same finish as the clamp.
- Terms
- Plain, EG, HDG and stainless, plus powder coating on request. Minimum order: none. Most orders are a few hundred pieces; smaller runs are quoted too. Production lead time: 5–7 business days, ex-factory. Counted from order confirmation and receipt of deposit (or drawing approval for custom parts, whichever is later). This does not include transit.
Before you order
- Trade size, not a tape measurement. Conduit is ordered by trade size; the clamp is picked from the actual outside diameter in the tables above.
- Say rigid or EMT. Below 2-1/2 in. the two series do not swap, and the parts look alike in the bin.
- Count the hardware. Catalog clamps include their screw and nut and beam clamps list theirs per part; say whether your count is clamps or complete assemblies.
- Name the finish, and match it to the channel. A thinner zinc coating (EG) or bare steel (PL) clamp will show rust well before hot-dip galvanized channel does, so a mixed run is only as durable as its least protected part — the bolt and the channel nut included.
- Say if you need submittal documents. What we can and cannot supply is settled in the quote, not after the PO.
Frequently asked questions
How much weight can a strut beam clamp hold?
Published maximum loads depend on the clamp and the rod size, and are listed per part in the beam clamp tables above — catalog ratings for the reference part, not for parts we supply. Ratings already include a safety factor, and angled loading reduces capacity: the P2897 is rated lower beyond 25 degrees than within it.
What size pipe clamp do I need for rigid conduit?
Match the clamp to the conduit trade size, not a tape measurement: a 2 in. rigid conduit has an actual outside diameter of 2.375 in. and takes a P1117 clamp. The table above lists every trade size from 3/8 in. through 8 in. with its true O.D.
Are EMT and rigid conduit clamps interchangeable?
Not below 2-1/2 in. EMT has a smaller outside diameter than rigid conduit of the same trade size — 1 in. EMT measures 1.163 in. O.D. versus 1.315 in. for rigid — so each uses its own clamp series. From 2-1/2 in. up, the rigid-conduit clamps P1118–P1121 serve both.
Do strut pipe clamps come with hardware?
Yes. Standard rigid and EMT clamps include the slotted hex-head screw and nut, in electro-galvanized finish. Beam clamps list their included hardware per part — P2676, for example, includes the set screw and nut but not the swivel nut.
Can a beam clamp be used at an angle?
Some are rated for it. The P2897 is FM-approved to 25 degrees at full load and usable to 45 degrees at reduced load. The P2676 allows a 15-degree rod swing in all directions. Always apply the reduced rating whenever the rod is not vertical.
Which 41 mm strut fittings are used for chilled-water pipe supports in plant rooms?
The catalog assigns pipe clamps, pipe hangers, brackets and rollers to the support of electrical and mechanical services (p. 137); it does not name chilled water or any other single service. For steel pipe the clamp is picked from the pipe's actual outside diameter in the table above, not from the trade size written on the drawing. Anything the catalog does not cover, insulation thickness among it, has to be stated in the enquiry.
Get these part numbers quoted
We source strut clamps and the hardware that goes with them from the mills that produce them. Tell us the part number, the finish, the quantity and the destination, and we come back with our part number, finish options, lead time and packing quantity. There is no list price — it is quoted per mill, finish and volume.
No minimum order · 5–7 business days ex-factory · Reply within one business day (Asia/Shanghai, UTC+8) · Finishes: plain, EG, HDG, stainless
Prefer email? Write to contact@channelstrut.com. Minimum order quantity, production lead time, transit and samples are set out in full under Ordering terms.