Cush A Clamp: Sizing, Vibration Isolation, and Strut Channel Guide
In commercial plumbing, industrial refrigeration, mechanical HVAC piping, and hydraulic fluid power installations, securing rigid metal piping to building structural framework presents a major engineering challenge. Hard metal-to-metal contact between steel pipes and structural strut channels transmits intense vibration noise, accelerates mechanical wear, and triggers severe galvanic corrosion between dissimilar metals. The Cush-A-Clamp (cushioned strut clamp) was engineered specifically to solve these challenges.
Comprehensive Overview and Foundational Insights
A Cush-A-Clamp is a specialized two-piece pipe and tube clamping assembly consisting of a heavy-duty steel outer saddle clamp and an engineered thermoplastic elastomer (TPE) or synthetic rubber cushion liner. Designed specifically to snap directly into standard 1-5/8 inch strut channels (Unistrut, B-Line, Superstrut), the cushioned insert grips the exterior perimeter of the pipe firmly while isolating it from the metal strut.
By providing high mechanical damping, thermal insulation, and an electrical dielectric barrier, Cush-A-Clamps eliminate vibration hums, absorb thermal pipe expansion and contraction, prevent galvanic corrosion between copper tubing and steel framing, and silence water hammer shocks across commercial mechanical rooms.
Cush-A-Clamps are precision manufactured to match exact copper tube outer diameters (OD) and nominal steel iron pipe sizes (IPS). Review the sizing specifications detailed below.
| Nominal Pipe / Tube Size | Actual Outside Diameter (OD) | Cush-A-Clamp Model Sizing | Compatible Piping Materials | Max Recommended Load Rating |
|---|---|---|---|---|
| 1/4 in. Tube (1/8 in. Pipe) | 0.250 in. OD | Model 004T (Tube Size) | Copper refrigeration, stainless capillary tube | 400 lbs vertical pull-out |
| 1/2 in. Copper Tube (CTS) | 0.625 in. (5/8 in.) OD | Model 010T | Potable water copper piping, mini-split lines | 600 lbs vertical load |
| 1/2 in. Steel Pipe (IPS / Sch 40) | 0.840 in. OD | Model 014P (Pipe Size) | Black iron gas pipe, galvanized water lines | 800 lbs vertical load |
| 3/4 in. Copper Tube (CTS) | 0.875 in. (7/8 in.) OD | Model 014T | Domestic water lines, commercial hydronic heating | 800 lbs vertical load |
| 1 in. Steel Pipe (IPS / Sch 40) | 1.315 in. OD | Model 021P | Hydronic supply/return, compressed air headers | 1,000 lbs vertical load |
| 2 in. Steel Pipe (IPS / Sch 40) | 2.375 in. OD | Model 038P | Commercial chilled water, industrial process piping | 1,300 lbs vertical load |
| 4 in. Steel Pipe (IPS / Sch 40) | 4.500 in. OD | Model 072P | Main fire protection headers, heavy drainage lines | 1,800 lbs vertical load |
In-Depth Analysis and Comparative Benchmarks
The engineering brilliance of the Cush-A-Clamp lies in its patented living hinge elastomer insert. The flexible thermoplastic cushion features a molded hinge that allows it to wrap effortlessly around copper, steel, PVC, or stainless tubing. On one side of the cushion, an integrated locating tab snaps securely into the pre-punched hole on the metal outer clamp half. This mechanical interlock ensures the cushion cannot shift, rotate, or walk out of place as the pipe expands and contracts during hot and cold thermal cycles.
Preventing galvanic corrosion is one of the primary reasons mechanical building codes mandate cushioned clamps. When copper water tubing or refrigeration suction lines touch carbon steel strut channel directly in the presence of ambient moisture, galvanic corrosion begins. The electrical potential difference between copper and steel causes the steel strut to corrode while degrading the copper tube wall, ultimately resulting in pinhole water leaks and expensive property damage. The non-conductive elastomer insert acts as a permanent 100% dielectric isolator.
The elastomer insert material dictates chemical resistance and operational temperature ranges across extreme industrial environments. Examine material benchmarks below.
| Elastomer Cushion Formulation | Operating Temperature Range | Vibration Damping Rating | Chemical & Oil Resistance | Primary Industrial Application |
|---|---|---|---|---|
| Thermoplastic Elastomer (Standard TPE) | -50°F to 275°F (-45°C to 135°C) | Excellent shock & vibration absorption | Resistant to mild oils, water, refrigerants | HVAC, refrigeration, domestic plumbing, Unistrut |
| High-Temp Silicone Cushion | -65°F to 340°F (-54°C to 171°C) | Superior thermal stability | Resistant to extreme heat and UV ozone | High-pressure steam lines, solar hydronics, engine exhausts |
| Electro-Galvanized Steel Outer Clamp | Standard ambient conditions | Rigid structural clamping strength | Mild corrosion resistance indoors | Commercial indoor mechanical rooms |
| 304 / 316 Stainless Steel Outer Clamp | Harsh marine & chemical environments | Maximum tensile yield strength | Immune to salt spray, acids, chemical washdown | Food processing, marine shipyards, pharmaceutical plants |
Strategic Guidance and Expert Recommendations
Vibration damping is critical in mechanical HVAC systems. Commercial chillers, air compressors, and hydronic circulating pumps generate continuous harmonic vibrations that travel along piping runs. If pipes are rigidly clamped to structural building steel with uninsulated metal brackets, the building steel framing acts like a giant sounding board, radiating loud mechanical droning noises into occupied office spaces and bedrooms above. The resilient Cush-A-Clamp absorbs high-frequency vibrations, reducing acoustic noise levels by up to 80%.
Understanding the critical sizing distinction between Tube Size (OD) and Pipe Size (IPS) prevents ordering errors. Copper tubing and refrigeration lines are specified by their actual Outside Diameter (OD). For example, 1/2-inch nominal copper pipe has an actual outer diameter of 5/8 inch (0.625 in.), requiring a 010T cushion clamp. Conversely, steel schedule 40 pipe is sized by Iron Pipe Size (IPS), where a 1/2-inch pipe has an actual outer diameter of 0.840 inches, requiring an 014P clamp. Always measure actual OD with calipers before purchasing.
Installation on standard metal framing channel is exceptionally fast. The technician wraps the elastomer cushion around the pipe, slides the two interlocking stamped steel clamp halves over the cushion, aligns the clamp feet into the strut channel lips, and threads the included grade-5 carriage bolt and prevailing-torque nylon lock nut. Tightening the nut to recommended torque values (typically 10 to 15 ft-lbs for small sizes) clamps the pipe rock-solid without crushing or denting the tube wall.
How to Install a Cush-A-Clamp on Strut Channel in 5 Steps
A step-by-step mechanical guide to sizing, positioning, and securing piping with Cush-A-Clamps.
Measure Actual Outer Diameter (OD) of Target Pipe
Use a digital caliper to measure the exact outside diameter of your pipe or tubing, confirming whether you need a Tube (T) or Pipe (P) clamp.
Wrap the Elastomeric Cushion Around the Pipe
Spread the flexible thermoplastic cushion at its living hinge, wrapping it snugly around the pipe at the target strut channel intersection.
Seat the Metal Clamp Halves Over the Cushion
Place the two stamped steel clamp halves over the cushion, ensuring the cushion locating tab locks firmly into the clamp positioning hole.
Insert Clamp Feet into the Strut Channel Lips
Slide the formed lower feet of both clamp halves into the inward-turned lips of the 1-5/8 inch Unistrut channel.
Tighten the Carriage Bolt and Nylon Lock Nut
Thread the included zinc-plated bolt through the upper ears and torque the nylon insert lock nut until clamp ears touch the cushion shoulder firmly.
Frequently Asked Questions (7 Questions Answered)
Q1: What is a Cush-A-Clamp used for in plumbing and HVAC?
It is a cushioned strut clamp used to mount pipes and tubes to Unistrut framing channel while isolating vibration, dampening noise, and preventing galvanic corrosion.
Q2: Can you use a Cush-A-Clamp on copper refrigeration tubing?
Yes. Cush-A-Clamps are the industry standard for copper refrigeration and AC line sets, preventing copper degradation and absorbing compressor vibration.
Q3: What temperature can a standard Cush-A-Clamp withstand?
Standard thermoplastic elastomer (TPE) cushions withstand temperatures from -50°F to 275°F (-45°C to 135°C), while high-temp silicone versions handle up to 340°F (171°C).
Q4: What is the difference between Tube Size and Pipe Size Cush-A-Clamps?
Tube size (T) clamps are measured by exact outside diameter (like copper and refrigeration lines), while Pipe size (P) clamps match schedule 40 steel iron pipe sizes.
Q5: Do Cush-A-Clamps fit all brands of strut channel?
Yes. They are universally engineered to fit standard 1-5/8 inch wide strut channels from Unistrut, B-Line, Superstrut, Flex-Strut, and Power-Strut.
Q6: Why does a Cush-A-Clamp prevent galvanic corrosion?
The thermoplastic elastomer cushion creates a non-conductive dielectric barrier, preventing direct metal-to-metal contact between copper pipes and steel strut.
Q7: Can Cush-A-Clamps be used outdoors in direct sunlight?
Yes. The thermoplastic elastomer is UV and ozone-resistant. For coastal or corrosive outdoor settings, pair the cushion with stainless steel outer clamps.
Final Thoughts & Key Takeaways
In conclusion, understanding cush a clamp: sizing, vibration isolation, and strut channel guide provides essential clarity, practical strategies, and actionable advice. By incorporating these foundational insights, adhering to verified safety guidelines, and following structured best practices, you ensure reliable, long-term outcomes while preventing common mistakes. Stay informed, consult certified professionals when needed, and maintain consistent quality care.