Clamps rarely get their spot in the limelight, yet in the case of the humble V-band clamp, the device has seen service in everything from common street cars to NASA spaceflight vehicles. A V-Band clamp even held the atomic bomb in transport aboard the Enola Gay bomber on it’s flight into history that ended WWII.

The humble V-Band clamp has played a significant role in history having held the atomic bomb aboard the Enola Gay as it traveled to Japan ending World War II and clamping the booster rockets on the John Glen’s Friendship 7 spacecraft as it launched to orbit the earth.

V-band clamps can be used to hold almost any flanged joints together. From light duty to the most demanding purpose, these clamps are produced in a wide range of materials for any application that requires a leak-free, easy to use restraint device.

These amazing fasteners can be used to hold almost any flanged joints together. From light duty to the most demanding purpose, these clamps are produced in a wide range of materials for any application that requires a leak-free, easy to use restraint device. We reached out to our friends at Race Part Solutions to discover the science behind these sealing devices.

History Of The V-Band Clamp Inventor

Herbert “Zeppo” Marx, inventor and company owner. His marman clamps have been used by military, racing and aerospace agencies for decades.

Zeppo, the youngest of the Marx brothers, was always cast in the straight man role. Reportedly frustrated that he couldn’t be funny, he left the group after just five films to join older brother Gummo in running a talent agency.

In addition to his role as an agent, He also was active in engineering, establishing Marman Products Company, Inc. of Inglewood, California.

After founding Marman Products in 1941, which made these clamping devices, he held three patents, two of which pertained to his invention of a watch that monitored the pulse of heart patients. This business made Zeppo a multimillionaire.

How V-Band Clamps Work 

V-band clamps have proven themselves in racing applications from the Indianapolis 500 to Bonneville land speed cars becoming the preferred connection for many turbo-housings. They are an excellent choice for any exhaust or intake system.

While they come in many different configurations and styles, their primary job is to join tubing, piping and other enclosures. A cross-view of the flange joint shows how the portion of the coupling that wedges the flanges together in a leakproof seal. The strength of the coupling is determined partly by the retainer thickness, the shape of the flange and the material.

Left: This cross view of the coupling shows how the clamping force is applied in a wedging action by the clamp's 'V' design. Right: As torque is applied to the fastening nut, radial force is applied evenly around the coupling's flange.

“V-Band clamps are basically a positive attachment retention system for tubing and components,” said Rob Stevenson of Race Part Solutions‘ tech support team.

V-Band clamps are basically a positive attachment retention system for tubing and components. – Rob Stevenson

As torque is applied to the nut of the coupling, the retainer applies an inward radial force compressing the flange together. Unlike bolted flanges, the retainer applies a uniform and equal closing force around the entire circumference of the flange during and after tightening.

Once tightened, friction between the flanges and V-retainer actually helps reduce the load on the bolt and clamp.

These clamps can be used to hold together virtually any flanged joint. Common applications range from light to heavy duty and include diesel engines, turbochargers, pumps, filter vessels, tubing and countless other flanged items.

Types of V-band Clamps

One of the most important aspects of selecting a V-band clamp is the latch style used in the coupling device. There are several latch styles available, with each one facilitating certain needs. Before selecting a latch style, the user should know how often the coupling will be removed and reassembled and what pressure the application is under. Race Part Soulutions are known for top quality V-Band assemblies and replacement parts with aluminum, steel and stainless steel versions available.

Latch Styles:

Race Part Solutions offers V-Band clamps with the standard T-Bolt and Trunion style latches or the T-Bolt quick release style latches. 

T-Bolt and Trunnion – The T-bolt and Trunnion latch is perfect for those applications when the clamp is not going to be removed frequently. This latch is one of the strongest available and will work on any sized coupling. 

T-Bolt and Trunnion latch

T-bolt quick release – If the clamp is going to be opened frequently, the T-bolt quick release latch can be quickly opened by loosening the nut and raising the hinged latch. They also work on any sized coupling and allow the operator to replace the T-bolt if necessary.

T-Bolt Quick Release Latch

Retainers

As far as the retainers go, there are two types of retainer styles. There are V-band couplings and V-band retainers although both styles are typically called V-band clamps. The V-band couplings are made from multiple V-segments spot-welded to a sheet-metal band, whereas the V-band retainer is made from a single V-segment welded to a band. The V-band coupling has the advantage of less distortion on the flange if the band is over-tightened.

“Even as complex as these clamps are, they are relatively inexpensive when compared to anything else out there that does the same job,” Stevenson reminded us. 

V-Band Flanges

There are two basic types of V-band flanges available, bulge-formed and machined. The bulge-formed flanges are formed from a tube that is “bulged” then collapsed to form a flat flange. Machined flanges are machined from metal stock. Machined flanges should be used with a gasket for most connections. The bulge-formed flanges are typically lighter than machined flanges and the thinner section of the flange is closer in thickness to the base tube resulting in a more compliant joint. This helps minimize stress cracking in the weld.

One of the advantages of using a V-Band clamp is that these retainers are perfect for applications requiring frequent removal. They provide a quicker disassembly yet provide a great seal with even pressure at the flange.

Advantages of V-band Clamps

When compared to 2 or 3-bolt flanges, the V-band connections are lighter, quicker and easier to take apart. In most cases the V-band clamps are economical when you consider the cost of time in installation and reassembly. V-band connections require a smaller fitment envelope as compared with multi-bolt flanges, and the biggest advantage, the design of the V-band clamp applies uniform force around the flange which maximizes the seal potential of the flanges. Stevenson says, “The biggest advantage with V-band clamps in racing is that it is a quick method of attaching components. They can greatly improve maintenance time between rounds during a race when you need to get a lot of parts taken off and put back on quickly.”

  • Reduces assembly cost, saves time and ease of accessibility
  • Ideal for applications requiring frequent access for cleaning, inspection or replacement of internal components
  • Smaller envelop dimensions, weight savings and improved appearance
  • Provides additional strength by absorbing circumferential load

Do’s and Don’ts

According to Stevenson, “One of the biggest do’s in regards to V-band clamps is using a drop of anti-sieze on the clamp’s retaining nut. This helps extend the life of the clamp and protects the ability of the fastener, which may diminish over time.”

  • Do make sure that any pressure in the system is released before unfastening coupler.
  • Do coat the inside of the retainers with dry film lubricant to reduce friction between the coupling and the flanges.
  • Do not use aluminum in applications over 400°F
  • Do not use titanium in applications over 600°F
  • Do not use stainless steel in applications over 800°F
  • Do not use A286 in applications over 1,000°F
  • Do not use nickel 718 for applications over 1,200°F

Installation

For a V-band clamp to work optimally, proper installation is critical. Tubes and components of the coupling must be joined and aligned before installing the coupling. The flanges must also be aligned correctly prior to coupling installation for good joint performance.

The V-Band clamp, with it’s simple design, provides a great seal at the coupling with even force applied around the entire radius of the clamp. It’s a must have item on race cars using large tubing for induction or power adders.

If the V-band couplings have multiple segments, each segment must have the V-shaped groove fitted onto the flange. Ensure that the retainer does not bottom out on the flange before reaching the required loading. Tighten nut.

Tighten the nut to approximately 70% of the required torque (on double-latch assemblies, torque both latches equally). Check to assure the coupling has seated over flanges equally around the periphery. Also, check for correct flange alignment. Radial flange alignment can be checked visually in the gap between adjacent retainer segments.

Every V-band coupling has a minimum torque value, dependent on the fastener or T-bolt size. The installation process should include torquing the latch to it’s proper torque value, then seating the coupling and re-torquing the coupling until the torque value is stable. For instance, a common torque value example would be 45- inch pounds. Torque the latch to 70% of the final torque (31-inch pounds) then tap the coupling with a rubber mallet. After seating the coupling, increase torque to 100% of the specified value, lightly tap around the outer periphery as necessary to prevent unequal loading. Torque the latch to the final torque value again. Repeat these steps until torque does not move the retaining nut. 

This ensures a good fit at the union, does not stretch the clamp, and does not over-stress the union causing cracks and early failure. Safety-wire the latch if applicable.

Tips and tricks

  • Coating the inside of the retainers with dry-film lubricants helps reduce friction between the coupling and flanges.
  • Dry-film lubricants are also recommended for T-bolt threads to reduce galling and extend thread life.
  • Dry lubricants also help in applying the true torque to the coupling, which contributes to proper joint performance, especially in high-vibration applications.

There are various sizes and styles of V-band clamps available from Race Parts Solutions, and one trip to their website can get you started in the right direction for your performance clamp needs.