What is the solution that was used before V-Bands were employed in the automotive industry and still is the more common alternative? Flanges, of course. Each setup has its range of applications, along with advantages and disadvantages.
What advantages do flanges have on V-Bands?
The main advantage held by flanges when compared to a V-Band setup is cost, as the flanges are cheaper to buy and install. Moreover, they require less precision when installing, as well as offering a certain level of compatibility with similar setups. In other words, you can mate a two-bolt or a three-bolt or a four-bolt flange to another two-bolt/three-bolt/four-bolt flange if they have the same size.
Another advantage of these flanges is that they can be machined easier to obtain custom shapes or profiles. From there, all someone needs to do is to fit a gasket (or an application-specific adhesive), align the flanges, and fix the nuts and bolts to each other.
The biggest disadvantage of flanges comes from the fact that they can leak if the gasket gets old and worn, or if the bolts have been loosened by vibrations. Moreover, flanges must be cleaned before reinstalling them, as well as fitting new gaskets and properly tightening the nuts and the bolts that hold them together.
In other words, if you have an exhaust system that fixes its pipes together with flanges, as many stock systems do (many aftermarket ones do the same), you should know that if you have to take the exhaust piping off of your vehicle, it needs to be properly fitted when reinstalled, as it needs new gaskets and proper sealing.
What is the advantage of V-band clamps?
Here comes the biggest advantage of V-Band clamps. Originally employed in the aerospace industry, but also used in other industrial applications, this solution both permits a perfect seal without any gaskets, and the possibility of dismantling the elements that are clamped together and then fitting them back without requiring any gaskets or additional seals.
The secret of a V-Band clamp is the fact that it has a machined surface on the inside of each of the parts that are fitted to the ends of pipes. Not all V-Band clamps come with the inner machined surface, so be sure you know what you are purchasing, but the idea is that a pair of V-Band clamps are held by an exterior seal, which is easier to tighten than conventional bolts on flanges.
As you can imagine, the increased precision offered by V-Band clamps comes at a cost, and these will be more expensive than traditional flanges.
Their biggest advantage comes not only through their seal, which should be superior to any conventional flange, but also through the fact that the said piping can be uninstalled and reinstalled faster and with more ease.
V-Band clamps are available in various materials, but most are from stainless steel or high-carbon steel. They can also be made from various alloys or even Inconel, in the case of high-end Inconel exhausts. Fortunately for us, we live in a world where it is easy to source V-Band clamps to fit anyone's needs.
V-Bands are an alternative to traditional flanges, and these systems can even suit quick-release mechanisms, which are perfect for maintaining reliability while having frequent disassembly and reassembly in a limited time.
As usual, the cheapest ones you can find online are not the best option when quality is concerned, not to mention durability. Some of the cheapest ones might warp when being welded on the pipes that they are meant to be fitted on, while others might last you a lifetime.