"ADD ANTI-SEIZE TO THE THREAD OF THE CLAMP TO PREVENT THE NUT AND THREAD FROM BINDING WHEN LOOSENING AND TIGHTENING" IF YOU UNDO THE CLAMP WHILE THE V-BAND IS HOT YOU WILL INCREASE THE CHANCES OF THE THREAD BINDING DUE TO THERMAL EXPANSION.
Different types of V band flanges
-Universal Exhaust V bands
-Turbo Inlet & Outlet V bands
-Wastegate V bands
V band flanges work along with a v band clamp, most exhaust v band flanges do not require gaskets and they can get away with no gaskets due to there design and how they are manufactured. They have a tapered design machined onto them where the clamp sits, the tighter the clamp gets the more tension is applied to the x2 v band faces pulling them together. Also when the flanges heat up they expand and this causes them to seal even more.
If your v band flange is distorted then you will struggle to seal the x2 faces together so it is important to minimize the distortion when welding.
How to measure V band flanges
All v bands are slightly different from universal v band sets, turbo outlet and inlet v bands & waste gate v bands. All manufactures make them to suit there own requirements, so none of them are a "one size fits all". You will need to check the dimensions before purchasing a v band for a certain turbo or waste gate. For example a 45mm universal v band flange or clamp will not necessarily suit a 45mm waste gate. The waste gate will have its own v band flange & clamp specifically designed for that model.
Flat V bands
These are relatively simple to measure, there is a outside diameter and an inside diameter (the inside diameter would be known as the tube diameter measurement) and this is displayed in the picture below.
Male/Female V bands
Male & female v bands are a bit more complicated, there is the outside and inside diameter and then there is the recessed section which needs to be measured from the outside diameter of the recess itself and then the depth of the recessed section. If the depth of the recess is to big then it will bottom out in the female section of the vband flange and not bolt up together correctly, this will cause it not to seal.
V band Clamps
One issue you can face when trying to match a v-band flange & clamp to a rear housing of a turbo or any other application is the retainer section of the v-band clamp can bottom out on the body of the turbo or flange.
This can be overcome by cutting a small section of the retainer lip off so it will not bottom out on the body section and be able to be tightened up correctly.