If you are new to beveling and welding operations, you may have heard of a V bevel and a J bevel but not know the advantages and disadvantages of each type—or the reasons why there are different types of bevels at all.
Many pipe-beveling specifications require taking off the metal at a constant angle relative to the end of the pipe. When both sections of pipe to be welded together have this bevel, the gap in the metal formed by the two beveled edges makes the letter “V,” so this type of bevel is also known as a V bevel. This gap fills with molten metal during the welding process and provides the bond between the sections.
One disadvantage of the V bevel is the gradient left throughout the pipe. At the very bottom of the gap (the base of the V), there is a very thin layer of metal forming the bonding layer; at the top of the gap there is a much thicker layer. If welded properly, the bond should be of good quality throughout the depth of the weld (and therefore the wall of the pipe), but the V bevel doesn’t leave as much margin for error. A V bevel also requires more material to fill the gap when very thick pipe walls are involved, which can increase welding costs.
In that case, why do a V bevel at all? They’re relatively easy to do even with hand-operated beveling methods. Beveling machines can expedite the process and increase throughput and precision, but non-automated methods are still used.
There is an alternative method known as a J bevel. As you might expect, the metal removed from each pipe section forms a letter J when looking at it from a 90-degree angle to the axis of the pipe. The angle of the bevel is not consistent, but begins sharply back into the pipe and then curves upward toward the pipe’s edge.
When a J bevel is applied on both sections of pipe to be welded, the gap between the two sections of pipe forms the letter U. Sometimes this type of weld is called a U weld, but the type of bevel that produces it is still called a J bevel.
The advantage of the J bevel is that it keeps the bonding layer more uniform through a larger section of the pipe, and uses less material to fill in the gap. There is also less total welding involved and thus a smaller heat-affected zone (HAZ).
The disadvantage of the J bevel is that it difficult to do by hand. Not only is it fatiguing, it’s hard to keep a uniform J pattern—and uniformity is one of the main reasons you would use a J bevel in the first place. A beveling machine is recommended if you have to apply a J bevel to a significant number of pieces.
Regardless of the type of bevel you need to create, you can find the beveling tool to help you do it within the fine line of GERIMA products represented by Saar-Hartmetall. Contact us today at (859) 331-8770 or by e-mail at contact@saarusa.com if you have any questions, or browse our website to look over the capabilities of our equipment. If you manage to invent a Q or a Z bevel, we’ll probably have a machine to handle that, too.