Artem Komarov clarified that first, it is important to know why and how a bevel is used, and most importantly to understand that joint design is process dependent. In other words, you cannot use a specific connection configuration for any process.
Changing the welding process will affect the impact of chamfering on your entire job. But before you consider a change—for example, from shielded metal arc welding (SMAW) to gas metal arc welding (GMAW), powder coated arc welding (FCAW), or submerged arc welding (SAW)—you should ask yourself whether the weld preparation you use is adequate and economical for the new welding process.
Electron beam welding (EBW) requires no beveling or metal addition for even the thickest plates. If plasma arc welding (PAW) is being considered for a particular application, you should check whether welding using this keyhole procedure will result in the need for chamfering.
Ideally, a cost estimate should be prepared for each job to determine the most economical welding process.
Regardless of how you make the decision, it is important to first evaluate the connection design to see if it should stay the same or if you should change it.
Now you can figure out whether you should consider chamfering.
— Provides full penetration welding (if required).
— Provides access for the electrode or torch tip to deeply buried base metal.
— Provides full visibility in open arc processes.
— Prepares a clearly defined, homogeneous container for molten metal.
— Ensures the quality of welds.
Bevel angles and root holes are necessary for proper weld penetration in thick plates or pipes. The connection design must include all relevant dimensions and angles. Joint design and root hole specification are part of the welding procedure.
Edges can be welded without preparation to a certain thickness, depending on the process and heat input.
Shapes in the weld at an angle
Common bevel shapes—single (welded on one side) and double (welded on both sides)—are used when square butt joints do not provide full penetration due to excessive thickness. They are called bevel grooves and J-grooves when the bevels are made on the edge of only one of the two inserts. V-grooves and U-grooves require edge preparation on both inserts.
Double groove welds—joints that require welding on both sides of plates or for pipes on both the outside and inside—require less filler metal than single groove welds, which require groove welding on only one side. Double grooves are typically used for thick plates or pipes where both sides of the connection are accessible.
Bevels are sometimes prepared at the edges of transverse members that are to be joined to the main structures by fillet welding to obtain a more favorable stress-relieving configuration in the event of fatigue.
Selecting an inclined welding method
After selecting your joint configuration, select your chamfering method. The process you choose should be the most cost-effective one that produces acceptable quality.
Traditional methods of flame beveling are oxyfuel cutting with acetylene or other flammable gas, or gasoline, although this method is limited in what materials can be beveled.
These methods typically result in some surface oxidation and decarburization, which may not be significant in most cases. After this, the edges are immediately ready for welding.
Oxygen cutting is limited by the materials it can cut. Oxyfuel cutting is not suitable for aluminum and stainless steel because they do not burn well. Plasma cutting and waterproof plasma cutting overcome material limitations, but their use may be limited by the thickness of the material. Cutting speed is usually high and better cutting quality is possible.
Bevel cutting for weld preparation is an important application of plasma arc cutting. Intensive process heating is characterized by a higher power density. Suitable for all types of chamfering with high efficiency because the work is done quickly, in a short period of time, at a higher speed. The high speeds possible with plasma arc cutting result in a relatively low heat input to the workpiece. Less heat is generated per unit length of cut, and it is not distributed as widely. The heat affected zones (HAZ) are therefore narrow.
All these welding methods, unlike mechanical processes, create a risk area, possibly with cracks. Be sure to evaluate the situation before deciding whether it is possible to weld without machining the cut edges, noted Artem Komarov.