Difference Between Braze Welding and Gas Welding Explained

Working with metals is not easy because they are reactive to heat. These metals are transformed into various shapes employing different techniques. Welding is one of these techniques, where metals are fused by the application of pressure and heat, as well as filler material. This technique has evolved over the years, and today various welding techniques are being employed. This post focuses on two such important welding techniques – gas welding and braze welding.

Braze Welding Overview

Braze welding, sometimes also referred to as bronze welding, almost resembles fusion welding. Earlier, it was only restricted to produce strong joints in bronze; however, now it is also used to produce excellent joints in cast iron, steel, copper, as well as copper-based alloys. The following are a few important features of braze welding, which differentiates it from gas welding, or acetylene gas welding, as it is referred generally.

1. The melting point of filler and base metal is different. Normally, the filler metal is chosen because it has a lower melting point than the base metal. A low fuming bronze is the common filler metal used for braze welding.
2. According to the American Welding Society, the filler metal to be used must possess a melting point above 425ºC (800ºF).
3. Many times, braze welding is confused with brazing; however, both these techniques differ in many ways. In the brazing process, the filler metal is filled into the tight-fitting joint through capillary action; however, in braze welding, the filler metal is deposited in many ways other than capillary action.
4. In this process, the molten filler material flows into prepared surfaces of higher melting point alloys or metals to form a strong molecular bond. The temperature of the base metal is increased to the point where a filler metal will form a smooth film on the joint surface.
5. Braze welding is mainly used for joining various types of steels. However, it utilizes lower temperatures than fusion welding, and it mainly involves oxy-acetylene process.
6. The intense heat produced by oxy-acetylene flame quickly increases the temperature of the base metal to the point of formation of a film. In this process, the welder can easily control the temperature of the base metal, the flame condition, as well as the melting temperature of the filler rod.

Gas Welding Process Explained in Brief

Gas welding is a common term used to indicate a group of welding processes, where fusion takes place owing to the heating of metals to be fused. The heating is done using a gas flame, with or without the application of pressure, or with or without filler metal. The following points will help you understand this process better:

1. The base and the filler metal (if used) are melted together using a flame produced by the welding torch. Mainly, the tip of the torch is used during this melting process.
2. The molten metals— a base metal and a filler metal are mixed together, and they fuse upon cooling, to form a seamless strong piece.
3. In case the filler metal is not used then the base metal as well as the metal to be fused are melted to a particular temperature.
4. The filler metals are mainly used for metals having thickness above 3/16″.
5. Mainly used for welding different types of steels, the steel surface to be welded is cleaned prior to the process. This is performed to ensure the surface is free from grease, oil, scaling, rusting, or any other impurities, which may affect the quality of the weld.
6. Oxy-acetylene is the fuel recommended for gas welding, which is why this oxy-fuel welding technique is also referred to as acetylene welding.

After knowing the specific processes involved in braze welding, brazing, and gas welding, you can easily make a decision on the right type. It is important that you use the right oxy-acetylene torch for both the processes. If you are planning to outsource welding, it is important that you get associated with a trusted service provider. Rexarc International Inc., is a leading provider of equipment for filling acetylene cylinders and for manifolds to distribute all types of gases.