You can find safety information warning labels on the welding rod and wire packaging and a Material Safety Data Sheet (MSDS) specific to each product. A MSDS lists the potential hazardous ingredients and instructions on how to avoid being overexposed. Contact your local distributor or the manufacturer of the product directly and ask for the MSDS. They are usually available on the manufacturer’s Web site.
American Welding Society
AWS is a source for much more than welding and cutting safety information. This nonprofit organization has about 65,000 members and it welcomes anyone to join.
AWS volunteers, who know their respective industries, prepare and write welding procedures and codes for automotive as well as many other areas from airplanes to bridges. Fabricators, equipment and filler metals manufacturers, and government agencies including the military, are members of the volunteer committees. Thousands contribute to these standards and certification programs that are used worldwide. AWS is headquartered near Miami, Florida, where fewer than 125 people provide the support to the volunteer committees.
Consult ANSI Z49.1, available from AWS, for additional details about welding and cutting safety issues. At the time of this writing, a free download was available from that organization. In addition, most manufacturers of welding machines, filler metals, and welding gases have safety information available on their Web sites.
AWS is a source for more than welding and cutting safety information. This nonprofit organization has about 65,000 members and anyone is welcome to join. It prepares and publishes welding procedures and codes for automotive as well as many other areas from airplanes to bridges. Volunteers, who know the industry, produce this information. Thousands contribute to these standards, which are used and respected worldwide.
WELDING PROCESSES AND EQUIPMENT
This chapter reviews the basic equipment used with each of the welding and cutting processes that are presented in detail in subsequent chapters. Process basics provide an understanding of why and how they work. Detailed equipment specifics of each process are covered in the separate chapters.
Oxyacetylene welding is more than 100 years old and is one of the oldest of the welding processes. My old friend, Butch Sosnin, was a welding training consultant and the 1979 president of the American Welding Society. To start all his weldor training, Butch used oxyacetylene because it was slow and students could easily learn welding fundamentals. A student could actually see the molten puddle develop.
Fig. 1.1. Oxyacetylene welding uses oxygen and acetylene gas supplied in cylinders. Regulators reduce the cylinder pressure and hoses deliver the gases to a torch where they are mixed and exit through a small hole in a welding tip. At the hottest part of the flame tip, the gas mixture burns at 5,720 degrees F. Acetylene is the only fuel gas that can achieve this high temperature in a small concentrated area. (Figure adapted from ESAB’s Oxyacetylene Handbook with sketch by Walter Hood)
After teaching oxyacetylene welding, he followed with TIG welding, which was similar to oxyacetylene in that the heat and filler additions were independent, and there was time to watch the weld puddle develop.
He proceeded to teach stick and MIG welding after some proficiency in the other two methods was achieved. Both stick and MIG welding are more difficult for a beginner to watch because the puddle process happens so fast!
The sequence of this book follows Butch’s course instruction and presents the welding processes in the order Butch would teach them.
My friend and colleague, Bob Bitzky, former training manager for ESAB Welding and Cutting Products, agrees with Butch’s instructional approach, and starts his new trainees with oxyacetylene followed by TIG welding.
The basic oxyacetylene welding process starts with two cylinders of gas—one oxygen and the other acetylene (Figure 1.1). Regulators reduce the cylinder pressure and hoses bring the gases to a torch where they are mixed and exit through a small hole in a welding torch tip. This mixed gas burns at 5,720 degrees F at the hottest part of the flame tip. Other fuel gases may even generate more total heat, but do not have this concentrated, high temperature at the flame tip.
Fig. 1.2. My old friend Butch Sosnin was a weldor training consultant and the 1979 President of the American Welding Society. Butch insisted on starting his weldor training with the oxyacetylene process because it was relatively slow and students could see the puddle develop. Bob Bitzky, former training manager for ESAB Welding and Cutting Products, supports Butch’s logic, stating, “It still holds true today.”
The oxyacetylene flame is the only one that can truly be used for welding. Other fuel gases can be used for cutting and brazing but are not effective for welding. It is the concentration of heat that allows welding to occur. Don’t be fooled by just temperature comparison with other gases.
Discussing combustion intensity is a way to explain the temperature concentration of various gases. Without going into too many technical details or specifying the units, an oxyacetylene flame produces more than 10,000 while the next best fuel gas produces about 5,000, or half the value. Steel has the highest melting point of materials that are typically welded. It melts at about 2,500 degrees F. The high-heat concentration and 5,720-degree F flame temperature can melt and fuse two pieces of steel.
Although difficult to master, oxyacetylene welding can be used to weld aluminum. However, unlike steel that turns red then white before forming a molten puddle, aluminum does not. Aluminum melts at 1,200 degrees F and gives little indication it is about to melt.
Note the AWS designation for oxyacetylene welding is straightforward—OAW, although few folks use it.
Gas flow rates for oxyfuel welding are relatively high compared to the shielding gas flow rates in TIG and MIG welding. Needle valves in the torch handle adjust the flow of the two gases. Setting the correct mixture is covered in the individual process section. However, carefully read the manufacturer’s instructions because controlling the flow rate of these gases is very important and potentially a significant safety issue. Be sure to follow the manufacturer’s recommendations for adjusting the cylinder regulators. Particularly for the oxygen cylinder, where the pressure adjusting screw must always be backed out before opening the contents valve on the cylinder. Failure to do this properly can cause a surge of high-pressure oxygen to rush into the small chambers of the regulator. Like a Diesel engine, this rapid rise in pressure creates heat and can ignite whatever is in the regulator, including the brass body. In pure oxygen, everything burns, and burns explosively! Follow the manufacturer’s recommendations carefully.
