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Welder training: The fundamentals, Part I

Welder training has advanced to more adequately reflect the original description that has been around since the early 20th century—the "Art and Science of Welding." The career is more highly recognized than ever before.

A recent statement by a presidential candidate that "welders make more money than philosophers" is being discussed in diverse circles. Some liberal arts educators are up in arms, while the technical and career folks are delighted.

During my lengthy time as a technical and career educator, I had several students enroll in my classes who had degrees in the liberal arts fields. At first I thought they were interested in welding as a hobby, but I soon learned that they were serious about establishing careers in welding and/or inspection.

In my early years as a student at the Hobart Institute of Welding Technology, I remember President Howard B. Cary saying, "Many of your friends and associates will say that you are in a down-and-dirty career akin to a mud wrestler." I heard some remarks to that effect from the people with whom I attended college before going into welding. After more than 50 years of never being out of work for even one day, I think I made the correct choice.

Safety First

In any technical, hands-on training, safety must be stressed in the very first orientation session. This is especially true in the welding field. Many excellent welding safety videos are available. They should be accompanied by live demonstrations in the welding laboratory.

Protective apparel and eyewear must be specified as absolutely required. Safety glasses with side shields should be worn, even under the face shield. When the student raises the face shield to observe the weld, slag or residue can pop off and injure the eyes. A full-face shield should be worn when grinding or power brushing.

A skull cap or hard hat protects the top of the head. One bit of hot slag or a spark in the hair will be remembered for a very long time. This is especially true for students who use hairspray, which is highly flammable.

A fire-resistant jacket is necessary to protect clothing from burns. Flannel should not be worn in a welding atmosphere, not even under the jacket. Leather is best, but can be uncomfortable in hot weather. Fire-resistant or leather sleeves are beneficial, but do not offer full protection.

Students should wear khaki or denim trousers with no cuffs and shoes with at least ankle-high protection. Hard-toed shoes with cloth uppers are not suitable for a welding area.

Leather gloves with long cuffs that extend beyond the fire-resistant jacket should be worn, even when handling the hot metal with pliers. Hot slag can be embedded in unprotected flesh.

Figure 1
Well-dressed welder.

Beginning students often prefer to sit while welding. In this case, they should wear a leather apron and bib (Figure 1).

Terms and Definitions

The student should be taught common welding terms and definitions. The American Welding Society (AWS) publishes an excellent book, A 3.0/A 3.0 M: 2010 Terms and Definitions. This book contains more than 1,400 entries. Priced at $168, it is relatively expensive for the student, but every school should have one for a reference standard.

Here are a few of the most common terms and the most common misnomers that are encountered in the welding field. These incorrect verbiages have been used for so long that they are difficult to diffuse. It is extremely important for the students who will go on to become instructors, inspectors, engineers, or technicians to learn the correct terminology.

IncorrectCorrect
Tanks, BottlesCylinders
GaugesRegulators
Torch HandleBlow Pipe
RodFiller Metal
Stick WeldingShielded Metal Arc Welding (SMAW)
MIG WeldingGas Metal Arc Welding (GMAW)
TIG Welding, Heliarc WeldingGas Tungsten Arc Welding (GTAW)

The reason for changing the MIG term to GMAW is that the shielding gas used in this process is not always inert. Thus, the "I' in MIG is incorrect. The same is true for the "I" in the TIG term. The "heliarc" misnomer in GTAW is incorrect because helium is not the only shielding gas used in GTAW.

Best Process to Learn First

Opinions abound as to which process should be taught first. I believe the oxyacetylene (oxyfuel) process teaches more about reading the puddle and manipulating the equipment than any other process. It also helps students learn the two-handed method GTAW requires. Used prominently with cutting and heating, it stresses the safe handling of gases. Learning how to set up the equipment is often a life-saver.

Handling Cylinders

One of the most important things students can learn about setting up the oxyacetylene equipment is making sure the cylinders are secured, either to a wall or on a cylinder cart (Figure 2).

If the valve on a high-pressure oxygen cylinder is broken off, the cylinder is capable of going through a concrete wall. In an experiment performed by the Linde Company, a 220-PSI nitrogen cylinder moved four loaded railcars 6 feet! The importance of cylinder safety can't be stressed often enough. Any high-pressure cylinder, whether it is an argon/CO2 mix for GMAW or pure argon for GTAW, must be treated with the utmost care.

Anytime cylinders are transported or moved, their caps must be kept intact to provide protection for the valves. The only exception is when they are properly chained to a cylinder cart.

When oxygen and acetylene cylinders are stored, they must be separated by a firewall that can sustain fire for a minimum of eight hours. Although oxygen is not flammable, it greatly accelerates a flame or other heat source. This is one reason it is used to generate heat for oxyacetylene welding and cutting. This is not recommended, but once a cut is initiated the fuel gas may be turned off and the oxygen will continue the cutting.

If a dent or arc strike is discovered on any cylinder, high-pressure or fuel gas, the cylinder must be set aside and the gas supplier notified. If a cylinder has not been hydrostatically tested within the specified time limit (usually 10 years), it also should be set aside and reported to the gas supplier.

Figure 2
A portable welding outfit, 
with oxygen and acetylene cylin
ders chained to an easy-rolling 
cylinder truck. The cutting attachment, 
normally a part of such an outfit, is 
not shown.

Setting up the Equipment

Absolutely no oil, dirty gloves, or any contaminated material should be handled before touching any oxyacetylene equipment. When setting up the equipment for use, the student must be sure the valve opening is pointed away from other people or flammable objects. The oxygen valve should be opened slightly and slowly to remove any debris from the cylinder before it is connected to the regulator (Figure 3).

The acetylene valve should be checked for debris and wiped clean; compressed air also can be used to clean it. Acetylene gas should never be released into the atmosphere! It is highly flammable and has a very low flash point (point of ignition or combustion).

It's important for students to learn and remember that the acetylene CGA 510 fittings have left-hand threads. The CGA 300 fittings have right-hand threads. CGA is the Compressed Gas Association, the organization that denotes and specifies types and identification for fittings and other gas apparatus.

Students need to use properly sized wrenches to tighten and loosen fittings. Brass is prone to spalling (deformation) if a pipe wrench or adjustable wrench is used. A quick jerking motion is recommended for the last turn of the wrench. Fittings should not be overtightened, because it can distort the threads.

After the regulators are tightened to the cylinders, the pressure-adjusting screws on both regulators should be loosened until no pressure is showing on the regulator's low-pressure gauge. This eliminates the possibility of oxygen entering the acetylene system and vice versa. If acetylene enters the oxygen regulator, the 2,200-PSI frictional force could cause the regulator to explode. The acetylene cylinder valve should be turned one-half turn only. Because it has a seat at the full open and full closed positions, the oxygen valve should be fully opened.

A fatal incident occurred in North Carolina when a welder left the pressure adjusting screw turned in and was standing in front of the oxygen regulator. The pressure screw flew out and entered the welder's chest, killing him (Figure 4).

The Welding Torch

Many different types, sizes, and brands of welding torches are available. Figure 5 depicts a typical torch with a mixer that is designed for a specific tip size. Some torch manufacturers use a single mixer for several different sized tips. This type of torch is not my preference. The torch shown in Figure 5 produces much better flame control than the single-mixer types. The injector type is mostly for lower-pressure use.

The welding head consists of a mixer or injector and a tip. The torch handle (blow pipe) contains the throttle valves for fine-tuning after the regulator is adjusted to the desired pressure. It's important for students to remember that only a certain amount of gas can pass through the tip orifice regardless of the pressure. Higher pressure settings do not increase the flow of the gas or heat produced.

Attaching Hoses to the Torch and Regulators

The hoses used must be specifically designed for oxyacetylene welding or cutting processes—green for oxygen and red for acetylene. Substitution is not permissible. The acetylene hose has left-hand fittings, and the oxygen has right-hand fittings. It is always a good idea to clear the hoses with nitrogen or clean compressed air. Debris can get into the regulator and create problems or even block the flow of gas and cause the hoses to rupture.

Hoses must be properly sized to handle the required gas flow. For most welding, a ¼-in. ID is sufficient, but for use with a heating torch or a large cutting torch, a 3/8-in.-ID hose is necessary. The higher gas flow requirement can cause a flashback in a smaller hose.

Figure 3
(left) Always crack cylinder valves to blow out dust and dirt 
from the outlets. (right) Always tighten regulator 
connection nuts with a wrench. The CGA 510 connection has left-hand threads, internal on the cylinder 
outlet; the CGA 300 connection has right-hand threads, external on the 
cylinder outlet.

It is a good idea to teach students to place flashback arresters or backflow check valves at the regulator or torch end of the hoses. Opinions vary regarding on which end to install these items. Usually the hoses are attached to the regulators first, although there is no significant reason for this.

It is a good idea to tell students to hand-tighten the hose all the way before using a wrench. The brass threads are very fragile, and cross threading with force ruins them. Once they are hand-tightened, a wrench of the correct size should be used rather than an adjustable wrench. Again, a quick jerking motion should be used at the final tightening with care taken not to overtighten.

Lighting Up

For welding torches, the following sequence should be used:

  1. With the torch valves closed, the pressure-adjusting screw on the oxygen regulator is turned to the desired pressure (about 5 PSI for a #3 tip)/
  2. Next, the acetylene regulator is turned to a low pressure (also about 5 PSI for a #3 tip).
  3. The acetylene throttle valve is opened and the torch is lit.
  4. The throttle valve opening is increased until the black smoke disappears.
  5. The oxygen throttle valve is opened until the desired flame shape is obtained.

The equal pressure regulator setting chosen should easily produce what is known as a neutral flame. The inner cone should be a bright blue color and should not cause a "blowing" sound. This flame is best for most applications.

For brazing or soldering, an excess acetylene flame is desirable. This flame shape will be more bulbous, and more yellow will appear on the outer cone.

For welding cast iron, some prefer the excess oxygen or oxidizing flame. This flame is longer and slimmer, a lighter blue, and produces a blowing sound. Teach students that the tip should not touch the workpiece during welding. This can cause flashback. If this situation occurs, the torch should be turned off immediately—acetylene valve first—the welding head disconnected, and the O-rings inspected for damage. The black residue must be cleaned from the affected area and the small orifices checked for blockage.

Shutting Down

When shutting down the system, students should follow this sequence:

  1. Close the cylinder valves, oxygen first.
  2. Back the regulator adjusting screws all the way out on both regulators.
  3. Close the torch throttle valves. If the acetylene valve is even slightly open, a fire could develop. If the oxygen valve is open, acceleration of any heat source in the area could occur.
  4. Some recommend that the hoses should be bled off, but if this is performed, the acetylene hose must be bled in a very well-ventilated area.
  5. Remove the torch and store it in a clean area with the threads protected.
  6. Remove the hoses and cover their openings to keep out contaminants.
  7. Remove and store regulators in a clean area with the threads protected.
  8. Replace the cylinder caps.
  9. Do not coil the hoses around the cylinders.

This is very fundamental but absolutely essential information for beginning welders. More will be discussed in Part II of this series.

About the Author
Weld Inspection & Consulting

Professor R. Carlisle "Carl" Smith

AWS CWI, CWE, NDE Level III

Weld Inspection & Consulting

PO Box 841

St. Albans, WV 25177

304-549-5606