The importance of avoiding the common welding mistakes cannot be emphasized enough; not only is this important to ensure a quality weld, but it also critical for avoiding welding accidents or injuries.
According to the Bureau of Labor Statistics, more than half a million people got injured due to a welding accident in 2015.
Welding accidents happen when appropriate precautions are not taken. Unfortunately, this is a mistake that many people make; they start to weld without putting on proper safety gear first. They miss out on some or all of these safety essentials for welding: safety glasses, hearing protection, safety boots, and a welding helmet.
The importance of welding properly and avoiding the common welding mistakes is not limited to safety; instead, you need to avoid welding mistakes to keep your costs under control. Generally, labor accounts for the majority or more than 80% of the welding cost. Other key costs include the cost of filler metals, raw materials, electric power, and shielding.
While most manufacturers can afford these costs, things can get a little trickier when mistakes are made in the welding process and a defected or missed weld goes undetected. This can increase costs significantly. Of course, we have to take the quality factor into the equation as well because a poor weld is prone to cracking. If the weld cracks or breaks, then this can have serious consequences. The perfect example of this is Alexander L. Kielland, a Norwegian semi-submersible drilling rig that capsized, killing 123 of the 212 peopleon-board.
Understanding the Dangers of a Poor Weld and the Defects Caused by It
It seems logical for people to follow some basic health and safety regulations when welding such as not breathing the fumes and clearing clear of them while gas welding. However, the statistics paint a different story as thousands of people suffer welding related injuries every year.
Not many people know that welding in a wrong or unsafe way can lead to fire and explosions. According to the American Welding Society, molten metal, spatter, and flying sparks can travel up to 10. 7 meters or 35 feet to cause fires and explosions.
The dangers of welding are not limited to welding accidents and injuries. Instead, they extend to a poor weld and the defects caused by it. Since it is critical for ensuring the integrity of a product, the ability to produce a good weld is considered as a key skill in the manufacturing industry. Therefore, many manufactures have rigorous procedures in place that are designed to ensure weld quality standards that are needed for the specific industrial applications. However, this may still not be enough to ensure a quality weld.
Even if a manufacturer has rigorous procedures and sophisticated welding technology in place, the use of improper techniques in the preparation for and execution of the weld can lead to poor or defective welds that seriously affect of the quality of both the weld and the final product. Following are some of the major defects that can be caused by a poor weld.
Significant mechanical stress in the weld bead can cause it to crack. Basically, two types of cracks can occur in this scenario: hot and cold cracking. Following is an explanation of each:
As the name suggests, hot cracking occurs when the metal is still hot and in the solidifying process. One of the main factors causing this defect is the weld assembly’s design. The amount of mechanical stress that occurs due to the solidifying process will depend the design/size of the bevel.
The mechanical stress will increase with an increase in the narrowness of the bevel and decrease as the bevel gets wider.Cracking will almost certainly happen during the change in phase if there is significant mechanical stress. Therefore, you must appropriately determine the bevel angles before you start to weld.
This type of cracks occurs after welding; this can be several hours to several days after you’ve finished welding. What causes this defect? It is coming together of three different factors. These factors include the residual mechanical stress, a temper structure, and diffusible hydrogen in the weld bead.
Poor edges preparation is a likely cause of the last factor. It is important for you to keep in mind that hydrogen in the hydrocarbons or the rust will disintegrate into the weld if you perform welding on a poorly degreased or rusty part.
When the metal is cooling down, the atomic scale will start showing signs of stress. If this stress becomes too high, the metal will begin to crack. You can the reduce the probability of this happening by dry machining the joint edges while taking other precautions such as preheating the parts to be welded and drying the electrodes in ovens.
A surface that is prepared poorly can not only cause cold cracking, but it can also cause the appearance of blowholes in the weld. Gas bubbles trapped inside the weld bead can result from the presence of rust, water, or greasy materials on the part being welded. Just like with cold cracking, you can reduce the chances of blowholes by dry machining the end that is to be welded.
This type of contamination often affects stainless steels. Whenever stainless steel comes in contact with iron particles and any medium that conducts electricity, it leads to the creation of a galvanic corrosion mechanism. What is the outcome of this? Progressive deterioration of stainless steel’s passive layer. Additionally, it increases the risk of pitting. Often, the use of inappropriate equipment or equipment used on carbon steel and that hasn’t been cleaned is what causes these iron particles. Another possible cause of these particles is grinding operations performed on carbon steel in the presence of parts made of stainless steel.
To prevent iron contamination, you must use cutting tools and clamping jaws that are compatible with machining operations of stainless steel; Also, make sure that the tools and jaws have not been used on carbon steel before you start welding.
There are two types of penetration defects that can occur in welding: excess or incomplete penetration and cold-clapping. Following is an explanation of each type:
Excess or Incomplete Penetration
A non-melted zone at the weld’s root is what typically characterizes an incomplete penetration. On the other hand, a molten metal surplus at the welded joint’s base is how excess penetration can be defined. However, both defects are caused by poor welding parameters and by land thickness that is poorly controlled. The parameters of welding that can cause the defects are welding speed, voltage, and amperage.
Incomplete penetration can arise if there is very little clearance. On the other hand, excess penetration can occur when clearance is much more than required. Highly accurate positioning may seem sufficient to eliminate this type of detect. However, that is not always the case.
Often, the lack of compatibility between bevel land thickness and welding parameters can cause incomplete or excess penetration. Determined beforehand, the welding parameters depend on the weld material, the welding method being used, and the welded joint’s geometry.
However, this does mean that you can completely a penetration defect by mastering the welding parameters. This is because there is another factor that cause incomplete or excess penetration in a weld. The defect can also occur due to poor preparation that causes variable land thickness. The good thing is that you can improve the weld’s final quality by profile tracking on pipes or by performing an internal counterboring operation to master land thickness.
This is basically a lack of fusion; a non-molten zone between the base metal and the filler metal is how cold-clapping can be characterized. A major cause of this defect is poorly prepared contact surfaces. One of the walls may attract the arc since the bevel is extremely thin when compared to the electrode’s diameter.
What does this lead to? Molten metal filling the bevel and the occurrence of fusion in one of the edges. However, the relevant zones are not melted. Instead, an extra layer of filler metal covers them. This happens because the arc has not directly reached the root and the bevel’s other side.
Although the weld may appear to be in good shape, you fail to achieve the metallurgical continuity that a welding process requires. One of the biggest issues with these defects is that they are not visible to the naked eye since there are typically present inside the welded joint. However, a non-destructive testing (NDT) method such as radiography or ultrasound may be able to detect them. You can reduce the risk of cold-clapping with accurate machining at a constant angle and by properly determining the bevel angle.
Deterioration of the Material’s Properties
Generally, metallic parts are cut using one of two techniques: cutting by mechanical machining or cutting by heat. The heat technique to cut metallic parts can include laser, plasma, torch, or other heat source.
Regardless of which method is used to cut the metal parts, inaccurate preparation before using the cutting technique can lead to sever consequences. If an experience operator or an automate system cuts the parts using the cutting by heat technique, then you can expect the quality of the cut to be satisfactory.
However, we find that most people are not experts in the use of this technique, and they end up creating a heat-affected zone near the cutting point. The significantly alters the material’s physical characteristics in the zone.
In addition to the above, you may compromise the weld quality and mechanical resistance if you weld directly on deteriorated material. This means that you must re-machine the area in question to eliminate the heat-affected zone and ensure the weld’s final quality.
You can eliminate accuracy problems in saws and grinding materials as well as theconstraints that cutting by heat and heat-affected zones lead to by using orbital machines. With this equipment, you can cut and bevel in a single operation with optimal and consistent quality and without any heat-affected zone.
These are some of the major defects cause by a poor weld. Often, these defects arise due to poor or inappropriate preparation for a weld. However, this is just one of the many mistakes that people make that lead to a poor lead. So, what are the most common welding mistakes that people make and how can you avoid them? We discuss that next.
The 11 Most Common Welding Mistakes to Avoid
A key part of the metal fabrication process, welding can cause a lot of problems when it is performed without proper preparation or with an inappropriate technique. However, mistakes are bound to happen in welding since it is an activity that requires increase patience and precision; the task is made even harder by factors such as weld procedures and equipment, consumables, and filler materials.
While there is a high chance of mistakes happening in welding by preparing well for welding and by using the right technique in the right way. Following are some of the most common welding mistakes that people make and how to avoid them.
1. Poor Preparation
Poor preparation can cause quality issues that welding inspectors must deal with. Often, the welding process is started without properly preparing the metal first. What does this mean? It means that dirt, rust, paint, or other contaminants are not removed from the weld area or the weld metal itself before it is welded.
In addition to the above, proper preparation requires that you grind out any cracks on the weld metal that are not visible to the naked eye. If you want a strong and non-contaminated weld, then you must properly clean and grind the metal to be welded.
Now, it is important to note that some metals need to be cleaned more thoroughly than others. For example, aluminum materials need to be cleaned thoroughly. However, you can start welding ferrous metals without significant cleaning beforehand.
In case you need to thoroughly clean the metal to be welded, you must perform two activities to get the job done. The first is removing the contaminants and oils from the material’s surface and the second is brushing the material’s surface to eliminate any oxides on it.
2. Not Taking Proper Safety Precautions
Safety should be the number one priority when welding metal. So many welding related injuries have occurred because people failed to take proper precautions prior to welding. While you can always re-weld a joint or fix a crack that develops in the assembly, an injury caused by welding hazards can be permanent and irreversible.
Some of the dangers of welding include loss of eyesight, dismemberment, hearing loss, arc burns, and general burns. To avoid these injuries that arise from welding, you need to put on the following safety essentials before you start to weld:
- Safety glasses
- Hearing protection
- Safety boots
- Welding helmet
Safety glasses protect your eyesight throughout the welding process. It keeps your eyes safe from hazardous material such as hazardous arc rays, spatter from a welding arc, and flying pieces of metal originating from a grinder.
Hearing protection is needed because it is an OSHA requirement and it helps to prevent hearing loss. This is because welding can be an inherently loud process. With hearing protection, you can minimize your exposure to higher decibel levels and maintain your hearing health.
Made from steel, the safety boots protect your feet from objects that fall down during the welding process. This can help to avoid an electric shock and injury to the foot.
Last but not the least, a welding helmet is needed to ensure protection from welding sparks and closely weld any piece of metal without any danger.
3. Not Having Enough Practice
Even if you have a certification in welding, you must practice welding on spare piece of metals for a considerable period of time before taking on a professional welding job. Often, people make the mistakes of thinking that what they have read in books and learned in the welding class/course can be easily applied in the real life.
Sure, books and courses can provide you with the knowledge of the welding process and the different methods used to perform them. However, they often do not prepare for hindrances that can occur when performing welding in real life; you can only learn about them when you practice welding. By practicing welding for some time, you will learn the hindrances that can occur in the process and how to overcome them. This will prepare you well for undertaking a professional welding job.
4. Storing and Handling Filler Metal in the Wrong Way
A common mistake that many welders make is keeping filler metals in a location that is constantly exposed to contaminants such as oil, dirt, or grease and is prone to moisture accumulation; the welding performance can be adversely affected by this.
If you want to avoid a poor weld that causes damage, then you should store the filler materials for the weld in a clean and dry place where the temperature is controlled; the materials should be kept here till the time they are needed for welding.
In addition to the above, you should cover wire coils and spools that are placed on the wire feeder for a long time with a plastic bag to secure them; you can also remove them from the feeder and keep them in the original packaging. Protection against contaminants is ensured by an enclosed wire feeder. By storing and handling the filler material in this way, you will be able to prevent damage that can cause a poor weld and ultimately rework.
5. Choosing the Wrong Electrode and Wires
Regardless of which welding method you use, it is critical for you to choose the right or suitable electrode and wires. This is because different electrodes are designed for different applications. Choosing the wrong electrode for an application or an electrode that isn’t designed for it can lead to a lot of problems in the welding process. The solution? Use an electrode that is designed for your specific application.
6. Choosing the Wrong Size Gun
You can need to incur the additional costs of buying and replacing the equipment if you use a welding gun that has a too-low or too-high amperage. Since a good amount of time is needed for part preparation, fixturing, and/or movement, welders cannot afford to spend an entire day welding.
Due to the above reason, it is recommended that you use a welding gun that has a lower than average amperage. For example, you can reduce fatigue downtime and ensure greater maneuverability by using a 200-amp welding gun instead of a 300-amp model. In addition to ensuring the longevity of the welding gun, a lower amperage helps to reduce operational costs as well.
However, it would be illogical to use a lower amperage gun on a higher amperage application. In this case, you need to use a higher-amp gun. If you use a lower-amp gun instead, then this can lead to several problems such as premature failure, overhead, and increased costs in the long term.
6. Using the Wrong Voltage or Wire Feed Speed
Another common mistake that welders make is using an inappropriate voltage or wire feed speed. This can often lead to an erratic arc. A lot of heat can generate in the welding gun’s handle if you set the voltage too high. This can ultimately cause problems on the contact tip.
If you set the speed of the wire feed too fast, then the wire will pile up instead of melting in an appropriate way into the weld pool. This can also lead to birdnesting or burnback. On the other hand, the penetration needed for a quality weld will be missing if the you set the wire feed too slow. The best way to avoid these issues is by following the recommendations of the welding gun manufacturer for the proper voltage and wired feed speed based on the application or the material being welded.
9. Letting the Arc Strike Out of Work
Although this mistake happens unintentionally, it is the result of not focus where you should be. Why is letting the arc strike out of work a problem? Because it can immediately ruin any metal it touches. You are likely to damage your work and the piece of metal you’re working on if you’re working on a material that requires increased precision.
To avoid the above, you need to stay calm and focused on the task at hand. In other words, you need to stay in your welding zone and not venture outside of it to avoid arc touches on the piece that are not needed and harmful.
10. Using the Wrong Preheat or Interpass Temperature Control
Often, welders make the mistake of preheating too little or skipping the procedure altogether. This is a mistake because preheating is one of the key processes used to prevent cracks from developing in the weld. The preheating process ensures this by slowing down the cooling process post welding.
However, it is important that you choose the right or appropriate preheat and interpass temperature control for your application. This will depend on the type and thickness of your weld material. You can get find this information in welding codes, the welding procedure of the application, or other fabrication documents.
In addition to the above, you should preheat the material all the way through; The heat should extend to an area that is almost three inches on both sides of weld joint. You should start welding when the material goes above the preheat temperature. Also, do not let the weldment to cool lower than the interpass temperature as this can cause cracking.
11. Not Performing Preventive Maintenance
The eleventh and final most common welding mistake that people make is not performing preventive maintenance. Like any other mechanical or electrical device, a welding machine requires maintenance to function optimally.
If you use the welding gun often, then its maintenance is no longer a choice; instead, it becomes a necessity. If you perform maintenance work on the welding gun regularly, then it is likely to perform well or as expected. Additionally, it will help to increase your welding efficiency and productivity which reducing the time, money and effort needed to perform the job.
To properly maintain the welding gun, you simply need to follow the maintenance instructions that are provided in the user manual that comes with the gun. This will increase your device’s lifespan and ensure that it performs optimally.
As seen above, there are many mistakes that people make when welding. Avoiding the most common welding mistakes is important to ensure a quality weld and prevent loss of time, money, and effort. You can do this by using the information provided above.