The Causes of GMAW Flaws … and the Cures to Help Welding Operators Get Back to Work Faster

Weld flaws come in all shapes, sizes and degrees of severity. Yet one thing holds true regardless of the application or material on which they occur: They are a common, and costly, cause of downtime and lost productivity. They are also an occurrence that even the most skilled welder can experience.

In the GMAW process, specifically, there are several typical weld flaws that can transpire. From porosity to undercut and burn through, each has multiple causes. Fortunately, there are also numerous cures that can help welding operators minimize their frustration over weld flaws and get back to work faster.

Porosity

When gas becomes trapped along the surface or inside of the weld metal, porosity occurs. Like other weld flaws, porosity results in a weak weld that must be ground out and reworked.

Causes: Typically, inadequate or contaminated shielding gas is the culprit of porosity. Using a nozzle that is too small for the application, or a nozzle full of weld spatter, can also cause this weld flaw. Having a dirty base metal and/or extending the welding wire too far beyond the nozzle is an additional cause. On warm days, air currents from cooling fans can disrupt the shielding gas envelope around the weld puddle creating this problem. Another common cause is a poor seal or a loose fitting in the shielding gas channel through the welding gun.  Any gas leaks have the potential to aspirate air into the gas flow.

Cures: To correct porosity, ensure that that there is adequate gas flow (increasing it as needed), and replace any damaged gas hoses or GMAW gun components that may be causing leaks. Also, place a welding screen around the work area if welding outside or in an area inside that is particularly drafty. Check that the nozzle being used is large enough for the application and replace with a larger one if it is not. Remove any spatter build up in the nozzle. Extend the welding wire no more than 1/2 inch beyond the nozzle and make certain that the base metal is clean prior to welding. Slowing travel speed to gain greater shielding gas coverage can also combat porosity, as can keeping the nozzle within 1/4- to 1/2-inch of the base metal during welding.

Burn Through

Just as its name implies, burn through results when the weld metal penetrates fully through the base metal, essentially “burning through” it. It is most common on thin materials, particular those that are 1/4 inch or less. Another weld flaw, excessive penetration (too much penetration into the weld joint), can very often lead to burn through. 

Causes: Excessive heat is the primary cause of burn through. Having too large of a root opening on the weld joint can also result in burn through.

Cures: If burn through occurs, lowering the voltage or wire feed speed can help rectify the problem. Increasing travel speed helps, too, especially when welding on aluminum, which is prone to heat build-up. If a wide root opening is the suspected cause of burn-through, increasing the wire extension and/or using a weaving technique during welding can help minimize heat input and the potential for burn through.

Incomplete Joint Penetration (Lack of Penetration)

Incomplete joint penetration or lack of penetration results when there is shallow fusion between the weld metal and the base metal, rather than full penetration of the joint. It can often lead to weld cracking and joint failure.          

Causes: Insufficient heat input and improper joint preparation are the main causes of incomplete joint penetration. The shielding gas mixture and wire diameter can also be a factor.

Cures: There are several cures for incomplete joint penetration, including using higher wire feed speed and/or voltages. Reducing travel speed also allows more weld metal to penetrate the joint, as does preparing and designing the joint properly. The joint should allow the welding operator to maintain the proper welding wire extension (no more than 1/2 inch beyond the nozzle) and still access the bottom of the weld joint. Make sure that the shielding gas or gas mixture, wire type and diameters are recommended for the application.

Undercutting

Undercutting is a groove or crater that occurs near the toe of the weld. When this weld flaw occurs, the weld metal fails to fill in that grooved area, resulting in a weak weld that is prone to cracking along the toes.

Causes:  Excessive heat, as well as poor welding techniques, can both lead to undercutting on a weld joint.

Cures: Reducing the welding current and voltage is the first step to rectifying undercutting. Using a weaving technique in which the welding operator pauses slightly at each side of the weld bead can also help prevent this weld flaw. Additional cures include reducing travel speed to a rate that allows the weld metal to fill out the joint completely and adjusting the angle of the GMAW gun to point more directly toward the weld joint.

Hot Cracking

Hot cracking typically appears along the length of a weld or directly next to it almost immediately after the weld puddle solidifies. This weld flaw occurs at temperatures greater than 1,000 degrees Fahrenheit (538 Celsius). There are multiple variations of hot cracking including centerline, bead shape and crater cracks.

Causes: Hot cracking can result from several factors. These include poor fit-up or joint design, creating too thin of welds and welding at too high of voltages. High levels of base metal impurities can also cause this weld flaw. In some cases, high levels of specific alloys (boron, for example) in filler metals can cause the problem.

Cures: Having the proper joint design and good part fit up is one way to help prevent hot cracking, as it keeps the weld puddle the appropriate size and minimizes the chance of the throat of the weld being too thin. In the case of crater cracking, in particular, using a backfill technique (backing up to fill in the joint fully) can minimize cracking by adding throat thickness to the crater weldment. Careful filler metal selection and shielding gas selection is also imperative.      

 Incomplete Fusion

When the weld metal fails to completely fuse with the base metal or with the preceding weld bead in multi-pass applications, incomplete fusion can occur. Some people also refer to this weld flaw as cold lap or lack of fusion.

Causes: Most often the cause of incomplete fusion is an incorrect gun angle, although contaminants on the base metal can also cause this weld flaw. In some instances, insufficient heat can be the culprit.

Cures: First, clean the base metal properly prior to welding, making sure it is free of dirt, oil, grease or other debris. Next, welding operators should place their GMAW gun at an angle of zero to 15 degrees in order to access the groove of the weld joint fully and keep the arc on the leading edge of the weldpuddle. Increase travel speed as necessary to keep the arc from getting too far ahead of the weld puddle. For joints requiring a weaving technique, holding the arc on the sidewall for a moment can help prevent incomplete fusion. Make certain, too, that there is enough heat input to fuse the weld metal and base metal fully. Increase the voltage range and adjust the wire feed speed as necessary to complete the weldment.

Remember, even the most skilled welding operators can experience weld flaws. The key to keeping them from affecting productivity and increasing costs in the welding operation is to identify and rectify the problems as quickly as possible. Proper maintenance of the welding equipment is also imperative. Repair or replace any worn or defective items.

10 Mistakes in Running a Welding Operation and How to Fix Them

Estimated reading time: 9 minutes

With so many factors to monitor — equipment, weld procedures, filler metals and MIG gun consumables — it’s inevitable that mistakes will occur in most welding operations on any given day. Human error dictates that a welding operator can easily set a power source and wire feeder to the wrong parameters or trim and install a MIG gun liner improperly. But there are other mistakes that can occur in welding operations on a regular basis — ones that many companies may not even realize that they are making.

The reality is, however, that these mistakes can have a significant impact on quality, productivity and a company’s bottom line. Fortunately, they don’t have to happen. Consider these top 10 mistakes involved in running a welding operation, along with some recommendations for solving them.

Mistake No. 1: Improper Filler Metal Storage and Handling

Storing filler metals in an area where they are prone to accumulating moisture or exposed to other contaminants (e.g., dirt, oil or grease) can have an adverse effect on their welding performance. To prevent damage, companies should store filler metals in a dry, clean area with a relatively constant temperature until they are ready for use. Spools and coils of wire that are kept on the wire feeder for an extended period should be covered securely with a plastic bag or removed from the wire feeder and stored in the original packaging. An enclosed wire feeder can also protect against contaminants. Such precautions prevent damage that can lead to poor weld quality, and ultimately, rework.

Mistake No. 2: Repurposing Old Equipment

It is important for companies to use the best equipment for the job. Repurposing old or dilapidated power sources, welder/generators or wire feeders can cause quality issues, not to mention downtime and additional costs for troubleshooting problems that inevitably arise from using dated equipment and technology. Instead, companies should consider the newer technologies available in the marketplace, recognizing the advantages these can offer in terms of improving weld quality and productivity. In most cases, newer equipment can provide companies with a quick return on investment and greater long-term savings – in a relatively short payback period.

Newer technologies often offer benefits like improved power efficiency, better deposition rates, lower weld prep time and faster training, all of which ultimately add up to greater arc-on time and productivity. Performing a thorough cost-savings analysis before buying new equipment can help companies assess their potential return on investment, as well as justify the capital expenditure. 

Mistake No. 3: Using the Wrong Size MIG Gun

Using a too-low or too-high amperage MIG gun can lead to unnecessary costs for purchasing and replacing this equipment. Welding operators rarely spend the entire day welding or welding continuously, as there is downtime for part preparation, movement and/or fixturing. For that reason, it may be possible to use a lower amperage MIG gun or one with a lesser duty cycle on some applications. For example, using a lighter and smaller 300-amp MIG gun instead of a 400-amp model can provide welding operators with greater maneuverability and reduce downtime for fatigue. Lower amperage MIG guns tend to cost less, as well.

Conversely, on higher amperage applications and/or those that require longer periods of welding, it is important to use a higher amperage gun. Skimping and purchasing a lower amperage MIG gun in this situation can lead to overheating, premature failure and greater long-term costs. Companies should consult with a trusted welding distributor for MIG gun recommendations for their application.

Mistake No. 4: Improper Preheat or Interpass Temperature Control

It is not uncommon for companies to preheat too little or skip this portion of the
weld procedure altogether. Yet preheating is one of the biggest deterrents against cracking, as it slows down the cooling rate after welding. The type and thickness of the material being welded will determine preheat and interpass temperature. These requirements can be found in the application’s welding procedure, welding codes or other fabrication documents. For the best results, welding operators need to preheat the material completely through and extend the heated area to approximately three inches on either side of the weld joint. Welding should commence while the material is at or above the preheat temperature. Allowing the weldment to cool below the required interpass temperature may also lead to cracking.

Mistake No. 5: Ignoring Preventive Maintenance

Preventive maintenance (PM) is a frequently overlooked part of the welding operation, but it is critical to preventing unscheduled downtime and keeping repair costs low. A well-performed PM program can also help increase productivity, extend equipment life and create a workplace philosophy that encourages shared responsibility for, and interest in, preserving the integrity of the welding equipment. Companies should develop a regular timetable to inspect their power sources, wire feeders and MIG gun or TIG torches during scheduled downtime in production. Between welding shifts is often enough time to perform routine inspections. Checking consumables regularly for spatter build-up — and replacing these components as needed — is also an important part of a viable PM program.

Mistake No. 6: Shielding Gas Inconsistencies

Using the correct type and/or mixture of shielding gas can help companies prevent weld defects, minimize excessive spatter and reduce costs for rework or post-weld cleanup. Shielding gases also determine arc characteristics and weld penetration on a given application. Straight CO2 provides good weld penetration, but it is prone to spatter and has a less stable arc than mixtures that include argon.

High argon mixtures (a minimum of 85 percent argon for solid wire or as low as 75 percent for metal-cored wires) are the best choice. These mixtures can be used in the spray transfer process to promote higher deposition rates and generate less spatter. For TIG welding, the appropriate argon/helium mixture can improve speed, quality and arc characteristics. For both MIG and TIG welding operations, companies should purchase their shielding gas from a reputable welding distributor and be certain that it meets the purity requirements for their application. All gas delivery systems should be free of contaminants that could enter the weld puddle and welding operators should use the correct shielding gas flow rate. Too little gas flow    won’t properly shield the molten weld pool, while too much flow can cause turbulence and aspirate air into the weld puddle. Protecting the weld puddle from drafts is also critical.

Mistake No. 7: Purchasing Filler Metals Based on Cost Only

Due to the initial up-front cost savings, the temptation may be great for companies to purchase less expensive filler metals. However, doing so can often lead to greater long-term costs and lower productivity levels. It is not uncommon, for example, to experience downtime associated with poor wire feeding, excessive spatter or, potentially, weld defects when using lower quality filler metals. Companies may also find themselves experiencing an excessive amount of time for non-value-added activities (those that do not directly contribute to their throughput), such as applying anti-spatter and post-weld grinding or rework. For that reason, it is important to look at the total cost of using particular filler metals, as opposed to the per-unit cost. If more expensive, higher quality filler metals can minimize labor costs for non-value-added activities and provide better weld quality and/or greater productivity, then the higher up-front cost makes good sense in the long run.

Mistake No. 8: Improper Weld Preparation

Skipping steps in weld preparation can lead to weld defects, rework or scrapped parts. Welding operators should always take care to clean the base material before welding to prevent contaminants like dirt, oil or grease from entering the weld puddle. Similarly, monitoring part fit-up is a critical part of the pre-weld process. Welding operators should carefully assess the weld joints to ensure there are no excessive gaps, as poor part fit-up can lead to issues like burn-through or distortion on all materials, but particularly when welding on materials like aluminum or stainless steel. Clamping or fixturing a part in the correct position is also a good practice to help protect materials like stainless steel against distortion or buckling.

Mistake No. 9: Disregarding MIG Gun Consumables

It is not uncommon for companies to overlook the importance of their MIG gun consumables. Unfortunately, that oversight can lead to a host of problems, including unscheduled downtime for changeover and/or rework of weld defects caused by a poorly performing contact tip, nozzle or liner. To help avoid problems, select consumables with a tapered design that locks conductive parts together to reduce heat buildup. Contact tips with coarse threads are a good way to speed up replacement and make sure installation is accurate. Look for consumables where the diffuser locks and aligns the liner with the contact tip and power pin for flawless wire feeding. These systems also offer error-proof liner installation with no measuring required; the liner is simply locked in and trimmed flush with the power pin at the back of the gun.

Mistake No. 10: Overlooking Training Opportunities

As with other parts of the welding operation, investing time and money in training can yield significant long-term benefits for companies. Not only do welding operators benefit individually from process and equipment training, but in many cases it can also help them optimize the welding operation for greater efficiency. Too, proper training can give companies a competitive edge over those who have less-skilled labor and it promotes greater teamwork among employees. Typically, training opportunities are available through equipment and filler metal manufacturers or through welding distributors. In some cases, working with a local technical college can lead to training for specific applications and markets, allowing companies to bring in welding operators who are already trained for a given application and better promote their position in a given industry.

Making mistakes is human nature, but with some careful consideration, it is easy to avoid some of the more common ones associated with running a welding operation. Measuring out long-term savings, versus cutting costs up front, is a particularly good way to avoid pitfalls that could lead to excessive downtime, quality issues or lost productivity. And it can have an excellent impact on a company’s bottom line. 

Stay Cool When Welding In The Summer Heat

It’s tough to stay cool in the hot summer months, let alone when you are “under the hood” welding. Unfortunately, that heat can take a toll on your body, mind and performance. In addition to affecting your mental acuity – causing loss of concentration or, in extreme cases, confusion – excessive heat can also affect your motor skills, cause irritability and increase fatigue.

Consuming liquids throughout the day is a critical part of staying cool. It is also helpful to supplement that approach with smart equipment selection and other cooling options. Consider these tips.

Tip One: Don’t go over amperage

As a general rule, selecting the lightest, most flexible MIG gun for the application is the best choice. In the case of a 400-amp application, a MIG gun rated at 300 amps may suffice for your application. That is because MIG gun amperages reflect the temperatures above which the handle or the cable on a MIG gun becomes uncomfortable. They do not indicate the point at which the MIG gun risks damage or failure.

Also, you spend time in the day doing other things besides welding – moving parts, prepping materials or fixturing them. It’s highly unlikely that you will be operating the MIG gun at full amperage and full duty cycle at all times. Duty cycle is defined by the amount of arc-on time in a 10-minute period that the equipment can be operated at maximum capacity. Some MIG guns will offer 100 percent duty cycle, while others are rated 60 percent or below.

It is important to research the MIG gun’s duty cycle prior to purchasing it in order to ensure it offers the necessary capacity for the application. But in most cases you don’t have to match your MIG gun amperage to the exact amperage of your application to get the job done. A lower amperage MIG gun can often suffice and keep you cooler.

Tip Two: Get a good handle 

Selecting a MIG gun with the appropriate handle, neck and cables for your application can also help you stay cool. Typically, as a MIG gun’s amperage decreases so too does the size of the gun handle and the cable. That decrease in size and weight can help minimize the amount of energy you exert and reduce heat stress.

Decide what type of MIG gun handle is most comfortable for you. MIG gun manufacturers often offer handles in curved and straight models. Regardless of the one you choose, make sure it is a lightweight, comfortable style that also meets the MIG gun and application’s amperage and duty cycle requirements. Typically, a smaller handle will be easier for you to maneuver.

Additionally, some MIG gun manufacturers offer ventilated handles, which help reduce heat and are more comfortable to hold when welding for longer periods of time. In some instances, a water-cooled MIG gun may provide the smaller size desired for an application and would be a good choice to reduce fatigue on higher amperage applications, especially in a shop setting.

Tip Three: Stay light and flexible

When selecting power cables, choose the smallest and shortest power cable possible that can still meet the needs of your application. Smaller and shorter power cables are lighter and more flexible, and can help reduce your fatigue. They can also minimize clutter in the workspace and prevent excessive coiling that may be cumbersome to unravel or that could lead to poor wire feeding. An added advantage is that smaller and shorter cables tend to be less expensive, as well.

Also, consider using a MIG gun with a rotatable or flexible neck to minimize unnecessary movement. Flexible necks can be easily adjusted to fit different welding angles. This feature helps minimize additional straining to reach a particular weld joint, and reduces the risk of fatigue or injury. Similarly, rotatable necks are a good option for welding out-of-position (including overhead), as they can be adjusted to reach the weld joint without changing the gun handle or its position. Bernard offers neck couplers, too, which allow you to connect multiple necks together to reach especially difficult joints more comfortably.

Tip Four: Consider a cool option

Cooling vests are one option for beating the summer heat, but these can make some people uncomfortable and actually increase fatigue. Instead, you may want to consider a lighter cooling option like a cooling belt.

For example, the CoolBelt™ from Miller Electric Mfg. LLC (an Illinois Tool Works company that Bernard is a division of) provides constant airflow over the welder’s head and face. The fan on the CoolBelt is secured on the lower back. Air flows upward through a piece of tubing that fits into your helmet; it’s then dispersed through the vents. The CoolBelt can reduce the temperature as much as 17 degrees. One advantage of the CoolBelt, compared to a cooling vest is its weight — it is significantly lighter so it helps improve stamina throughout the workday. Additionally, the CoolBelt doesn’t obstruct your range of motion, allowing you to perform more efficiently.

Find additional safety gear to help you keep cool in the summer heat 

Teaching New Welders to Improve Quality and Productivity

Estimated reading time: 7 minutes

For companies faced with training new welders, it is important to instill good habits early in the process. Doing so helps ensure the welders are well prepared not only to create quality welds, but also to contribute positively to the operation’s productivity. It can also help the welders gain the confidence they need to become increasingly proficient.

Following are 10 important things to teach new welders, to help them improve their skills and stay safe in the process.

1. Make safety a priority

It is critical that welders protect themselves from the heat and electricity generated by the welding process with the proper personal protective equipment (PPE). The arc is dangerous to both the eyes and skin. PPE includes: flame-resistant gloves, safety glasses, a welding helmet and a long-sleeved welding jacket. Flame-resistant clothing and steel-toed shoes are also recommended. Both the American Welding Society (AWS) and OSHA offer guidelines for PPE for specific environments.

Be sure to use enough ventilation, local exhaust at the arc, or both to keep the fumes and gases below the Permissible Exposure Limit (PEL)/Threshold Limit Value (TLV)/Occupational Exposure Limits (OELs) in the breathing zone and the general area. Always train new welders to keep their heads out of the fumes. Explain the importance of reading and understanding the manufacturer’s instructions for equipment, your company’s safety practices, and the safety instructions on the label and the material safety data sheet for the filler metals being used.

Routinely check for proper ground connections and stand on a dry rubber mat (indoors) or a dry board (outdoors) during welding to minimize the possibility of electrical shock

2. Install consumables properly

Good conductivity (the ability for the electrical current to flow along the welding circuit) helps gain good weld quality. New welders should always install their consumables – diffusers, nozzles, contact tips – according to the manufacturer’s recommendation, making sure that each component is securely tightened. In a gas metal arc welding (GMAW) operation, for example, the connection between the GMAW gun neck and diffuser needs to be secure to prevent shielding gas leaks. Secure connections also provide the surface area necessary to carry the electrical current throughout the GMAW gun to create a stable arc. Good connections also help prevent weld defects, support consistent productivity and reduce the risk of premature consumable failure due to overheating.

3. Cleanliness is critical

Dirt, oil, grease and other debris can easily enter the weld pool causing contamination that leads to poor weld quality and costly rework. Excessive oxidation and moisture can compromise quality weld. New welders need to learn proper cleaning procedure for the base material they are welding. In some cases, wiping the base material with a clean, dry cloth may suffice. However, welding on aluminum, for example, requires the use of a stainless steel wire brush designated for aluminum to clean out the joint before welding. A wire brush removes dirt and any of the oxides that may still reside on material surface.

Regardless of the material, it is important to follow the proper instructions for cleaning before welding.

4. Always follow welding procedures

Welding procedures are the “recipe” needed to create consistent welds and should be followed at all times. The procedures for a given application have been carefully determined and qualified by experts to ensure that the recommended parameters are capable of yielding the desired results. Weld procedures include the required shielding gas mixture, recommended gas flow rate, and voltage and amperage ranges. These procedures also provide information on the type and diameter of filler metal to use, as well as the proper wire feed speed in the case of a GMAW or flux-cored arc welding (FCAW) application.

5. Understand the importance of filler metals

New welders can benefit from familiarizing themselves with the attributes of various types of wires, including flux-cored and metal-cored wires, as well as the techniques for welding with each type. For example, they should learn whether their filler metal requires a “push” or “pull” technique. Following old adages like, “If there’s slag, then you drag,” can help; it indicates that flux-cored wires, which produce slag, should be operated using a pull technique. New welders should also become familiar with the manufacturer’s specification sheet for additional operating recommendations.

Learning to handle and store filler metals properly is also critical for new welders to learn. They should always wear clean gloves when handling filler metals and if they are responsible for storing them, should do so in a clean, dry environment.

6. Stay comfortable

Keeping cool and comfortable during the welding process can help welders lessen the chance of injuries associated with repetitive movement and reduce overall fatigue. When possible, new welders should learn to minimize cumulative strength moves, material handling or constant motion. They should also use a GMAW gun with a comfortable handle and cable style, as these factors contribute to the equipment’s maneuverability. New welders should be encouraged to play an active role in improving workspace ergonomics. Typically, the more input a welder offers about the job, the more satisfied he or she will be. Plus, that involvement can help ensure greater safety compliance and lower workers’ compensation costs for injuries.

7. Know the material properties

Every material has different mechanical and chemical properties. Helping new welders understand the difference between materials — particularly how they react to heating and cooling — is a key component of training. For example, austenitic stainless steel conducts heat at around half the rate of mild steel, but has a much higher rate of thermal expansion when welded; it also has a more localized heat affected zone (HAZ) that can lead to buckling when the weld cools. Welders who are aware of such properties can take precautions such as clamping to prevent distortion. Similarly, many materials require pre- and post-weld heat treatments to control the cooling rate and prevent cracking. When welders are familiar with such material attributes, they’re better prepared to make necessary adjustments during the welding process.

8. Visually inspect the welds

Knowing how to conduct an accurate visual inspection of a completed weld is the first step in quality control. It is also the quickest and least expensive method of inspection. New welders should learn how to identify weld defects that have porosity, for example, since the presence of this weld defect on the surface often indicates a similar problem throughout the weld. Identifying the defect early on helps prevent the time and cost associated with other testing methods, including x-ray or NDT (non-destructive testing) inspections. Other defects that new welders should learn to identify include lack of penetration (high, ropey welds), excessive penetration (sunken welds) and undercutting (characterized by a notch in the base material). It is important that welders inspect for weld cracks, which are among the most common weld defects to occur.

9. Learn how to troubleshoot

Identifying and rectifying welding problems quickly is a key skill for new welders to learn. Good troubleshooting skills not only help reduce downtime, but they also contribute to good weld quality and productivity. Such skills can also help reduce costs associated with rework. New welders can benefit from learning how to adjust gas flow rates properly and/or identify gas leaks in order to solve instances of porosity. They should also know how to make adjustments to amperage and voltage settings if they encounter issues such as lack of penetration, excessive penetration or undercutting. Identifying welding problems associated with worn consumables is also important, since poor conductivity can result in an unstable arc and lead to a variety of weld defects.

10. Maintenance makes a difference

From the power source to the GMAW gun and consumables, every part of the welding system requires maintenance to keep it operating efficiently and effectively. New welders should become familiar with proper maintenance procedures — preferably preventive ones — as part of the ongoing upkeep of the entire welding system. Regularly checking that the connections throughout the length of their gun or torch are tight is important, as is visually inspecting the front-end consumables for signs of wear.

In the case of a GMAW gun, the welder should replace nozzles or contact tips that have spatter buildup on them to prevent issues such as poor gas coverage or an erratic arc that will likely lead to weld defects. Welders should regularly check the power source, primary power line, gas cylinders and gas distribution system to ensure that they are working properly. They also need to replace faulty gas regulators or cables and hoses that show signs of wear, cracks or damage.