Part 1. Many factors go into a successful weld.
By Gary Shawver, MGWC
That is unless all wells you install are PVC-cased. But even with that, many repairs on a drill rig or related equipment will require welding skills.
For steel-cased wells, welding plays a vital part of the integrity of the well. It’s as essential to the well integrity as grouting.
Often when one thinks about welding, it’s simply pulling out the leads from the welder, hooking the ground to the casing, and putting a rod in the stinger and welding the casing. I wish it were that simple.
There are many factors that go into a successful weld. I will outline basic tips that hopefully will help those who are entering the water well industry and serve as a refresher for industry veterans. What follows are eight vitally important factors.
- What type of material are you welding? Is it mild steel casing or is it high carbon content steel?
Most water well casing is A53 B casing. A53 B is a grading of the casing based on the America Society of Testing Materials (ASTM) standards, and most state codes require the minimum grading of water well casing be A53 B. A53 B casings are a mild steel casing with a yield content of the steel of 40,000 yield. When welding a casing of this type, the most common rod used on stick welders is 6011.If you’re using an American Petroleum Institute (API) graded casing, this often has a much higher carbon content to it, and therefore a higher yield strength. There are many different grades of API casings that are available, and you need to check the API markings on the casing to verify which grade you have. You should then verify what the yield strength is—be that from the manufacturer, supplier, or manual from the API that outlines the specifications and yield of each classification.The yields are from 40,000 on the low end to more than 100,000 on the high end. It’s ideal that you use a welding rod that is compatible with the yield strength rating of the casing to ensure your weld will meet the yield so that your weld doesn’t provide a weak link in your casing string. Many API casings have a rating of 60,000 yield. A 7018-welding rod, which is a low-hydrogen rod, is ideal for this type of welding.
- What type of environment are you welding in? Is it high moisture and cold, or is it warm and dry?
Regardless if you are welding ASTM or API graded casing, it’s important to have the material dry and devoid of any moisture. Moisture in casing can cause pinholing of the welds and subsequently end up with a non-watertight weld. For example, if you are welding in the morning when the dew is high or welding during a day when there is a cooler or colder temperature, the casing will draw moisture. Using a high-volume liquid propane (LP) torch and heating the casing to drive the moisture from the casing is a good way to eliminate this moisture.In addition, getting the casing warm to hot will also help the rod flow more smoothly as the rod then only has to make the weld as opposed to also having to raise the temperature of the casing to make the weld. When in doubt, preheat your casing using a high-volume LP torch. Often you’ll be able to see the moisture leave the casing as you heat the end of the beveled area. It’s important that both pieces of casing being welded together be preheated.As a side note, you need to be aware of your surroundings while using the LP torch as it’s quite easy to start a fire. Keep all flammable materials (including any fuel or rags) away from the area you are welding or preheating the casing.
- Cleanliness is vital to facilitating a good weld.
Care and time should be taken to carefully clean and prepare the joints of the casing to be welded. If there is dry or caked mud on the ends, use a good wire brush and brush them free of all dirt and debris. If this is not sufficient, wash the ends until the ends are clean and free of dirt. Many casings are coated with either a lacquer or paint to keep the casing from rusting. If this is the case, preheat the casing again with an LP torch until the material is burnt off, or until such time as the lacquer or paint is loose enough to be wire brushed off. If the joints are rusty, using a high-powered, air-operated, or electric wire brush may be required to clean the bevels.
- Speaking of bevels . . .
All bevels of graded casing (either ASTM or API) should have what is called a 37-degree bevel with a small flat landing area where two joints of casing can marry up. A 37-degree bevel is the ideal bevel to facilitate placement of the weld material when the casings are joined. You should routinely check your bevels on your casing to ensure that they are also square. This can be done by simply using a carpenter’s square on the ends of the casing.I have personally had a load of casing come onto a jobsite where more than 50% of the joints, while having a nice machine bevel, were not square. The mills manufacturing the casing can often have issues with their machining of the bevels.If the bevels are not square, getting an aligned string of casing down the hole can be a difficult challenge. If the casing supplier has only 40 feet lengths of casing in stock and is going to supply you with 20 lengths of casing, they will often cut the casing in half with a saw. This doesn’t give you a 37-degree bevel on one end of the casing. You need to discuss with the supplier this issue prior to ordering and shipping.
Some suppliers can re-bevel by a machine, or if not machine, can torch bevel the cut ends with a cutting torch to help make a good weld. However, be sure to emphasize that those torch bevels must be square and free of slag from the torch beveling of the casing. Even if the casing is torch beveled, you will not get that landing area that allows setting one joint of casing on top of the previous joint and can make alignment extremely difficult. Using casing alignment clamps to align the casing when installing will help facilitate this issue.
- Alignment clamps.
These clamps clamp around each piece of casing to be welded together. The purpose of the clamps is to make it easy to align the two
pieces of casing to ensure they are aligned with each other. Alignment clamps are typically available from many drilling supply houses and can be found in sizes of 4 inches to 16 inches and sometimes larger.Using alignment clamps for welding casing in a water well are almost a must-have item. I would highly encourage you to get the different sizes for the casings you install.
- Joining the joints.
After you have preheated the joints and have them aligned in the alignment clamp, you are now ready to begin welding. I would strongly recommend that you spot weld the casing in three uniform locations around the joint. Spot welding is where you strike a weld long enough to get the weld to take to the casing and hold it in place. Three spot welds placed uniformly around the casing will ensure the weld does not pull the casing to one side due to the heat of the weld. After the three spot welds are in place and you’re sure the spot welds will hold, you can now remove the alignment clamp. Removing the clamp will facilitate the movement of your welding rod unimpeded and allow for a nice uniform weld.
- Placing the weld.
Placing the weld can vary from a single pass for smaller diameter casing such as 4-, 5-, or 6-inch casing. Larger diameter casings can require up to three passes to completely fill the 37-degree bevel. The larger the casing, the longer the length of the bevel. It’s imperative between passes to clean the slag created from the weld with a chipping hammer or a mechanical chipper or wire brush. This makes for a clean surface to place the second or third pass.While placing the weld, look for any pinholes that may be observed. If pinholes are noticed, try raising the heat on the welder or reheating the casing with your LP torch to drive out any moisture.
- When the weld is complete.
You can now lower the string of casing down the borehole. If the well you are drilling is a fluid drilled well and the fluid is at the surface, I would encourage you to wait at least 5 minutes to allow the heat to dissipate before lowering the hot joint through the drilling fluid. Quick cooling could potentially crack the weld and cause a failure. While time is of the essence on any project, waiting 5 minutes for the weld to cool can prevent a failed well.
In my next column, I will share additional tips that are helpful to welding in the drilling environment.
Gary Shawver, MGWC, is president of Shawver Well Co. Inc. in Fredericksburg, Iowa. He has been in the water well industry for more than 40 years and is a Master Groundwater Contractor. He served on the NGWA Board of Directors. Shawver is semi-retired, having sold his business to his employees. He can be reached at firstname.lastname@example.org.