We receive plenty of questions regarding welding pipe. Whether it’s about welding high-pressure pipe, Stainless Steel Pipe Manufacturers for food and beverage industries, or pipe for the oil and gas industries, there are a variety of common elements we see in pipe welding and fabrication which lead to problems. Such as anything from improper shielding gas and drive rolls to choosing a MIG gun with too low of an amperage rating. As companies push to train new welders, work with new materials, increase quality and productivity, and improve safety, it is essential to give attention to some of these basic variables within the pipe welding process that can impact these efforts. In this article, we’ll look at 13 of the most common issues we see in pipe welding applications and the way to resolve them.
1. Forgetting to grind the joint after oxyfuel or plasma cutting
Both the oxyfuel and plasma cutting processes give a layer of oxide towards the cut edge. This oxide layer must be removed prior to welding, because the oxide often includes a higher melting point than the base metal. Once the arc gets hot enough to melt the oxide, it’s too hot for your base metal and can result in burnthrough. The oxides can also stay in the weld and cause porosity, inclusions, lack of fusion and other defects. It is important that welders make sure to grind the joint as a result of the parent material prior to welding, as well as grind the inside and outside diameters from the pipe to eliminate these oxides as well as other potential contaminants.
2. Cutting corners with cutting
When welders work with materials more prone to distortion and also the affects of higher heat input, such as stainless steel and aluminum, a bad cut can lead to poor fit-up and make unnecessary gaps. Welders then compensate by putting more filler metal (thus, heat) in to the joint to fill it up. This added heat can cause distortion and, with corrosion-resistant pipe like stainless, can reduce the corrosion-resistant qualities from the base metal. Additionally, it may lead to absence of penetration or excessive penetration. Poor preparation also leads to longer weld cycle times, higher consumable costs and potential repairs.
Shops currently using chop saws or band saws to reduce pipe utilized in critical process piping applications should consider buying dedicated orbital pipe cutting equipment to ensure cuts within mere thousandths of the inch in the specified parameters. This precision helps ensure optimum fit-up and keeps the quantity of filler as well as heat put into the joint at least.
3. Forgetting to cut out and feather tacks
Tacking is essential to match-up, and best practices recommend that the welder eliminate and feather that tack to guarantee the consistency from the final weld. Particularly in shops in which a fitter prepares the Seamless Steel Pipes then another person welds it, it’s important that the welder knows precisely what is incorporated in the weld. Tacks left in the joint become consumed by the weld. If you have a defect in the tack, or maybe the fitter used a bad filler metal to tack the joint, you will find a risk for defects within the weld. Cutting out and feathering the tacks helps eliminate this potential problem.
4. Preparing a joint for MIG processes is different than with Stick welding
Training welders is a main concern for most fab shops, and – for better or worse – many welders bring past experiences with them for the new job. These experiences may be addressed with adequate training, but one common mistake we have seen is welders with Stick experience not understanding how to properly prepare a joint for wire processes common in pipe fabrication applications. Welders trained traditionally in Stick and TIG welding often prepare the joint having a heavy landing area and would like to maintain the gap as narrow as you can. As pipe shops switch to easier, more productive MIG processes including Regulated Metal Deposition (RMD™), we prefer welders take that landing area down to a knife’s edge and space the joint at approximately 1/8-inch. This region is wider compared to those trained in Stick and TIG processes are used to and can result in a number of problems: focusing excessive heat in to the edges of the weld, a lack of penetration and insufficient reinforcement on the inside the pipe. Shops should train their welders towards the details of each application and be sure they understand different weld preparation and operational techniques before they go to work.
5. More shielding gas is not always better
Some welders use a misconception that “more shielding gas is better” and definately will crank the gas wide open, mistakenly believing they are providing more protection towards the weld. This procedure causes numerous problems: wasted shielding gas (resources and price), increased and unnecessary agitation of the weld puddle, and a convection effect that sucks oxygen to the weld and can cause porosity. Each station needs to be outfitted using a flow meter and every welder should discover how to set and adhere to the recommended flow rates.
6. Buy mixed gas – don’t count on mixing with flow regulators
We have seen shops that, for any stainless steel application that needs 75/25 % argon/helium, create a different tank of argon and a separate tank of helium then count on flow regulators to bleed inside the proper level of shielding gas. The reality is you truly don’t understand what you’re getting in a mix with this method. Buying cylinders of Galvanized Carbon Steel Tube from reliable sources, or investing in a proper mixer, will guarantee you already know just what you’re shielding your weld with which you’re implementing proper weld procedures/qualifications.
7. Welding power sources don’t cause porosity
It is far from uncommon to obtain a call coming from a customer who says “Hey, I’m getting porosity from the welder.” Plainly, welding power sources don’t cause porosity. We tell welders to recount their steps back from the point where the porosity began. Welders will often find that it began just whenever a gas cylinder was changed (loose connections, incorrect gas used), a whole new wire spool was devote, when someone didn’t prep the content properly (oxides present in the weld), or maybe the content was contaminated someplace else across the line. Usually the issue is brought on by an interruption or trouble with the gas flow. Tracing back your steps will often lead dkmfgb the variable that caused the porosity.