Field Pipe Welding - Is Stick Stuck? Flux Cored May Provide Added Benefits
Is field pipe welding stuck on Stick welding? While other industries that weld in the field have moved from SMAW to some type of faster process, typically the GMAW (MIG) or FCAW (flux cored) process, the pipe welding industry still relies heavily on the Stick electrode. Why?
Some people erroneously question the integrity of welds made using the GMAW short circuit transfer process. This occurred because when the code books were written, the specifications for prequalified joints stated that short circuit transfer was not acceptable. The common interpretation is that short circuit transfer cannot be used per AWS D1.1 or API codes when welding pipe. This is not true, and people often misquote the codes. When it has been qualified, the short circuit transfer process can be used.
Historically, welders have also shunned FCAW for on-site welding, even though they use it in the shop. But today, flux cored wires have been developed to run in a non-gas shielded atmosphere, and their performance in windy conditions equals that of Stick electrodes. In addition, manufacturers such as Miller Electric have developed dependable, light-weight wire feeders.
Compared to the bulky feeders of the past, these portable feeders can be carried with one hand around the job site. Another feature of the newer feeders is remote voltage control at the feeder with just a two cord system from the power source.
When wire welding units are first brought to the job site, many operators are reluctant to give up their Stick electrode. Often they are concerned that if they finish the job too quickly, they will be out of work. Managers and site superintendents must assure welders that completing a job faster benefits everyone. Other times, fear of the unknown or inexperience produces a resistance to change. By providing the appropriate training, management can allay these concerns.
Other reasons for the industry's hesitancy to use GMAW or FCAW could stem from the initial expense of qualifying "new" joints and processes, as well as the training and testing of operators. While qualifying processes and people takes money and effort, changing from Stick to a continuous welding process delivers a proven return on investment.
For example, a 5/32 in. E6010 electrode will deposit approximately three lb. per hour with a 64 percent efficiency rate. Compare this to an .035 in. solid wire, which deposits almost 9 lb. per hour with a 96 percent efficiency rate (using 75 percent Ar/25 percent CO2 shielding gas). The wire welding process has three times the deposition rate and is 30 percent more efficient. With job bidding so fierce today, the substantial time savings could be the difference between getting the contract or not.
Note: The author emphasizes that GTAW remains the preferred process for the root pass when pipe welding. As described in this article, GMAW and FCAW are used for the fill and cover passes.