The hostile environment in power generation plants present ample opportunity for weld repairs. In coal-fired power plants particularly, the steam-generating tubes of a boiler inevitably corrode over time, requiring scheduled shut downs to remove and replace damaged sections. Weld quality on these repairs – because of the extreme temperatures and environment the tubes encounter – is absolutely crucial, so when journeymen welders from Boilermaker Local 108 (Birmingham, Ala.) experienced weld discontinuities, they acted quickly to find a solution.

Evaluations showed porosity at the starting and stopping portions of the weld, slag inclusions and lack of fusion from Local 108’s current E8018-B2 stick electrodes were causing the rejects. The seven percent rejections rate they experienced (91 out of a total 1,300 welds) cost around $32,000 in rework after accounting for labor and overhead.

When Local 108 contacted Hobart Brothers about the problem, the company evaluated its own and competitive E8018-B2 stick electrodes, concluding the definite need for a new product.

Hobart Brothers’ representatives met with Local 108 journeymen welders to determine the attributes the ideal stick electrode would possess.  All agreed the new stick electrode should meet these six benchmarks:

1.    Provide good amperage spread (75-95 A) to allow welding on both thin- and heavy wall boiler tubes without burn- through.
2.    Create light, non-sticking and small particle spatter.
3.    Have easy-to-remove slag, especially at arc starts and stops, to avoid inclusions.
4.    Offer excellent bead wash to prevent slag inclusions due to weld undercut.
5.    Prevent porosity at the starts and stops of welds and on pass-throughs.
6.    Burn-off evenly, particularly when performing pick-ups on the tube side, and produce X-ray quality welds.

Based on these requirements, Hobart Brothers developed a series of E8018-B2 prototypes and asked Local 108 journeymen welders to test and rank each one’s performance.  The fourth and final electrode evaluated by Local 108 showed a dramatic improvement compared to the previous samples – scoring nearly perfect on all key benchmarks.

In actual use on an outage, the new product – called Boilermaker™ E8018-B2 – reduced Local 108’s weld rejection rate to approximately four percent, or 52 welds instead of 91 needing repair out of 1,300 total welds. That equals $18,720 for rework, or a savings of over $14,000 compared to previous stick electrodes. Hobart Brothers also formulated three other Boilermaker products (E7018, E7018-A1 and E9018-B3) that the Local 108 plans to use for other outage projects.