Recently, while preparing for a turnaround in the Delayed Coker Unit (DCU) at the Suncor Energy Oil Sands facility in Alberta, Canada, BHI Energy learned that its client was at risk of losing the production of two petroleum coke drums.
BHI Energy first layer temper-bead
First layer temper-bead
The aging drums had been in service since 1967, and in the preceding three years had experienced a handful of through-wall cracks. The cracking raised concerns with the provincial governing body, the Alberta Boilers Safety Association (ABSA).
ABSA feared that the drums had reached the end of their service life and, therefore, were threatening to shut them down. This unexpected loss would immediately impact profitability, and would pose a problem without a quick solution.
Faced with this challenge, BHI was asked to provide ABSA with an explanation for the repair of these drums using a tem- per-bead, structural weld overlay. Fortunately, during three previous projects at the same location, BHI had experimented with a cloud-based, real-time data logging system.
The use of data loggers is not a new technology. Data capture has been in use for several years within the nuclear industry to record and monitor the parameters of super critical welds. Although this process had never been used for coke drums, trials indicated that the collection of this data, and the ability to act on it, would improve the temper of structural weld overlays.
A temper-bead weld procedure is a two-layer approach: the second layer tempers the first, thus avoiding the time-consuming and costly need for a post-weld heat treatment(PWHT)to temper the base material. However, for this procedure to be successful, knowing and controlling the heat input of each layer is crucial.
Heat inputs that are out of parameter indicate higher Brinell hardness readings, which signal that the base metal is susceptible to cracking. Historically, heat inputs have been measured manually at the site where the welding was being performed, using a wattage meter. While this method is code compliant, it provides only a snapshot of the parameters in that moment.
BHI Energy improved hardness readings
Improved hardness readings
Now, using real-time data loggers one can see the heat input for every weld bead on each individual machine, within seconds of installation. Since the data is transmitted from the power source directly to a web-based cloud, quality control personnel can monitor weld parameters anywhere an internet connection is available. This continuous flow of information allows for adjustments, which in turn improves Brinell hardness readings and extends the service life of the drum.
Results
• Based on the inclusion of the data loggers, ABSA allowed the coke drums to return to service as designed.
• Overall Brinell hardness readings dropped by an average of 50 points. Suncor’s specification for Brinell hardness requires a range of 145 to 240. Actual hardness achieved averaged 179.
• Transparent quality control and real-time weld parameters are continuously shared with the client, which removes un- certainty, ensuring compliance and predictable outcomes.
“The development of real-time data capture sets a new standard for coke drum temper-bead repair. This application will now become a scope requirement at our refinery,” said Michael Juma, senior mechanical reliability engineer, upgrading, at Suncor Energy Inc.
For more information, visit www.bhienergy.com or call (800) 225-0385.
