Part 8. Are you ready for Take-off?
This is the 8th in a series of 10 articles that further explore the key concepts in “Simplifying Mine Maintenance” by Gerard Wood.
In my last article about KPI’s, I highlighted the importance of using the right “measures”. KPI’s provide the big picture and a clear overview of performance. The problem with KPI’s is that they are often a lagging indicator - particularly when it comes to maintenance.
“What is done today in maintenance will show in the results 6 to 12 months down the track”
This means that it is necessary to be able to immediately measure and monitor the quality of work that is being done in order to be able to provide immediate feedback and course corrections in the process of instilling culture and performance objectives.
For weld repairs of cracking, quality is essential in achieving an “effective” repair, as is noted in Simplifying Mine Maintenance.
"Welds require particularly high-quality standards. Welds are prone to re-cracking if correct pre- and post-heating standards are not employed and the weld surface is not finished properly. However, many mine welders rarely consider the required quality standards
What does it mean for a repair to be “effective”?
Simply put, an effective crack repair is one that lasts. This requires the repair to be completed to the necessary quality level and that the fatigue life of the repair has been optimised. An effective repair may have a fatigue life that is 5x to more than 10x of typical repairs. In fact, effective repairs will often have far better fatigue life than the original weld!
It is important to recognise that although quality is important, it is not the primary objective. It is also important to understand that “quality” is a subjective measure. You could have a “high quality” weld when assessed to AS/NZS 1554 for manufacturing, but it is low quality in terms of the effectiveness of the repair in preventing repeat cracking.?It is important to apply appropriate QA for maintenance welding. It is necessary to get the basics right in terms of addressing the fundamental causes and prevention of fatigue cracking and managing technical risks.
While fundamental in concept, this is a huge issue, as noted in “Simplifying Mine Maintenance
”We stress the basics because 80% of the mining industry does the basics poorly. There is a tremendous need in the industry for strategies focused on quality execution, ownership, and practical simple solutions."
The problem is that weld repairs of cracking are actually quite complicated once you get into the details. An important factor to consider is that for complex tasks there is an increased risk of forgetting a step/action. Missing just one important step or introducing a defect will lead to rapid re-cracking. Gerard gives the following example
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“Years ago, we welded keepers on dragline bucket teeth, chains and pins. These are all bolted today, but they used to be welded and they frequently would fall out. There wasn’t a complicated root-cause analysis back then. We just engaged the mechanical engineer, who worked with the welder and figured out that the keepers weren’t preheated before being welded. We made a change to the acceptable standard and when the welders started preheating in this way, the unscheduled downtime plummeted - all because we use correct welding procedures on a simple welded keeper”
The issue of task complexity and the ramifications of not following each step was highlighted when the Boeing B-17 was first developed and the test plane crashed on take-off. The pilot who was making his first familiarization flight neglected to remove the control locks. Subsequent investigations found it to be due to pilot error - there were simply too many controls to remember to operate in the correct sequence and the plane was deemed “too much airplane for one man to fly.” In response, the humble checklist was born. Now, every time a plane takes off, the pilots are running through their checklists, making sure that all the necessary steps and actions have been completed in order to fly safely.
Atul Gawande’s “The Checklist Manifesto” provides a deep look into how and why to use a checklist. In the book, Gawande makes a distinction between errors of ignorance (mistakes we make because we don’t know enough), and errors of ineptitude (mistakes we made because we don’t make proper use of what we know). Experts need checklists - written guides that walk them through the key steps in any complex procedure.
“Checklists …. remind us of the minimum necessary steps and make them explicit. They not only offer the possibility of verification but also instil a kind of discipline of higher performance.”
I believe that instructions and QA for crack repairs should be more like a checklist than a detailed record. It needs to provide clear and actionable steps that are easy to review, and in this way it can also establish accountability and responsibility for following the necessary best practices. The QA in itself should act as a prompt for the welder to ensure all the essential steps are done properly.
As I previously wrote about in “Finding the Sweet Spot”, when it comes to repair welding of cracking, providing more instructional information is not better. Neither is more detailed QA documentation. Having highly detailed welding QA sheets just adds more time and more friction to doing the job. Comprehensive welding QA is for manufacture when compliance design and related WPS’s is necessary. Mines are not manufacturing equipment so strict compliance to a WPS should not be the goal. Quality is not the primary objective. Effective performance is.
I believe it is better to focus on what is important for achieving the desired outcomes (KPI’s) of an effective crack repair. The objectives of an effective crack repair should be improved reliability and availability, lower maintenance costs, and extended viable structural life. In order to achieve an effective weld repair of cracking, there are some essential criteria that must be met for pretty much any crack repair. These are
These criteria should therefore form the basis of the QA documentation checklist. But this is different from what people are used to doing by incorrectly applying AS/NZS1554 - a change in mindset and culture.
However, to create and maintain culture change, it is also necessary to be able to hold people accountable. Therefore, the QA needs to support the asset management system for crack repairs and provide the foundation data for KPI monitoring. This also requires Supervisors to have sufficient welding knowledge to know “what good looks like”, and also some means of recording who did what to reinforce the sense of responsibility and ownership.
WQMS has taken all of this into account in the development of the AICARM framework.
Use the checklist concept for QA to provide a simple guide for the maintenance task and get your team ready for take-off.
Contact us at [email protected] to find out more.
Companies talk about simple, effective asset management and reliable equipment. Few achieve it and most keep implementing the same failed solutions . The problem is culture based and the solution starts with leadership.
4 年Great article Simon Krismer