Maintenance Welding - Caution

 Maintenance Welding - Caution

 

 

Electric Arc caused by welding on equipment is one of the Failure Modes for Rolling Element Bearings. Electric Arcing can could cause electrical component failure in MCCs and Electric Motors and Drives.  So why do we accept this failure mode when it can be eliminated?

General Rules which must be followed by maintenance personnel and contractors: 

(Caution: follow these recommendations only if you want to stop self induced failures caused by welding)

1. Ground leads and welding leads must be the same length on all welding machines by maintenance and contractors. (correct immediately)  

2. Grounding of welded surface must be within 6” of welded surface or a Reliability Engineer must approve the variation to the process. (Post this notice on welding machines)

Failure Modes experienced from Maintenance Welding

- Electrical Component Arcing caused by Welding on equipment  

- Bearing Flaking caused by Electric Arcing

My recommendation: Ensure your contractors follow the same process to eliminate electric arcing. Warning: failure to accomplish this one task properly will cause bearing failure by “electric arcing” which is a failure mode of bearings. In addition it will cause failure of many different electrical components. Remember: Electric current from welding will always follow the path of least Resistance.

Remember Welders are not reliability experts but professionals who know how to weld to construct and repair using all types of welding processes. I was a certified welder for many early years and later became a reliability specialist and conducted Root Cause Analysis on many failures around the world and have seen this problem in almost every plant and site I have visited. Stop this at your site now.

The Author: Ricky Smith CMRP, CMRT, CRL

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