Fmea Analysis
Thanks George,
It is good to look at the real world of commissioning in this Forum.
I have found the FMEA [Failure Mode and Effects Analysis] very practical and helpful in doing detective work on site. This allows young engineers to focus full attention on one variable at a time. Once you go through the process in a rigorous way the solution often stares you in the face.
Regards - John.Rz
www.cospire.com / Engineering Tips / Hazard Analysis
http://www.cospire.com/koviewer.aspx?id=13577 ■
One Thing At A Time.....
Thanks John for your comment. The old gentlemen that I had as a mentor.......(he was 73 with 50 years experience and I was 35) always said:
1. Well........Did you learn anything new today? Tell me what.
2. When troubleshooting problems with vibrating screens.....always do ONE THING AT A TIME. Do not for example.....change the speed and change the wirecloth opening, and increase the stroke all at the same time.....
ONE STEP ELIMINATION ....at a time........so when you fix the problem.......you understand what it was that fixed it. ■
Startup commissioning story
Last week had an interesting problem on a new DEISTER screen startup. Big 8x20 3 dk 20 degree decline angle WET SPRAYS
Unit would not startup (BRAND NEW) after numerous attempts...actually unit was test started day before.....sooo hmmmmm why not today?
Upon troubleshooting here is what we learned:
- Did startup day before no problem, it was dry
- Day after, (today) THE unit would not start at all...what changed? ANYTHING?
- Upon arriving on site....i smelled a distinct aroma of burnt rubber in the air. My indication that belts were maybe slipping.
- Upon climbing tower and looking about, I saw small bits of nice black rubber dust on the new framework...intermingled with the water on the frame below the drive guards of this 2 shaft machine.
- This confirmed my inkling, that belts may have been slipping and hence NOT STARTING screen
- Had mtce guys pull guarding off.....and noted the ULTRA BAND BELTS WERE IN DEED SLACK.....and one of the drives were MISALIGNED to boot.
- The pivoted motor bases (rosta) were fine but, the motor platform was not aligned properly and was adjusted.\
- Upon aligning the one drive sheave and tightening the belts to proper tension.....we put the power to it........and STARTUP was achieved nicely.
- This situation is an old one.......but, gets repeated time and time again on new machine startups.
Wishing you all GOOD VIBRATIONS...... ■