by Tom Shumka Tom Shumka 2 Comments


SAG Mill

34′ X 20′ SAG Mill
Nameplate Mill Power (HP)17,000
Motor Power (HP) Max8,985
Face Width [mm]1,016
Mill Speed (RPM) Nominal10.3
Gear Ratio20.2
Mesh Per Revolution2.0
Operating Hours at First Detection35,345
Gear tooth load cycles43,686,420

March 2016: Detecting Cracks with ASTM E 2905

  • A complete cleaning and girth gear inspection was conducted March 15, 2016 per ASTM E2905.
  • 4 Cracks were detected and relieved onsite. This is extremely important to stop or slow down the propagation of any cracks detected, extending the PF curve of each effective flank.
  • The prior inspection by Global personnel on June 2014 did not detect any cracking.
ToothTotal Crack Length [mm] on 3/15/2016
1867
11122
189254
22567
Crack Detection in Tooth 189

Crack Detection in Tooth 189

Crack Detection in Tooth 189

Crack Detection in Tooth 189

Mitigation Technique

Mitigation Technique

Dykem Blue is used to monitor the contact in the vicinity of the crack.

Dykem Blue is used to monitor the contact in the vicinity of the crack.

Monthly Follow up Inspections

  • Monthly MPI of the surface
  • Monthly Conventional Ultrasonic Inspection of the Depth
  • Complete ASTM E2905 Inspection at 11 months, recommended every 4 months for compromised gearing.
Follow Up Inspection

Monthly Follow Up Inspection

Phased Array Ultrasonic Inspection to Map Depth [NOT for Crack Detection]

Phased Array Ultrasonic Inspection to Map Depth [NOT for Crack Detection] Phased Array Ultrasonics is beneficial as a secondary inspection method for mapping out cracks

This picture shows an excellent representation of crack mapping using PAUT. We can track growth and orientation of the crack over a period.

This picture shows an excellent representation of crack mapping using PAUT. We can track growth and orientation of the crack over a period.

February 2017: Additional Cracking Found

ToothTotal Crack Length [mm]
1867
6628
7419
7919
10713
11151
13036
189306
22582
253166

Surface Crack Lengths Over Time

Surface Crack Length [mm]
Tooth3/15/20164/13/20165/3/20166/7/20167/12/20168/9/20169/7/201610/12/201611/22/201612/14/20161/17/20172/15/20173/14/2017
1867676870707070707070707070
662828
741919
791919
1071313
11122514848484848484848515151
1303638
189254276286286286306306306306306306306306
22577777878787878828282828282
253166166

April 2017: Girth Gear Replacement

Global conducted all the QA/QC with the manufacturer to ensure the new gear met the appropriate specifications.

Global also conducted oversight of the new 40′ gear installation. Ensuring the gear was installed properly giving it the best chance to meet or exceed its design life of 25 years.

replacing the girth gear

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