HomeMy WebLinkAbout06.a.1) (Handout) Final report on recent emergency situation involving Dissolved Air Flotation (DAF) tank, District Project 7265.Dissolved Air Flotation (DAF) Tank
Lessons Learned
Donald C. Parker
Provisional Plant Maintenance Superintendent
July 25, 2013
Central Contra Costa Sanitary District
Lessons Learned
• Clutches have been replaced with smaller units that
have a lower mechanical trip on torque for DAF tank
Nos. 1 and 3. DAF tank No. 2 still has original drive.
• Per Manufacturer: Inspect at regular intervals - We have
been inspecting tank every two years and the drive
annually.
• Ensured manufacturer's recommendations are included
in checklist.
• Use new Tank Inspection Checklist from American
Petroleum Institute (API) Certified Inspector Mark
Reinhart.
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DAF Tank Inspection Checklist
OAF TANK WSPECTIGN CHECXUST
PM W rix FA rn
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MECHANICAL SKIMMER ARMS
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BEACH ASSEMBLY
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ANODES
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Lessons Learned
• API certified person inspecting with several years of
experience.
• Inspectors have been trained what to look for: Types of
corrosion, more thorough inspections, etc.
• Increase inspection interval from two years to one year.
As equipment gets older, the frequency should be
increased.
- Preventative maintenance (PM) frequencies are periodically
adjusted depending on what is found on previous inspections
and the age of the equipment.
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Yearly Preventative Maintenance (PM)
• Additional items have been included in our yearly PM
which include:
- Torque test yearly when inspected per manufacturing methods.
• Purchase a Dynamometer to be used on the three DAF tanks as
well as eight Clarifiers and test for mechanical trip of clutch.
- Test the Torque Limit Switch to ensure the alarm is sent
and the motor is disabled.
- Check arm roller track thickness and condition; record it
on the PM.
- Check arms to center column connector bolts for correct
torque. D
3
Yearly Preventative Maintenance (PM)
• Inspect every three months above the waterline until the
tanks have been renovated.
• Incorporate changes into other equipment and systems.
• A result of what was found in a previous inspection on
the DAF tanks was the installation of the sacrificial
anodes to protect the baffles from corroding.
Yearly Preventative Maintenance (PM)
• DAF tank No. 2 arms and new Eurodrive will be installed
by District Staff this Fall.
• DAF tank No. 1 arms will be sandblasted and recoated
and DAF tanks No. 2 and No. 3 will be renovated during
the next fiscal year.
• Once the DAF tanks are completely renovated, this will
be used as our baseline for condition assessment in our
developing Asset Management Program. With proper
PM, will last us another 25+ years.
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DAF Tank No. 1
Cost Summary
• D.W. Nicholson Corp.
- Change Order executed July 2013
• Vendor Costs
- Equipment Purchase (arms)
- Consultant /Inspection Services
- Engineering Capital Project Staff
- Scaffold! ng/Crane
• Total Construction Cost
$ 156,855
$ 21,778
$ 22,662
$ 30,032
$ 2.310
$ 233,637
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