All Member Open Forum

Hello all,

My company has recently shut down a cast film line. We assume that the line will be down for at least 3 years. 

I'm planning on draining the cast drum and capping it with nitrogen as well as blowing down steam heat exchangers with compressed air. However, dozens of rollers are heated and cooled using closed-loop systems. My original thought was to drain all of these systems as well until someone brought up corrosion inhibitors.

Does anyone have experience with this sort of situation or can offer some insight into best practices for this situation?

Thanks

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Patrick Blais, CMRP
Senior Maintenance Mgr

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I'm more familiar with rotating equipment than I am with heat transfer systems. For the rotating equipment, yes, you will want corrosion inhibitors in any of your oil systems/reservoirs. Put it in, then run at full speed to thoroughly mix it in and coat all internal surfaces. If you don't already use them, make sure you have desiccant breathers installed. That will help protect your equipment as gradual heating & cooling cycles breath in atmospheric moisture. Also, the equipment should be rotated every month to keep oil & grease distributed in the bearings. Otherwise, false Brinelling (a microscopic cold-welding process) will ruin them. It doesn't take much - motor manufacturers recommend at least eight shaft rotations, which is basically just a bump. You don't want to run things long enough to warm them up. You may be able to get away with quarterly turns, rather than monthly, if the equipment doesn't experience vibrations from nearby production, railroads, etc. 

One catch is that large motors can deteriorate with each start, due the huge inrush current, but I assume your main cast drum drive is on a VFD. The VFD can be programmed to provide a much gentler start, and there's no need to bring it to full speed.

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Dale Nicholson, PE, CMRP, CRL
Reliability Engineering Mgr
Evonik Corp
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Hi Dale,

Thanks for the reply. I hadn't thought about regular rotation, that's a great point. All of our rollers are on VFDs so we can creep them along.

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Patrick Blais
Senior Maintenance Mgr
Toray Plastics (America)
N Kingstown RI
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Original Message:
Sent: 05-13-2024 06:46 AM
From: Dale Nicholson
Subject: Long-term shutdown considerations

I'm more familiar with rotating equipment than I am with heat transfer systems. For the rotating equipment, yes, you will want corrosion inhibitors in any of your oil systems/reservoirs. Put it in, then run at full speed to thoroughly mix it in and coat all internal surfaces. If you don't already use them, make sure you have desiccant breathers installed. That will help protect your equipment as gradual heating & cooling cycles breath in atmospheric moisture. Also, the equipment should be rotated every month to keep oil & grease distributed in the bearings. Otherwise, false Brinelling (a microscopic cold-welding process) will ruin them. It doesn't take much - motor manufacturers recommend at least eight shaft rotations, which is basically just a bump. You don't want to run things long enough to warm them up. You may be able to get away with quarterly turns, rather than monthly, if the equipment doesn't experience vibrations from nearby production, railroads, etc. 

One catch is that large motors can deteriorate with each start, due the huge inrush current, but I assume your main cast drum drive is on a VFD. The VFD can be programmed to provide a much gentler start, and there's no need to bring it to full speed.

------------------------------
Dale Nicholson, PE, CMRP, CRL
Reliability Engineering Mgr
Evonik Corp
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