# Cryogenic pump failure



## gpop (May 14, 2018)

Could the inrush be the caps charging and the motor is open?


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## oldsparky52 (Feb 25, 2020)

I didn't think of the capacitors, but I did wonder if you knew the motor was turning (and how)?


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## Lazyelectrician (Aug 9, 2021)

gpop said:


> Could the inrush be the caps charging and the motor is open?


The system starts to build pressure up to 70 psi, but normal pressure from the pumps is 500 PSI. this is the only indication I have that the pump is turning.


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## Lazyelectrician (Aug 9, 2021)

oldsparky52 said:


> I didn't think of the capacitors, but I did wonder if you knew the motor was turning (and how)?


 The system starts to build pressure up to 70 psi, but normal pressure from the pumps is 500 PSI. this is the only indication I have that the pump is turning.


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## CAUSA (Apr 3, 2013)

how high is the lift for your pump flow.? what's the head rating of the pump?

sound like you might have a mechanical link problem on the pump shaft. or key way is lost and just spinning the impeller and the back pressure of the impeller just drops and the motor just spins freely.

can you disconnect the power factor bank? does the currant change?

is it a gear pump of a multi stage impeller pump? if multi stage you could have lost one or more of the multi stage impellers.

Of the top of my head that's only 14% of flow capacity. not a lot of load on the motor. I do not know what kind of pump you have.

if you had a winding problem you would have protection issues.


Either way time to pull the girl out and send to shop bay for further analysis.


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## just the cowboy (Sep 4, 2013)

Couple of things.
Is it 2300v medium voltage starter or are they stepping it up after starter?
What is the nameplate amps?
Almost zero amps don't sound right even if motor is unloaded, what hp motor.

Cowboy.


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## MikeFL (Apr 16, 2016)

Empty tank?


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## Lazyelectrician (Aug 9, 2021)

CAUSA said:


> how high is the lift for your pump flow.? what's the head rating of the pump?
> 
> sound like you might have a mechanical link problem on the pump shaft. or key way is lost and just spinning the impeller and the back pressure of the impeller just drops and the motor just spins freely.
> 
> ...


We have around 100 ft of head. (yes I'm a guy, no I'm not exaggerating). impeller is attached directly to the pump, so a lost keyway is a possibility. I'll have to get into the MCC to remove the lugs for the power bank, which is something I am willing to do. My mechanic will be back tomorrow, I'll hit trouble shooting hard then. I have a fire pump that is in the same MCC, I'll have him fire that off and I'll check current on it. He can give me more info on the pump.


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## Lazyelectrician (Aug 9, 2021)

MikeFL said:


> Empty tank?


tank has 50 ft of liquid in it


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## Lazyelectrician (Aug 9, 2021)

just the cowboy said:


> Couple of things.
> Is it 2300v medium voltage starter or are they stepping it up after starter?
> What is the nameplate amps?
> Almost zero amps don't sound right even if motor is unloaded, what hp motor.
> ...


medium voltage starter. I'm their first electrician, and I only started 5 months ago. I'll gather more information.


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## Lazyelectrician (Aug 9, 2021)

oldsparky52 said:


> I didn't think of the capacitors, but I did wonder if you knew the motor was turning (and how)?


System builds up to 70 psi of pressure but its normally 500 psi. That is how they noticed an issue.


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## gpop (May 14, 2018)

No amps yet it started to make pressure.

One of the statements is wrong.
Possible valve opened and you read back pressure or you did have amps


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## Lazyelectrician (Aug 9, 2021)

gpop said:


> No amps yet it started to make pressure.
> 
> One of the statements is wrong.
> Possible valve opened and you read back pressure or you did have amps


I see what you are saying. Plant operator says he doesn't open any valves, and no valves automatically open upon start. I don't have a meter to hookup to read current, but watching the meter for the CTs I see the inrush current, and then the analog meter backs off all the way down to near zero.


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## just the cowboy (Sep 4, 2013)

Lazyelectrician said:


> System builds up to 70 psi of pressure but its normally 500 psi. That is how they noticed an issue.


Some other things to look for to check.
Could something else be giving you the 70 PSI you see? If a valve opens that 70 PSI you see could just be head pressure.
Do you hear or smell anything?
Why did they rebuild the last pump?

Welcome to the world of maintenance, you need to be a mechanic also to prove it is not electrical.
Best advice I can give you is to make a note book on what fixed something before, things that did not fix something ect...
Also if they don't have prints learn how to draw them, in the book I posted in your welcome thread there is a section in there, prints are your best friend now. Keep asking on here for help we almost know what we are doing.

Cowboy


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## just the cowboy (Sep 4, 2013)

gpop said:


> No amps yet it started to make pressure.
> 
> One of the statements is wrong.
> Possible valve opened and you read back pressure or you did have amps


There you go again thinking like me, only I type slower and give longer answers.


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## Lazyelectrician (Aug 9, 2021)

just the cowboy said:


> Some other things to look for to check.
> Could something else be giving you the 70 PSI you see? If a valve opens that 70 PSI you see could just be head pressure.
> Do you hear or smell anything?
> Why did they rebuild the last pump?
> ...


I appreciate all the help from everyone, being the new guy sometimes it is hard finding the information you need. Prints are a hard thing to come by in a thirty year old plant that has had bits and pieces replaced here and there. The best tool they have gave me was this laptop. I already have folders and folders of notes from both of my plants.

Pumps were finally rebuilt after being installed for 30 years. Doesn't sound like there was an issue with them, just preventative maintenance. With the MCC being 600 ft away from the pump, I didn't hear any thing other than the starter engaging. and with the pumps being inside the liquified natural gas at cryogenic temps, not going to get a smell either.


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## CAUSA (Apr 3, 2013)

no Electrician till you?

what about, instrumentation? was there and calibration/maintenance system in place at this plant. Cryogenics is a difficult place to work in. liquid CH4 is unforgiving. 

Prints? any? if not make them. manufactures should keep a build record or is plant old as the hills?

what about P&ID, This should show the single line pipe work with instrumentation to help you plan the attack, even if it is a fill station. Had to be approved by the AHJ at one time or another.

Can you trust the panel display? there will be a +- % of error, but that is for another time Cowboy can tell you. so the pressure can be lower or higher.


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## Lazyelectrician (Aug 9, 2021)

CAUSA said:


> no Electrician till you?
> 
> what about, instrumentation? was there and calibration/maintenance system in place at this plant. Cryogenics is a difficult place to work in. liquid CH4 is unforgiving.
> 
> ...


Let's just say this summer they had 2 interns going through prints, getting them digitized and organized, and they didn't get through it all. I could go on and on but it would turn into me complaining about people that don't work here, do work here but don't work, and it would waste everyone's time. 

I have already told several people that I will not do that because it is not safe, and one guy tried to fire me because of it my first week here. 

I am digging and scratching to get my info, luckily the mechanic I work with at my north plant is super knowledgeable and willing to share. We work through most problems together, usually he looses out due to mechanical issues, but I help him fix those.

Most calibration is done by outside contractors, I am expanding my knowledge there so it is something I will be doing sometime in the future. I'm using PIDs to learn how things are supposed to work, but I have yet to see any electrical prints except for PLC cabinets that are 30 years old and been changed quite a few times.


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## gpop (May 14, 2018)

Rule of thumb.

A motor requires 40 to 60 of name plate amps to run at zero load. What type of starter do you have (make and model). Is the bucket racked in, does the bucket have a test mode rack position.


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## mburtis (Sep 1, 2018)

Maybe you've already ran down this road but 
1. You said you meggered it from the MCC. What were your connections and what was the result?

2. Did you do a simple continuity test at the same time, line to line and line to ground ? 

3. Is the capacitor bank wired in parallel with the output of the starter or asked a different way are the capacitors only powered when the starter is closed and the motor is running. If so could the "inrush" your seeing just be the capacitors coming online and the motor is toast? 

I know nothing about medium voltage stuff and very little about capacitor banks so I'm just guessing. If all else fails just blame it on a mechanical issue and sit back and enjoy your coffee. That's what I do... oh wait I'm the mechanic to.


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## McClary’s Electrical (Feb 21, 2009)

Excuse me if I missed it but have you done a fall of potential test across the starter and breaker?


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## just the cowboy (Sep 4, 2013)

McClary’s Electrical said:


> Excuse me if I missed it but have you done a fall of potential test across the starter and breaker?


it is medium voltage and he is not setup to test it.


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## 460 Delta (May 9, 2018)

This is the down dirty hillbilly in me, but is it possible to loop the motor wire through the CT again to effectively double the ammeter reading? If it’s so low on the scale you can’t read it, this will get it upscale where you can.


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## oldsparky52 (Feb 25, 2020)

Lazyelectrician said:


> I see what you are saying. Plant operator says.....


You need to be careful about what other people tell you. Read between the lines, verify if possible.


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## 460 Delta (May 9, 2018)

oldsparky52 said:


> You need to be careful about what other people tell you. Read between the lines, verify if possible.


Operations can be a wealth of knowledge, and can be a fountain of misinformation. It takes time to learn who to ignore, and who knows how the plant should run by sound and feel.


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## micromind (Aug 11, 2007)

gpop said:


> Rule of thumb.
> 
> A motor requires 40 to 60 of name plate amps to run at zero load. What type of starter do you have (make and model). Is the bucket racked in, does the bucket have a test mode rack position.


This is true but with capacitors, it's much less. 

I seriously doubt if this is an electrical problem. At 2300 volts, just about anything that goes wrong will result in some sort of an explosion, I'd bet the motor is turning at its rated speed and the pump is the problem. 

Depending on what type of pump it is, it could be anything from a broken shaft, a sheared keyway, an exploded impeller (and/or casing), a blown seal or a simple blockage somewhere.


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## just the cowboy (Sep 4, 2013)

@Lazyelectrician see the talent at your fingertips literally. You will do fine in maintenance just stay safe.
Cowboy


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## Mbit (Feb 28, 2020)

Great info in this thread.

Just to echo: listen to the engineers/operators but they don't understand electrical and will make interesting logical jumps when they're trying to make sense of things. Trust but verify.


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## JRaef (Mar 23, 2009)

Was it working fine and just started doing this? Or was the pump just refurbished and now will not build up pressure? Depending on the type of pump, it may be spinning backward. It would still pump, just not as much.


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## oldsparky52 (Feb 25, 2020)

JRaef said:


> Was it working fine and just started doing this? Or was the pump just refurbished and now will not build up pressure? Depending on the type of pump, *it may be spinning backward*. It would still pump, just not as much.


Yea, but I would think the amps would be higher than almost nothing. Maybe not, IDK.


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## micromind (Aug 11, 2007)

JRaef said:


> Was it working fine and just started doing this? Or was the pump just refurbished and now will not build up pressure? Depending on the type of pump, it may be spinning backward. It would still pump, just not as much.


That's a good point, if it's centrifugal, it'll still pump going backward but both flow and pressure will be reduced. And since the motor is not working very hard, and it has capacitors, the amps will be low.


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## Lazyelectrician (Aug 9, 2021)

gpop said:


> No amps yet it started to make pressure.
> 
> One of the statements is wrong.
> Possible valve opened and you read back pressure or you did have amps


*A very Special Thank You to GPOP. *
Thank you for making me slow down and pay closer attention.

I finally got name plate ratings on the pump today.
400 HP 2300V 3 Phase Motor
start up current: 678 Amps
No load current: *19 amps*

That is what I was missing. Analog amp meter's, on the bucket, first reading line is 30 amps. Which means thee isn't much difference between 0 and 19 amps.

Sent my findings to my supervisor and our operation manager. The only explanation is that the pump section has become disengaged from the motor shaft.

Thank you CAUSA I believe you were spot on with that one.

I will definitely reply back when we finally hoist the pump out and see the issue. for now we still have one of the three pumps working.


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## JRaef (Mar 23, 2009)

I had a customer years ago that made LNG pumps, which are cryogenic pumps in that they are immersed in the LNG at something like -300F. Every time there was a pump problem is was a big freaking hairy deal involving truckloads of money to shut down, isolate and remove the pump. So consequently when something didn't work, they wanted to blame everything BUT the pump, which always came down to me as the electrician. It was NEVER the electrical system though, it was ALWAYS the pump...


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## oldsparky52 (Feb 25, 2020)

Hey LE, it's sure nice of you to report back. Sometimes we never hear how things wind up, I hope you do report what the final outcome is. Thanks for sharing.


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## Lazyelectrician (Aug 9, 2021)

I gave my report up the chain. they were pretty receptive of the finds, but I wouldn't put it past them to bring in a contractor to with better tools to check my finds. We have the pump supplier coming in next month for another pump that is having a filter installed for the new VFD. Apparently, between the engineer and Eaton group, they didn't realize that the needed a filter after the VFD even though there is about 600 ft between the VFD and the pump. I excepted this position after that project was under way so I didn't catch it. 

As far as the money goes, I see it already. it's not a small task do bring in a crane to lift the pump out of the LNG so it can warm up for a day, then pull it the rest of the way out of the 125 ft tank just to check it. Then, you have to reverse the process to put it back into the liquid. Check everything before we check the most logical, but most expensive, option.


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## Lazyelectrician (Aug 9, 2021)

This last week we finally had the Elliot pump specialist in to look at our pump. Of course before that my company brought in an electrical contractor to retroubleshoot what I have already done. But I promised I’d come back and give the findings. I’ll include pics. Seems that after continuous running of the pump deadheaded the wear rings and bearings gave out. The pump induser is mangled and in able to produce flow to the rest of the pump. Pump is meant to be ran with a minimum flow of 271 gpm, this allows the pump and motor, on a solid shaft to float.
































































Our “process engineer” (quotes are for the guy being neither an engineer nor someone I would allow to control the process) is looking for ways to prove that he didn’t tell everyone to run the pumps deadhead.

Again thank you all for your help on this project.


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## gpop (May 14, 2018)

Thanks for the update Lazy


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## micromind (Aug 11, 2007)

Thanks for the pics, that's some cool looking stuff!

No, that's some REALLY cold looking stuff.......lol.


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## mburtis (Sep 1, 2018)

I learned the hard way about running to far to the left on a pump curve (low flow high head). We have a sludge pump station that in the past we would run 60-80 gpm. Well we switched pumps a couple years ago and then were just burning pump motors out every couple of months. Did some autopsies of the motors and bearings in a 2 month old motor were shot and you could see where the rotor had drug on the windings. These pumps were rated at 140gpm or so. Only thing I could come up with was that by choking the flow back (thereby increasing the head pressure) we were adding more force to the impeller and overloading the shafts, and the new pumps just wouldn't run like that. Changed pump designs again and changed how we operated them and it seems to be good now. My situation wasn't nearly as expensive as yours, why in the world would you run a pump deadheaded for long periods of time, that's like pumping no-nos 101. Thanks for the update and the awesome pictures.


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## Lazyelectrician (Aug 9, 2021)

mburtis said:


> I learned the hard way about running to far to the left on a pump curve (low flow high head). We have a sludge pump station that in the past we would run 60-80 gpm. Well we switched pumps a couple years ago and then were just burning pump motors out every couple of months. Did some autopsies of the motors and bearings in a 2 month old motor were shot and you could see where the rotor had drug on the windings. These pumps were rated at 140gpm or so. Only thing I could come up with was that by choking the flow back (thereby increasing the head pressure) we were adding more force to the impeller and overloading the shafts, and the new pumps just wouldn't run like that. Changed pump designs again and changed how we operated them and it seems to be good now. My situation wasn't nearly as expensive as yours, why in the world would you run a pump deadheaded for long periods of time, that's like pumping no-nos 101. Thanks for the update and the awesome pictures.


Comes down to someone with out the proper knowledge not asking someone with the proper knowledge what will happen. In this situation, there are recirculation valve they can use to keep deadhead from happening, but this causes product to vaporize, equals lose of money. Production doesn't consider maintenance cost, and when all the company officers are investors, they do the same thing.

We have recently been bought out by a bigger company, but the same production people are in place. Will it change, probably not until the old people are gone.


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## just the cowboy (Sep 4, 2013)

Thanks for the update.
Yael come back again yea hear.

Cowboy


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