Steam system at something like 1000F and 1000PSI. Cast steel. Rust particles stick to the inside and cause oxide buildup. I need for the buildup not to happen. I can't eliminate the source of the rust. I can't change the materials. I can't redesign the system.
Thoughts?
Can you add something inert (to the rest of the process) that keeps the rust from sticking? Like atomized oil or something?
Can you coat the inside? Ceramic coating of some sort?
You may want to try inserting some anodes into the system. They would be a consumable, requiring periodic replacement. I have no idea what the correct metal would be for your application, but a materials engineer would. Hope this points you in a helpful direction
Robbie wrote: Can you add something inert (to the rest of the process) that keeps the rust from sticking? Like atomized oil or something?
no, good thought though
CGLockRacer wrote: Can you coat the inside? Ceramic coating of some sort?
Yes I can. Tell me which coating will work and can be applied in situ.
WildScotsRacing wrote: You may want to try inserting some anodes into the system. They would be a consumable, requiring periodic replacement. I have no idea what the correct metal would be for your application, but and materials engineer would. Hope this points you in a helpful direction
Interesting. Are you assuming that I would need to charge the rust particles somehow?
In reply to tuna55:
The anode works due to the natural charge differential between the base metal (your system) and itself. You essentially trade uncontrolled corrosion of one meatal for the controlled corrosion of another. Boats have been using zinc anodes on their props forever, aviation has some uses for the principle as well.
Closed loop system? What is going on with your traps that you're getting wet steam?
There are particle filter/traps for lines that can catch a whole lot of the material.
But really, you shouldn't be having wetness in a steam system. You're trying to band-aid a bigger problem. If you can show them how to fix that problem, you might be a hero.
I'll ask at work tonight and get back to you in the morning, assuming someone will be there between 10:00 pm and 6:15 am who has the answer, for what we use to prevent that from happening.
We have steam heat and it's a VERY old system.
foxtrapper wrote: Closed loop system? What is going on with your traps that you're getting wet steam? There are particle filter/traps for lines that can catch a whole lot of the material. But really, you shouldn't be having wetness in a steam system. You're trying to band-aid a bigger problem. If you can show them how to fix that problem, you might be a hero.
Extremely variant and out-of-control steam process conditions. The customer is operating these things, and we can tell them what to do, but that doesn't mean they do it. Factually, there are thousands of feet of carbon pipe which rust readily and have been since we started this business.
If it's a closed-loop system it looks like you need to shoot for a pH level of 10.1-11, provided you have a way to add the proper alkaline or acidic compounds to achieve then measure and monitor the pH.
Some closed water system corrosion inhibitors:
Sodium Nitrite
Sodium Metaborate
Sodium Molybdate
Phosphonates
Sounds like you may need to add some sodium sulfite as well to prevent the buildup.
Is the buildup recurring in one particular area or section of pipe?
tuna55 wrote:WildScotsRacing wrote: You may want to try inserting some anodes into the system. They would be a consumable, requiring periodic replacement. I have no idea what the correct metal would be for your application, but and materials engineer would. Hope this points you in a helpful directionInteresting. Are you assuming that I would need to charge the rust particles somehow?
Call Swain http://swaintech.com/ They'll atleast point you in the right direction.
They coated parts for free for my Baja team.
I would think that a boiler operating at that temperature and pressure would be monitored VERY closely. It is a chemical process to control rust, much like antifreeze in a radiator. A licensed boiler operator should have a handle on this.
WildScotsRacing wrote: In reply to tuna55: The anode works due to the natural charge differential between the base metal (your system) and itself. You essentially trade uncontrolled corrosion of one meatal for the controlled corrosion of another. Boats have been using zinc anodes on their props forever, aviation has some uses for the principle as well.
Then the anode oxides will do the same things that the iron oxides are doing now. Plus there will be more of them.
TRoglodyte wrote: I would think that a boiler operating at that temperature and pressure would be monitored VERY closely. It is a chemical process to control rust, much like antifreeze in a radiator. A licensed boiler operator should have a handle on this.
Two miles of very large pipe between the boiler and the issue. Plenty of spots and components to rust between.
The_Jed wrote: Is the buildup recurring in one particular area or section of pipe?
No, but in some locations it's way more important than others.
Are there adequate strainers and traps in the system?
Sounds like the system was designed for superheated steam, but the boiler is producing saturated steam.
What is the size of the vessel(s) you're looking to treat/coat? I'd look into metal/thermal spray for any coatings in this setting - I've managed similar contracts for boiler tube coatings at a mill I worked at.
Two miles of very large pipe between the boiler and the issue...Not closed. We use lots of water.
That's bad.
Extremely variant and out-of-control steam process conditions. The customer is operating these things, and we can tell them what to do, but that doesn't mean they do it.
And that makes it all but insurmountable. At best, non-corrosive lines. Which would be a darn expensive upgrade. That and screens would only keep the lines from failing. The rest of the components, pfft.
1000 psi steam? 
Datsun310Guy wrote: 1000 psi steam?
I was estimating. Closer examination shows 1250.
foxtrapper wrote: That and screens would only keep the lines from failing.
Screens don't work with rust. We have experience with that. Rust is really neat. Imagine a big iron oxide particle. It just whacks into the screen. No big deal, it's bigger, so it just hangs out. Sort of. In real life, it gets bobbles around and shaken and turned over and over until it makes a bunch of much smaller oxide particles, and then they just fly right through.
In reply to Mezzanine:
There is a trap. We are not sure if it is working as well as it needs to, but it is expensive and big. We are talking about a fleet of boilers, not just one.
The component in question is something like 12 feet high.
Boiler water chemistry issues. Do they test boiler, feedwater, condensate and soft water every day and adjust chemical feeds as necessary? Do they monitor boiler water conductivity and blow down the boiler to maintain proper range?
Sulfite, Chelant and Amine are typical boiler water treatment chemicals. Their chemical rep (w/ the approval of the facility manager) will set the standards where their chemicals will work in the system, same w/ Ph. Make up water must be soft water, verify the softeners are working.
A chemical rep who gets the chemistry wrong or maintenance neglect can wreak havoc on steam and condensate systems. It's far enough into boiler season that post start up checks be all done. Chemical feed pumps and lines working, water chemistry dialed in, softeners verified working etc.
I came from a place that treated the steam plant like an appliance, only did chemistry tests once/ month, ran out of salt every winter for weeks, even ran out of Sulfite... how the berkeley do ya run outta Sulfite? And they wondered why the steam and condensate pipes leaked like sprinklers.
Check your water chemistry first.
You'll need to log in to post.
