The Right Grease

Ahhh, clean the vents and prevent a fire, that way you won't have to replace the whole building? Sounds like you have been lucky so far; don't count on it to continue.

Gavilan

Thanks Bob C

I went to the Dow Corning website, I was amased that there was so many greases.

Yeh! A high temperature silicone based grease should work in this service. I suspect that the temperature in the stack is < 500 F at the point of the damper.

If they are only being greased intermittently or every few years than most greases will dry out and add heat the grease will dry out faster. A high temperature grease will slow the evaporation of the oils but will not stop it. If maintaining a fresh supply of grease in the bearings on a periodic bases is a problem I would look for a grease less solution.

Not knowing what the temperature is or the contaminates faced by the bearing you could look at Rulon lined plain bearings or some of the hybrid bearings. Rulon can handle up to 550º F. Have used the Rulon in a linear application with no lubricant. Have had no problems as to date. motion on the bearing 2000 times a day for two years.

Hybrids I have installed but have no history to give you.

Thanks ozzb

I put them in my favorites and will see if they have a suitable size for me.

I should have measured them when I had it apart.

ozzb,

Why is grease needed for this application? Sometimes grease is the problem if it is in the way or precipitates and issue such as this thread indicates.

I don't think the pressures or speed or intensity of actuation requires grease and application of grease is the problem.

What do you think...

We have a similar problem on the main bearing of a medical linear accelerators. The grease goes hard with radiation and the grease nipples are well buried. Our solution was to put a tube into the grease nipple hole and the grease nipple onto the other end of the tube (where we can get to it). Is it possible to do a similar thing with the damper bearing. Then give it a squirt of fresh grease every 6 months

The remote grease fittings are excellent upgrade. The task of lubricating the bearings becomes so easy, operators no longer hate the job. If you put a fitting in the bearing lube hole that will allow the use of "inverted flare " fittings, you can use readily available steel brake lines from an automobile to route all of the grease fittings to one easily accessible location. Automotive brake lines are designed to allow bending without kinking. Sounds like one day's work might save future bearing replacement.

andrecncman,

When new the damper has a protective coating of grease to prevent oxidation prior to installation. Clean that goo off, dampers don't need grease the benzene residue can lube it.

I've used high temperature silicone grease to good effect. I wouldn't recommend it for rotating bearings but for a damper bushing I think it would work well if the viscosity was OK.

Just my 2 cents...the Dow website is probably your best bet.

Have you looked in to a graphite or Teflon impregnated bushing? Even an older style oil impregnated bronze bushing.

I have also used a grease called Krytox ,I think Mc Master Carr carries it.

The best idea would be a tube to relocate a grease fitting and use a high temp grease in my opinion.

re: #10

I have also used a grease called Krytox ,I think Mc Master Carr carries it.

Yes Krytox is sold by McMaster Carr as well as several other quality suppliers. This is a good suggestion and might be the right answer, but be careful which member of the Krytox family you try. If memory serves, what I used cost about $125.00 for a 4 Oz container. It is very costly, but highly inert, can handle extreme temperatures, and does not react with other chemicals.

My gut feeling is that this is using a rolls royce where a simple cart is sufficient.

As it turns out I also have "Krytox" grease. It is a small tube(2 oz).It is labeled Ktrtox RFE. It has both Locktite and Dupont brand labels on it, and was purchased form a local NAPA store.The label reads "PFPE High Performance Lubricant. I have been using it to lube discharge valves on fire trucks. It is Chemically inert because the people that build the valves will not disclose the material the valve seats are made of. Again probably overkill, but I use only small amounts of it, and it does free up a new valve that usually is difficult to move. Krytox is only a brand name. There are probably a few varieties of lubes available from them.

Contact Lubrication Technologies out of Ohio. I've worked with them in the past on other difficult environments, they will have a solution for you.

Including all the fine recommendations provided, you may want to consider a scheduld maintenance of the dampers. Perhaps a inspect and clean process, which will reduce the buildup over time. The OEM should be able to help you with a procedure.

Good Luck.

Marty

No-one has said anything against extending the position of grease nipples to a more accessible place. Perhaps a better grease as has been described, and placing the nipples where they may be more easily accessed would solve the problem admirably

See blog 7 and 12

I am sorry to say that there are no grease nipples and no simple way to put some on. I have to dismantle the unit to clean and grease it. I thought about either going graphite, or adding tiny lubrication tubes so I can lubricate with WD40 or light oil the unit twice a season without taking it apart.

Hi there,

am not sure of the actual construction of the bearings, flue gas temperature/dew-point..? Anyhow just use graphite based dry lubricant.

I agree with the graphite lube, as there seems to be a build-up of soot and ash during your combustion process, which is activating a coagulation, as the grease cakes from thermal effect.

Have you tried to find carbon ceramic bushings for the damper?

They are made by the same guys who made the cool grease mentioned above.

No lubrication needed, ever again. There are several sintered metals manufacturers who can produce high temperature bearings, which are self lubricating and not very expensive.

Sounds as if you are having troubles with creosote and pitch build-up.

We used a product called Supa-Flue which has thermal barrier and double wall with liner, and it controlled the cooling effect of the pipe, so it collected less soot and was much safer than the tile flue, we were working with previously.

May we know exactly what are you incinerating or forging and what temperature ranges are you expecting the damper to reach / withstand?

Clearly there are a few questions about temp., chemical environment, etc., but I would have thought a Silicone Grease would be your best bet. I have used DOW MS4 with some success and if you check-out their website, you'll have lots of specs to choose from - good luck!

Instead of a grease you can try a ceramic paste. It has some lubricating effects , protect against corrosion and protect till + 1100 Celsius.

NAPA sells Ceramic Extreme Brake Parts Lubricant. It is manufactured by Permatex, and carries NAPA # 765-1831. It's purple, paste-like, comes in a brush top jar, and protects to 1,537*C. Good thought.

Thoroughness of preventative maintenance a probable cure...

This is a common problem on dampers used on boiler fans used at coal power stations. The gases are hot and dirty. You did not provide enough details to pick the best solution but you have a few things to try.

First do the bearings have any seals? Keeping out particles and heat is often the first step. Bearings can be purchased with integral seals and or with shields that can be on one side or both. I would not necessarily recommend sealed for life bearings because these tend to have seals for lower temperatures and the bearings are not 100% filled. You need 100% grease fill to keep out dirt and hot air. Rotational speed is not an issue. You might be able to get them or if the seals are on one side you can hand pack the bearings.

You also did not mention what grease you are using now. If not a complex, clay, polyurea or calcium sulphonate it is probably has a simple soap thickener. While okay for low temperatures they are seldom long life products. So go out and buy some tubes of a premium grease. If NLGI GC/LB rated or better this might help. You probably also want an NLGI Grade 2.

Certainly greasing more often is required as well but where does the grease go? If not an issue do this as well. Running longer lines with grease fittings that are easier to get at can help but do not run the lines up the side of hot ducting or make them so long that the grease sits in them for years before it gets to the bearings. You can also buy simple spring loaded grease cups that you can refill or there are those that generate a gas to move the grease.

Certainly a carbon graphite bearing can work as well but you still have to keep out dirty air because otherwise it can pack up. A simple cover with a bit of plant air supplied might be one option.

Ken Brown