Cleaning Rust Inside Hydraulic Cylinders

On the right side of the CR4 page, there is a flexible hone guy with whom you might talk. Good luck.

Prevent it occurring.
The surface finish is spoiled once it has occurred.
Del

The ONLY correct solution is to rework the surface since rust creates craters and the seal contact surface will be destroyed VERY fast. You should look if you can find a company specialized in honing on the spot there are such machines to be mounted on the cylinder itself for the operation.

Your pressure is high enough to destroy the seals and may be the guide rings if they are non metallic.

I thought of the honing articles, but the pressures and wider than tolerance walls concerned me.

Is there a deposition process that might fit his price?

Hone down to remove pits, build back up with ?some? material, final finish for the seal life?

Depending on the value I have honed and then sleeved, (honed is probably not the correct term if it will take a sleeve after) when the replacements were simply unobtainable.

Dear all,

many thanks for your inputs.

@Tornado, I have not been able to find the link you refer to. Could you please paste the link here?.

@Del, You are right, but your indication arrives a bit late, or a generation too early, for this project. The concepts of good practices and maintenance are unknown around here. :P

@Nick, I have no doubt that is the right thing to do when the seating surfaces are damaged. I have experienced it before. Upon opening, it will be possible to see if the rust occurred in the seal-working areas or not.

To all of you, thanks for your advise. Will keep posted about results.

Abel

pd:Some input about the pickling?

Abel,

Subject to operational temperature and the cylinder maker's approval, consider the minimum mechanical cylinder corrections (perhaps minimal tickling with the Flexhone already suggested) and a different seal material.

Seals whose wearing surface is UHMWPE are extremely tolerant of poor surface finish, while still exhibiting low friction. They must be energised, whether by elastomer insert or by metallic finger-spring. I have salvaged perfectly dreadful cylinders using such abrasion resistant seals. They are readily available to custom sizes from several "instant seal" companies, who will need to be consulted about pressure/temperature of service.

Mark Bingham
Relativity PL

There are rust conversions but with pitting it would not be successful neither would be pickling, seal damage would happen.

Honing out all pits is only alternative if you are concerned with wall thickness then the pits are to deep. With adequate wall thickness oversized seals and plunger assembly could be fitted

Pickling then honing lightly then re-cleaning then re plating the bore followed by honing again might be a way out but the process could be more expensive than new cylinders.

What is the hydraulic system used for? What is the operating time/day? What is is the duty cycle? How much of a problem is downtime to change out a cylinder?

It seems to me that your posts are implying the system is garbage and you are there to salvage a few bits for the savages. If thats the case you had better get the owners to scrap the system and purchase all new stuff, 'cause its all junk!

However, there is always middle ground, where cylinders can be honed and rods can be repolished to make things work. They might start to leak a little sooner than if they are factory-perfect, but they will work. You have a huge advantage because this is a very low pressure system and modern seals will take a lot of abuse at this pressure.

I don't know why you have a problem with sandpaper, since in the backwoods you are in, properly dealt with, polishing a cylinder rod in a lathe with the correct grit cloth can be your friend. We aren't talking 32 grit sandpaper here. So can the proper bead honing stones for the bore. All it takes is to train your helpers the importance of cleanliness and the idea of flushing out the swarf after the honing action. And stepping down in hone grit sizes in two or three passes.

You can't do much about the existing rust in the piping. Introduce them to pressure filters and kidney loop filters if they don't have them already. Decent filters will keep the garbage in the lines down to a dull roar. Is the system susceptible to water infiltration? (sounds like it could be quite humid there.) If so, you should look at introducing them to a sealed system.

The valves and pumps need to be looked at, too. They aren't as forgiving as the cylinders and may be a bigger problem, since they use metal to metal clearances for sealing.

Keep us posted.

Jon.

Dear Sawmill,

It is the system that press the rollers against the table of a Vertical roller mill.

As you can see in this really nice scheme,

To see one moving, just type "vertical roller mill" in youtube.

Designed to tun 24/7. Main motor, not being the biggest, it is still 5600kW power.

Now we are in phase of assembly, so there is some time to do things right.

The project is a complete new line that, as sometimes happen, was slowed due to really important and strategical reasons, that only some big shot will know.

Not me really.

During the stoppage, maintenance routines of the assembled equipment were sometimes neglected, and here we are now. The equipment it is far from junk but, as said before, upon opening we will see (I include all of you who took the time to read and give your better advice).

As per the system, I think the pressure it is not that small (110bar/1600PSI), and conditions are harsh. Quite.

Cylinders in less than optimal conditions are not an option here, since downtime is, to put it mildly, not cheap at a cement plant.

All the equipment is new and, although local fabrication is... depressing, the key parts come from reliable suppliers abroad.

About the cylinders, I will not think of honing till the cylinders are open and examined.

Best regards, and thanks for your input,

Abel

Abelmh,

Bad news, if the pitting is too deep, you have no choice but to replace the rods in the cylinders. If you hone them and they have to be honed too deep, you weaken the rods resulting in a failure. What you did not mention was the actual power system. How is the pump and motor? Have you checked out the rest of the system? Are the valves OK? have you checked out the pipes/hoses for corrosion? Is the pump a piston or vane? Variable and what is the condition? If corrosion is too bad, the entire system should be replaced. I have been in your shoes like this before.Not so long ago. Multi million $$ issues that happened in a matter of minutes and all crashed. Many weeks later to recover and never recovered the amount of $$ to cover it all. It will be years before this issue breaks even. Time, maintenance, materials all way too tight on the budgets. Not to mention bean counters cutting every corner possible and it all blew up in their faces.

I wish you the best. Keep us updated.

Dear Jim77...

I am checking actually the rest of the system, finding little things at every step...

Whant a bit of one year old VG68 with a hint of condensed water and some carbon based organisms developing there? feel free to take a spoonful... ;)

Wanto to know what I found inside some pipe??

http://youtu.be/OgalIR11JxA

I have just uploaded it.

Salu2

Oh my - you do have your hands full

I have done inspections in which nothing could be gotten out of the various drains, not a happy start.

http://www.youtube.com/watch?v=OgalIR11JxA
I think this one will do...

jimh

hardchromed rods will not be rusty . why would he replace those ?

the rust will be in the barrels

rust can be removed with the right type of acid

important to understand the question iznit :)

Dear all,

I would like to clarify that the pickling it is to be applied only to the piping system.

Not the cylinders.

I am wondering if there will be some company around here in that business.

Thanks for your support!!

Abel

Once we encountered exactly similar problem of pitting corrosion due to long storage on big fan rotor shaft journal area. We could make it good by burnishing which is nothing but plastic deformation process pushing peaks to the vellies. Bearing clearance we found little higher but within the norm. But your case is on internal cylindrical surface which is little difficult for burnishing operation.

Hi,

You need to tell us what type of seals are in the piston and rod area. Also the finish on the rod. Also you should consider whether or not the cylinder has to hold a load without any movement. Judging how deep the pitting is is difficult and the rusting does need to be removed but many seals will absorb small particulate. It also matters if the cylinders have been stored horiziontally or vertically as the seal will deform and there could be metal to metal contact between the piston and the cylinder walls. Talk to the cylinder/seal manufacturer and if the rusting is light remove with very fine emery paper and clean and you may get away with minimal restoration.

Regards

Oliver Dunthorne

Hydraulic Engineer

If the pitting is too deep to be cleaned up by honing and still maintain a seal, perhaps they could be bored out and sleeved, with stainless steel sleeves being pressed in.

This is done very successfully on automotive brake master cylinders.

i would not be jumping to hone them until doing a sample rust removal with non mechanical means

rust can be removed very effectively with diluted pool cleaner ( hydrochloric acid )

its cheap , it only dissolves the rust and doesnt attack the parent metal but dont leave it exposed too long.

50 - 70 % solution would need only 10 - 15 minutes exposure , then your rust is gone

wash it down with water then immediately coat the steel with oil or turps to prevent rust starting again.

use a respirator , safety goggles and do it in a vented room , wear gloves too if you dont want the skin turning yellow and falling off your fingers

next step use an optical magnifier to check how deep the pits are , if not too deep then no honing or very light honing to take off any sharp edges.

take a look at Hallite seals i think from memory they had a 770 series and some newer ones too, that are rated to 50,000 PSI and have a very tough material that wouldnt wear out if you dragged it across granite for a hundred years.

good luck

and stop drinking that chocolate soup from your hyd pipes !

:)

Dear all,

cylinder was opened and, luckily, the rust was limited to non polished surfaces.

More specifically, no surfaces where the seals will work.

The existing rust and other things, can be cleaned without problems. A bit of WD40, brass brush, and patience

.

Among the rust particles, it has been found a big amount of (dead) diminute cockroaches... did somebody left the coneections open during lunchtime??... Probably.

Many thanks to all of you for your time and advice.

Abel.

PD: I do not intend to start a new thread with this, but I could not keep it for myself either.

Here is introduced to you, the home made "Hydraulic flushing unit" by the customer.

90kw, 450 ltr/min, and threaded plumbing fittings and valves. With teflon tape.

No, you do not want to open the "sealless flap cover" to look inside the "oil tank" and, yes, there it is, the filter cartridge in the return line...

Sounds like you dodged a bullet!

Now that you are in charge things will be different right!

I will NEVER understand managers who think that maintenance can be skimped on. On the other hand, they must live in fear of the maintenance man who creates his own work. I have seen that. It is easily guarded against, but NOT by simply cutting the maintenance budget.

Dear Yusef,

I would like to say that this flushing unit will not be used but, the customer has decided to use it with small improvements (I would say a hand of paint)

It is his scope of supply. He knows that this will void guarantees and, althought I have tried my best to convince him otherwise, and have delivered a legal notice about the consequences... keeps going.

My position is covered legally, and I have acted honestly to all extent. But It feels like sand in my bearings, seeing someone so to proceed in such a naive manner.

With others money.

Only remains to keep people as far as possible from there.

I have experienced this style of management in some projects, specially when the manager has been hired for the project only, and have a bonus on budget savings.

If the final customer does not get involved in the development of the project, he will inherit an ever failing plant but, hey, the actual project manager will be away already!!.

This usually happens in developing countries, state owned companies. (As it is now!)

Well, somebody will be happy selling spares!!

Saludos cordiales, (heartfelt greetings)

Abel

" the maintenance man who creates his own work "

a company imported a million dollar machine ( second hand )

it had 4 big hydraulic pumps each powered by a 130 kW electric motor

When the "mechanic" commissioned the machine he found a terrible noise coming "from the pumps" and instructed his employer to purchase new pumps.

The new pumps were purchased and installed and the day came to commission the machine again........

.......oooops

there is that terrible noise again..... still there even after replacing the pumps

I looked over his shoulder and suggested the noise was worn bearings in the electric motors ( it sounded like armature segments touching the field winding ) , he was going to strip one of the brand new pumps but i told him to pull one motor away from the pump and run it without load , which he did and discovered the noise was still there

. . .

the bearings were pulled out and replaced at a cost of around $480 compared to $ 160,000 that it cost for new pumps.

Before any of you pass around the vomit bucket. the owner of the company was the kind of guy who regularly invites such karma due to his kind of unique treatment of other human beings.

Well done, thank you for letting us know.

looks like that guy needs a water trap before the oil filter from the previous photos you showed

people try and save money in dumb places and it costs them bigger $$$ somewhere else

;)