Cleaning Hydraulic lines

[FireRat]

Hello, I have a question about cleaning rigid hydraulic lines. My company manufacturers rigid steel hydraulic lines and we also powder coat them. No the problem I have is that somewhere along our process the insides become incredibly dirty and oily. We use the ultra-clean projectile system to clean the lines but we end up shooting about 10 projectiles through each line to clean it. I'm wondering if this is too much? Do the projectiles have to be white when they come out or are we supposed to just remove particulate? Is there a better way? It takes longer to process the lines and clean them that it does to make them. Thank you for any help you might provide.

 

[MikeHalloran]

You might try cleaning the lines before the powdercoat line bakes the crud in place.


Mike Halloran
Pembroke Pines, FL, USA

 

[FireRat]

Hi, we have tried cleaning them before powder coat and we have not noticed a difference. We also tried venting the caps to let out anything inside while baking and still no noticeable difference.

 

[MikeHalloran]

You can buy precleaned tubing, but you are still paying someone to clean it.


Mike Halloran
Pembroke Pines, FL, USA

 

[romke]

A few questions:

What exactly is in the pipes before cleaning - what is the composition of the dirt you are trying to remove? Does it consist of oily deposits or of hard particles?

How clean needs the piping to be, assuming that later on is used in hydraulic systems?

What kind of hydraulic fluid will be used later on when the pipes are mounted?

 

[FireRat]

We get the pipes pickled before we use them so in theory there is nothing in them but maybe a little oil. The projectiles come out brown and sometimes black, we aren't sure if it's rust or something leaching out of the pipe while baking.

All resources I can find on cleaning hydrolic tube is either rubber or stainless steel. In all cases they say shoot a projectile through each end and cap them. There is no mention of how clean the projectiles are so I assume it's only to clear out any solid particulates. We shoot anywhere from 5-15 projectiles through till the projectile comes out clean.

I'm most curious what the actual standards for cleanliness are when it comes to hydrolic lines. Are we going overkill? Is there a better way? It takes as much time to process the lines are it does to make them.

 

[romke]

I do not know whether there are cleanliness standards for hydraulic piping as such. There are standards for hydraulic systems, where the suggested cleanliness of the fluid is linked to the pressure in the system.

In practice that usually means that when a hydraulic system is filled with fresh oil that those standards are not yet met, unless the system is filled in a "clean room" with especially cleaned fluid. Under normal operating conditions when starting up, the oil is cleaned by filtering and depending on the quality of the filtering system and the amount of dirt and wear material generated the filtering system will be able to keep the fluid as clean as required. In critical situations systems may be started up with a temporarily mounted extra bypass filter that will help to bring down the original contamination to a level that can be maintained with the filters mounted permanently in the system.

 

[HPost]

The ultimate standard, that is the one that cleanliness levels of components are set to achieve, is ISO 4406. The level of cleanliness of the system, under 4406 is measured as the number of 4,6 and 14 micron particles per ml of fluid.

Part cleanliness, including tube and hose, is measured in quantity, type, gravimetric level and size. The standard for automotive part cleanliness is ISO 16232. Individual standards on part cleanliness are usually derived from this standard.

Projectiles are not 100 percent efficient. The only way to clean tubing is to hot flush the tubes/pipes with turbulent flow. Clean is a relative term of course and it is up to the customer to provide clear requirements of the level of cleanliness that they need.

Where super high levels of cleanliness are required, the builder of the system should specify the level of cleanliness required and they will flush the system themselves. Controlling the levels of contamination serve to reduce the time required to flush the system.

Equally, where cleanliness levels are not so high, the customer may provide lower levels of cleanliness requirements.

If you are being squeezed by your customer to provide clean tubing, you first need to have the debris on the projectiles analysed to find out what it is, then take steps to remove it.

It’s all relative and the first thing to do is to establish what level of cleanliness you are trying to get to against ISO 16232 or it’s derivative.

 

[ASIT859]

I work for a filtration company and we make offline oil and fuel filtration skids. We purchase tubing and hose from suppliers and essentially - we just assume it's not
very clean. We blow air through some lines that are upstream of sensitive components but otherwise we simply just wet test and clean and flush our skids after assembly. I don't know about our tubing suppliers but our hose supplier shoot "pigs" through and I'm not sure how many they shoot before they cap the hoses and ship.

Sometimes our customers have specific cleanliness specifications our products must adhere to - and that's a whole process which is documented and we adjust pricing for. So far to date, none of our systems customers have required a cleanliness specification so we simply just flush.

I think it really comes down to your customers and what they need and what they're doing with the tubing. 15 pigs may be overkill. 1 pig might do the trick, however if your customers have been receiving tubing that's been cleaned with 15 pigs and all of a sudden you only do 1 pig that extra dirt may be a problem.

I'd at least recommend opening up discussion with your customers or at least saving a round of 15 pigs and getting them analyzed in some way so you know what you're actually pulling out of the tubing. As well as doing a wipe down of the tubing before and after so you can see what's going on.

At the end of this you may be able to offer "certified clean" tubing for a premium price while also offering standard tubing.