We are focusing on oil mist in this how-to article. Suppose oil-mist preservation had been applied to a machine in an oil-mist storage yard. Whenever that machine is being moved to its permanent-installation site (usually a foundation), turn off the oil-mist system or simply remove the plastic oil-mist tubing at the manifold. Plug (or cap) the manifold opening from which the tubing has been removed.
Regardless of how many plastic tubes are removed from the preservation system and how many manifold openings are being plugged, the total volumetric output of an oil-mist generator remains unchanged. Because one less asset is connected to the system, the oil-mist header pressure will increase until the oil-mist cabinet controls are reset to achieve the pressure reading it had before.
This article is based on a chapter in the author’s book
“Optimized Equipment Lubrication, 2nd Edition, 2021;”
De Gruyter, Berlin/Boston, (ISBN 978-3-11-074934-2).
Additional chapters will be highlighted on this website in the future.
STEPS BEFORE REMOVING A MACHINE
Before a machine is removed from the oil-mist storage yard, remove the casing-drain plug and allow the coalesced oil to flow out. With the possible exception of steam turbines, where residual oil might contaminate the steam condensate recovery system, the bearing housings and, occasionally, the interiors of all oil-mist-protected machines can now be refilled with whatever lubricant was recommended for equipment in operation. No commercial situations are known where the thin oil-mist film clinging to interior parts or surfaces needs to be removed.
If a preservative (lubricating) product had been previously applied to the exterior surfaces of machines, it can now be removed with a solvent recommended by the product’s vendor or supplier-manufacturer.
Interior spaces of various machines may, perhaps, have been coated or filled with certain types of products, such as inhibited turbine oils. In some cases, those products could stay in the equipment for reuse while operating. In other cases, because the machines would already have been well protected by drained preservatives, they can operate at part load or at normal load for a few days. (IMPORTANT NOTE: Always consult with the equipment manufacturer and lubricant supplier before proceeding with these recommendations.)
If the decision is made to drain lubricants while a machine is in the storage yard, the equipment can be tilted. This allows the preservative to flow to the low point drain and the drain plug is then removed. After the solid drain plug is again threaded into the drain port, the machine is ready for its normal refill. Oil quantity and type should correspond to the manufacturer’s recommendations.
Be sure to verify that the breathers are back in place. Electric heaters or instruments also may need to be reconnected.
THE PROCESS PUMP EXAMPLE
Using process pumps as an example to guide our thinking, we might dwell briefly on a typical cleaning sequence. Recall our previous article regarding short-term storage preservation where we described straightforward steps involved with removing a fluid machine (pump) from an oil-mist storage yard (see link below).
For machines that have been in storage while protected with coatings, we would simply follow the preparatory sequence below. In essence, we would be preparing to restart after donning protective clothing and using a solvent to remove the external protective coating.
1. Check with the seal manufacturer to verify that the date of storage, in conjunction with the materials
of construction, does not exceed the shelf life of the mechanical seal. If the expiration date is exceeded,
check the face condition to ensure flatness.
2. Remove the masking tape, duct tape, or sealant from the opening between the shaft or seal sleeve
and the gland.
3. Valve off the pump and remove the plugs from the seal ports.
4. Flush with a solvent compatible with the seal’s materials to remove all possible residues. Rotate the
shaft by hand during this process.
5. Drain the fluid from the casing.
6. Reconnect the seal’s environmental controls and/or plug the seal’s ports.
7. Open the suction valve fully and crack open the discharge valve(s) about 10% of full travel.
8. Vent the seal chamber to allow the seal to become surrounded by the liquid.
9. Start the pump, using a relevant, approved, and pump-specific checklist or procedure.
INERT GAS PURGE VERSUS THE OIL-MIST PREFERENCE
Unless defined otherwise, disconnecting the inert gas line and/or oil-mist supply line is all that’s needed to prepare a machine or asset for removal from the outdoor-storage yard and transport to its permanent installation on site. No steam purge will be needed.
The same preparatory sequence can be followed if vapor-phase inhibitor products have been used. However, if for any reason the residue of those products must be removed, steam cleaning may need to be done just prior to on site re-commissioning.
WORDS TO THE WISE
Best practice is for a responsible Reliability Professional to discuss the above guidance with crews that would be tasked with implementing the recommended procedures, as well as with the appropriate equipment manufacturer(s) and lubricant supplier(s). Obtain their buy-in and/or resolve differences before proceeding with implementation.TRR
ABOUT THE AUTHOR
Heinz Bloch’s long professional career included assignments as Exxon Chemical’s Regional Machinery Specialist for the United States. A recognized subject-matter-expert on plant equipment and failure avoidance, he is the author of numerous books and articles, and continues to present at technical conferences around the world. Bloch holds B.S. and M.S. degrees in Mechanical Engineering and is an ASME Life Fellow. These days, he’s based near Houston, TX.
Tags: reliability, availability, maintenance, RAM, equipment storage preservation, lubrication, lubricants, oil mist