In large and small plants across the globe, machines wear out daily - breaking down or just becoming too old or obsolete to meet current needs. Hopefully, in our proactive world, we are able to foresee this happening before the equipment dies at our feet.

As part of the procurement process, the replacement equipment has already been discussed. Decisions have been made whether to directly replace the equipment or to upgrade and modernize it for future operations. The specifications have been stated, reviewed, and reviewed again. The vendors have been contacted for price quotes. From the beginning, this process may take a year or two for scheduling and budgeting purposes. And the scenario is not unique to production equipment; it may also be true for aging maintenance tools as well.

As lubrication professionals, the first line of defense for maintaining the health of our new and old hydraulic systems is a filter. Combine this filter with the proper dispensing equipment and you are steps ahead in the battle against dirt ingression into your hydraulic systems.


Replacing Skids
At our facility, we recently replaced two old hydraulic oil filtration and transport skids. These skids were used to transport hydraulic oil to the many sumps throughout the plant and to filter the oil as it was dispensed. After 12 years of service, the capacity and performance of the units had fallen behind equipment and system advances in the plant. Because these units were on loan to us by our hydraulic oil provider, we were not able to upgrade the units.

The first action performed during this renewal/replacement process was to talk to personnel using the equipment. Find out both the positive and negative characteristics of the old skids, and what improvements should be made to the replacement skids. Let personnel know you are building a skid for them.

Was the supply tank capacity sufficient for replenishing multiple hydraulic units, or did it frequently require returning to a bulk tank to top-off? Considering the layout of the old skids, were they easy to service and maintain, or was the spaghetti bowl of piping challenging in maintaining cleanliness of the skids? Asking questions like these and implementing the suggestions into the new skids creates a sense of ownership among operators.

Plant Layout
The next step is to take this information and evaluate your plant's configuration. Start with the physical conditions of the plant - the aisles and floor plan. How does traffic move through the plant? Are the aisles wide enough for two-way traffic? This will help to determine a dimensional footprint for the skid. Is the floor surface smooth for light traffic or made to handle heavy mobile equipment? Smooth floors mean a lot less chance of damage from jarring or bouncing around during transport and no real need for a heavily built unit. Consider the placement and number of sumps to be serviced and the related accessibility issues that must be addressed, including the length of dispensing hose to reach furthest sump location and the locations of power supply outlets. What size are the fill connections?

Early Assessment
A first quick look should give you a reasonable idea of some of your requirements. In our plant, a heavy-duty skid was the first consideration. Everything moves with heavy mobile equipment on hard tires in our facility, carrying loads up to 15,000 pounds. A lightly built skid unit would not survive long in this type of service. Our sumps have one-inch quick-connect fill fittings. This means a one-inch delivery hose with a 50-foot length was needed to reach our furthest sump. This also required a suitable hose reel. Armed with this information, we were on the way to putting together a solid general specification sheet for the new skids.

Spec Sheets
When compiling the specification sheet, list the operational requirements and what you want to accomplish with the equipment. Transporting and filtering are obvious choices, but what about filling and polishing (kidney loop filtration)? The addition of a couple of valves, fittings, and an extra piece of pipe installed after the filter and in the pump suction line will allow for recirculation of the oil back to the tank and filtering it before it goes into the tank when filling.

Next is the list of "wants" and "must-haves". A "want" is a general preference, such as a tank capacity. The brand name or the manufacturer's name is not always the most important factor; as long as the equipment meets a general approved tank specification, it is good enough. A "must-have", on the other hand, is more specific. This includes pumping requirements, filter designations and control circuits.

This part of the list can be quite detailed, from stating how the piping is assembled all the way down to a specific brand of valve used on a sight glass. Your plant's electrical department may have certain electrical specifications, including a particular brand of control system that has parts supported by them or your plant's parts storeroom. If this is the case at your facility, then you must include that information here. The last part of your spec sheet should list any detailed information for construction requirements such as dimensions and placement of forklift pockets or welding requirements.

After your list of wants and must-haves is complete, it's time to review it with the vendors selected to bid on the job. This is best done in person rather than via phone or e-mail. It is far too easy for someone to assume that you meant one thing when you were trying to tell them something altogether different.

Present a sketch of your skid layout ideas to give the vendors a clear understanding of what you expect. You may also want to show them the equipment that is being replaced. This will help them understand the operating environment. Take time to discuss the project, because the vendor will often make suggestions that you may have overlooked. Make sure you discuss flushing of the unit, operational testing, and painting requirements to ensure compatibility with the oil you are using. Be sure to include these in the quotation specifications.

Cross-check Specs
Upon receiving and reviewing the vendor quotations, carefully check that your specifications have been met or, in some cases, exceeded. Now is the time to research any unfamiliar equipment listed on the bill of materials. The bill of materials lists everything that will be used in the assembly of your skid, complete with a name and part/model number for the item. Review this carefully. If an item is not listed here, it likely won't be included on your skid either. Make sure that the skid will perform as you requested. Schedule a meeting with the vendor and request that the fabrication shop representative accompany him. Take a tour of the fabricator's shop, and request to view any similar projects he may have completed. Remember, the vendor is a salesman, the fabricator is the one building your skid.

Ask for general layout drawings with dimensions if they are not stated on the quote. Some vendors will balk at the request for drawings prior to being awarded the job. If this is the case, let them know that construction will not begin without approved drawings. It should be stated at the onset that if submitted drawings continue to not meet your approval that the bid will be rejected. This is an important step. Some drawings will be outrageous - we had a drawing submitted with everything listed on the spec sheet, but the skid dimensions of 6 feet wide by 10 feet 6 inches long were much too large.

Upon selecting a vendor, ask for detailed construction drawings for review and approval. Our project had four sets of drawings with changes until a final set was approved. Check the drawings closely for components extending beyond the skid perimeter where they can be damaged during transport. Check the placement of components for accessibility - a hose reel mounted with the recoil spring next to the tank would be a headache to service. A filter vessel placed in front of a sight glass renders the glass useless. Sometimes repositioning by just an inch or two will make quite a difference.

Once a final drawing has been approved, plan at least two visits to the fabricator, one during initial fit-up and the second during the operational testing. Take the original bill of materials along on these visits to verify that the parts are on the skid as listed. Now is the time to question any missing or altered parts. You may be requested to supply a drum or two of oil to be used during the flushing and testing of the unit.

Provide Training
When the new skid finally arrives at the plant, you must train the personnel in its operation and maintenance. Point out the features included from suggestions at the onset of the project. By the end of your training session, you will notice that the skid is no longer "yours", that ownership is now shared.

With our "as built" skid, we filter the oil as the tank fills using a jumper hose from the pump suction line to the bulk storage tanks. The skid has also been used to drain a hydraulic sump being replaced, and has filtered the oil in a recirculation mode, using the same oil to fill the new sump. The forklift pockets have an intersecting design that allows the skid to be picked up from any direction. The filter elements utilized are a common type used in our plant and are easily serviced.

This information should assist you in planning your own lube filtration skid and prevent you from getting something you didn't want.

Remember the oversized skid mentioned earlier? The vendor reduced the skid to 4 feet by 6 feet and 2 inches - and won the contract.

Lubrication Storage and Transfer Skids
General Specifications
1. 200-gallon capacity tanks
2. Pump and motor combo 20 GPM bidirectional
3. 1-½ hp motor, 440-volt 60 Hz 3ph TEFC
4. Control circuit on/off switch etc., step down to 110-volt
5. Motor bidirectional control on panel
6. NEMA classification on panel standard
7. Panel marked with proper labels for all control functions a. AB electrical control components
8. Reelcraft hose reel, 50 feet of 1-inch hose auto-return
     a. JIC flared fittings on swivel joints
9. Plain hose end (capped)
10. Parker IL2 filter housing simplex with bypass 25 psid and local indicator
     a. IL222QM25P9P91 11. 3 micron beta 200
12. SAE straight thread with O-ring fittings, no NPT
13. Hard-piped from pump outlet to filter housing and from filter housing to hose reel

1. Fill tank with pump through filter.
2. Recirculate (polish oil) tank.
3. Pump out of tank through filter to plant systems (through hose reel).


Valves (SAE straight thread - with O-ring) hand-operated full-port ball valves to isolate and control oil fluid path to perform above listed operational functions.

Tank Details
1. UL 142 rated
2. 1-inch bottom drain NPT capped
3. Fittings for 
     a. Fill - 3-inch NPT capped 

     b. Vent - desiccant breather NPT 
     c. Level gauge - API valves with ball check shut-off and red-line glass with armor protection. Gauge to be mounted within perimeter of skid not on the outside of tank edge perimeter. 
     d. Recirculate (see operations spec)

Skid Details
1. ¼-inch steel construction
2. All components to be bolted to ¼-inch minimum steel brackets
3. All brackets to be welded solidly to skid
4. Fork pockets to run with 54-inch width