Developing Commissioning Procedures for Hydraulic Equipment

Brendan Casey
Tags: hydraulics

A significant cause of infant mortality in hydraulic equipment can be attributed to the failure of maintenance personnel to follow proper procedures, such as oil flushing, before startup or when recommissioning hydraulic systems after carrying out maintenance work.

Cavitation, aeration, and inadequate lubrication can all damage equipment that has not been properly commissioned or recommissioned. Often, this damage will not be revealed until a component fails. This can take hundreds, or even thousands, of hours, but the results can still be unexpected and catastrophic in some cases.

Common Misconceptions About Hydraulic Systems

There are common misconceptions among maintenance personnel who have limited training in hydraulics. One is that because oil circulates through the hydraulic components that no special attention is required during the installation beyond bolting the component into position and connecting the hoses. This couldn’t be further from the truth.

Damage to hydraulic components during initial startup can be prevented by:

Depending on the type of equipment in operation, detailed commissioning procedures may be available from the machine manufacturer upon request. If this information is not available for a specific piece of equipment, appropriate procedures should be developed. If necessary, consult a fluid power engineer for assistance. The following generic procedure illustrates many of the issues that should be considered.

Pre-start Procedures

If the system is down as a result of a major component failure:

When installing pumps and motors, check the fit of the drive coupling on the pump or motor shaft. Loose-fitting couplings cause accelerated wear of the driveshaft and should be replaced.

On closed-circuit systems (hydrostatic transmissions), inspect the high-pressure hoses or pipes between the pump and motor, and replace any suspect lines. A burst hose or pipe in service can result in the destruction of the pump and/or motor through cavitation.

Cylinders – Before connecting service lines, fill the cylinders with clean hydraulic fluid through the service ports. This helps reduce the risk of air compression, or dieseling, which would result in damage to the cylinder and seals.

Motors – Fill the case of piston-type motors with clean hydraulic fluid through the highest case-drain port and connect the case-drain line. Failing to do so causes inadequate lubrication and will damage the motor upon startup. Vertically mounted units require special attention to ensure fluid levels are high enough to lubricate the front shaft bearings.

Pumps - After installing the pump(s) and connecting service lines:

Startup Procedures

Once commissioning procedures for a specific piece of hydraulic equipment have been developed and the necessary training has been provided, from a preventive maintenance perspective, ongoing costs are limited to the training of new maintenance employees. This is a much more predictable and manageable cost than unplanned downtime or more frequent component failures that come with poor commissioning and recommissioning procedures.