Everyone agrees that reactive maintenance is probably the worst pump reliability strategy. Maintaining equipment only after it breaks can mean unexpected downtime, emergencies, rush charges, overtime, and replacement of expensive parts.
The best pump reliability strategy is not either preventive or predictive maintenance, it’s a combination of the two, strategically applied. In this post, we’ll discuss the differences between predictive and preventive maintenance and when it’s best to use them.
PREDICTIVE AND PREVENTIVE MAINTENANCE OVERVIEW
Many operators rely heavily on “reactive” maintenance rather than preventing and planning for future repairs. As discussed in our eBook, 36 Ways to Kill Your Pump, “reactive” maintenance accounts for unplanned equipment downtime and increased costs.
Preventive and predictive maintenance programs extend the overall life of the equipment and result in fewer unplanned breakdowns. The choice is not one or the other, it’s a combination of the two.
PUMP PREVENTIVE MAINTENANCE (PM) PROGRAM
Preventative maintenance is any variety of scheduled maintenance to a pump or other piece of equipment. Generally, it includes scheduled routine maintenance, such as equipment calibration, greasing, oil change, and analysis.
One of the biggest ways to prevent failures is to make sure your equipment is properly aligned and balanced. Misalignment and pump unbalance are the two most common reliability problems for rotating equipment. Laser alignment also fits within this category since its a service completed upon installation, setting the pump up for success.
These programs are designed to keep your maintenance costs low by preventing costly failures before they happen. If you need a preventative maintenance checklist, you can download one here.
Up to 50% of damage to rotating machinery is directly related to misalignment. Misalignment can cause increased vibration, premature seal and bearing failure, and increased power consumption. An unbalanced pump causes similar issues, such as vibration, which can be easily avoided with the right preventative maintenance measures.
PREDICTIVE MAINTENANCE (PdM) SERVICES
Predictive maintenance services are used to monitor the condition of equipment over time. Vibration analysis, for example, measures the vibration of the equipment while it is still in service. This allows the technician to see the change in vibrations over time to predict when a problem may occur, and why.
Predictive maintenance should be part of routine maintenance for pumps and rotating equipment that absolutely can NOT go down. Operators and maintenance managers get a glimpse into the future life of the pump as it's running today. This allows them to plan for repairs and avoid unexpected downtime.
BUILDING A PREVENTIVE / PREDICTIVE MAINTENANCE PROGRAM
Not all pumps are equally important in a manufacturing process, so not all pumps should receive the same maintenance plan. It wouldn’t make sense to spend time and money on vibration analysis for a pump in a non-essential application.
Before creating a maintenance plan, put the pumps into categories. This will help determine how much time and money to invest in each one. Use these categories to get started:
- Critical - Put a pump in this category if:
- It is CATASTROPHIC for the facility or process if this pump goes down
- The effects of failure could be dangerous or even deadly
- A violation of governmental regulations could result
- There is no backup
- Essential - If this pump goes down:
- Production may cease on this line
- Parts for this pump may be unavailable or have a long lead time
- A backup pump exists
- The pump is operating in a non-essential application
Next, devise a plan for each equipment category. The best reliability plans will involve varying degrees of the following tactics:
Regularly maintaining pumps will extend the life of your pump. When a pump is properly maintained, the parts that need replacing are usually the less expensive wear parts.
A preventive maintenance for pumps usually includes the following:
- Check the bearing temperature, lubricant level, and vibration
- Mechanical seals to show no sign of leakage, packing to leak at the rate of 40-60 drops/min
- Overall vibration – visual, sound, touch analysis
- Discharge pressure – check to ensure gauges are reading at acceptable levels
On a quarterly basis, check the following items:
- Equipment foundation – check anchor bolts for tightness
- For oil or grease-lubricated equipment, change the oil or re-grease every three months or 2,000 operating hours, whichever comes first
- Check shaft alignment – believe it or not, shaft alignment can change! Thermal growth and machine movement due to load shifts can cause pumps to move out of alignment.
- Re-grease the motor bearings according to the manufacturer’s instructions.
This is a general checklist. Reference the O&M manual for items specific to each machine.
Up to 50% of damage to rotating machinery is directly related to misalignment. That’s huge. Machine vibration, bearing damage, premature seal wear, and coupling damage are all examples of issues pumps experience when misaligned.
There are 3 common methods of pump alignment, straight edge, reverse dial indicator, and laser align.
For the most accurate alignment, we always recommend laser alignment. It’s the most accurate method available (to .0001), and once familiar, an operator can align a pump/motor very quickly. It is the most expensive method to get into if doing alignments in-house and can be difficult to learn at first. But when looking for long-term results, the laser align method is the better choice.
Precision rebuild or precision maintenance is the practice of rebuilding a pump as close to OEM specifications as possible. Attention to detail is required for precision rebuilds.
Precision rebuilds are proven to reduce failures and should be a central piece of a pump reliability strategy. If the team lacks capacity, tools, or expertise to rebuild pumps to OEM standards, look for a capable local shop.
Installation & Start-Up
Proper pump installation is the first step in ensuring the most energy and cost efficient operation possible.
For best reliability from the start, follow these rules at install and start-up:
- Add taps with isolating ball valves into piping on the suction and discharge sides of the pump. Use these to mount pressure indicators to ensure the pump is performing properly.
- Never use force to connect a pump to a pipe. This causes pipe strain and a myriad of issues that come with it.
- Laser align before startup.
- Proper lubrication – new pumps arrive without lubricant inside. Make sure pumps have the proper amount of the correct lubricant before turning on.
- Read the pump manual and follow each step in the procedure. The procedures therein give the best possible instruction for long and trouble-free life for the pump.
- Upon start-up, record the pump performance baseline data – amps, suction pressure, discharge pressure. This is handy when troubleshooting issues, should they arise.
Vibration monitoring is a very helpful tool for predicting pump failures. Some manufacturing facilities have a vibration technician on staff to take readings on critical pumps. These technicians may read the results themselves or send them to a firm that can interpret the readings and provide a report.
Unfortunately, this is not a skill easily attained by a maintenance team. It requires expensive equipment and a great deal of training to be an effective vibration technician. Unless the facility has a large population of critical equipment, this is a service best hired out.
There’s an alternative available, condition monitoring technology. Technology like ITT's i-Alert2 can take readings on equipment 24/7 and alert the team to problems.
Reading results still requires a professional eye, but this technology can at least give you a heads up that a problem exists.
Arguably the most important piece of a preventative/predictive maintenance plan... The TRAINING! Training isn’t just for the maintenance team, it’s for everyone in contact with pumps, operators especially! Failure prevention is everyone’s responsibility.
The maintenance team is the keeper and protector of equipment in the facility. Train operators on the signs of failure so they can report it quickly. Show them how to properly start-up or shut down a pump and how their actions will affect other parts of the system.
Hire outside help when needed
If all these steps were do-able by a maintenance team alone, everyone’s reliability goals would be already met. Some of the steps we’ve laid out require specialized training, tools, or specialized training on tools to make them effective. It’s likely the team doesn’t possess all these as they’re expected to know how to fix every machine in the plant. Hire outside help where it makes sense.
Look to a preventative maintenance program and predictive maintenance measures to save on annual maintenance costs and unscheduled downtime. We recommend working with your local equipment supplier to schedule a preventative or predictive maintenance program for your pumps.
Need more information about our preventative and predictive maintenance services? We are happy to help businesses in Wisconsin and upper Michigan. Got a noisy, underperforming pump? Consider our FREE Bad Actor Pump Assessment!