Water Forum: When to install a condition monitoring system

Equipment and repair costs are not the only factors to consider when deciding whether to apply continuous, integrated condition monitoring to rotating equipment.

By Paul Studebaker

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“How expensive is a failure going to be?” asked Kim Chapman, senior project engineer, Hubbell, Roth & Clark, Inc. “We don’t monitor to protect the equipment, we monitor to protect our wallets.”

Chapman presented “Monitoring Advancements Help Reduce Costs and Protect Critical Asset Life for County Water System in Michigan” at the Automation Fair Water & Wastewater Forum this week in Atlanta. His talk described a recent pump and pipeline project to bring Lake Ontario water to Flint, Michigan, but centered on when and how to improve reliability by monitoring the condition of rotating equipment.

Chapman has more than 40 years of experience in reliability across industries from power generation to steel. “They say I’m an expert. And what’s an expert? Someone who used to be a spurt,” he joked. “In fact, I’m simply a guy who has a lot of experience doing things that needed to be done. Along the way, I listened to the old guys who are familiar with the equipment and how it behaves. They are the true experts.”

Why monitor continuously?

If a small pump fails, that may be OK if it’s easy to replace and not critical. “That might cost $10,000,” Chapman said. “But a big pump can cost $200,000, even half a million dollars. If you’re not there every day to look and listen, you need to monitor it.”

For expensive or critical equipment, periodic monitoring is not enough. “You may check it once a month, but as soon as you leave, you’re uncovered,” Chapman said.

Varying loads, shocks, lubrication failure, bearing failure, equipment imbalance and excess wear can lead to rapid motor failures as well as destruction of fans, pumps and compressors. Continuously monitoring bearing temperatures and vibration gives early notice of pending failures, making users aware “so they can keep small problems from becoming big, expensive problems,” Chapman said.

Typical places to install temperature and vibration sensors include vertical pump upper and lower bearings, horizontal pump and compressor inner and outer bearings, and thrust bearings on pumps and other driven machines such as conveyors, blowers and fans. Also monitor winding temperature and other motor sensors, and where needed, motor bearing temperature and vibration. “Standard motor protection is not enough,” Chapman added.

Understand the costs

While monitoring systems costs much less now ($15,000 to $20,000) than in the past (about $50,000), they’re still not inexpensive. To understand when they’re worth the investment, add up the cost of periodic testing versus the risk in the “between” times. Compare the cost of repairs under planned outages against the cost of emergency repairs, including the costs of being out of service in lost production, sales and opportunity.

Chapman’s district includes a number of houses in the $3-10 million range with their own sprinkler systems. “If a house catches fire while a pump is down and we can’t deliver full pressure to the sprinklers, those homeowners are going to be upset. They’re likely to get a lawyer and sue.”

The costs of equipment repair and replacement are highly variable. For example, if the normal cost of a repair is $15,000, the cost of repair under emergency conditions may be double, triple or more. Paying for special handling and shipping, as well as a special work schedule (24-hour, overnight, weekend) might add $30,000, for a total cost of $40,000, $50,000 or more.

In one example, a pump caught fire and burned the building. “The replacement pump cost $60,000 plus $35,000 to expedite it,” Chapman said. "The total loss was $250,000 just because the equipment wasn't monitored."

If temporary (rental) equipment will be required, “That cost will not be insubstantial,” Chapman said. “$1,000 per week? $5,000 per week? $10,000 per week or more? One client recently paid more than $50,000 in rental charges while waiting for a replacement part." That does not include the cost of changes to the work schedule and extra manpower (overtime) resulting from impairment to operations. Or the extra monitoring and maintenance of remaining equipment that is now being worked more.

Finally, will the loss result in a review by a regulatory agency? “There is a real cost in complying with such a review, and it should be added to the total cost of failure,” Chapman said.

Reap the benefits

Today’s integrated continuous monitoring systems provide benefits to engineers, installers, owners and operators, as well as maintenance. For engineers, the systems are easy to specify and to detail the installation and integration requirements. They are easy to install and connect to motor control centers (MCCs).

“Just screw in the sensors and wire them to the MCC,” Chapman said.

And they’re easy to integrate to SCADA, supervisory controls and alarms. “The monitoring system can be just another node on the SCADA network, making it easy to integrate, access and support.”

Owner/operators get ease of use and an intuitive interface with the ability to call up historical trends to see what was happening when an alarm occurs. With that information, “Probable causes can be readily identified and corrective measures taken as necessary to return the equipment to operation, or to determine what maintenance is required,” Chapman said. “He can know whether to send an electrician, a mechanic or a tech.”

For the maintenance provider, interfaces are easy to use and understand. They can call up the historical trend data and compare it to the baseline to see what was happening when an alarm occurred, and what was happening in the time prior to the alarm. This allows experienced maintenance personnel to be consulted regarding probable causes and probable required repairs, removing a lot of guesswork.

“Maintenance gets the records they need, the diagnostics to know what’s going on in the machine instead of guessing,” Chapman said. “An experienced maintenance guy can diagnose the machine without having to travel to go see it.”

They can quickly see, for example, what time the pump kicked out, the fault description, the motor current, whether the pump was cavitating, the motor bearing temperature and the motor voltage.

“Where are the operating and maintenance manuals?” Chapman asked. “Information is power. The manuals are all digital—they can bring up the drawings, wiring diagrams and manufacturers’ manuals. Maintenance loves it.”

The bottom line

Chapman’s recent project installed 60 miles of pipeline and two pump stations to bring Lake Ontario water to Flint, Mich. The crib is two miles out in the lake, and as much as 70 million GPD is drawn from a 90-ft. well by the first station at the lake shore. The second station is about 27 miles down the pipe.

The two stations provide 16,000 HP of pumping capacity and run 99% of the time unmanned, so they have SCADA to central management at the water plant. There, they can access all of the details, not just alarms, warnings and general statistics.

“Breaking a pump or fan is not a good thing,” Chapman said. And while monitoring is easy to do—sensors are easy to install, pre-wired and preconfigured— at $15,000 to $20,000 per machine, it’s not cheap. “We have eight machines, so it still adds up,” Chapman said. “But pumps gotta run—people don’t want to hear that they can’t use their bathrooms.”

If the costs to repair are low and the cost of a failure is not high, perhaps monitoring, or full monitoring, is not in your interest. “Monitoring everything can easily become a bigger cost and problem than the possible failure,” Chapman said. “It generates a lot of information to look at, and if you monitor everything, data can become the be-all and end-all, and the equipment gets short shrift.

“If it’s less than 100 HP, I would monitor it only if a failure has bad consequences. If it’s more than 100 HP, at least monitor the temperature, and maybe bearing vibration. If it’s worth a lot, monitor everything. And do monitor any critical application, regardless of size.”

In the old days, experienced on-site operators could see or hear a problem. “They could feel it in the floor—in their feet—if something was wrong,” Chapman said. “Now, they’re not there enough.”

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