Smart-sensing technology contributes to the predictive maintenance of wastewater and other facility pumps.
By Bobbie Montagno, Pulsafeeder Engineered Products
Pumping infrastructure represents an enormous investment for large processing facilities. In any given plant, thousands of pumps are needed to move liquids from point A to point B.
Some of the primary applications for which rotary-gear pumps are used in refineries and chemical-processing plants involve treating wastewater to be reused for cooling towers, boiler feeds, or to dilute chemicals that are required for other processes. For these applications, harsh chemicals such as bleaching chemicals, cleaning agents, and corrosion inhibitors are dispersed on a high-volume, continuous basis. Over time, this can take a toll on the pumping equipment, establishing the need for proper maintenance programs.
The cost of maintenance
In most plants, annual maintenance costs for pumping infrastructure can range from 2% to 5% of the replacement value of the infrastructure. At first glance, that range seems minimal. But the delta between 2% and 5% can equal millions of dollars (or in some cases, tens of millions) throughout the life of the plant. Total maintenance costs must also be measured beyond the physical expense of the parts, the tools, and the engineers who wield them. Maintaining pumps in a chemical plant, refinery, or wastewater facility directly affects uptime, which in turn affects the bottom line.
Pumps that run regularly, feature wear items, and handle hazardous and corrosive chemicals will inevitably require maintenance. This can be a blessing and a curse.
Plant managers who get it right, in a preventive and predictive fashion, can streamline operations and maximize uptime. Those who let maintenance slip into a reactionary or “run to fail” approach can hinder operations and create ripple effects that shorten the life expectancy of equipment.
Predictive maintenance requires a long-term view. It involves planning, scheduling, condition monitoring, analysis, and spare-parts management. Predictive maintenance for pumps is aided by smart-sensing technology that can alert engineers to dry-run conditions, temperature changes, increases in vibration, or decreases in pressure.
Today, sensors are readily available and their value (and deployment) will continue to expand as wireless communications connect plant infrastructure to maintenance personnel using tablets and smart phones across the Industrial Internet of Things (IIoT).
Predictive maintenance can also be done without advanced communications technology. Readily available information and historical pump performance can be used to schedule the replacement of wear parts with minimal disruption to plant operations and minimal investment in sophisticated cloud-based controls.
Short-term reactive maintenance
Although predictive maintenance is always the goal, sometimes reactionary maintenance becomes the reality. When budgets are cut, maintenance is often considered a quick fix to address short-term financial constraints.
Reactive maintenance provides short-term savings, until equipment fails. When a failure occurs, the response relies on the skills of the on-site team and the availability of spare parts. If either fails to meet expectations, substantial losses can result from downtime and lost production.
Maintenance starts with a simple design. Some pumps are designed for a limited life, and purchasing decisions are purely based on cost. Other pump designs seek to provide reliability over a longer life, while balancing the anticipated cost of repairs. Rotary-gear pumps are often deployed to pump harsh and aggressive chemicals, so sealless designs are easier to maintain because there is no leak point for the harsh chemicals to damage the pump or surrounding equipment.
When it comes to rotary-gear pumps, the number of spare parts should always be considered. Maintaining a sufficient inventory of gears, shafts, O-rings, and liners is critical. Spare-parts kits should contain every part that a pump requires, and kits should be easy to procure (with just a single part number). If tied to a proper design, spare parts should be simple and easy to install. Some pumps feature symmetrical parts that only fit in one way, making parts replacement mistake proof, and keeping time to repair at a minimum.
Access to the inner workings of a pump is another important design feature that affects maintenance. If the pump’s gears are not readily accessible, then engineers need to decouple the motor, close the valves, and remove piping at the suction and discharge ports of the pump. Pumps that feature a front pull-out design can be repaired in place. This minimizes downtime by eliminating the need to lock-out/tag-out the pump, and move it to the repair shop.
Maintenance costs for a single repair will always be insignificant, compared with the costs associated with lost production and process restarts. The true return on investment associated with maintenance should be connected to a plant’s uptime. The simpler the equipment is to maintain, the faster it can be done. This gives plant operators more flexibility to schedule maintenance between shifts or whenever it is most opportunistic (or least disruptive).
Although the demographics for engineering staffs continue to change, the loss of vast experience is gradually being offset by new technology that can sense issues and alert engineers to problems before they occur. This type of sensing technology, coupled with simple designs, intuitive access, and fewer parts to maintain, forms the cornerstone of preventive-maintenance programs that keep plants up and running, and also provides management with the data it needs to make better decisions for capital budgets and long-term infrastructure improvements. RP
Bobbie Montagno is the aftermarket business line leader at Pulsafeeder Engineered Products, Rochester, NY. For the past 30 years, she has held leadership roles in application engineering, product management, and aftermarket. She can be reached at firstname.lastname@example.org.
Series MP7100 mechanically actuated diaphragm metering pump incorporates the ruggedness of a hydraulic diaphragm metering pump, eliminates the need for intermediate fluid or hydraulic oil to actuate the diaphragm, and reduces the potential for gearbox oil to contaminate the process. The result is a pump design said to provide reliable and accurate dosing of a wide range of mild to aggressive chemicals, including those used in municipal water and wastewater treatment. The pump has a maximum capacity range to 275 gph, pressures to 235 psi, and a suction-lift exceeding 20 ft. on water-like chemicals.
Neptune Chemical Pump Co.
North Wales, PA
Grand Terrace, CA-based EnviroGear Pump (part of PSG, a Dover company) PSG Group, has announced the release of G Series models G1-82, G1-133 and G1-222 (3-in, 4-in., and 6-in.) metal-sealed internal gear pumps.
Well suited, according to the manufacturer, for the most challenging and demanding transfer applications (thin and viscous fluids), the G Series lineup is available in cast iron, carbon steel, and stainless steel models. Delivering flow rates up to 500 gpm, they’re offered with both packing and mechanical seal options, and can be used for a wide range of application types, i.e. chemicals, adhesives, paints, coatings, food & beverage, and heat transfer, among others,
Features and Capabilities
G Series pumps provide positive, non-pulsating flow, and can operate equally in both directions. Features include enlarged bearing housings at the backside of the units that allow for convenient drive-end access to the shaft seal and single-point end-clearance adjustment.
EnviroGear notes that members of its G Series family are interchangeable with up to 95% of existing internal gear pumps on the market, with no modifications to piping, driver, coupling, or baseplate required. The pump casing can be easily rotated for multiple liquid porting positions, making for simple installation in existing applications.
For more information, CLICK HERE.
While pumps may be the foot soldiers of the process industries, their quiet dedication means they’re often ignored. That’s a risky business strategy for any site: Components break down, pumps run below optimal efficiency levels, and entire processes suffer. Experts at SKF (Gothenburg, Sweden, and Lansdale, PA) highlight several proven strategies to help optimize your plant’s pump-fleet performance.
Select the right bearing.
Bearings in centrifugal pumps support hydraulic loads imposed on the impeller, the mass of the impeller and shaft, and loads due to couplings and drive systems. They also keep the shaft axial and radial deflections within acceptable limits for the impeller and shaft seal. The bearings often will face high axial loads, marginal lubrication, and high operating temperatures and vibration, all while attempting to minimize friction. If uncontrolled, friction can result in power loss, excessive heat generation, increased noise or wear, and early bearing failure. To optimize a pump’s performance, be sure to evaluate the unit’s bearings (types, designs, and arrangements) in the context of their anticipated operating environment. Suitable bearings are available to satisfy even the most difficult centrifugal-pump applications.
Ensure proper lubrication.
Improper lubrication accounts for more than 30% of bearing failures. Good lubricants prevent metal-to-metal contact and undesired friction. The common methods for the effective lubrication of pump bearings include grease, oil bath, oil ring, and oil mist and air-oil. Oil mist generates the least amount of friction (allowing rotational speed to be based on the bearing design instead of lubrication limitations) and creates a positive pressure within the bearing housing (fending off invasive contaminants). Regardless of lubrication method, always specify lubricants according to the demands on vertical shafts and resistance to solids, pressure, temperatures, loads, and chemical attack.
Seal the system.
Bearing seals in centrifugal pumps retain lubricants or liquids, exclude contaminants, separate fluids, and confine pressure. The choice of a seal for centrifugal-pump bearings depends on the unique demands and operating conditions of the application. Keep in mind, though, that the bearing and sealing arrangement represents an integrated system. Dynamic radial seals generally are the best choice for centrifugal pumps. These designs create a barrier between surfaces in relative motion. Seal selection ultimately must be based on a thorough review of application parameters and environmental factors. For example, seals in pumping applications are often exposed to relatively constant pressure differentials. That makes pressure seals, with their pressurized seal cavities, the preferred choice.
Keep in mind that seals usually have a much shorter service life than the components they protect. Don’t fall into the common habit of scheduling seal replacement only at intervals dictated by other components, such as bearings.
Monitor equipment health.
Regular measurement and analysis of key physical parameters, such as vibration and temperature, can detect pump-system problems before they occur. Basic instruments can assess and report on vibration, temperature, and other parameters. More advanced tools include online surveillance systems and software that can deliver real-time data. Many problems will manifest as vibration, which is widely considered the best operating parameter to judge pump-train condition. Vibration can detect problems such as imbalance, misalignment, bearing oil-film instabilities, rolling bearing degradation, mechanical looseness, structural resonance, and a soft foundation.
Don’t overlook the pivotal role operators can play in pump reliability. They can serve as “eyes and ears” in the detection of equipment faults before problems escalate and also perform basic maintenance tasks. MT
SKF is a global supplier of bearings, seals, mechatronics, lubrication systems, and services that include technical support, maintenance-and-reliability services, engineering consulting, and training. For more information on motor bearings and other technologies and topics, visit skf.com.
Optimizing existing AODD pumps with energy-efficient, air-distribution technology has helped Chromalloy improve its gas-turbine-engine service operations.
Founded in 1951, the technology company Chromalloy (chromalloy.com) is a leading provider of solutions that reduce manufacturing and operating costs and extend the life of gas-turbine engines for customers in the commercial-aviation, military, and power industries. One of Chromalloy’s major facilities, its 120,000-sq.-ft. site in Tilburg, The Netherlands, has been in operation since 1975. The components serviced there reflect a veritable who’s who of turbine-engine manufacturers.
“The Tilburg facility is a repair shop for parts used on airplane engines and in other applications,” explained John Bollebakker, the site’s manager of maintenance and facilities. “If an engine needs an overhaul, certain parts will be sent here, whereupon they will be inspected and repaired, and all necessary paperwork completed. We then deliver the part(s) back to the OEM in the shortest time possible.”
The need to improve
A key stage in the engine-repair process involves the continuous transfer of cooling fluids that help keep repair and refinishing machinery operating safely. Since 1998, Chromalloy has been relying on several Wilden Original Series (clamped) air-operated double-diaphragm (AODD) pumps to reliably facilitate the process.
As Bollebakker describes the process, a press pipe in one area introduces the cooling fluid into the process and from there it runs back to the tank where the Wilden pump pulls it out and sends it to the next installation. “In another area,” he said, “we are pumping with the main pumps to the machines and the Wilden gets the fluid to the tank and back to the filter where it is cooled. After that, the main pumps remove the fluid and pump it back to the machine again.” The Wilden units are used for cooling and filtering.
Bollebakker noted that the Wilden pumps had performed admirably during the 16 years since their installation. The only maintenance seemed to have been associated with seal replacements, “once a year or so.” Still, evolving operational demands regarding air usage, efficiency, noise levels, and overall operating costs had led him to consider ways that pump performance could be improved.
Although the Tilburg site was seeking more efficiency from its pumps, it also needed to consider safety issues. “We want a healthy work environment,” Bollebakker stated. “Therefore, we were looking at where we could improve environmental issues or create cost savings by doing whatever it takes to make our ROI the right percentage. From all aspects, we try to do the best thing we can for the company. It should fit into the complete organization, but also fit into the budget.”
In 2013, to help identify pumping technologies that could improve efficiency and cost effectiveness while making operations more “green,” Bollebakker contacted Chromalloy’s pump supplier, Holland Air Pumps, Oirschot, The Netherlands—specifically its commercial director Gerrit Klaassen.
Too good to be true?
Klaassen pointed out that Bollebakker’s search for a more efficient AODD pump came at an ideal time. In June 2013, Wilden introduced its Pro-Flo SHIFT air-distribution system (ADS), featuring an air-control spool that eliminates costly air “overfilling” at the completion of the pump stroke. According to the manufacturer, Pro-Flo SHIFT-equipped pumps lead to savings in air consumption of as much as 60%, while costing 50% less to operate than AODD units with traditional mechanical or electronically actuated ADS technologies.
Reports of that level of performance might have sounded “too good to be true” in some quarters. Committed to proving otherwise, Holland Air Pumps built a skid-based Pro-Flo SHIFT-equipped pump unit and transported it to actual customer sites where the technology was put to the test. Klaassen and others on the distributor’s team, including owner Leo de Haas, have fond memories of the traveling “road show” and its ability to clearly demonstrate how the new ADS worked and what it could do for customer operations. “When they saw it [in operation] for themselves and listened to the pump [as it ran],” he said, “they realized that they suddenly had 30% to 40% more capacity.”
Chromalloy’s Bollebakker was one of those customers. Klaassen conducted a test for him and a colleague at the Tilgren facility in Dec. 2013. Both were intrigued by what they saw. Later, when Wilden provided an overview projection of what the site could save by upgrading existing AODD units with the Pro-Flo SHIFT ADS, Bollebakker was convinced. At that point, he went on to convince the facility’s general manager, and the purchase was quickly approved.
The upgrade itself went smoothly. According to Bollebakker, removing the old ADSs from the site’s existing Wilden pumps and inserting the new Pro-Flo SHIFT ADSs was a simple task. In fact, there was negligible impact on the facility’s 16-hr. daily operating schedule.
“From a production point of view,” Bollebakker said, “I can’t allow myself to go without production for four or six or eight hours, because we have to run for 16. In reality, each of the eight pumps was out of production for only one or two hours. It was an easy job.”
Once the pumps with the new Pro-Flo SHIFT ADS were up and running, it wasn’t long before Bollebakker began to notice—and document—the cost savings. “We’ve taken four cents per cubic meter per hour (m3/hr.) off the operating cost, and at 16 hours per day, five days a week, we calculated that we will be saving €11,000 (US$12,020) per year for the eight pumps,” he marveled. (Translation: The Pro-Flo SHIFT ADS investment would pay for itself in 12 months.)
Seeing is believing
“The Tilgren plant has several areas where we try to improve our systems and look constantly for ways to do things quicker, better, faster,” said Bollebakker. “From the moment we rebuilt the air section on the Wilden pumps, there was an immediate reduction in air supply, but the flow remained the same. When the pump comes in and it’s working the way we want it to work, the case is closed.” MT
This white paper from Emerson Process Management, released in July 2015, delves into the ramifications of the API 682 standard for pump sealing systems in the oil and gas and chemical industries. The standard provides new roadmaps for operations and maintenance (O&P) teams on how to move towards continuous monitoring of pump systems.
This paper examines asset management strategies, along with IIoT foundation solutions, as seen below from this except:
According to API Standard 682 Fourth Edition, offshore platforms, onshore wellheads, refineries, and petrochemical plants need to evaluate what pump monitoring measurements are in place, which measurements require manual field checks, and which should be automated or upgraded to a better option.
Due to the costs associated with monitoring the process using wired instruments, only a small percentage of a typical process facility’s pumps are monitored online. The balance of pumps are inspected only periodically by operations or maintenance personnel on field rounds.
Horizontal split-case pumps transfer gas from storage wells to the pipeline.
By Bryan Orchard
The BB3 horizontally split-case API pump is used extensively by pipeline companies operating in the shale gas, liquefied-petroleum gas (LPG) and liquefied-natural gas (LNG) markets.
“BB3 pumps are used within terminals to transfer the gas into the pipelines from storage wells,” explained Richard Martinez, managing director at Standard Alloys Inc., Port Arthur, TX. “These pipelines employ pump stations at various intervals along their length, and many of these pumps are coming to the end of their service lives. There is no desire to replace redundant pumps with new units. The last thing that they want to do is change drivers, put in new foundations, and change piping connections to accommodate new designs.”
The most cost-efficient solution is to use a bare-shaft pump that can be easily dropped into the existing infrastructure where operators know that the nozzles, casing feet, and shaft couplings will fit.
A SUCCESSFUL APPLICATION
Targa Resources Corp., Houston, is a provider of midstream services in North America. In 2015, Targa installed a BB3 pump for the specific duty of injecting ethane propane mix (EP) into storage wells at the plant’s salt dome. The double volute, eight-stage split-case centrifugal pump is fitted with 10.187-in. closed impellers and provides a flow of 1,200 gpm running at 4,000 rpm, with a suction pressure of 260 psig, and a total developed head of 3,800 ft. The pump can graduate from moving a product of specific gravity 0.38 all the way up to 0.50, which gives them the ability to move heavier end products. Installed on an existing product train, the pump has been built specifically for this application.
“We were given the flow parameters and head capacities. We went into our database to see what we had that was closest to the specification,” Martinez said. “We found a closely-matched pump and used this as a platform to custom build the flow and head required. We produced a special package that went beyond the generic specification typically found in API-610. It had to fit the same foundation as the original pump, so a custom base was designed to facilitate a perfect fit.”
Martinez said his company had already supplied similar pumps for transfer duties, but this one was specifically engineered for well injection.
Steve Ferguson, Targa’s rotating-maintenance supervisor emphasized the importance of extreme reliability for this application. Regular maintenance inspections are implemented by Ferguson’s reliability team. The new injection pump has replaced a standby pump that had reached the end of its service life. For reasons associated with the casing, it had to be condemned. “A problem with older pumps is that in the event of failure, weld repair from erosion will be required,” Ferguson said. “This is not possible because, over time, electrolysis leaches the carbon out of the material so the base metal will not accept the weld metal. Also, there is the problem of carbons leaching, which weakens the case. Pressure testing repairs cannot be performed. Therefore, replacement pumps are required.”
For years Standard Alloys’ core business was in manufacturing replacement pump parts. In 1992 this changed when the company made its first complete bare-shaft pump. Now they produce API qualified bare-shaft replacement pumps for brownfield and greenfield applications, exploiting opportunities where an existing pump may be obsolete or where material or engineering upgrades are needed.
“Our target is pump operators that may have seventh or eighth edition API pumps that need replacing with a direct ‘drop-in’ ,” Martinez said. “They don’t want to change the foundation due to the casing foot location or modify the suction and discharge nozzles. They also don’t want to relocate the drive unit. RP
Bryan Orchard is an independent journalist reporting for KSB Group.