Are you gearing up to start your industrial centrifugal pump after a shutdown? Whether it’s been sitting idle for weeks or even just a few hours, starting up a pump can be a daunting task. With the right pre-startup procedures and some troubleshooting know-how, your pump will run smoothly in no time.
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In this blog post, we’ll walk you through the steps to start your centrifugal pump after shutdown while offering valuable tips on best maintenance practices.
Before starting your centrifugal pump, following a few pre-startup procedures is essential. First and foremost, check for any damage that may have occurred during the shutdown period. Look for leaks or cracks in the pump casing and check all bolts and flange connections for tightness.
Next, inspect both the pump and piping system thoroughly. Ensure that all valves are correctly positioned before opening them, and look out for any obstructions in the suction line. If debris is inside the pipe, remove it before starting up your pump.
Lubrication is also important when starting up your centrifugal pump after shutdown. Ensure enough oil is in the bearing housing to prevent frictional wear between moving parts.
The alignment of your centrifugal pump should be checked before startup as well. If necessary, ensure its properly aligned with its driver using dial indicators or laser alignment tools.
Before starting a centrifugal pump, it is crucial to check for any signs of damage. This includes thoroughly inspecting the pump and piping system, and looking for any cracks, leaks or wear and tear.
Examining the pump’s exterior is the first step in checking for damage. Look for any signs of corrosion or physical damage to the casing, impeller, or shaft. Further inspection may be required if any issues are discovered at this stage.
Next, carefully open up the casing cover and check the interior components of your industrial pumps. Look out for broken seals or gaskets that could lead to leaks later during operation.
It’s also important to inspect all pipe connections and fittings as they can often be damaged by improper installation procedures or even accidents that might happen at worksites. Check whether all bolts are tightened properly so as not to cause leakage when running.
It is crucial to inspect the pump and piping system thoroughly. Any potential damage or wear and tear can lead to severe problems during operation, resulting in costly repairs and downtime.
Lubrication and alignment are critical components of maintaining the performance of a centrifugal pump. Proper lubrication ensures all moving parts work smoothly, reducing friction and wear. Adequate lubrication also helps prevent overheating, which can cause damage to the motor or impeller.
Aligning the pump correctly is equally important. Misalignment can cause excessive vibration and noise, leading to premature failure of bearings and seals. It’s essential to ensure that the motor shaft and pump shaft are perfectly aligned before starting up.
Different types of pumps require additional lubrication, so it’s crucial to consult the manufacturer for specific recommendations. Typically, oil-based lubricants work well for most applications.
When aligning a pump, it’s advisable to use precision tools such as dial indicators or laser alignment tools. These instruments help achieve accurate results quickly and efficiently.
Before starting, it’s necessary to prime the pump and open the discharge valve. Priming helps remove air from the system and ensures adequate water flow through the impeller.
To prime the pump, fill up its suction line with liquid by opening a vent valve or filling plug and releasing trapped air. Once primed, slowly turn on the power to start rotating shafts until they reach full speed.
Next, open the discharge valve gradually while keeping an eye on the pressure gauges. It’s essential to open slowly as this could damage pumps or other components in your system.
Increase the flow rate incrementally until you reach your desired level of output. Ensure there are no leaks or blockages in any part of your piping before fully operating centrifugal pumps.
When starting a centrifugal pump, there are common problems that can arise. It is important to troubleshoot these issues promptly to avoid any potential damage or downtime.
One problem that may occur is low flow or no flow. This could be due to clogged pipes, air pockets in the system, or a malfunctioning impeller. To remedy this issue, check for any blockages and bleed the air from the lines before restarting the pump.
Overheating can also be a concern with industrial pumps. Insufficient lubrication on bearings or excessive friction in the piping system may cause this. Regular maintenance and monitoring of temperatures can prevent overheating and prolong the lifespan of your equipment.
Excessive noise and vibration during operation is another common problem with centrifugal pumps. This could indicate misalignment, worn-out bearings, or cavitation within the system. Addressing these issues immediately can prevent further damage to your pump.
Experiencing a low-flow or no-flow situation can be frustrating. This issue can arise for several reasons, such as air pockets in the pump, clogged suction strainer or impeller, insufficient liquid level, and many more.
Overheating is a common problem with industrial pumps. Several potential causes of overheating include a lack of lubrication or alignment issues within the pump itself.
One possible cause of overheating is an obstruction in the piping system that prevents proper fluid flow. This can be caused by debris or buildup accumulating over time and may require cleaning or replacing affected components.
Another potential issue is improper installation or maintenance practices, such as failing to inspect and clean the pump regularly. Over time, this neglect can lead to excessive wear and tear on internal components, ultimately overheating.
Excessive noise and vibration in centrifugal pumps can cause concern, as it may indicate underlying issues with the pump system. These could include imbalances, misalignments, or even mechanical defects.
To address these issues effectively, consult your centrifugal pump manufacturer’s guidelines for proper installation procedures. Regular maintenance practices such as checking alignment periodically will ensure optimal operation while reducing unnecessary strain on equipment parts.
Proper pump maintenance is crucial for ensuring the longevity and efficiency of your industrial centrifugal pumps. By following best practices, you can reduce downtime, minimize repair costs, and maintain optimal performance.
One essential aspect of pump maintenance is regular inspection and cleaning. Periodically check for signs of wear or damage on components such as seals, bearings, impellers, and gaskets. Clear away debris buildup that could interfere with the pump’s operation to prevent blockages or reduced efficiency.
Lubrication plays a vital role in prolonging the life of your pump. Adequate lubrication reduces friction between moving parts while protecting against corrosion. Always adhere to the manufacturer’s lubricant type and frequency guidelines to keep your equipment running smoothly.
Monitoring performance metrics like flow rate, pressure levels, and energy consumption rates will help identify potential issues before they become significant problems.
Regular inspection and cleaning of industrial pumps, especially centrifugal pumps, is crucial to ensure proper functioning. Neglecting this aspect can lead to severe problems such as pump failure or accidents.
Keeping an eye on performance metrics like discharge pressure rates helps you identify potential issues before they become serious enough to stop production – ensuring that your investment returns value over time!
Monitoring the performance of your centrifugal pump is crucial to ensure its longevity and efficiency. Regular monitoring lets you detect any issues early on, preventing costly repairs.
Starting a centrifugal pump after shutdown may seem daunting at first. Still, it can be done safely and efficiently with proper pre-startup procedures, careful attention to the priming process, and regular maintenance and inspections. Always follow the manufacturer’s guidelines for your specific pump model and consult with experts if you encounter any problems during startup or operation.
By implementing these best practices for industrial pump maintenance, you can help prevent costly downtime due to equipment failure and ensure that your operations run smoothly. Regular inspection, cleaning, lubrication, and alignment are key factors in ensuring the optimal performance of your centrifugal pumps.
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Centrifugal Water Pump
Centrifugal Water Pump
I am frequently asked for pump startup commissioning advice and procedures—and from experience I begrudgingly predict that what most folks are actually looking for is the abridged CliffsNotes version. I typically start asking specific questions about the pump and the application, but the conversation quickly falters and fades to sports or a binge-worthy series on Netflix.
I have personally commissioned hundreds of pumps over my career, from small to really big and with drivers of all types ranging from steam turbines to engines and motors. Not all of these startup events went well, but from the failures came experience and from those experiences came wisdom.
There are a few basic steps no matter the pump type or application that I will cover, and then I will also address the often overlooked details (common mistakes) that can deliver both people and equipment into pump purgatory. For the purposes of this column, I am speaking only for centrifugal pumps and, unless otherwise noted, the pumps are not self-priming. Many of these tips and comments are for initial startups (commissioning evolutions), but will also deftly apply to the pump you start up every Monday morning.
When I am scheduled to supervise a pump startup, I immediately remind myself of one of my old and trusty mnemonic devices. This one is borrowed from the medical profession and in Latin is “primum non nocere” or in English, “first, do no harm.”
Over my career, I have often been summoned to the crime scene as the post-disaster forensic pump pathologist. I have witnessed some expensive startup mistakes that could have easily been avoided if only the operator had simply read and observed a few key points in the instruction book.
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Let’s start with a few basic steps that are true regardless of the pump type, model and application.
Sounds pretty simple so far, but please let me offer some advice. In the words of author Stephen Covey (“Seven Habits of Highly Effective People”), you must “start with the end in mind.” Before starting the pump, did you first envision a smooth operating pump that was producing the proper flow and head while operating at the best efficiency point (BEP) with no problems? If you did, then you missed a few steps in the previous startup procedure.
All too often we will find ourselves at the pump, not properly prepared for the initial startup and accompanied by an impatient operations supervisor pushing to “just start it up.” The issue here is that in reality there is a long list of items that should have been accomplished and/or checked before this high drama startup moment arrives. Pumps are expensive, and you can easily waste all of the cost and more in the one second it takes to push the start button.
Another troublesome issue I frequently observe is that the person with the least amount of operating experience is selected as the supervisor for the startup. The person is selected for several reasons, which are unofficial but nevertheless realistic, including: the startup is on third shift or a weekend or a holiday; the building is not heated; the building is not cooled; there is no building and the weather is miserable; the site is remote; and finally, the fatal assumption that a formal education means you surely had a class on pump startup somewhere in the past.
I will limit the discussion to “things” that are required and or recommended prior to startup. The more complicated the pump and the system, the more steps and checks required. I will not cover more sophisticated installations and procedures, because these operators typically have extensive training and experience.
Regarding proper pump selection, there are also countless numbers of decisions and action steps that should have taken place long before this critical moment we call startup (alternate title: “Things You Should Have Done Prior to or During Installation”).
Examples of these basics that should have been done earlier are foundation design, grouting, elimination of pipe strain, ensuring sufficient net positive suction head (NPSH) margin, pipe size and system geometry, materials choices, system hydro test, system instrumentation, submergence calculations and auxiliary systems.
American National Standards Institute (ANSI) pumps are some of the most ubiquitous pump types in the world. Consequently, I will address a few things that are important for this group.
ANSI pumps include adjustable impeller clearance settings. There are basically two styles that are the opposite of each other, but regardless of the style they must be adjusted to the proper clearance prior to startup. The mechanical seal will also need to be adjusted and set. Note: It is imperative to set the seal after the impeller clearance is set or the setting/adjustment will change.
The direction of rotation on ANSI pumps is extremely important because if the pump is rotated in the wrong direction, the impeller will immediately “expand” (unscrews from the shaft) into the casing and cause expensive damage to the casing, impeller, shaft, bearings and mechanical seal. For this reason, these pumps are typically shipped without the coupling installed. It is essential to perform the driver rotation check prior to the coupling installation. Skipping this step is unfortunately a common problem.
Often misunderstood, or simply overlooked, the pump must be primed prior to startup. Even a self-priming pump must be primed the first time. The brief definition of primed means that all the air and noncondensable gases are removed from the pump and suction line and that only liquid is present in the system. If the pump is in a flooded system, the process of priming is easy. A flooded system simply means that the source of liquid is at an elevation above the pump impeller centerline—gravity is your friend in the priming process. To remove the air and noncondensable gases, you still must vent them outside of the system. Most systems will include a vent line with a valve or a removable plug to facilitate this. If there is no means of venting, you will need to be creative, and those methods are perhaps the subject of a future column.
You cannot properly vent a running pump. The heavier liquid will be expelled while the lighter air/gas and will stay in the middle of the pump, often trapped in the eye of the impeller and/or the stuffing box/seal chamber. Think centrifuge principles of operation and realize water is almost 800 times heavier than air. Improper venting explains that squealing noise you will hear on startup that goes away after a minute and immediately before the mechanical seal starts to leak because it ran dry. Most seal chambers/stuffing boxes should be separately vented prior to startup. Pumps with throat bushings (restrictive) bushings in the stuffing box will present specific challenges to vent. Some designs, specific seal flush systems and some accessories will allow this evolution to occur automatically. Don’t assume your system has the special design.
Vertical pumps present their own special requirements for venting. Because the stuffing box is at the high point, you need to take extra precautions in these cases.
A pump that has a centerline discharge nozzle will typically lend itself to automatic venting, but not necessarily the stuffing box or seal chamber. Pumps that are horizontal split case or have a tangential discharge will require that the casing be vented by some other means. No matter the pump type, the air still needs somewhere to go, so be sure it has a place to go. Magic is not an acceptable response.
When the liquid source is below the centerline of the impeller (lift situation) you will need to vent and prime the pump in some other manner. The three main methods are:
Foot valves are notorious for failing or jamming at the worst time in either the full-open or full-closed position. You may not realize that it is not working when it fails in a partial position.
Any air in the suction line still needs somewhere to go (otherwise it is trapped), and the pump will not be able to compress it. You will require some type of vent line or automatic air relief valve. If there is a downstream check valve, the pump will not be able to create sufficient pressure to lift and open the check valve.
Self-priming pumps or pumps that are primed from another source will need to have lubrication to the mechanical seal during the startup and priming process. Many self-primers handle this issue with a design that uses an oil-filled seal chamber. Of course, the pump is not necessarily shipped with oil in that chamber, and you need to add it prior to startup. Other pumps will require an external source of lubrication and or independent seal flush system.
Self-primer pumps in operating mode will not leak liquid out of the suction line or the seal chamber because those areas are typically under some vacuum, but do realize that air will leak in.
Keep a record the data: bearing temperatures, flow, pressure (head), amps, voltage, frequency, vibrations and ambient conditions.
Part 2 of this column will appear in the next issue of Pumps & Systems. Read it here.
Read more Common Pumping Mistakes articles here.
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