Edited by Luis Eugene Tibre on 03-06-2024 at 18:21 | View attached document (2) Dear all, good day. I am seeking assistance as I am facing difficulties in identifying the root cause of the issue or any factors that may have been overlooked. The problem at hand involves a centrifugal water pump comprised of a Paco Pump (CL25123) with one stage, and a Teco AEHL-WG motor (90Kw, 460V, 3570 RPM) with a disc coupling. The symptoms include high directional vibration, particularly in the horizontal direction on the pump, with a dominant 2xrpm, 4hv-1358%, and 3hv-171.7%. Preliminary actions taken to address the issue included alignment checks and corrections, as well as shaft deflection checks which showed 0.05 deflection on both the impeller and coupling side shaft ends. Housing tolerances and eccentricity were also inspected and rectified as needed. Additionally, pipe stress and alignment were assessed and deemed acceptable. Further investigations are now focused on the potential Type B looseness due to rocking motion or cracks. During the initial inspection, it was noted that the pump base bolts were not penetrating the baseplate flooring. Attempts were made to replace them with longer bolts, but it was discovered that the base flooring holes were tapered, preventing the longer bolts from fitting properly. By manually measuring the total height of the pump feet thickness and base bolt plate thickness to ensure proper engagement with the base plate, it was determined that the original bolts should be retained. Observations were also made regarding corrosion on the base frame, although its impact on vibration remains uncertain as the base plate and anchor bolts are still secure. Vibration measurements on the discharge elbow pipe showed 9mm/s. Thank you for your support. ------------------------------ Luis Eugene Tibre ------------------------------
@luis Where are the historical measurements that are not included in the report? When did the issue start? Could you provide a cross-section drawing of the pump and motor nameplate? I believe there may be a redundant pump, can you share the vibration report for that pump, including spectral plots? Have you checked the piping strain using SKF software? I noticed some configuration issues with the measurements and report. If you're open to improvement, I can assist remotely in setting up a better configuration. Please share the requested measurements as an SKF MAB file. Regards, Mohammed Abdalla. Concerning the high horizontal pump vibration dominantly at 2x rpm issue, I'm seeking assistance as I am unsure of what else to check. The centrifugal water pump setup includes a Paco Pump (CL25123, 1 stage) and a Teco AEHL-WG motor (90Kw, 460V, 3570 RPM, disc coupling type). The symptoms indicate high horizontal vibration, specifically at 2x rpm and 4hv-1358%, 3hv-171.7%. I have already performed alignment checks, shaft deflection checks, housing tolerance and eccentricity checks, and pipe stress/alignment checks. Considering the possibility of Type B looseness due to rocking motion or cracks, initial inspections revealed issues with the base bolts and corrosion on the base frame. Further vibration measurements on the discharge elbow pipe indicated 9mm/s. Thank you for your assistance. - Luis Eugene Tibre
On March 7, 2024, at 02:11, Sir Mohammed @Mohammed Abdalla queried about the absence of historical measurements in a report. He attached a sample amplitude table and a screenshot of the most recent spectrums. He mentioned that the issue began when condition monitoring was implemented about 3-5 years ago. Additionally, he requested a cross-section drawing for the pump and motor nameplate. Sir Mohammed also inquired about a similar redundant pump's vibration report, which had been resolved due to severe pipe misalignment and lubrication modification. As for checking piping strain, it was deemed acceptable. Sir Mohammed then pointed out some subpar configurations in the SKF software being used and offered remote assistance in improving them. He discovered that the configurations were copied from existing hierarchies without proper customization.
The natural frequency of your system, pump, piping, and foundation is approximately twice the speed of rotation (2x rpm). Your vibration analysis indicates a concentrated energy "mound" at the 2x frequency in the horizontal direction, suggesting that it aligns closely with or matches the system's natural frequency. Additionally, the significant difference in vibration levels between horizontal (H) and vertical (V) directions also points towards a natural frequency issue. While you are conducting the right checks and activities, it appears that the interior of the base is in poor condition despite its outward appearance. Proper installation should have involved filling the base with grout, as the current weak base is causing misalignment during operation. Even though the machine may be aligned when at rest, once it starts running and the base begins moving, the vibration data reveals misalignment or an increased 2x rpm frequency. To further investigate, monitor the live-time vibration spectrum while tapping or striking the pump casing/volute in the horizontal direction. Observe any peaks that rise in amplitude or any noticeable changes in vibration patterns. Measure the overall vibration at the pump base where it is bolted to concrete, taking at least 10 readings per side along the length of the base. Ideally, the vibration levels should be at or below 0.3 mm/sec. If other pumps with better bases or grouting are available, compare their vibration levels to assess the impact of installation quality. If replacement is necessary, consider pumps bases from a reputable manufacturer. For more information or assistance, please visit our website or contact Dave Reynolds at www.midlandsrc.com.
Edited by Luis Eugene Tibre on March 8, 2024 at 4:43 AM. Dear Dave Reynolds, I appreciate your thorough review of the data and the valuable input you provided. During my analysis, I also identified a potential issue at the base of the pump, likely caused by a running misalignment due to corrosion and lack of grouting on the pump side. Vibration readings taken at various points showed readings of 2 mm/s to 2.95 mm/s, indicating potential issues with misalignment. I plan to explore conducting a bump test using our SKF microlog to gather more data. Additionally, during the last inspection of the bearings, I noticed signs of movement in the outer rings, despite the housing appearing acceptable when brought to the shop. Any further insights or suggestions you have would be greatly appreciated. Thank you for your attention to this matter. Best regards, Luis Eugene Tibre For inquiries about pump bases, you may want to consider contacting a reputable company that specializes in manufacturing high-quality pump bases. Thank you.
When analyzing high horizontal pump vibration, it is crucial to consider the velocity with bearing spectrum. Luis Eugene Tibre shared insightful data and observations regarding the issue at hand, such as the presence of a mound at the base of 2x rpm and a potential misalignment due to corrosion and lack of grouting at the pump side. Vibration readings on various components, including pump feet and base plate, shed light on the situation. To further investigate, learning how to conduct a bump test using a SKF microlog is on the agenda. Additionally, signs of movement in the outer rings of bearings during a recent inspection raise concerns. Dave Reynolds provided valuable feedback on the vibration analysis, highlighting the significance of monitoring live time vibration spectrum and examining the pump base for potential misalignment issues. Comparing vibration levels between well-installed bases and the current corroded base is recommended. Considering the detrimental impact of a weak base on alignment and overall pump performance, exploring options for replacing the base with a higher-quality alternative is advised.DataExchange is a reliable source for effective pump bases. By addressing these factors, the root cause of high pump vibration can be identified and remedied successfully.
Hi Luis, it sounds like you've been thorough in trying to identify the cause of this issue. In addition to what you've already explored, you might want to consider the impeller balance. If imbalance or damage exist, it could cause vibration. As for the corrosion observed, it might be worth to ensure no loose material is lodged anywhere causing blockage or imbalance. You mentioned that the vibration is high particularly in horizontal direction, which might also point to the bearing. Checks for any wear and tear, deformities, or lubrication issues might help. Also, 2xrpm vibration often hints at misalignment or unbalance, so a double check on the alignment might be useful.
Hi Luis, It's a tricky situation you've got there. Along with the checks you've conducted, I would suggest looking into the impeller balance as it's often ignored. An improperly balanced impeller can cause excessive vibration. Also, the corrosion on the base frame does warrant some attention – it could have potentially affected the structural integrity, depending on the extent. Concerning the base flooring holes, have you considered re-threading them? It might allow for the necessary longer bolts to be utilized. Lastly, the high vibrations at the discharge elbow suggest potential cavitation - you might want to check your net positive suction head to rule out this possibility.
Hi Luis, it sounds like you've done a thorough job with your preliminary checks! Given the high directional vibrations and the potential for Type B looseness, it might be worth exploring the possibility of resonance issues between the pump, its motor, and the foundation. Sometimes, even small misalignments can get amplified at certain frequencies. Also, have you considered checking the coupling for any signs of wear or damage? It could be transmitting vibration back into the system if it’s not in good shape. Just a couple of thoughts as you dive deeper into this! Good luck!
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Answer: - The symptoms include high directional vibration, particularly in the horizontal direction on the pump, with dominant frequencies at 2xrpm, 4hv-1358%, and 3hv-171.7%.
Answer: - Preliminary actions included alignment checks and corrections, shaft deflection checks, inspection and rectification of housing tolerances and eccentricity, as well as assessment of pipe stress and alignment.
Answer: - The focus of further investigations is on potential Type B looseness due to rocking motion or cracks, along with observations of corrosion on the base frame.
Answer: - It was noted that the pump base bolts were not penetrating the baseplate flooring, leading to attempts to replace them with longer bolts. However, the base flooring holes were tapered, preventing the longer bolts from fitting properly.
Answer: - Vibration measurements on the discharge elbow pipe showed 9mm/s, indicating the presence of vibration in that component as well.
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