Abstracts CMVA 2022 ATC

 

Here are some of the abstracts from presentations you will be seeing at the CMVA Annual Technical Conference on October 26 & 27, 2022 at Niagara Falls, Ontario.

 

Examination of the FFT Batch Process with Calculation of the RMS Energy

The Fast Fourier Transform (FFT) is used in vibration analysis. It is well known that Window Filters (Hanning, Flat Top, etc.) can be applied to the time waveform during the batch processing of the FFT, and as a result, decrease the resolution of the FFT. The resolution is decreased by a numerical Window Factor based on the applied filter. It is not well known that the Window Factor (WF) can also be described as the Equivalent Noise Bandwidth (ENBW) or Noise Power Bandwidth. This paper will explain how to calculate the RMS Energy of the FFT when the WF or ENBW used to process the FFT has a numerical value greater than one.

 

Vibration 101 – Fundamentals for Asset Management and Reliability Professionals

Although the asset management or reliability professional are not necessarily analyzing vibration spectrum and waveforms, basic understanding of the vibration world goes a long way to understanding why vibration techniques are a cornerstone technology for asset management strategy (ISO 55XXX).  This short course will review nine (9) elements of ISO 18436-2 vibration knowledge that provide the asset management or reliability professional with basics knowledge and skills for vibration application  – principles, acquisition, processing, monitoring, fault isolation, acceptance testing, diagnostics, severity and balancing.

 

Hydro generator Vibration Troubleshooting

This paper follows the case study of troubleshooting elevated and unstable upper guide bearing vibration on a 120 MW Pelton hydro unit following a recent rotor major inspection. Inconsistent responses during testing were observed based on the rate of change of turning speed during startup, bearing and stator temperatures, generator field excitation and therefore magnetic unbalance, as well as generator active and reactive power loading. A single plane field balance procedure was employed near the upper guide bearing to minimize turning speed frequency excitation forces at this location. Additional testing was performed to confirm that vibration levels were successfully reduced to within acceptable limits for normal operating regimes allowing for unrestricted release to operations. However, this only addressed the symptoms and not the root cause which is believed to be related to early indications of fitment issues, either, the thrust block to shaft and/or of the generator rotor rim to spider due to aging. Further investigation will be performed on a sister unit which anecdotally seems to have a similar issue at an upcoming outage. More to come…

 

Primary Heat Transport Pressurizing Pump – Commissioning Problems

This case study summarizes the problem of repeat thrust bearing failures encountered during the commissioning  of the primary heat transport (PHT) pressurization pumps and the resolution of the issue. The PHT pressurizing pumps is an Ingersoll Rand – HMTA, 10 stage pump designed with impeller suction facing the same direction creating a resultant thrust which is absorbed by the balance drum and thrust bearings. The pumps were initially commissioned in the 1970’s. The PHT system is a closed loop that removes heat from the reactor fuel and transports to the boilers, the PHT pressurizing pumps is used to maintain the system pressure of the system. U2 was in laid up state and had undergone a major refurbishment. During the pump start up of 2-33310-P2, the thrust bearing failed within 20 seconds. Resolution of repeat failures required the understanding of the cause, revising the maintenance procedures to resolve the problem. Keyword: Precision Maintenance.

 

Overcoming Challenges for Accurately Measuring Vibration in Vertical Pumps

Vertical turbine pumps have unique reliability challenges identifiable through vibration analysis of the below-ground stationary assembly. Sump-induced problems, excitation of a stationary assembly mode shape, and recirculation-induced cavitation all reveal themselves through vibration analysis. Unfortunately, most vertical pumps do not have the monitoring that detects these failure modes. Vibration measurements are usually only taken at the motor and/or accessible above ground components; this does not provide a clear picture of the overall health of the pump and machine train. Damping from the foundation, false readings from an above ground resonance, and distance from the vibration source all result in observations that do not accurately represent conditions at the impeller. There are many challenges that make measuring vibration at the source difficult to achieve. Ensuring secure attachment of submerged accelerometers and durability of connecting cables can be challenging. At the above ground level, providing wiring, power, cables, and PLC connections can be costly and create a hazardous work environment. To get a more accurate picture of vertical pump health, Hydro has developed a solution that overcomes the challenges of monitoring vertical pumps.  Our vertical pump monitoring system combines wired accelerometers and wireless transmission to capture data at high frequency intervals. This innovation greatly reduces the required cables, does not require wired power, and allows remote access and analysis of collected data. By instrumenting the below-ground assembly of vertical pumps, plants can achieve significant improvements in warning time when unfavorable conditions are developing. This can also confirm that conditions have not deteriorated, justifying a lifetime extension – lowering total cost of ownership and improving plant reliability. Finally, high frequency, continuous data acquisition provides a better understanding of how different operating conditions – such as seasonal changes, water level changes, etc. – affect reliability so that improvements can be designed to counteract these factors.

 

Pickering B Emergency Low Pressure Service Water (ELPSW) Pump Vibration Case Study

“There are 4 ELPSW vertical pump-motor sets per Unit (5/6/7/8-71310-P1/2/3/4) for a total of 16 across Pickering B units. Although the Pickering B ELPSW pumps were intended to provide backup cooling water flow, they are commonly used for continuous service with the unit at power. There has been elevated vibration levels at the motor locations and this was addressed by a dynamic absorber mass installed at motor non-drive end to eliminate resonance at running speed. However, recently there has been increases in vibration levels at the motor locations that required further troubleshooting to determine the cause.

 

Case study of a Power Turbine

A power turbine had been experiencing vibration trips during normal operation. During the event, a one-half (1/2X) vibration component emerged in the spectrum. This usually a good indication of that a light rubbing may have been developed at a seal area. Data analysis helped understand its vibration behavior and locate the rubbing area.  The understanding was rather helpful for maintenance and operation teams going forward.

 

A Proven Approach to Condition Monitoring for Reciprocating Machinery

Traditional Vibration Analysis (VA) or Spectrum VA is widely utilized on rotating machinery in all types of industrial applications to diagnose and troubleshoot machinery issues. In conjunction with other technologies, VA allows predictive maintenance personnel to pinpoint machinery failures like unbalance, misalignment, bearing issues, etc. This diagnosis is completed by analyzing the vibration frequency spectrum of an event and its correlation to the machine and conditions. For reciprocating machinery, however, spectrum analysis is not the most effective tool for determining defects as the expected mechanical events and the failure modes are best identified in a time-based waveform and referenced to a known point on each cylinder such as Top Dead Center (TDC).  In the reciprocating analysis world, this is known as crank angle-based data, which does not utilize the frequency spectrum, but rather examines events relative to crankshaft positions. By combining vibration in different frequency ranges with in-cylinder pressure data and utilizing basic thermodynamic and combustion principles, it is possible to determine defects in reciprocating machine equipment such as compressor cross head damage and cylinder leakage (valves, rings, and packing) as well as engine valve train and cylinder-related issues. This paper will provide an overview of engine and compressor analysis and explain how crank angle-based data can pinpoint issues as compared to traditional VA.  A review of ISO Guidelines for reciprocating compressors will also be discussed.

 

What can go wrong with vibration sensors?

“Subjects covered in presentation are putting attention on challenges which are connected to vibration sensors details to be successful with projects.

1) Vibration sensors details as part of Reliability Culture Implementation

2) Selection of right type of output

3) Selection of proper sensitivity – over saturation and too low signal

4) Internal sensor construction

5) Enviromental conditions

6) Screening

7) RFI interference

8) Mounting aspect”

 

Oil Sample Procedures and Used Oil Analysis Interpretation

“Oil sampling is one the ways to check and identify the health of an equipment, which can prevent a costly unexpected shut down and / or equipment repair. The knowledge of oil sampling, its best practices, and Oil Analysis and Result Interpretation plays a crucial and critical role in proactive / predictive maintenance planning. The corrective actions can save millions of dollars of production. In this presentation, I will cover the followings:

– Justification for Oil Sampling and Oil Analysis

– Best Practices in Oil Sampling

– Oil Analysis and Result Interpretation”

 

Experimental and Numerical (FEA) Investigation of Vibration Modes of Propeller Type Blade of a Hydro Turbine

Runners of hydroelectric power generation system are subjected to various excitation mechanisms.  The natural frequencies and mode shapes are important parameters which determines the behavior and response of the runner to different excitations.  One of the important aspects of dynamic response of runner is the effect of water known as added mass effect.  Added mass effect lowers the natural frequency of a system while submerged in water as compared to in air.  This paper presents the mode shapes of a propeller type runner blade determined experimentally and through Finite Element Analaysis (FEA). Good agreement was found between the experimental and FEA results.  FEA analysis was further extended to include the added mass effect and determine the natural frequencies and mode shaped in water.  The results are compared and discussed.

 

Wireless Sensor Technology – A New Era for Data Security

As wireless sensor technology begins to take the leading edge within the industrial internet of things community, a new era of data security has emerged that requires diligent thought and consideration on the part of end users, system integrators and key stake holders. Critical machine health and process data being transmitted wirelessly and hosted internally as well as externally creates an entirely new series of security concerns that must clearly be understood to maximize the value of the technology. This presentation will focus on the key security tools available to end users to ensure the security of their data when deploying wireless sensor networks and hosting data internally as well as externally to their organizations.

 

Wanted – Vibration Analyst

Personal thoughts on where we have been and where we are going with vibration analysis.

 

My 30 years of experience as a reliability specialist.

“A career in vibration analysis cannot be improvised. It takes a whole entourage to train a good analyst. Interest in vibration analysis begins early, with the influence of a teacher, the expertise of a consultant who came to diagnose an old compressor or a colleague who is himself a reliability specialist. Then comes the CAT I training and certification, and CAT II, ​​a

few years later. These trainings allow the analyst to understand the basics of the job; but this is not enough. The reliability specialist is regularly confronted with new problems, with new machines, which often behave strangely. To overcome this, the analyst will have to pursue training of all kinds throughout his career: lubrication, thermography, etc. He will also have to surround himself with mentors, more experienced analysts who will help him through his many diagnoses. The CMVA is one of many tools that help analysts make new contacts, learn and gain experience. Being an analyst is not only technical, it is also having the qualities of a diplomat! When it comes to stopping a plant following the diagnosis of a serious problem with an engine bearing, it is not always easy. It takes tact and a lot of credibility. This work also requires high availability: the machines don’t always break down at 9 a.m. on Monday morning. In summary, this work is not routine and almost requires a vocation!”

 

Online vibration monitoring system selection and installation – trials, tribulations and successes

The selection and installation of an online vibration monitoring system can be a complicated task with many variables and potential problems to be aware of. Considerations include cost, availability of components and replacement parts, warranties, ease of installation, configuration and maintenance. The least or most expensive system may not be the ‘best’ for your reliably program goals, and those goals may not be clearly defined. This paper discusses some of the experiences of the authors’ observations over the last 20+ years of being involved with online vibration systems, including the more recent and increasingly popular wireless systems. Pricing, physical characteristics, long term considerations including maintenance and software evolution will be included in the discussion.

 

The Electric Motors and Their Vibration

Most of the equipment that we monitor every day is driven by an electric motor.  All these motors may look similar but, they are different.  Each motor has been selected for a specific application.  When looking inside the motor, we can see that the rotor and the stator are different from one motor to another one.  This will modify the behavior of the motor.  A motor design for driving a compressor will not necessarily fit for a water pump or a conveyor.   Theses difference in their construction will have an important influence on their own vibration.  In this presentation we will examine different types of motors and their vibration.