A Better Black Liquor Process – Vacuum Leak Inspection

August 15, 2017

Reposted from ReliabilityWeb

One method of detecting vacuum leaks is to use airborne ultrasound detection, a technology already widely used for positive leak detection in compressed air systems. But finding vacuum leaks is not as straightforward as finding pressure leaks, and often times, the method is abandoned in frustration.

One problem here is the quality of the ultrasonic instrument which can vary significantly from one manufacturer to another. Lesser quality detectors cannot function well in high noise situations.  They simply have difficulty differentiating a leak sound from ambient plant noise. Since vacuum pumps already generate a lot of background noise, rarely will an inspector perform vacuum leak inspections in a quiet atmosphere.  Another problem is lack of inspector training which really plays a role when searching for vacuum leaks in high noise environments.

Just like positive pressure leaks, vacuum leaks produce a rushing, whooshing ultrasonic signal with peaks around 35-40 kHz. The ultrasound is caused by turbulent flow of air molecules at the leak site. Positive pressure leaks, such as those found in compressed air systems, push the turbulent flow outward making them easily detectable from several feet with a quality ultrasound tool. Vacuum leaks behave quite the opposite, drawing the turbulent flow inward, decreasing the distance of detection as compared with positive pressure leaks. Most of the telltale leak sound is contained within the body which means inspectors must diligently trace an entire installation leaving no stone unturned in the search for ingress.

Read the full story by Allan Rienstra – SDT International and Karl Hoffower – Failure Prevention Associates including details and photos for a Vacuum Leak Inspection on Multiple Effect Evaporator at major Pacific Northwest Pulp & Paper Mill.


Reliability Project – Don’t Stop the Beatings!

August 8, 2017

The word “thrashing” can mean many things.  Words like flogging, whipping, beating, head banging and many more are always included in the definition.  Do you constantly feel these effects when trying to manage or participate in a reliability project?  As a result, does the project become overwhelming, or lack support, or have steps and goals that keep changing and a desired outcome that is never reached?

One of the most overlooked ingredients for a successful project is overcoming resistance to change by key individuals.  These individuals may resist because they do not agree with the project steps, the outcome, or simply believe they will not benefit.  You must look at things through their eyes!  You cannot wait until the project is near completion to let these individuals “thrash” it and for you to “see” it from their perspective.  Schedule time and welcome thrashing at the beginning of the project.  As a result, you will be able to better convey project value, identify crucial things that should be included in the project design and then focus on the target completion date (ship date) and returning value back to your company.

The unfortunate fact is that we cannot stop our reliability projects from being flogged, beat up and whipped.  Take advantage of this reality and understand key aspects from everyone’s viewpoint early in the project.  Otherwise, you run the risk of having your project delayed and yourself beaten to death at the end.


Monitoring Plain Bearings With Ultrasound

August 1, 2017

For rotating machines, it is necessary to reduce friction most of the time to increase efficiency, decrease power losses and support loads. The element of choice is the well known team of bearing and lubricant. Bearings, in their different configurations, are one of the most efficient ways to reduce friction between a stationary and a rotational part of a mechanism.

Two broad classes of bearings exist: plain bearings and rolling contact bearings. Which type of bearing is used depends on several factors related to the design of the machine and its process. Sometimes both types are used in the same machine doing different jobs. For this article, the focus is on plain bearings.

Choosing the best technology to monitor friction and condition in plain bearings is a challenge. Due to the physical characteristics of plain bearings, using vibration analysis (VA) is more effective for rolling contact bearings and less so for plain bearings. Ultrasound (US) is trending more frequently for condition monitoring of rolling contact bearings and it also shows promise for plain bearings. Understanding the physical differences between the two bearing categories is critical for developing condition monitoring strategies for plain bearings using ultrasound.

Read on to find out more about plain bearing types, failure modes and how to monitor.

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Defining a Reliability Engineer

July 25, 2017

In order to determine what a Reliability Engineer should be, we must first look at the definition of Reliability.  Reliability can be defined as the probability that a device, system or process will continue to perform its given function without failure for a known time in a known environment.  Based upon this, the role of a Reliability Engineer can be easily defined as increasing the probability that assets will operate when required by determining and driving strategies that prevent failures.  In order to do this, the Reliability Engineer must apply analysis techniques that identify causes of failures, apply practices which prevent these failures and determine strategies which mitigate the consequences of failures that cannot be prevented.  In other words, keep equipment and processes running well.  When they do not, find out why and do something about it.  If you cannot do anything about it, then find a way to protect the processes or mitigate the consequences.

Reliability Engineers have a strategic and tactical role within an organization.  This means being a leader, mentor and teacher.  Developing, supporting and maintaining a reliability roadmap in accordance with clear reliability targets that contribute to the operational goals of the company.  Support efforts that ensure the reliability, operability and maintainability of equipment and processes.  And provide education and analysis that contributes to all of the above.

A Reliability Engineer should be many things, but definitely not a part time position, a firefighter, parts expeditor or reactivity manager when a failure occurs.

As an interesting exercise, write down how you define the role of a Reliability Engineer.  Ask several people to write down the top five things they believe define the role of a Reliability Engineer within your company.  The answers may be quite surprising and very telling about the real reliability culture within your company.

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4 Tips to Help Avoid Soft Foot in Your Machines

July 18, 2017

Soft foot can severely affect the operating condition of a machine, which will undoubtedly shorten its life expectancy. Here are a few simple tips to help avoid soft foot in your machines:

  1. Eliminate rust, dirt and any other contamination from the contact surfaces of the machine feet, shims and frame or foundation.
  2. Never insert more than four shims at a time beneath a single machine foot. More than three shims may cause a spring effect.
  3. Eliminate external forces on the machine such as those from connected piping, conduit, auxiliary supports, etc.
  4. Use high quality, clean and uniform shims when shimming is necessary.

Watch our Shaft Alignment Know-How video on Soft Foot

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