Do you listen to your equipment? Do you hear motors complaining about overload? Do you see your pump packings crying a flood? Do you hear you bearings whine about contaminated lubricants? Do you notice your steam system that coughs excessive condensate and it’s complains about strained elbows?
There are two types of people in mills. There are people who notice when equipment show signs of distress, and people who don’t.
We often call people who don’t see the signs of distress in equipment “mill blind” people. The mill blindness may not be intentional, but rather a product of being so used to the environment, poor equipment condition just isn’t noticed.
Let us supply you with a small informal “mill blindness” test for you. Below are a few examples of “mill blindness” we often see in pulp and paper mills. Most of you have at some point seen these equipment problems before, but ask yourself, are we accepting these conditions or are the problems corrected in our mill?
Basic Equipment Condition Monitoring
Leaking rotary joints are so common in many mills that they have become accepted over the years. It’s not unusual for new employees in a paper machine area to be told that leaking rotary joints are normal, and that leaks can’t be detected before steam is coming out of the joint.
Steam joints often leak when the carbon ring wears inside the joint, the carbon ring is designed to wear and begin leaking after a certain amount of wear. The wear in most joint designs can be easily measured since the carbon ring is spring loaded and two surfaces of the joint move as the ring wears.
For example, a certain Valmet model requires carbon ring change when the distance (a) in figure 1 wears to 0.59 in. (15 mm). Many Johnson joints have a pin to indicate the amount of wear on the carbon ring.
Figure 1. Valmet steam joint.
Spare Parts Storage
Spare parts storage can have a huge impact on the level of planning and scheduling of maintenance jobs and the reliability of equipment. But, we often forget that reliability can also be directly impacted in a negative manner if there is incorrect management of spare parts.
Some spares are perishable goods, such as components with rubber or plastic materials like belts, couplings and o-rings.
The commonly used orange peel coupling has a “best before date” when purchased, they are designed to last five to six years whether in use or in storage. It is common to find couplings 5+ years old in stores even though their life has already been exceeded.
Bearings should be wrapped and sealed in order to avoid contaminants in the bearing. It’s not uncommon to find bearings unwrapped and dusty in a store room.
Mill sites often have a small vibration in the store room from surrounding equipment.
When bearings are fixed in the same position, the vibration causes fatigue damage inside the bearings, because the bearing balls keep “tapping” the outer bearing race.
Shafts on stored motors should therefore be turned a quarter turn on a periodical interval to reduce the damage.
Take a look in your store room, are the shafts of motors for store room personnel to be turned?
Figure 2. Top, bearing stored without protective wrapping. Bottom an “orange peel” coupling with manufacturing quarter and year on the sticker to indicate perishable date.
If you have questions or comments regarding this article, please contact us at info@idcon.com or visit the website for more information.
Oil analysis is a valuable tool for determining the condition of lubricating oil and the equipment it lubricates. It is best used as a trending process — not a one-time event. When collecting oil samples for routine oil analysis, where and how should you do it?
Oil analysis is a valuable tool for determining the condition of lubricating oil and the equipment it lubricates. It is best used as a trending process — not a one-time event. When collecting oil samples for routine oil analysis, where and how should you do it?
The need for health monitoring in industrial machines using vibration analysis for diagnosis is an ever growing requirement in all types of industries and equipment. Vibrations in machinery can take various forms, and most of the time these vibrations are unintended and undesirable. Therefore, monitoring the vibration characteristics of a machine can provide the information of its health condition, and this piece of information can be used to detect problems that might be incipient or developing.
The need for health monitoring in industrial machines using vibration analysis for diagnosis is an ever growing requirement in all types of industries and equipment. Vibrations in machinery can take various forms, and most of the time these vibrations are unintended and undesirable. Therefore, monitoring the vibration characteristics of a machine can provide the information of its health condition, and this piece of information can be used to detect problems that might be incipient or developing.
Vibration analysis, properly done, allows the user to evaluate the condition of equipment and avoid failures. Maintenance personnel can minimize unplanned downtime by scheduling needed repairs during normal maintenance shutdowns. How can you interpret — at a glance — the comprehensive spectrum information available? In layman's terms, here is how to interpret the vibration signature of rotating equipment. You can learn to recognize misalignment, a defective bearing, bent or loose parts — and tell them apart.
Vibration analysis, properly done, allows the user to evaluate the condition of equipment and avoid failures. Maintenance personnel can minimize unplanned downtime by scheduling needed repairs during normal maintenance shutdowns. How can you interpret — at a glance — the comprehensive spectrum information available? In layman's terms, here is how to interpret the vibration signature of rotating equipment. You can learn to recognize misalignment, a defective bearing, bent or loose parts — and tell them apart.
Predictive maintenance (PdM) techniques are commonly used on motors and drives. But how often is the power to the equipment inspected? Adding basic power quality measurements to equipment maintenance procedures can head off unexpected failures in both the equipment and the power system.
Predictive maintenance (PdM) techniques are commonly used on motors and drives. But how often is the power to the equipment inspected? Adding basic power quality measurements to equipment maintenance procedures can head off unexpected failures in both the equipment and the power system.
Pump reliability is an old topic, but it is just as relevant today as it was the first time we heard it a few decades ago. There are some very good reasons to focus on improving pump reliability. The rewards for achieving pump reliability are great and the effort, on the surface, seems fairly simple. After all, most of the elements of reliability are just common sense. But Ralph Waldo Emerson expertly put this idea into perspective when he said: "Common sense is as rare as genius."
Pump reliability is an old topic, but it is just as relevant today as it was the first time we heard it a few decades ago. There are some very good reasons to focus on improving pump reliability. The rewards for achieving pump reliability are great and the effort, on the surface, seems fairly simple. After all, most of the elements of reliability are just common sense. But Ralph Waldo Emerson expertly put this idea into perspective when he said: "Common sense is as rare as genius."
Every component of a bolted flange joint has a maximum allowable stress level. The mating flanges will begin to rotate or warp at a defined stress threshold. The studs or bolts of a given specification also will yield or be stressed past their elastic properties at a defined level. Non-metallic and semi-metallic gaskets will crush under excessive applied stress loads.
Every component of a bolted flange joint has a maximum allowable stress level. The mating flanges will begin to rotate or warp at a defined stress threshold. The studs or bolts of a given specification also will yield or be stressed past their elastic properties at a defined level. Non-metallic and semi-metallic gaskets will crush under excessive applied stress loads.
When Benjamin Franklin wrote, “An ounce of prevention is worth a pound of cure,” he was referring to fire safety. But, as you may know from experience, this saying holds true with regard to preventive maintenance (PM). Simply stated, preventive maintenance is an activity performed at a set interval to maintain an asset, regardless of its current condition. It’s a properly planned activity, where materials and parts are on hand and labor is scheduled ahead of time.
When Benjamin Franklin wrote, “An ounce of prevention is worth a pound of cure,” he was referring to fire safety. But, as you may know from experience, this saying holds true with regard to preventive maintenance (PM). Simply stated, preventive maintenance is an activity performed at a set interval to maintain an asset, regardless of its current condition. It’s a properly planned activity, where materials and parts are on hand and labor is scheduled ahead of time.
