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.
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The potential-to-functional failure interval (P-F interval) is one of the most important concepts when it comes to performing Reliability-Centered Maintenance (RCM). Remarkably, the P-F interval is also one of the most misunderstood RCM concepts. The failure mode analysis becomes even more complicated when you are dealing with several P-F intervals for one failure mode. This paper will help clarify the P-F interval and the decision-making process when dealing with multiple P-F intervals.
The potential-to-functional failure interval (P-F interval) is one of the most important concepts when it comes to performing Reliability-Centered Maintenance (RCM). Remarkably, the P-F interval is also one of the most misunderstood RCM concepts. The failure mode analysis becomes even more complicated when you are dealing with several P-F intervals for one failure mode. This paper will help clarify the P-F interval and the decision-making process when dealing with multiple P-F intervals.
This column is likely to create a lot of reactions from the academia of reliability and maintenance management, and all comments are welcome. Reliability Centered Maintenance (RCM) has its place, but many times plants jump into training programs and attempt to implement RCM long before they are ready for it. This application makes RCM more of a trap, than a helpful tool to implement.
This column is likely to create a lot of reactions from the academia of reliability and maintenance management, and all comments are welcome. Reliability Centered Maintenance (RCM) has its place, but many times plants jump into training programs and attempt to implement RCM long before they are ready for it. This application makes RCM more of a trap, than a helpful tool to implement.
Reliability Centered Maintenance is a step-by-step instructional tool for how to analyze a system's failure modes and define how to prevent or find those failures early. RCM become a very detailed study of things we already know, you will often hear the justification "it's to make sure we don't miss anything." If you are considering implementing a reliability centered maintenance program, you. should be aware of the problems you may run into.
Reliability Centered Maintenance is a step-by-step instructional tool for how to analyze a system's failure modes and define how to prevent or find those failures early. RCM become a very detailed study of things we already know, you will often hear the justification "it's to make sure we don't miss anything." If you are considering implementing a reliability centered maintenance program, you. should be aware of the problems you may run into.
Maintainability can be defined as the ease in time and resources of retaining equipment in or restoring it to a specified operational condition. It directly affects the bottom line because it can impact operations, downtime, maintenance costs, and safety. Maintainability is an important aspect of any system's lifecycle, but process plant engineers typically give it little direct consideration. This is primarily the result of a short-term view of capital project costs that fails to consider lifecycle costs and downstream activities.
Maintainability can be defined as the ease in time and resources of retaining equipment in or restoring it to a specified operational condition. It directly affects the bottom line because it can impact operations, downtime, maintenance costs, and safety. Maintainability is an important aspect of any system's lifecycle, but process plant engineers typically give it little direct consideration. This is primarily the result of a short-term view of capital project costs that fails to consider lifecycle costs and downstream activities.
When maintenance is allowed to interact with the plant and production Original Equipment Manufacturer (OEM), a prosperous relationship for both parties will often ensue. This OEM partnership results in first-hand information for maintenance to set up its maintenance approach, and valuable operational and design feedback for the OEM. There are seven main circumstances in which maintenance will interact or communicate with an OEM and form an OEM partnership.
When maintenance is allowed to interact with the plant and production Original Equipment Manufacturer (OEM), a prosperous relationship for both parties will often ensue. This OEM partnership results in first-hand information for maintenance to set up its maintenance approach, and valuable operational and design feedback for the OEM. There are seven main circumstances in which maintenance will interact or communicate with an OEM and form an OEM partnership.
