on Maintenance Reliability

Reduce the Variability in Your Work Routines and Procedures

Based on our understanding of the six failure patterns, we can see that there is a large probability of failure when the equipment is first installed and started up.   One of the Englisch causes of this increase in probability is the fact that the equipment was not installed or maintained correctly.  This may be due to the installer or maintainer not using or following procedures.  Having procedures is the first step to reducing these failures, but the procedures must be written in a clear, easy to follow manner.  When writing procedures, it is critical to ensure that there are no interpretations in the written instructions.  How can this be accomplished?

The universal language for aviation is english, which is considered very safe and reliable.  How has this industry been able to overcome the fact that many of the people involved in aviation are not native English speakers?   How does a large company such as Boeing supply aircraft all over the world and the customers perform the maintenance in a consistent manner?  The aviation and defense industries use a controlled language by the name of Simplified Technical English.

What is Simplified Technical English?

Simplified Technical English is a controlled version of English, that is designed to help the users of English-language maintenance documentation understand what they read.  Technical writing can be complex and difficult to understand even for native English speakers.  Complex writing can be misunderstood, which may lead to accidents or premature failures.  Simplified Technical English makes procedures easy to understand and follow, eliminating language issues and reducing premature and maintenance induced failures.

Simplified Technical English provides a set of Writing Rules and a Dictionary of controlled vocabulary. The Writing Rules cover grammar and style.  The Dictionary specifies the words that can be used and those that can’t be used. For the words selected, there is only one word for one meaning and one part of speech for one word.  Some of the benefits of Simplified Technical English may include;

• Reduce ambiguity
• Improve the clarity of technical writing, especially procedural writing
• Improve comprehension for people whose first language is not English
• Improve Reliability concerns of maintenance and assembly by reducing their probability to introduce defects

The Simplified Technical English specification is not easy to learn, but there are training and software available (if you are interested in this standard, please visit the ASD Simplified Technical English website).   The detailed contents of the Simplified Technical English specification will not be covered, but instead, the rest of the post will cover what you can immediately do to make your procedures more readable and drive reliability.

Writing Procedures Using Simplified Technical English

So without becoming an expert in Simplified Technical English, how can you begin to write better procedures?   You can begin with some basic writing practices and by reviewing the procedures before it issued.  Some of the basic practices to use when writing procedures include;

• Use short sentences. (The recommended maximum is 20 words in a procedural sentence and 25 words in a descriptive sentence.)
• Restrict noun clusters to less than 3 nouns
• Restrict paragraphs to less than 6 sentences
• Avoid slang or jargon
• Avoid the passive voice
• Be as specific as possible
• Use articles such as “a/an” and “the” wherever possible
• Use simple verb tenses (past, present, and future)
• Write sequential steps as separate sentences
• Put commands first in warnings and cautions, with the exception of conditions
  • For example, write Make sure that the valve is open. Do not write Make sure the valve is open.Use the conjunction that after subordinate clauses that use verbs such as make sure and show.
• Introduce a list item with a dash (hyphen).

Once the procedure is written, be sure to review and delete any information which is not relevant (i.e. Instead of synthetic lubricating oil, use only).  well-written should help in eliminating any interpretation and driving clarity.

Here is an example of how the wording of a procedural step could be open to interpretation.  The task “Replace the filter” could mean either of the following:

• Put back the filter that you took out.
• Install a new filter.

Now you can see how one person may perform a task and how another would perform it differently.  Once the task is clear, a technical specification should be added to ensure the task is performed to a standard such as;

• Tighten to 15 ft-lbs

The end result of ensuring the task is clear, and a specification is present is “Install a new filter and tighten to 15 ft-lbs”  This task is simple, clear and easy to understand.

When following these basic steps a well written procedure will be developed to ensure clarity and repeatability, thereby reducing maintenance induced failures.  Do you use a Simplified Technical English or a form of it in your procedures or job plans?  If not, how are you actively working to reduce maintenance induced and start-up related failures?

Remember, to find success, you must first solve the problem, then achieve the implementation of the solution, and finally sustain winning results.

I’m James Kovacevic
Eruditio, LLC
Where Education Meets Application
Follow @EruditioLLC

References;

• ASD Simplified Technical English, Specification ASD-STE100

Ensuring the Failure Data Collected Can Be Used To Drive Improvements In Any Organization

If you were to go into your CMMS and look at the hierarchy and equipment, would it be well laid out and organized?   Would you be able to drill down the to the lowest level of components to know what failures have occurred?  Can you see how pumps are performing across a specific area or the entire plant?  The chances are that for many organizations, this is not possible.   Why is that?  The asset hierarchy was not thought out ahead of time, nor was the right data collected and recorded in the CMMS.

Having a well-defined asset hierarchy is critical to the ability of the plant to drill down in costs and identify where the improvements efforts should be focused.  It also allows reliability staff to identify common issues across specific equipment types and classes, enabling what may be an improvement targeted for a specific area to be spread out across the site. [Read more…]

Preventing The Consequences Of A Hidden Failure From Devastating Your Organization.

Ever wonder how some of the worst industrial disasters occur?  It is usually the result of multiple failures.  Failure of the primary system and failure of the protective systems.   Ensuring the protective system(s) are not in a failed state should be of utmost importance to any organization.  But how often should we test the protective systems to ensure the required availability?

Establishing the correct frequencies of the inspection/ testing activities of these protective system(s) is critical to not only the success but safety and reputation of any organization.   Too infrequently and the organization is at risk of a major incident.  Too frequently, and the organization is subjected to excess planned downtime, an increased probability of maintenance induced failures and increased maintenance cost.
This article will continue the discussion on establishing the correct inspection frequency in a maintenance program.  There are three different approached to use, based on the type of maintenance being performed;

• Time-Based Maintenance
• On-Condition Maintenance
• Failure Finding Maintenance

This article will focus on Failure Finding Maintenance.

What Are Protective Systems, Hidden Failures and Failure Finding Maintenance

A protective system or device is a system or device which is designed to protect and mitigate or reduce the consequences of failure.  These consequences may be safety, environmental or operational in nature.   These devices or systems are designed to;

• Alert – to potential problem conditions (i.e. alarm)
• Relieve – prevent failure conditions causing greater problems (i.e. pressure relief valve)
• Shutdown – stop a process to prevent greater problems from occurring (i.e. motor overload)
• Mitigate – alleviate the consequences of a failure (i.e. fire suppression equipment)
• Replace – continue to provide a function by an alternative means (i.e. back up pump)
• Guard – prevent an accident from occurring  (i.e. E-Stop)

Knowing what a protective device or system is, you may see that if a pressure relief valve became corroded and seized in the closed position, it would not be evident to the operators.   This is a hidden failure.   A hidden failure can be defined as; a failure which may occur and not be evident to the operating crew under normal circumstances if it occurs on its own.  Obviously, this could lead to significant consequences if the tank that the pressure relief valve is protecting is overpressurized.   This is where failure finding maintenance comes in.

Failure-finding maintenance is a set of tasks designed to detect or predict failures in the protective systems or devices to reduce the likelihood of a failure in the protective system and the regular equipment from occurring at the same time.  So how to do you determine how often the protective systems should be checked for failure?  Establish the frequency using a formula.

Establishing Failure Finding Maintenance Frequencies Using Formulas

There is a single formula that will take into consideration of all variables to establish the failure finding interval (FFI);  FFI = (2 x M_TIVE x M_TED) /M_MF

Where;

• M_TIVE = MTBF of the protective device or system
• M_TED = Mean Time Between Failure of the Protected Function
• M_MF =   Mean Time Between Multiple Failures

So if we use an example from RCM2, we can see how this works; The users of a pump and a standby pump want the following from the system.

• The probability of a multiple failure to be less than 1 in 1000 in any one year (M_MF)
• The rate of unanticipated failures of the duty pump is 1 in 10 years (M_TED)
• The rate of unanticipated failure of the standby pump is 1 in 8 years (M_TIVE)

Therefore the correct failure finding interval would be;

• FFI = (2 x 8 x 10) / 1000
• FFI = (160)/1000
• FFI = 0.16 years
• 0.16 years x 12 months = 2 months

This indicates that the standby pump must be checked every two months to verify it is fully operational.   If this check is not performed, the likelihood of a multiple failures increases.

Lastly, if the failure of the protective device can be caused by the failure finding task itself, there is another approach to be used, which is beyond the scope of this article.

Do you have a program in place to check your protective systems?  If not, are you aware of the risk that your organization is exposed to?   Take the time to determine your protective systems and establish your failure finding tasks.

Remember, to find success; you must first solve the problem, then achieve the implementation of the solution, and finally sustain winning results.

I’m James Kovacevic
Eruditio, LLC
Where Education Meets Application
Follow @EruditioLLC

References;

• RCM2 by John Moubray
• Fixed Time Maintenance
• On-Condition Maintenance