All Member Open Forum

Sounds like yes for all questions.

Trips or auto shutdowns are normally not decisions made by the operator, hence, failures.

Of course it depends on the context. And the severity of the failure depends on the context also.

An operational upset not requiring repair is still a failure.

---------------------------------
Karl Burnett

Solvay
Anderson SC
---------------------------------



Original Message:
Sent: 01-19-2020
From: Tamunoteyim Karibo
Subject: Unscheduled Trips

Hello Everyone,

Please i have this inquiry.

Are unscheduled trips considered as failures and should they be used to calculate MTBF and subsequently, reliability?

Lets say a machine trips due to factors not relating to its own operations, will this be considered a failure of the machine? 

I have 3 machines. if machine 1 shuts down due to a particular failure mode (say low suction), Machines 2 and 3 shut down as well. Will we consider the shut downs of machine 2 and 3 as failures as well?

Thank you for your support

Regards

Tammy Karibo

Yes and it is very critical to define What is failure before we start our reliability improvement journey is key .

------------------------------
Krishnan Shrikanth
CMRP
SINGAPORE
------------------------------

Original Message:
Sent: 01-19-2020 05:26 AM
From: Tamunoteyim Karibo
Subject: Unscheduled Trips

Hello Everyone,

Please i have this inquiry.

Are unscheduled trips considered as failures and should they be used to calculate MTBF and subsequently, reliability?

Lets say a machine trips due to factors not relating to its own operations, will this be considered a failure of the machine? 

I have 3 machines. if machine 1 shuts down due to a particular failure mode (say low suction), Machines 2 and 3 shut down as well. Will we consider the shut downs of machine 2 and 3 as failures as well?

Thank you for your support

Regards

Tammy Karibo

Original Message------

Yes and it is very critical to define What is failure before we start our reliability improvement journey is key .

------------------------------
Krishnan Shrikanth
CMRP
SINGAPORE
------------------------------

Consider looking at your KPIs differently. Consider OEE which looks at a function or process that consists of multiple pieces of equipment that make up that function or process.

In your situation for these vacuum pumps, the process you might consider monitoring or measuring is your entire vacuum system. I'll leave out an explanation of OEE and how to measure it. But basically you measure the uptime that your entire (and well defined) vacuum system is delivering the capacity you desire. When it's not, you account for the time and the cause of each "loss".  This is any loss the system sees. It could be operational, mechanical, electrical, environmental, acts of God, etc. Anything that causes the system to fall short of its intended function.

And with each loss comes a Lost Production Code. This is for later analysis. So you need a table with a list of codes for the most probable losses your system will see. These codes should be segregated by Operational Losses, Mechanical Losses, Electrical Losses, etc. Next is an associated field for the Equipment Causing Loss. You want to identify the culprit if there is one. There will not always be one. So in your example this would be the vacuum pump #1 that caused the loss. The remainder of the equipment in the Vacuum Pump System is not penalized for the loss. But the loss is accounted for by the losses incurred by the overall system. This impacts the OEE number.

And finally, there should be a field for general comments. There will always be the need for this.

​

------------------------------
Terry Taylor
Senior Consultant
IDCON INC
Raleigh NC
t.taylor@idcon.com
------------------------------

Original Message:
Sent: 01-19-2020 05:26 AM
From: Tamunoteyim Karibo
Subject: Unscheduled Trips

Hello Everyone,

Please i have this inquiry.

Are unscheduled trips considered as failures and should they be used to calculate MTBF and subsequently, reliability?

Lets say a machine trips due to factors not relating to its own operations, will this be considered a failure of the machine? 

I have 3 machines. if machine 1 shuts down due to a particular failure mode (say low suction), Machines 2 and 3 shut down as well. Will we consider the shut downs of machine 2 and 3 as failures as well?

Thank you for your support

Regards

Tammy Karibo

------------------------------
Jaishankar Balasubramanian Founder Director
Chennai TN
------------------------------

Original Message:
Sent: 01-19-2020 05:26 AM
From: Tamunoteyim Karibo
Subject: Unscheduled Trips

Hello Everyone,

Please i have this inquiry.

Are unscheduled trips considered as failures and should they be used to calculate MTBF and subsequently, reliability?

Lets say a machine trips due to factors not relating to its own operations, will this be considered a failure of the machine? 

I have 3 machines. if machine 1 shuts down due to a particular failure mode (say low suction), Machines 2 and 3 shut down as well. Will we consider the shut downs of machine 2 and 3 as failures as well?

Thank you for your support

Regards

Tammy Karibo

Thanks  Jaishankar,

What i have done was to have two separate columns: One for Trips and the other for failures
Following the example i gave above about the 3 machine; We have Three trips and one failure
So in calculating the MTBF per unit, I DO NOT use the trips from Machine 2 and 3 that were caused by Machine 1
and subsequently for the system as well (Consisting of 3 machines)
But isn't the data flawed this way?

------------------------------
Tammy Karibo
Reliability Engineer
Enerflex
Abu Dhabi
------------------------------

Original Message:
Sent: 01-21-2020 10:52 PM
From: Jaishankar Balasubramanian
Subject: Unscheduled Trips

There are multiple questions ! And tricky ones!
There appears to be a play of Equipment not performing its function largely due to System Reliability /  safety measures...

In general MTBF relates to an inherent problem in the equipment.  If we look from that perspective :

A. Are unscheduled trips considered as failures and should they be used to calculate MTBF and subsequently, reliability?
Not necessarily. An equipment can trip due to many reasons, including malfunctioning of the trip mechanism. If the equipment tripped from a safety perspective  but can perform functionally, then the event will not be counted as Equipment failure for MTFT calculations.

B. Lets say a machine trips due to factors not relating to its own operations, will this be considered a failure of the machine?
Not necessarily, from an MTBF perspective

C  I have 3 machines. if machine 1 shuts down due to a particular failure mode (say low suction), Machines 2 and 3 shut down as well. Will we consider the shut downs of machine 2 and 3 as failures as well?
This relates to shutdown of equipment due to safety measures. If all three machines are fit for normal functional performance, this event will not be considered for MTBF

------------------------------
Jaishankar Balasubramanian Founder Director
Chennai TN

Original Message:
Sent: 01-19-2020 05:26 AM
From: Tamunoteyim Karibo
Subject: Unscheduled Trips

Hello Everyone,

Please i have this inquiry.

Are unscheduled trips considered as failures and should they be used to calculate MTBF and subsequently, reliability?

Lets say a machine trips due to factors not relating to its own operations, will this be considered a failure of the machine? 

I have 3 machines. if machine 1 shuts down due to a particular failure mode (say low suction), Machines 2 and 3 shut down as well. Will we consider the shut downs of machine 2 and 3 as failures as well?

Thank you for your support

Regards

Tammy Karibo

Hi Tammy,

Howard has effectively answered.

Machine 1,2 and 3 are being treated as separate equipment, I think.
So, normally,  the stoppage of machine 2 and 3 will not be considered as failure for MTBF calculations. 
But certainly the 'system' should be studied to ascertain why machines 2 and 3 stopped, if the root cause of the problem was related to Machine 1.

Hope this helps..


------------------------------
Jaishankar Balasubramanian
Asset Management Consultant
------------------------------

Original Message:
Sent: 01-22-2020 09:00 AM
From: Tamunoteyim Karibo
Subject: Unscheduled Trips

Thanks  Jaishankar,

What i have done was to have two separate columns: One for Trips and the other for failures
Following the example i gave above about the 3 machine; We have Three trips and one failure
So in calculating the MTBF per unit, I DO NOT use the trips from Machine 2 and 3 that were caused by Machine 1
and subsequently for the system as well (Consisting of 3 machines)
But isn't the data flawed this way?

------------------------------
Tammy Karibo
Reliability Engineer
Enerflex
Abu Dhabi

Original Message:
Sent: 01-21-2020 10:52 PM
From: Jaishankar Balasubramanian
Subject: Unscheduled Trips

There are multiple questions ! And tricky ones!
There appears to be a play of Equipment not performing its function largely due to System Reliability /  safety measures...

In general MTBF relates to an inherent problem in the equipment.  If we look from that perspective :

A. Are unscheduled trips considered as failures and should they be used to calculate MTBF and subsequently, reliability?
Not necessarily. An equipment can trip due to many reasons, including malfunctioning of the trip mechanism. If the equipment tripped from a safety perspective  but can perform functionally, then the event will not be counted as Equipment failure for MTFT calculations.

B. Lets say a machine trips due to factors not relating to its own operations, will this be considered a failure of the machine?
Not necessarily, from an MTBF perspective

C  I have 3 machines. if machine 1 shuts down due to a particular failure mode (say low suction), Machines 2 and 3 shut down as well. Will we consider the shut downs of machine 2 and 3 as failures as well?
This relates to shutdown of equipment due to safety measures. If all three machines are fit for normal functional performance, this event will not be considered for MTBF

------------------------------
Jaishankar Balasubramanian Founder Director
Chennai TN

Original Message:
Sent: 01-19-2020 05:26 AM
From: Tamunoteyim Karibo
Subject: Unscheduled Trips

Hello Everyone,

Please i have this inquiry.

Are unscheduled trips considered as failures and should they be used to calculate MTBF and subsequently, reliability?

Lets say a machine trips due to factors not relating to its own operations, will this be considered a failure of the machine? 

I have 3 machines. if machine 1 shuts down due to a particular failure mode (say low suction), Machines 2 and 3 shut down as well. Will we consider the shut downs of machine 2 and 3 as failures as well?

Thank you for your support

Regards

Tammy Karibo

Tammy

We normally use MTBF for a component or system that is directly related to a failure mode.  For instance, the MTBF would be related to what caused the low suction, which is the failure mode, and the effect is low suction with extended effects being the shutdown of equipment.  The failure mode would effect the availability of the equipment.  The reason why you would attach it to the failure mode at the component level (ie: vacuum pump fails resulting in low vacuum resulting in reduced availability) is to use it as a basic measure that can be addressed, such as investigating the cause for the vacuum pump failure (or filter, or whatever is causing the low vacuum).

------------------------------
Howard W Penrose, Ph.D., CMRP
Random Past SMRP Chair (2018), 2019+ Govt Relations Smart Grid, Infrastructure and Cybersecurity Working Group Chair, and
President
MotorDoc LLC
Lombard, Illinois
------------------------------

Original Message:
Sent: 01-19-2020 05:26 AM
From: Tamunoteyim Karibo
Subject: Unscheduled Trips

Hello Everyone,

Please i have this inquiry.

Are unscheduled trips considered as failures and should they be used to calculate MTBF and subsequently, reliability?

Lets say a machine trips due to factors not relating to its own operations, will this be considered a failure of the machine? 

I have 3 machines. if machine 1 shuts down due to a particular failure mode (say low suction), Machines 2 and 3 shut down as well. Will we consider the shut downs of machine 2 and 3 as failures as well?

Thank you for your support

Regards

Tammy Karibo

Hello Howard,

Thank you for your feedback.

In this case, the failure mode was already identified in the equipment that caused the shutdown.
But capturing the subsequent shutdowns of other equipment due to the shutdown of the failed equipment is the problem.
In the example i gave, the Uptime of the other 2 subsequent equipment will reduce of course, but the question is will their trips be used to calculate their MTBF?

------------------------------
Tammy Karibo
Reliability Engineer
Enerflex
Abu Dhabi
------------------------------

Original Message:
Sent: 01-22-2020 08:21 AM
From: Howard W Penrose
Subject: Unscheduled Trips

Tammy

We normally use MTBF for a component or system that is directly related to a failure mode.  For instance, the MTBF would be related to what caused the low suction, which is the failure mode, and the effect is low suction with extended effects being the shutdown of equipment.  The failure mode would effect the availability of the equipment.  The reason why you would attach it to the failure mode at the component level (ie: vacuum pump fails resulting in low vacuum resulting in reduced availability) is to use it as a basic measure that can be addressed, such as investigating the cause for the vacuum pump failure (or filter, or whatever is causing the low vacuum).

------------------------------
Howard W Penrose, Ph.D., CMRP
Random Past SMRP Chair (2018), 2019+ Govt Relations Smart Grid, Infrastructure and Cybersecurity Working Group Chair, and
President
MotorDoc LLC
Lombard, Illinois

Original Message:
Sent: 01-19-2020 05:26 AM
From: Tamunoteyim Karibo
Subject: Unscheduled Trips

Hello Everyone,

Please i have this inquiry.

Are unscheduled trips considered as failures and should they be used to calculate MTBF and subsequently, reliability?

Lets say a machine trips due to factors not relating to its own operations, will this be considered a failure of the machine? 

I have 3 machines. if machine 1 shuts down due to a particular failure mode (say low suction), Machines 2 and 3 shut down as well. Will we consider the shut downs of machine 2 and 3 as failures as well?

Thank you for your support

Regards

Tammy Karibo

The failure mode or related equipment would normally be your MTBF, the equipment would be availability - from an industrial engineering perspective.

For example, if the circuit breaker that protects your refrigerator outlet fails, the outlet or the refrigerator did not fail, but the outlet and the refrigerator were not available due to the component failure.

The exception is if you draw a bigger box around your equipment such that all three machines and the component that failed is part of the same equipment.  For instance, in a machine shop a CNC lathe stops operating and you have selected the whole machine as a component, then the MTBF would be related to the lathe - although I would not do that myself.

In the wind industry we look at the average tower in the USA being 90% available with 6-8% unavailability due to wind and 2-4% related to operations and maintenance.  The maintenance MTBF would be related to the components such as generator, controls, blades, etc.

Within IEEE for electrical systems the MTBF is presented at the component level such as motors, circuit breakers, transformers, etc. (IEEE Gold Book) and not the system level.

------------------------------
Howard W Penrose, Ph.D., CMRP
Random Past SMRP Chair (2018), 2019+ Govt Relations Smart Grid, Infrastructure and Cybersecurity Working Group Chair, and
President
MotorDoc LLC
Lombard, Illinois
------------------------------

Original Message:
Sent: 01-22-2020 08:54 AM
From: Tamunoteyim Karibo
Subject: Unscheduled Trips

Hello Howard,

Thank you for your feedback.

In this case, the failure mode was already identified in the equipment that caused the shutdown.
But capturing the subsequent shutdowns of other equipment due to the shutdown of the failed equipment is the problem.
In the example i gave, the Uptime of the other 2 subsequent equipment will reduce of course, but the question is will their trips be used to calculate their MTBF?

------------------------------
Tammy Karibo
Reliability Engineer
Enerflex
Abu Dhabi

Original Message:
Sent: 01-22-2020 08:21 AM
From: Howard W Penrose
Subject: Unscheduled Trips

Tammy

We normally use MTBF for a component or system that is directly related to a failure mode.  For instance, the MTBF would be related to what caused the low suction, which is the failure mode, and the effect is low suction with extended effects being the shutdown of equipment.  The failure mode would effect the availability of the equipment.  The reason why you would attach it to the failure mode at the component level (ie: vacuum pump fails resulting in low vacuum resulting in reduced availability) is to use it as a basic measure that can be addressed, such as investigating the cause for the vacuum pump failure (or filter, or whatever is causing the low vacuum).

------------------------------
Howard W Penrose, Ph.D., CMRP
Random Past SMRP Chair (2018), 2019+ Govt Relations Smart Grid, Infrastructure and Cybersecurity Working Group Chair, and
President
MotorDoc LLC
Lombard, Illinois

Original Message:
Sent: 01-19-2020 05:26 AM
From: Tamunoteyim Karibo
Subject: Unscheduled Trips

Hello Everyone,

Please i have this inquiry.

Are unscheduled trips considered as failures and should they be used to calculate MTBF and subsequently, reliability?

Lets say a machine trips due to factors not relating to its own operations, will this be considered a failure of the machine? 

I have 3 machines. if machine 1 shuts down due to a particular failure mode (say low suction), Machines 2 and 3 shut down as well. Will we consider the shut downs of machine 2 and 3 as failures as well?

Thank you for your support

Regards

Tammy Karibo

Good Morning Tammy;
  There are a lot of good thoughts here, my opinion is that the MTBF should be calculated on each pump for it's own run time as one could be less reliable than the other. I would also due the same calculation on the system because you have redundancy for a reason and if the system fails you I would want to know how often and why​. to answer your question plainly, calculate MTBF on each pump and the system, a little more work but most everybody here can agree that too much data is better than not enough.

Thank you,
Tim Cowan

------------------------------
Tim Cowan
Reliability Technician
Blount Int.
Portland, Oregon
------------------------------

Original Message:
Sent: 01-19-2020 05:26 AM
From: Tamunoteyim Karibo
Subject: Unscheduled Trips

Hello Everyone,

Please i have this inquiry.

Are unscheduled trips considered as failures and should they be used to calculate MTBF and subsequently, reliability?

Lets say a machine trips due to factors not relating to its own operations, will this be considered a failure of the machine? 

I have 3 machines. if machine 1 shuts down due to a particular failure mode (say low suction), Machines 2 and 3 shut down as well. Will we consider the shut downs of machine 2 and 3 as failures as well?

Thank you for your support

Regards

Tammy Karibo

I suppose all the 03 Machines are part of the same System that is designed to deliver a function. We need to be clear about what constitutes a Failure (a) a clear definition and understanding of what a failure is for your MTBF Calculations, and b) why that was defined that way (Questions like...Is failure only the breakdown of the Equipment or does it include all Functional Failures of the Equipment? Are failures caused by external factors to be included in the calculation of MTBF? Why only certain failures are included in the definition?). Also a clear understanding of the design by which Machines 2 and 3 need to shutdown if Machine 1shuts down for any reason (i suppose Machine 1 feeds to Machines 2 and 3). 

In your example, the Machine A has a functional failure (inability to perform the function due to low suction and hence is shutdown to prevent any damage). In my view, as the Machines 2 and 3 can't run with out Machine 1, they're are being shutdown proactively (similar to Machine 1), and I'd consider their shutdown too as a Functional Failure (inability to perform their Function without Machine 1) and include their Shutdowns in their MTBF Calculation at the Asset Level. MTBF could be also calculated at the System level when shutdown of Machine 1 would cause the System to fail (functional failure).

Only in the case of Equipment trips due to external reasons (e.g. Trip of all Equipment due to power outage caused by external events), their trips could be excluded from the MTBF Calculation. 

Hope this helps. Thanks for posing a great question...

------------------------------
Sundar Naranammalpuram P.
Navi Mumbai
Maharashtra
India
------------------------------

Original Message:
Sent: 01-19-2020 05:26 AM
From: Tamunoteyim Karibo
Subject: Unscheduled Trips

Hello Everyone,

Please i have this inquiry.

Are unscheduled trips considered as failures and should they be used to calculate MTBF and subsequently, reliability?

Lets say a machine trips due to factors not relating to its own operations, will this be considered a failure of the machine? 

I have 3 machines. if machine 1 shuts down due to a particular failure mode (say low suction), Machines 2 and 3 shut down as well. Will we consider the shut downs of machine 2 and 3 as failures as well?

Thank you for your support

Regards

Tammy Karibo

Sundar, I think you hit nail on the head.  Functional failure of the system of assets vs individual asset failure within the system.  It depends on how you want to classify and define your systems.  ​

Machine 1 would be the asset or component failure which caused the system failure to shut down machine 2 & 3.  That would be like series reliability if you were calculating the system equivalent reliability or availability.  Some component or function in machine 1 failed which caused the system of machines 1, 2 & 3 to go down.  At the asset level, machine 2 & 3 did not fail and you did not do any repairs to get back in operation.

------------------------------
Randy Riddell, CMRP, PSAP, CLS
Reliability Manager
Essity
Cherokee AL
------------------------------

Original Message:
Sent: 01-24-2020 07:49 AM
From: Sundar Naranammalpuram
Subject: Unscheduled Trips

I suppose all the 03 Machines are part of the same System that is designed to deliver a function. We need to be clear about what constitutes a Failure (a) a clear definition and understanding of what a failure is for your MTBF Calculations, and b) why that was defined that way (Questions like...Is failure only the breakdown of the Equipment or does it include all Functional Failures of the Equipment? Are failures caused by external factors to be included in the calculation of MTBF? Why only certain failures are included in the definition?). Also a clear understanding of the design by which Machines 2 and 3 need to shutdown if Machine 1shuts down for any reason (i suppose Machine 1 feeds to Machines 2 and 3).

In your example, the Machine A has a functional failure (inability to perform the function due to low suction and hence is shutdown to prevent any damage). In my view, as the Machines 2 and 3 can't run with out Machine 1, they're are being shutdown proactively (similar to Machine 1), and I'd consider their shutdown too as a Functional Failure (inability to perform their Function without Machine 1) and include their Shutdowns in their MTBF Calculation at the Asset Level. MTBF could be also calculated at the System level when shutdown of Machine 1 would cause the System to fail (functional failure).

Only in the case of Equipment trips due to external reasons (e.g. Trip of all Equipment due to power outage caused by external events), their trips could be excluded from the MTBF Calculation.

Hope this helps. Thanks for posing a great question...

------------------------------
Sundar Naranammalpuram P.
Navi Mumbai
Maharashtra
India

Original Message:
Sent: 01-19-2020 05:26 AM
From: Tamunoteyim Karibo
Subject: Unscheduled Trips

Hello Everyone,

Please i have this inquiry.

Are unscheduled trips considered as failures and should they be used to calculate MTBF and subsequently, reliability?

Lets say a machine trips due to factors not relating to its own operations, will this be considered a failure of the machine? 

I have 3 machines. if machine 1 shuts down due to a particular failure mode (say low suction), Machines 2 and 3 shut down as well. Will we consider the shut downs of machine 2 and 3 as failures as well?

Thank you for your support

Regards

Tammy Karibo

Randy, 

Thanks so much for your kind words and the valuable inputs...

------------------------------
Sundar Naranammalpuram P.
Navi Mumbai
Maharashtra
India
------------------------------

Original Message:
Sent: 01-24-2020 10:26 AM
From: Randy Riddell
Subject: Unscheduled Trips

Sundar, I think you hit nail on the head.  Functional failure of the system of assets vs individual asset failure within the system.  It depends on how you want to classify and define your systems.  ​

Machine 1 would be the asset or component failure which caused the system failure to shut down machine 2 & 3.  That would be like series reliability if you were calculating the system equivalent reliability or availability.  Some component or function in machine 1 failed which caused the system of machines 1, 2 & 3 to go down.  At the asset level, machine 2 & 3 did not fail and you did not do any repairs to get back in operation.

------------------------------
Randy Riddell, CMRP, PSAP, CLS
Reliability Manager
Essity
Cherokee AL

Original Message:
Sent: 01-24-2020 07:49 AM
From: Sundar Naranammalpuram
Subject: Unscheduled Trips

I suppose all the 03 Machines are part of the same System that is designed to deliver a function. We need to be clear about what constitutes a Failure (a) a clear definition and understanding of what a failure is for your MTBF Calculations, and b) why that was defined that way (Questions like...Is failure only the breakdown of the Equipment or does it include all Functional Failures of the Equipment? Are failures caused by external factors to be included in the calculation of MTBF? Why only certain failures are included in the definition?). Also a clear understanding of the design by which Machines 2 and 3 need to shutdown if Machine 1shuts down for any reason (i suppose Machine 1 feeds to Machines 2 and 3).

In your example, the Machine A has a functional failure (inability to perform the function due to low suction and hence is shutdown to prevent any damage). In my view, as the Machines 2 and 3 can't run with out Machine 1, they're are being shutdown proactively (similar to Machine 1), and I'd consider their shutdown too as a Functional Failure (inability to perform their Function without Machine 1) and include their Shutdowns in their MTBF Calculation at the Asset Level. MTBF could be also calculated at the System level when shutdown of Machine 1 would cause the System to fail (functional failure).

Only in the case of Equipment trips due to external reasons (e.g. Trip of all Equipment due to power outage caused by external events), their trips could be excluded from the MTBF Calculation.

Hope this helps. Thanks for posing a great question...

------------------------------
Sundar Naranammalpuram P.
Navi Mumbai
Maharashtra
India

Original Message:
Sent: 01-19-2020 05:26 AM
From: Tamunoteyim Karibo
Subject: Unscheduled Trips

Hello Everyone,

Please i have this inquiry.

Are unscheduled trips considered as failures and should they be used to calculate MTBF and subsequently, reliability?

Lets say a machine trips due to factors not relating to its own operations, will this be considered a failure of the machine? 

I have 3 machines. if machine 1 shuts down due to a particular failure mode (say low suction), Machines 2 and 3 shut down as well. Will we consider the shut downs of machine 2 and 3 as failures as well?

Thank you for your support

Regards

Tammy Karibo