Hi,

I heard from collogue that they are calculating plant MTBF by dividing number of equipment by number of failures. I've never seen this approach before. There was a comment that this is an industry practice. Any information about such practice ? 

------------------------------
Omar Etman
Field Service Engineer
John Crane
Al Khobar
------------------------------

Original Message:
Sent: 4/8/2025 7:36:00 AM
From: Omar Etman
Subject: Plant MTBF

Hi,

I heard from collogue that they are calculating plant MTBF by dividing number of equipment by number of failures. I've never seen this approach before. There was a comment that this is an industry practice. Any information about such practice ? 

------------------------------
Omar Etman
Field Service Engineer
John Crane
Al Khobar
------------------------------

Thanks Dhrumil, of course you're right this is the normal and logic. That's why I asked about the practice, I thought I may miss something.

------------------------------
Omar Etman
Field Service Engineer
John Crane
Al Khobar
------------------------------

Original Message:
Sent: 04-09-2025 06:48 AM
From: Dhrumil Shah
Subject: Plant MTBF

MTBF it self for Something about Time, in my Plant we are calculating by operation time divide by total number of failures.

Original Message:
Sent: 4/8/2025 7:36:00 AM
From: Omar Etman
Subject: Plant MTBF

Hi,

I heard from collogue that they are calculating plant MTBF by dividing number of equipment by number of failures. I've never seen this approach before. There was a comment that this is an industry practice. Any information about such practice ? 

------------------------------
Omar Etman
Field Service Engineer
John Crane
Al Khobar
------------------------------

Hi, Dhurmil

Please find my reply to Micheal 

------------------------------
Mustafa SalahEldin Eljilany
CRE, CMRB, CAMA, CEng IMeche
Maintenance and reliability section head
ANRPC
------------------------------

Original Message:
Sent: 04-09-2025 06:48 AM
From: Dhrumil Shah
Subject: Plant MTBF

MTBF it self for Something about Time, in my Plant we are calculating by operation time divide by total number of failures.

Original Message:
Sent: 4/8/2025 7:36:00 AM
From: Omar Etman
Subject: Plant MTBF

Hi,

I heard from collogue that they are calculating plant MTBF by dividing number of equipment by number of failures. I've never seen this approach before. There was a comment that this is an industry practice. Any information about such practice ? 

------------------------------
Omar Etman
Field Service Engineer
John Crane
Al Khobar
------------------------------

Omar,

I am not really sure what that would calculate, but industry standard for MTBF is:

total machine run hours / number of failures

This KPI will help steer the team toward the equipment with the most problems.

------------------------------
Michael Wise
Production Operations Manager
Aqua Membranes
Maryville TN
------------------------------

Original Message:
Sent: 04-08-2025 07:35 AM
From: Omar Etman
Subject: Plant MTBF

Hi,

I heard from collogue that they are calculating plant MTBF by dividing number of equipment by number of failures. I've never seen this approach before. There was a comment that this is an industry practice. Any information about such practice ? 

------------------------------
Omar Etman
Field Service Engineer
John Crane
Al Khobar
------------------------------

Thanks Michael,I totally agree with you

------------------------------
Omar Etman
Field Service Engineer
John Crane
Al Khobar
------------------------------

Original Message:
Sent: 04-09-2025 07:05 AM
From: Michael Wise
Subject: Plant MTBF

Omar,

I am not really sure what that would calculate, but industry standard for MTBF is:

total machine run hours / number of failures

This KPI will help steer the team toward the equipment with the most problems.

------------------------------
Michael Wise
Production Operations Manager
Aqua Membranes
Maryville TN

Original Message:
Sent: 04-08-2025 07:35 AM
From: Omar Etman
Subject: Plant MTBF

Hi,

I heard from collogue that they are calculating plant MTBF by dividing number of equipment by number of failures. I've never seen this approach before. There was a comment that this is an industry practice. Any information about such practice ? 

------------------------------
Omar Etman
Field Service Engineer
John Crane
Al Khobar
------------------------------

Hi Michael

This calculation if feasible for exponential distribution (random failures not a wear model)

As an example: if you have a machine run for 10 years

And have 5 failures, so you will say MTBF is 2 years

You are right mathematically, but it doesn't give any useful information or guidance if that 5 failure happened as follow: 

1 in the first year

4 failures in the last 2 years 

In this example you can't tell the right probability of failure if you just divide the total running years over the total number of failure

You will probably miss the next coming failure without a corrective plan 

So you can firstly check is the shape parameter is almost 1 or not 

And even if it's 1 (random failure) you can face an internal component in your asset with a mttf nearly equal to 11 years, which will come up soon 

So my advice (according to you level of analysis and asset or plant criticality) you should apply crow amsaa analysis for repairable systems and LDA for non repairable items and then you can perform your RAM to predict or calculate system or plant or even asset availability

------------------------------
Mustafa SalahEldin Eljilany
CRE, CMRB, CAMA, CEng IMeche
Maintenance and reliability section head
ANRPC
------------------------------

Original Message:
Sent: 04-09-2025 07:05 AM
From: Michael Wise
Subject: Plant MTBF

Omar,

I am not really sure what that would calculate, but industry standard for MTBF is:

total machine run hours / number of failures

This KPI will help steer the team toward the equipment with the most problems.

------------------------------
Michael Wise
Production Operations Manager
Aqua Membranes
Maryville TN

Original Message:
Sent: 04-08-2025 07:35 AM
From: Omar Etman
Subject: Plant MTBF

Hi,

I heard from collogue that they are calculating plant MTBF by dividing number of equipment by number of failures. I've never seen this approach before. There was a comment that this is an industry practice. Any information about such practice ? 

------------------------------
Omar Etman
Field Service Engineer
John Crane
Al Khobar
------------------------------

Hi, Etman 

I think they mean plant availability, if they want to calculate plant availability they should go for repairable system analysis

------------------------------
Mustafa SalahEldin Ahmed abdelsadek
Rotating equipment maintenance and reliability section head
alexandria national refining and petrochemicals company (ANRPC)
Alexandria
------------------------------

Original Message:
Sent: 04-08-2025 07:35 AM
From: Omar Etman
Subject: Plant MTBF

Hi,

I heard from collogue that they are calculating plant MTBF by dividing number of equipment by number of failures. I've never seen this approach before. There was a comment that this is an industry practice. Any information about such practice ? 

------------------------------
Omar Etman
Field Service Engineer
John Crane
Al Khobar
------------------------------

Hello my friend, unfortunately they meant MTBF not availability, which was weird for me

------------------------------
Omar Etman
Field Service Engineer
John Crane
Al Khobar
------------------------------

Original Message:
Sent: 04-09-2025 07:09 AM
From: Mustafa SalahEldin Ahmed abdelsadek
Subject: Plant MTBF

Hi, Etman 

I think they mean plant availability, if they want to calculate plant availability they should go for repairable system analysis

------------------------------
Mustafa SalahEldin Ahmed abdelsadek
Rotating equipment maintenance and reliability section head
alexandria national refining and petrochemicals company (ANRPC)
Alexandria

Original Message:
Sent: 04-08-2025 07:35 AM
From: Omar Etman
Subject: Plant MTBF

Hi,

I heard from collogue that they are calculating plant MTBF by dividing number of equipment by number of failures. I've never seen this approach before. There was a comment that this is an industry practice. Any information about such practice ? 

------------------------------
Omar Etman
Field Service Engineer
John Crane
Al Khobar
------------------------------

If what you are describing is accurate (# of equipment / # of failures), that is not Mean Time Between Failure since there is no time component and not something I've seen done. However, in practice it might crudely give you the same info if you are comparing plants over the same time period.

If Plant 1 has 100 pieces of equipment and 10 failures in 1 year then its plant wide average MTBF would be ( 100 x 1 year) / (10 failures) = 10 years (assuming MTTR = 0, all equipment operates continuously, etc.)

If Plant 2 has 200 pieces of equipment and 5 failures in 1 year then its plant wide average MTBF would be 40 years.

If you take the time component out of the equations above, you get the same numerical answers (10 and 40) for comparison purposes but it's not an MTBF.

------------------------------
Matthew Hiatt
Hydrocarbons Senior Reliability Manager
Dow Chemical
------------------------------

Original Message:
Sent: 04-08-2025 07:35 AM
From: Omar Etman
Subject: Plant MTBF

Hi,

I heard from collogue that they are calculating plant MTBF by dividing number of equipment by number of failures. I've never seen this approach before. There was a comment that this is an industry practice. Any information about such practice ? 

------------------------------
Omar Etman
Field Service Engineer
John Crane
Al Khobar
------------------------------

Omar,

The question of how to best use an MTBF metric aside, I have never seen MTBF applied at a plant level.  It could be done on a system basis where you have actual system functions and counting literal functional failures could provide a system MTBF.  The calculation you describe sounds very simple.  That said, my work in CMMS implementation and migration taught me that the simple act of counting equipment (in a plant) is actually never simple.  I have also learned that the counting of failures is also a challenge.  To be meaningful, there would have to be unusually high consistency in the way that assets are counted (e.g. is a pump, coupling and driver one or three equipment items) and how a "failure" is identified (i.e. where in the maintenance data is this flagged, and, even more so, according to what criteria).  I'm not sure what type of management or maintenance decision support I would expect people to get from a plant level MTBF.  You would want it to be stable or increasing, but it is a lagging indicator and at the plant level would not point at all to the cause.

------------------------------
Roger Shaw
APM Consultant
Salem CT
Roger_Shaw@comcast.net
------------------------------

Original Message:
Sent: 04-08-2025 07:35 AM
From: Omar Etman
Subject: Plant MTBF

Hi,

I heard from collogue that they are calculating plant MTBF by dividing number of equipment by number of failures. I've never seen this approach before. There was a comment that this is an industry practice. Any information about such practice ? 

------------------------------
Omar Etman
Field Service Engineer
John Crane
Al Khobar
------------------------------

Dear Omar,

MTBF is used for reparable machines and is calculated as: total operating time /numer of failures.

The commom unit of measurement is hours.

........................

Best regards,

------------------------------
Jose Alejandro Castañeda Surco
Reliability Engineer
lima
------------------------------

Original Message:
Sent: 04-08-2025 07:35 AM
From: Omar Etman
Subject: Plant MTBF

Hi,

I heard from collogue that they are calculating plant MTBF by dividing number of equipment by number of failures. I've never seen this approach before. There was a comment that this is an industry practice. Any information about such practice ? 

------------------------------
Omar Etman
Field Service Engineer
John Crane
Al Khobar
------------------------------

Hello Omar 

 Hello Eng. Omar its a pleasure to communicate with you, we use the "Runlog System" to track our critical assets. The team manually records when assets start and stop, and selects a stop code to categorize the reason:

> Planned Stops:

>  * MSD: Normal manual stop (routine maintenance, changeovers, planned shutdowns - no impact on MTBF).

> Unplanned Stops:

>  * TMSD: Trip due to external causes (process issues - no direct impact on MTBF).

>  * MSDT: Mandatory manual stop (equipment issues - impacts MTBF).

>  * Trip: Protection system activation (known trip - impacts MTBF).

> Downtime and MTBF (calculated from the last 12 months of operating hours out of 8640) are automatically calculated. Note that "Trip" and "MSDT" codes directly lower MTBF, which in turn negatively affects our reliability performance percentage

------------------------------
Mohamed Adil Abdalla
Eng
ADNOC Gas O&M LLC
sharjah
------------------------------

Original Message:
Sent: 04-08-2025 07:35 AM
From: Omar Etman
Subject: Plant MTBF

Hi,

I heard from collogue that they are calculating plant MTBF by dividing number of equipment by number of failures. I've never seen this approach before. There was a comment that this is an industry practice. Any information about such practice ? 

------------------------------
Omar Etman
Field Service Engineer
John Crane
Al Khobar
------------------------------

Original Message:
Sent: 4/10/2025 7:28:00 AM
From: Mohamed Adil Abdalla
Subject: RE: Plant MTBF

Hello Omar 

 Hello Eng. Omar its a pleasure to communicate with you, we use the "Runlog System" to track our critical assets. The team manually records when assets start and stop, and selects a stop code to categorize the reason:

> Planned Stops:

>  * MSD: Normal manual stop (routine maintenance, changeovers, planned shutdowns - no impact on MTBF).

> Unplanned Stops:

>  * TMSD: Trip due to external causes (process issues - no direct impact on MTBF).

>  * MSDT: Mandatory manual stop (equipment issues - impacts MTBF).

>  * Trip: Protection system activation (known trip - impacts MTBF).

> Downtime and MTBF (calculated from the last 12 months of operating hours out of 8640) are automatically calculated. Note that "Trip" and "MSDT" codes directly lower MTBF, which in turn negatively affects our reliability performance percentage

------------------------------
Mohamed Adil Abdalla
Eng
ADNOC Gas O&M LLC
sharjah
------------------------------