# How to decipher RPN in FMEA analysis?

Discussion in 'FMEA - Failure Modes and Effects Analysis' started by Ruslan, Apr 13, 2017.

1. ### RuslanNew Member

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hello, everyone.

please, help me. how decipher abbreviation in FMEA analysis RPN?

2. ### tony sWell-Known Member

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RPN (Risk Priority Number). It's the mathematical product of the seriousness of the effects of the failure (S - severity), the likelihood that a cause will create the failure (O - occurrence), and the ability to detect the failure (D - detection). In equation form, RPN = S x O x D.

Though RPN gives us a basis for determining what failures should be given priority for taking actions, it's just one of the criteria that we should use. To effectively use FMEA in implementing controls, development of actions should be first directed to those with critical classification, next with high severity rate, then those with high RPN.

3. ### ncwalkerWell-Known Member

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Tony S is exactly correct. But be advised - all my sources are telling me RPN is going to be done away with in the next release of the PFMEA Manual (5th Ed) in favor of something called the "Risk Limiting Method" where your result is an RPL.

You still determine Sev, Occ, Det the same, but the new method involves lookup tables and the RPL result is 1, 2, 3 with 1 being high priority for an action plan, 3 doesn't need one.

It's a better system, honsetly.

4. ### Bev DModeratorStaff Member

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I haven't seen this process yet, but anything that gets us away from the fake math of the RPN is a step in the right direction...

5. ### ncwalkerWell-Known Member

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BAM !!

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6. ### Bev DModeratorStaff Member

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Oh. sorry - this is really just more hokey-pokey math on top of hokey-pokey math. I get the sentiment, but why try to solve a problem with the sam etype of thinking that created the problem? this score mentality only encourages and enables lack of thinking.

7. ### _Zeno_Member

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Agreed Bev. Adding more smoke in the air does little to clear things up. And you thought RPN was useless. Now they're raising the bar.

8. ### ncwalkerWell-Known Member

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I think human nature is we don't want to think. Or only few of us do. So if we can take a thinking process and relegate to a sequence of steps that don't require thinking, everyone's all in. I agree with the sentiment that this isn't the end all/be all. But that said, it IS a step up from pure RPN and stuff like this ... isn't going away any time soon.

9. ### Bev DModeratorStaff Member

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it certainly won't if professionals who know better don't teach, demonstrate and provide alternative approaches that DO work.
I sound like a broken record but I'll never stop opposing this kind of "stuff".

"If you ignore science, the empirical will strike back!"

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