Quality Progress - October 2017 - 22

F E AT U R E

ISO 9001:2015
TA B L E 3

failure. After this is completed, the
team can calculate the RPN by
multiplying the three ratings:

Example RPN action requirements

RPN = severity x occurrence x
detection.
For example, a pFMEA has
been developed for a new product. A certain characteristic has
a severity of four, a probability of
occurrence of three and a probability of detection of three. The
RPN is calculated as:
RPN = 4 x 3 x 3 = 36.
As shown in Table 3, an RPN of
36 is considered undesirable. The
severity and probability of occurrence, however, also should be
evaluated for this characteristic.
Table 4 indicates when there's a
severity of four with a probability
of occurrence of three, the risk is
considered to be unacceptable.
Because the result is considered unacceptable, it was decided
to develop a solution to reduce
the criticality of the product's
characteristic. The characteristic
then has a severity of three, a
probability of occurrence of three
and a probability of detection of
three.
RPN = 3 x 3 x 3 = 27.
According to Table 3, an RPN
of 27 is considered tolerable.
The severity and probability of
occurrence, however, also should
be evaluated for this characteristic. Table 4 indicates when there's
a severity of three with a probability of occurrence of three, the
risk is considered to be as low as
reasonably possible (ALARP).
Table 5 shows by reducing the
detection from three to two, we

22 QP

October 2017 ❘ qualityprogress.com

Risk priority
number
(RPN)

Risk
acceptability

Action

1 to 14

Low

Although low risk, continue mitigation
process as far as possible.

15 to 29

Tolerable

This should only be revisited in future
design review if corrective action
enhances the reliability or product
appeal.

30 to 49

Undesirable

Risk is acceptable only if it cannot be
further mitigated by organizational or
technological solutions, which do not
reduce the clinical or functional utility
of the product.

Above 49

Intolerable

Risk should be eliminated or reduced
by protective measures. Justification
required for risk that is accepted.

TA B L E 4

Example of criticality and occurrence action
requirements
Criticality/severity

Occurrence

Catastrophic

Critical

Serious

Minor

Negligible

5

4

3

2

1

Certain

5

Unacceptable

Unacceptable

Unacceptable

Unacceptable

ALARP

High

4

Unacceptable

Unacceptable

Unacceptable

ALARP

ALARP

Occasional

3

Unacceptable

Unacceptable

ALARP

ALARP

ALARP

Few

2

Unacceptable

ALARP

ALARP

ALARP

Acceptable

Unlikely

1

ALARP

ALARP

ALARP

Acceptable

Acceptable

ALARP = as low as reasonably possible
TA B L E 5

Reducing the RPN score
Criticality/
severity

Occurrence

Detection

Risk priority
number (RPN)

Initial

4

3

3

36

Revised

4

3

2

24

Percentage reduction in the RPN score
% RPN reduction =
RPNi - RPNr / RPNi
in which:
RPNi = initial RPN
RPNr = revised RPN

33%

% RPN reduction =
RPNi - RPNr / RPNi =
36 - 24 / 36 = 0.33 or 33%


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Table of Contents for the Digital Edition of Quality Progress - October 2017

Seen and Heard
Progress Report
Mr. Pareto Head
Expert Answers
Career Coach
In Focus
The Results Are In
Visual Aid
Experimental Learning
Statistics Spotlight
Standard Issues
Marketplace
Footnotes
Try This Today
STANDARDS AND AUDITING GUIDE
Quality Progress - October 2017 - intro
Quality Progress - October 2017 - cover1
Quality Progress - October 2017 - cover2
Quality Progress - October 2017 - 1
Quality Progress - October 2017 - 2
Quality Progress - October 2017 - 3
Quality Progress - October 2017 - 4
Quality Progress - October 2017 - 5
Quality Progress - October 2017 - Seen and Heard
Quality Progress - October 2017 - 7
Quality Progress - October 2017 - Progress Report
Quality Progress - October 2017 - Mr. Pareto Head
Quality Progress - October 2017 - 10
Quality Progress - October 2017 - 11
Quality Progress - October 2017 - Expert Answers
Quality Progress - October 2017 - 13
Quality Progress - October 2017 - Career Coach
Quality Progress - October 2017 - 15
Quality Progress - October 2017 - 16
Quality Progress - October 2017 - 17
Quality Progress - October 2017 - In Focus
Quality Progress - October 2017 - 19
Quality Progress - October 2017 - 20
Quality Progress - October 2017 - 21
Quality Progress - October 2017 - 22
Quality Progress - October 2017 - 23
Quality Progress - October 2017 - 24
Quality Progress - October 2017 - 25
Quality Progress - October 2017 - The Results Are In
Quality Progress - October 2017 - 27
Quality Progress - October 2017 - 28
Quality Progress - October 2017 - 29
Quality Progress - October 2017 - 30
Quality Progress - October 2017 - 31
Quality Progress - October 2017 - 32
Quality Progress - October 2017 - 33
Quality Progress - October 2017 - Visual Aid
Quality Progress - October 2017 - 35
Quality Progress - October 2017 - 36
Quality Progress - October 2017 - 37
Quality Progress - October 2017 - 38
Quality Progress - October 2017 - 39
Quality Progress - October 2017 - Experimental Learning
Quality Progress - October 2017 - 41
Quality Progress - October 2017 - 42
Quality Progress - October 2017 - 43
Quality Progress - October 2017 - 44
Quality Progress - October 2017 - 45
Quality Progress - October 2017 - 46
Quality Progress - October 2017 - 47
Quality Progress - October 2017 - Statistics Spotlight
Quality Progress - October 2017 - 49
Quality Progress - October 2017 - Standard Issues
Quality Progress - October 2017 - 51
Quality Progress - October 2017 - 52
Quality Progress - October 2017 - 53
Quality Progress - October 2017 - 54
Quality Progress - October 2017 - 55
Quality Progress - October 2017 - STANDARDS AND AUDITING GUIDE
Quality Progress - October 2017 - 57
Quality Progress - October 2017 - Marketplace
Quality Progress - October 2017 - 59
Quality Progress - October 2017 - Footnotes
Quality Progress - October 2017 - 61
Quality Progress - October 2017 - 62
Quality Progress - October 2017 - 63
Quality Progress - October 2017 - Try This Today
Quality Progress - October 2017 - cover3
Quality Progress - October 2017 - cover4
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