Functional Safety 2016

November, 2016 - London

Page 7 of 17

Competency in relation to C

The competency of the persons involved in all lifecycle aspects can have significant impact on

the SIFs ability to provide the required risk reduction. As stated (Nunns, 2002), persons

participating in all aspects of proof testing process should have; clearly demonstrable

competency to carry out their alloted task, clearly identified and communicated responsibilities

and documented verification that the proof test is suitable and sufficient in terms of content and

execution.

If the proof test is developed by a person who lacks the required knowledge and understanding

there is an increased probability elements essential to the safety path may be excluded from the

proof test therefore decrease the C

. Equally if the person conducting the proof test does not

fully understand or appriciate why they are conducting the test or elements of the test there is

increase probability that these will inadequately completed and therefore decreasing the actual

risk reduction the SIF is providing.

What does the regulator expect

For the purposes of the UK HSE Enforcement Management Model the UK HSE rely on defined,

established and interpretative standards for which, based on the perceived risk gap, they may

issue verbal warnings, letters or improvement notices. With respect to proof testing the following

apply and the author has applied this approach to the review of current proof testing regimes

and the application of proof test coverage factors for a number of clients:

BS EN 61508:2010 – Established Standard

ii) BS EN 61511:2004 – Established Standard

iii) UK HSE OG00054 - Interpretative Standard

iv) UK HSE CRR 428/2002 – Interpretative Standard

v) EEMUA Publication 222 - Established Standard

vi) ISA-TR84.00.03-2002 – Established Standard