Actuator Working Group
Functional safety – “SIL” for mechanical devices and systems
The working group discussed a proposal made to ISO/TC153 (valves/ actuators) regarding functional safety standard IEC 61508 and specifically the reliability assessment for mechanical devices. IEC 61508 addresses electric, electronic and programmable electronic components whose reliability measures tend to come from component databases. Such databases do not exist for mechanical devices and so transferring the standard’s methodology to classification of mechanical components/systems is problematic. The proposal, led by Germany, is for the development of an ISO document specific to mechanical “final elements.” Our working group’s conclusion is in agreement and is generally supportive of the proposal. We will actively feed into any development work at ISO.
European standards activity (CEN)
Working group members along with the BVAA Technical Consultant attended several meetings of CEN/TC 69/WG 1 ‘Basic Standards’ and CEN/TC 69/WG 1/SG 10 ‘Actuators’ in 2017.
Current CEN standard development includes work developing prEN 15714-6 ‘Industrial valves – Actuators - Part 6: Linear pneumatic and hydraulic actuators’ and WI 69189 ‘Industrial valves — Gearboxes for industrial valves.’ As a working group and UK experts, we continue monitoring and actively providing input.
The preliminary work item PWI 00069187, to harmonise the EN15714 series with ISO 12490 ‘Petroleum and natural gas industries — Mechanical integrity and sizing of actuators and mounting kits for pipeline valves’ has now been cancelled. The reason being that actuator experts believed there to be no significant conflicts or overlap.
International standards activity (ISO)
Working group members along with the BVAA Technical Consultant attended several meetings of ISO TC153/WG1 - Basic Standards & ISO TC153/SC2 – Actuators in 2017.
Standards under development include a gearbox standard, PWI 00069189 and an Electric actuator standard, ISO 22153. As CEN are also developing a gearbox standard and are nearing completion of a final draft, it has been agreed that ISO experts will consider the CEN draft. Similarly, EN15714-2 ‘Electric actuators’ is published and current and it has been agreed by ISO experts to be the basis of their work.
As CEN and ISO standardisation continues apace, more meetings will be convened in 2018. BVAA experts will continue to attend and the WG, as a whole, will provide valuable support and input. Our working group will aim to meet twice this year, dates to dovetail if possible with CEN and ISO milestones. Dates will be announced in due course, probably late spring and autumn. The potential opportunity to develop a more appropriate means for the assessment of mechanical device reliability/availability provides an interesting and exciting challenge. It will remain a major topic for our working group.
As ever, I very much welcome any input, your contribution or attendance in our 2018 meetings.
Published in Valve User Magazine Issue 44