OG54 provides a useful summary of failure modes that can often be missed during proof testing

The test method suggested in OG54 could help improve the coverage of your proof testing and assist in your performance in future compliance assessment and audits.

OG54 HSE Appendix 4 common failings

http://www.hse.gov.uk/foi/internalops/og/og-00054-appendix4.pdf

This OG54 document covers:

Sensors

  • Redundant channels (e.g. in voting arrangements)
  • Use of simulation without testing the sensing element
  • Sensor diagnostic features
  • Sensor reading correctly - use of cross-comparison
  • Sensor reading correctly - use of gauges etc.
  • Sensor testing tolerance
  • Pressure impulse lines or process connections blocked / leaking partially or completely
  • Level sensors with test button
  • Level sensors - unable to test due to access hazardous substances
  • Temperature sensors - process connection
  • Flow sensors reading correctly - unable to test
  • Interface devices reading correctly

Logic solvers

  • Relay Logic redundancy with components
  • Redundant channels
  • Diagnostic functions in the logic solver (PES, trip amps etc)
  • Control System trips
  • Trip amps - changing trip settings to test
  • Hardwiring logic functions (e.g. timing relays)

Final elements

  • Cessation of flow, heat input etc - testing to instruments only
  • Valve operation - position indicators
  • Valve operation - latent failure modes
  • Valve operation - testing solenoids
  • Backup arrangements - e.g. accumulators, trip, batteries, backup power

Whole SIS

  • Response times
  • Ancillary items - trace heating etc.
  • In-built diagnostics
  • All failure modes - test by operation
  • All failure modes - use of overrides

Nationwide course schedule

We run a nationwide schedule of courses throughout the year. Course information.

Bespoke In-House Technician Training

If you have four or more Instrument Technicians who need training, then =Method can arrange a bespoke in-house course for you. This could include time on-site prior to the course learning about what you do and customising the course and case studies based on your own procedures. To talk about custom training call 01462 713313.

 


Title: OG54 provides a useful summary of failure modes that can often be missed during proof testing
Date: 2019-06-06
Published by: Method Functional Safety