A draft version of API RP 21A is currently out for ballot (see attached; also available at https://eballotprodstorage.blob.core.windows.net/eballotscontainer/RP 21A Ballot Draft.pdf ). Annex D of this draft standard is on "Risk Assessment for Bolting Specification Levels". The annex is only a couple pages long, followed by an example that is another couple pages long. The “risk assessment” methodology seems to be terribly misguided in a few ways, including:
- Rather than assessing the likelihood of failure due to anticipated service conditions, a “Risk Factor Multiplier (RFM)” is assigned for each risk factor “based on the likelihood that the risk factor could lead to a bolting failure”. A high RFM could be assigned due to cyclic service despite low stress levels and stress cycle amplitude, which should mean no significant risk. The highest RFM controls.
- Risk assessment is combined with risk mitigation, with the only one possible risk mitigation action (requiring higher BSLs) allowed.
- There is an implied certainty that bolting that does not meet API 20E or 20F is vulnerable to all kinds of failures in all service conditions, without evidence to support this, and that meeting 20E/20F reduces the likelihood of all types of failure in all service conditions.
