API API-580 - API 580 - Risk Based Inspection

API 580, Section 13.1 states:

“Inspection may not always provide sufficient risk mitigation or may not be the most cost-effective method. The purpose of this section is to describe other methods of risk mitigation.”

And further clarifies:

“RBI offers the added advantage of identifying gaps or shortcomings in the effectiveness of commercially available inspection technologies… In cases where technology cannot adequately and/or cost-effectively mitigate risk, other risk mitigation approaches can be implemented.”​

API 580, Section 13.11 states:

“Water curtains mitigate water-soluble vapor clouds by absorption as well as dilution... Early activation is required to achieve significant risk reduction. The curtain should preferably be between the release location and ignition sources or locations where people are likely to be present.”

Toxic scrubbers are used for venting or building protection, but water curtains directly mitigate dispersion of water-soluble acidic clouds in open areas.

According to Section 11.2.1 of API 580:

“The probability of credible events leading up to the specific consequence should be factored into the probability of the specific consequence occurring.”

Additionally:

“It is important to understand this linkage between the POF and the probability of possible resulting incidents… The probability of a specific consequence is tied to the severity of the consequence and may differ considerably from the probability of the equipment failure itself.”

Option A is correct and emphasized directly in API 580.

Option B is incorrect because considering all credible events is essential.

Option C is incorrect: the probability of a consequence typically decreases with severity.

Option D is incorrect: the probability of consequence is linked to the probability of failure.

API 580 Section 14.3.2 clearly states:

“Users should set default maximum time periods for reassessments. The governing inspection codes (such as API 510, API 570, and API 653) and jurisdictional regulations, if any, shall be reviewed in this context.”

This means the codes and regulations are explicitly consulted to determine maximum allowable intervals between RBI reassessments. This ensures compliance with inspection frequency expectations across different jurisdictions and standards.

API 580, Section 12.4 and 12.6 emphasize that inspection should be optimized and risk-focused. Excessive inspections can increase exposure to damage mechanisms (such as mechanical or corrosion risks introduced during inspection activities), especially if not needed.

From Section 12.4:

“Organizations should be deliberate and systematic in assigning the level of risk management achieved through inspection and should be cautious not to assume that there is an unending capacity for risk management through inspection.”

Further, in risk-optimization contexts (Section 12.5):

“While there is a potential for reduction of inspection costs through utilization of RBI, increased equipment integrity and inspection cost optimization should remain the focus.”

Therefore, excess inspections may be:

Unjustified

Economically wasteful

Risk-enhancing (e.g., opening equipment unnecessarily may lead to deterioration)

Per Section 11.7 of API 580:

“Thresholds that divide the risk plot matrix or table into acceptable and unacceptable regions of risk can be developed. Corporate safety and financial policies and constraints or risk criteria influence the placement of the thresholds.”

This confirms that risk thresholds define boundaries between acceptable and unacceptable regions, not simply levels of consequence or probability.

According to API 580, Section 9.4.3:

“It is important to link the damage mechanism to the most likely resulting failure mode. For example:

a) pitting generally leads to small-hole-sized leaks;

b) stress corrosion cracking can develop into small through-wall cracks or in some cases rupture…”

This highlights that identifying the specific failure mode (e.g., leak, rupture) related to the damage mechanism is critical for accurate probability and consequence analysis.