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API RP 754:2010 pdf download

API RP 754:2010 pdf download.Process Safety Performance lndicators for the Refining and Petrochemical Industries.
7 Tier 3 Performance Indicators—Challenges to Safety Systems
7.1 Purpose of Indicator
A Tier 3 PSE typically represents a challenge to the barrier system that progressed along the path to harm, but is stopped short of a Tier 1 or Tier 2 LQPC consequence. Indicators at this level provide an additional opportunity to identify and correct weaknesses within the barrier system.
Tier 3 indicators are intended for internal Company use and can be used for local (site) public reporting. A Company may use all or some of the example indicators below:
— safe operating limit excursions;
— primary containment inspection or testing results outside acceptable limits;
— demands on safety systems;
— other LOPCs.
or identify others that are meaningful to its operations.
A Company shall develop and use Tier 3 Indicators.
7.2 Examples of Tier 3 PSEs
7.2.1 Safe Operating Limit Excursions Indicator Definition
A process parameter deviation that exceeds the safe operating limit (SQL) applicable to the phase of operation. Different operating phases (e.g. regeneration or steps in a batch process) may have different SOLs for the same equipment. Figure 3 depicts the relationship between normal operating limits, high/low alarm limits, and the SQL. Exceeding the SQL represents the point beyond which troubleshooting ends and pre-determined action occurs to return the process to a known safe state. The predetermined action may range from manually executed operating procedures to a fully automated safety instrumented system. Indicator Data Capture
A Tier 3 PSE is counted for each SQL excursion that occurred in a specified time period.
A Company may want to record the duration of individual SQL excursions and may even calculate the total duration of all SQL excursions.
A single initiating event may result in multiple SQL excursions (e.g. site-wide failure of a utility) and each excursion should be counted as a separate Tier 3 PSE. A process condition that hovers near the SQL value may result in multiple excursions. These excursions should be counted as a single Tier 3 PSE.
7.2.2 Primary Containment Inspection or Testing Results Outside Acceptable Limits Indicator Definition
An inspection or test finding that indicates primary containment equipment has been operated outside acceptable limits. These findings typically trigger an action, such as replacement-in-kind, repairs to restore fitness-for-service, replacement with other materials, increased inspection or testing, or de-rating of process equipment.
A Tier 3 PSE is counted for vessels, atmospheric tanks, piping, or machinery when previous operating pressures or levels exceed the acceptable limits based upon wall thickness inspection measurements.
A single Tier 3 PSE is recorded for each pressure vessel or atmospheric tank regardless of the number of individual test measurements found to be below the required wall thickness.
A single Tier 3 PSE is recorded for each pipe circuit regardless of the number of individual test measurements below its required wall thickness as long as it is the same line, constructed of the same material, and is in the same service. Calculation
Number of equipment pieces found to have operated outside fitness-for-service rating per 100 or 1000 inspections or tests. Equipment types (e.g. pressure vessels, pipes, atmospheric tanks, machinery) should be calculated separately.
7.2.3 Demands on Safety Systems Indicator Definition
A demand on a safety system designed to prevent a LOPC or to mitigate the consequences of a LOPC.
An emphasis is placed on the “system” approach to recognize that many safety systems consist of multiple elements. For example, a system may include sensors, logic solvers, actuators, and final control devices designed to prevent a LOPCI or it may include a PRD and flare or scrubber that function together to mitigate the consequences of a LOPC. All of these elements function together as a system and when a demand is placed on the system, a single event is counted, regardless of the number of devices that must function within the system. An example is a process vessel that uses multiple PRDs to either handle large relief loads or to minimize the potential for chattering. Activation of these multiple PRDs constftutes activation of one safety system and would be recorded as one Demand on Safety Systems.


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