Annex G, Application of Threshold R

Annex G, Application of Threshold Release Categories to Multicomponent Releases provides guidance on thresholdrelease category determination for a variety of multicomponent streams.Annex H, PSE Tier 1/Tier 2 Determination Decision Logic Tree provides a flowchart to assist companies indetermining if a loss of primary containment is a Tier 1 or Tier 2 process safety event.5.3Calculation of Tier 1 PSE RateThe Tier 1 PSE Rate shall be calculated as follows:Tier 1 PSE Rate 20.000 = (Total Tier 1 PSE Count 1 Total Work Hours) X 200,000, orTier 1 PSE Rate 10000 = (Total Tier 1 PSE Count 1 Total Work Hours)x 1,00,000NOTETotal Work Hours was chosen as the normalizing factor for PSE Rate as a balance between ready availability ofthe value, relevance to harm, and applicability to various refining and petrochemical operations. Other suggestednormalizers such as throughput, Dow Fire and Explosion Index, etc. did not strike this balance. Total work hours includesemployees and contractors (see 3.1.51 for defnition).The choice of calculating PSE Rate utilizing either a 200,000 or 1,000,000 man hour multiplier should be consistentwith the basis for calculating the Company's occupational injury rate or public reporting conventions.5.4 Optional Tier 1 PSE Severity WeightingSeverity weighting, whether Company defined or industry association defined, can provide additional usefulinformation about Tier 1 PSEs that may help drive performance improvement. Annex D provides an examplemethodology for calculating a severity weight for Tier 1 PSEs that a company may find beneficial.6 Tier 2 Performance Indicator- Process Safety Events (T-2 PSE)6.1 Tier 2 Indicator PurposeThe count of Tier 2 process safety events represents LOPC events of lesser consequence. Tier 2 PSEs, even those