OPS TTO13 - Potential Impact Radius formulae for flammable gases other than natural gas.

PDFTech ReportTTO Number 13DTRS56-02-D-70036Flammable materialsFuel gasGasesUnited States. Office of Pipeline SafetyMichael Baker Jr., Inc.United States. Office of Pipeline SafetyUS Transportation CollectionThis report was prepared in accordance with the Statement of Work and proposal submitted inresponse to RFP for Technical Task Order Number 13 (TTO 13) entitled \ue2\u20ac\u153Potential Impact RadiusFormulae for Flammable Gases Other Than Natural Gas.\ue2\u20ac?A key element of the Gas Integrity Management Rule (49 CFR 192, Subpart O) is the calculation ofthe potential impact radius (PIR) of a circle within which the potential failure of a pipeline couldhave significant impact on people or property.The original derivation of the PIR formula referenced in 49 CFR 192 is contained in the GasResearch Institute (GRI) report by C-FER Technologies (C-FER), \ue2\u20ac\u153A Model for Sizing HighConsequence Areas Associated with Natural Gas Pipelines\ue2\u20ac? (Stephens 2000). It must be recognizedthat this formula was derived solely on the premise that thermal radiation from a jet/trench fire is thedominant hazard related to pipe rupture and subsequent ignition. Since natural gas is non-toxic andsignificantly lighter than air, this premise is valid.However, there are certain pipeline operators transporting flammable gases other than natural gas(e.g. hydrogen) that will be governed by the jet fire hazard, and thus there is a need for derivation ofPIR formulae for use in identifying high consequence areas for these pipelines. While the C-FERreport provides a basis for derivation of such formulae, the dimensionless values for emissivityfactor, release rate decay factor, and efficiency factor used in the original derivation of the PIRformula have not been validated or optimized for flammable gases other than natural gas.An introduction to this report is contained in Section 1, while Section 2 presents the more detailedbackground on the reasoning and assumptions used in the development of the PIR formulaepresented in this report.Section 3 documents the process utilized in identifying the various products that are known orreasonably assumed to be currently transported by pipelines in the US. Four products were chosenfor PIR formula development: ethylene, hydrogen, rich natural gas and synthesis gas (syngas).Section 4 comprises the majority of the report and describes the actual PIR formula development ina logical progression. At each step, the underlying formulae are given with the required variablespresented and explained. This section concludes with a generalized methodology for use indetermining the PIR for flammable gas mixtures. The PIR formula for natural gas referenced in 49CFR 192 is also presented to allow the reader to compare the results of this study with the earlierwork.Section 5 describes the efforts conducted to validate the PIR formulae. These efforts were essentiallyfruitless due to the lack of actual incident data for the products of interest. Section 6 presents acommentary on the usage of constants for selected model factors that are in fact variables and wouldbe treated as such if a more rigorous modeling approach were to be employed. Section 7 summarizesthe results of the PIR formula development process. Finally, Section 8 presents a list of referencedocuments cited throughout the report.The information included in the report that was entirely compiled by C-FER Technologies iscontained in Appendix A