Session: 07-01-02 Natural Gas Release Consequence

Paper Number: 129992

129992 - Risk Modeling for Rupture Mitigation Valve 

Abstract: 

Per PHMSAs recent additions to 192.935 (c), if an operator determines that a Rupture Mitigation Valve (RMV) would be an efficient means of adding protection to their High Consequence Areas (HCAs) then they must install them.  In order to determine if an RMV would be an efficient means of adding HCA protection, a risk analysis approach must be devised which considers the impacts of installing additional RMVs.  RMV installation can improve both failure response time and valve spacing, both of which have an impact on the total time that a rupture with ignition can be sustained.

PHMSAs definition of Potential Impact Radius (PIR) in 192.903 is associated with a sustained heat flux for a thirty second timeframe which results in a one percent likelihood of mortality.  Because the PHMSA defined PIR has a fixed timeframe of concern and an RMV installation can impact the time that a rupture with ignition is maintained, in order to assess the impacts of an RMV, we cannot rely upon PHMSA PIR definition for this analysis.  Instead, a correlation between heat flux over time (heat dosage) and distance with the likelihood of mortality and building ignition need be established to assess the impacts of RMV installation on reducing consequences associated with a sustained rupture with ignition.  In developing that correlation, and operator can then evaluate if the installation of an RMV would be an efficient means of protecting their HCAs.

DNV has developed an RMV risk modeling tool to help operators minimize the consequences of a pipeline incident surrounding their HCAs.  This presentation will cover the flow modeling approach, heat flux calculations, approximation of the transient state, and consequence modeling included in DNV’s RMV approach. This model supports operators in selecting optimal RMV spacing and locations surrounding their HCAs to most effectively protect public safety.

Presenting Author: Alex Woll DNV

Presenting Author Biography: Alex is a principal engineer and heads DNV's pipeline risk advisory section. With over a decades experience working for major oil and gas operators as a risk and integrity engineer, Alex realized his passion for risk modelling and came to DNV to focus on helping operators improve their risk and PMM programs.

Authors:

Alex Woll DNV
Guanlan Liu DNV
Zhuoran Zhang DNV