The Korea Gas Safety Corporation (KGS) has selected Phast Risk for assessment of risks from high-pressure gas pipelines. It has found that QRA is one of the most useful techniques for assessing risks from such pipelines and in developing a strategy for land use planning guidelines in their vicinity.

KGS, originally founded as the High Pressure Gas Safety Institute, has devoted more than 30 years to driving gas safety culture and improving safety technology, to fulfill its mission of securing life and property from gas incidents. The major activities promoted by KGS to prevent incidents include facility inspection, education and training, advertising and profiling to foster a safety culture and exchange of technical information internationally with other gas-related organisations.

KGS recently conducted Quantitative Risk Assessment (QRA) for the Korean national natural gas transmission line using DNV’s Phast Risk 6.54. A national audit of major accident hazard facilties, carried out by the Board of Audit and Inspection, found that risks from the highpressure natural gas pipeline were increasing due to growing population resulting from development adjacent to the pipeline. As a result, KGS was asked to carry out a risk assessment.

The natural gas transmission line is operated under 70 bar, and there were no land use planning restrictions in place near the pipeline. KGS decided to use a hybrid Route and Long Pipeline model approach after discussion with DNV in Shanghai. Three representative release cases were considered for each scenario; small leak, medium leak, and rupture, as well as flash fire and jet fire in consequence modelling.

For frequency analysis, KGS used pipeline reliability data from EGIG (European Gas pipeline Incident data Group) due to the scarcity of data available in Korea.

As a result of these Risk Assessments, and considering societal risk, the following recommendations have been made:

• For a pipeline where the risk is greater than the upper limit of the ALARP zone from F-N curves, the pipeline should be relocated since this level of risk is socially unacceptable.
• For a pipeline where the risk is within the ALARP zone, risk reduction measures should be implemented such as periodic inline inspection and a Pipeline Integrity Management System (PIMS) programme.
• For a pipeline where the risk is broadly acceptable and below the ALARP zone, no action is required.

For new pipelines, it was recommended that restrictions be applied to the installation of high-pressure pipelines in populated areas in accordance with the above recommendations, and that QRA be used to assess these risks.

Author: Lee, Seung Kuk, manager, Process Diagnosis Department, KGS

Date: 2010-01-07