Executing Quantitative Risk Assessments Effectively on a Project

Transcription

1 Executing Quantitative Risk Assessments Effectively on a Project Leisa Porter Sanjeev Dusija Fluor Corporation - Sugar Land, TX

2 Design Project QRA In the engineering design stage, an effective Quantitative Risk Assessment (QRA) is a highly integrated activity between the QRA team and the engineering design team. It is a multi-discipline effort inputs by multiple disciplines Process, piping, control systems, civil/ architectural, operations, etc. outputs are used by multiple disciplines

3 QRA Goals & Objectives Objectives Verify risk tolerance criteria Provide data that can be transformed into information to the design team for decision making Ultimate goal fully utilize the QRA effort to facilitate inherently safer design decisions

4 Need for Execution Effectiveness The QRA contains many steps that impact a project schedule Hazard identification, consequence analysis, frequency calculations, mitigation requirements Parallel design phase execution Risk based designs and Safety Case philosophy execution becoming more prevalent Comparison to risk tolerance criteria/regulatory Requested to be done in early project phases Projects setting design HSE goals Anticipate quantitative work to increase, not decrease, in the future

5 Execution Strategy During a design stage the QRA is often sourced out to a third party consultant Highly specialized resources Project/prime contract requirements The tendency in this type of execution is to place all the responsibilities on the third party consultant Adequate representation from the design team is often neglected, making it difficult to obtain an effective end product

6 Keys to Successful Execution Project team assign a QRA coordinator Point person/contact Transfer of information/data between the parties Available throughout the project to ensure successful interpretation, follow-up and completion of QRA recommendations Develop technical scope of work (SOW) document Allow adequate time to Write the SOW, and Go through bid process

7 Formal Scope of Work Provides a mechanism to execute the QRA integral to the project QRA Milestones to align with the overall project milestones and to track progress Provisions can be made to integrate the QRA recommendations in the design

8 Benefits Good scope definition increases the likelihood of Quality inputs Alignment during execution Meeting schedules & budgets Achieving quality outputs/results Risk tolerance criteria Inherently safer design decisions Building positive relationships

9 SOW - General Information Standard information Introduction Definitions Objectives Project Overview Overall project schedule Roles & Responsibilities Define for both parties

10 Technical Scope of Work Technical Information Description Methodology Likelihood Of Hazardous Events Assessment of Risk Levels QRA schedule & milestones Deliverables Communication/coordination

11 Other Issues Additional Scope of Work Alternate scope items QA/QC expectations Proposal submittal requirements References Policies & Procedures Client/company specific, regulatory, etc. Project Risk Management Models Project Data Plot plans, PFD s, P&IDs, equipment lists, etc.

12 Sample Schedule Activities Time Length Define Scope of Work Identify Sensitivity Analysis Cases Data Collection PFDs P&IDs Heat and Material Balance Layout Population (& Building) Data Weather Data Identification of Hazards Summarize Set of Hazards as Scenarios Estimating rates and duration of release, quantities and composition of material involved Building Model Input Values in Risk Model Validate Model Analyze the Results Report Writing and Draft Final Report QRA Coordinator Process/ Risk Engineer HAZOP Specialist/ HSE Lead Risk Engineer Team effort initiated by QRA coordinator

13 Milestone Examples QRA Study Milestones Kick-Off Meeting Proposed QRA Table of Contents QRA Report Proposed Format Finalizing QRA Inputs CFD Analysis for Toxic Dispersion Summary of Hazards & Isolatable Sections Frequency Assessment of the Hazard Sources Preliminary Blast Requirements for Occupied Buildings Consequence Assessment of the Hazards Scenarios Riser Risk Study Dropped Object Study Consequence Plots CFD Explosion Analysis for Occupied Buildings Overpressure Rating for Occupied Building Draft QRA Report Presentation of Results Incorporation of comments Final QRA Report Dates 17-Jul Jul Aug Aug-09 1-Sep-09 5-Sep-09 5-Sep Sep Sep-09 1-Oct Oct Oct-09 1-Nov Nov Dec-09 2-Jan-10 4-Jan Jan-10

14 Deliverables/Presentation of Results Final Report Table of Contents Data presentation Assumptions Inputs Parameters Results presentation Tables Plots & graphs Risk criteria verification Summary and recommendations

15 SAMPLE MATERIAL COMPOSITION Scenario Case # Material H2S CO2 N2 C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C14 C15-C20 Benzene Toluene Xylene H20 TEGlycol

16 SAMPLE MODEL INPUTS Case No Scenario Scenario (Description) Scenario (Description) Scenario (Description) Scenario (Description) Scenario (Description) Scenario (Description) Scenario (Description) Scenario (Description) Line Size (in) Process P (Psia) Temp ( F) Height (m) Scenario Conditions Orient. deg Hole Size (in)

17 SAMPLE SUMMARY TABLE CONSEQUENCE MODELING Weather Case 1.5 m/s / "F" Stability Class (occurs approx. X% of the time) Dispersion Downwind Distances (m) Jetfire kw/m2 Distance (m) Pool kw/m2 Distance (m) ½ LFL LFL Toxic TLV STEL IDLH Other Scenario #1 5 mm 25 mm 100 mm 250 mm Scenario #2 5 mm 25 mm 100 mm 250 mm

18 Sample Table Explosion Explosion Distances Case No. Scenario Description Explosion Distances* Hole Size 5-psi (m) 3-psi (m) 1-psi (m) in psi psi psi

19 Summary The QRA is a highly integrated process on a design project. Proper definition of the scope of work is necessary for a successful execution of the QRA. A scope of work alignment allows for integration of the project schedule and QRA output by the use of milestones. Providing a QRA coordinator allows the project and QRA team to integrate the results of the QRA into the design in an efficient manner, and provide formal documentation of data transfer and tracking.