Page 11 - Corrosion Engineering Principles and Practice

viii C o n t e n t s C o n t e n t s ix

12 Corrosion as a Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . 477
12.1 Risk Assessment . . . . . . . . . . . . . . . . . . . . . . . . 477
12.2 Risk Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 478
12.3 Risk and Corrosion Control . . . . . . . . . . . . . . . 481
12.4 Key Performance Indicators . . . . . . . . . . . . . . 484
12.4.1 Cost of Corrosion
Key Performance Indicator . . . . . . . 485
12.4.2 Corrosion Inhibition Level Key
Performance Indicator . . . . . . . . . . . 486
12.4.3 Completed Maintenance
Key Performance Indicator . . . . . . . 488
12.4.4 Selecting Key Performance
Indicators . . . . . . . . . . . . . . . . . . . . . . . 488
12.5 Risk Assessment Methods . . . . . . . . . . . . . . . . 491
12.5.1 Hazard and Operability . . . . . . . . . . . 491
12.5.2 Failure Modes, Effects,
and Criticality Analysis . . . . . . . . . . . 493
12.5.3 Risk Matrix Methods . . . . . . . . . . . . . 495
12.5.4 Fault Tree Analysis . . . . . . . . . . . . . . 496
12.5.5 Event Tree Analysis . . . . . . . . . . . . . . 500
12.6 Risk-Based Inspection . . . . . . . . . . . . . . . . . . . . 503
12.6.1 Probability of Failure
Assessment . . . . . . . . . . . . . . . . . . . . . 504
12.6.2 Consequence of Failure
Assessment . . . . . . . . . . . . . . . . . . . . . 504
12.6.3 Application of Risk-Based
Inspection . . . . . . . . . . . . . . . . . . . . . . 505
12.7 Industrial Example:
Transmission Pipelines . . . . . . . . . . . . . . . . . . . 507
12.7.1 External Corrosion
Damage Assessment . . . . . . . . . . . . . 512
12.7.2 Internal Corrosion
Damage Assessment . . . . . . . . . . . . . 515
12.7.3 Hydrostatic Testing . . . . . . . . . . . . . . 518
12.7.4 In-Line Inspection . . . . . . . . . . . . . . . . 518
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 522
13 Cathodic Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . 525
13.1 Cathodic Protection Historical Notes . . . . . . . 525
13.2 How Cathodic Protection Works in Water . . . 526
13.2.1 Sacrificial Cathodic Protection . . . . . 527
13.2.2 Impressed Current
Cathodic Protection . . . . . . . . . . . . . . 529