The Pilot Scheme
The key ingredients we looked for in this corrosion management initiative were:
- • A move away from a reactive approach to problem finding
- • A move toward a preventive approach underpinned by a belief that failures were not necessarily inevitable
- • To capture all relevant knowledge from whoever had it
- 90 Chapter 10
- • As a first step, to bring together in a series of briefings and meetings those parties with the most to contribute to the declared aims, including:
- • Inspectors for the area under review
- • Facility corrosion engineer
- • Technologist for the area
- • Plant maintenance supervisor
- • Senior Plant operator
- • Plant Manager (Chairman)
Figure 10.4 Corrosion Review and Analysis Process
Much debate took place before the meeting in management circles on the tactics that should be adopted which would bring the most chance of success. We decided that the plant manager had to be clearly identified as the owner of the equipment and made responsible for reliability end results. To that end, he had to manage a process of bringing together many disparate strands of activities (operators, inspectors, and maintainers) and integrating them into an effective whole. We tried to promote a move away from the compartmentalized past where Production operated and broke the equipment and Maintenance then mended it.
Our next step was to get the concepts agreed by all parties and the group acting as a team in concert. We chose the Crude Distillation area to pilot this effort. The people there were open-minded and positive, so our chance of success was better there. Not surprisingly, the ways of the past were quickly seen as absurd and enthusiasm grew for the new method.
The next step involved a structured approach to identify jointly potential corrosion problems in the plant. Inspection, operations, and maintenance contributed in an atmosphere of openness. This synergy brought a learning experience for all and an increased awareness and understanding of the corrosion issues in the plant. Counter-measures could then be developed jointly.
The review and analysis process is summarized below.
- • Review all process modes and operating conditions, and understand implications
- • Agree operating envelope for the plant
- • Establish corrosion circuits for the plant
- • Identify all potential corrosion problems
- • Formulate preventive or remedial measures
- • Make an implementation plan
- • Review and follow up
Figure 10.4 summarizes the corrosion monitoring review and analysis process for the plant.
2 The operating envelope of a plant consists of the set of operating conditions (temperature, pressure, flow, corrosivity etc.) which balances the plant degradation against the economics of production. Operating within this envelope ensures that the failure modes, mechanisms, and rates remain reasonably consistent. When this is done, the time to failure is predictable with a high degree of confidence. Lack of confidence is a major determinant of inspection (and hence shutdown) intervals. The lower the confidence level, the more frequent the inspections tend to become. Increased predictability of degradation brings increased confidence. so intervals between inspections can be increased, reducing the need for shutdowns and increasing uptime.
-  A Corrosion Circuit covers that section of the plant that has a similar corrosive environmentand is made of similar materials. The Corrosion Circuit concept helps to do five things: - Provide clear corrosion footprints in the plant - Show where the different corrosion problems start and stop - Highlight the most vulnerable areas - Assist monitoring of different types and severities of corrosion - Assist use of most appropriate remedial measures