||Manufacturer of differentiated chemicals (due to commercial interests the client as requested to remain anonymous)
Risk-Based Inspection (RBI)
Risk-based inspection is a systematic process for factoring risk into decisions concerning how, where, and when to inspect a process plant.
- RBI focuses inspection resources on the highest priority equipment to determine asset integrity.
- RBI cost effectively helps make process plants safer and more reliable.
- Compared with a typical inspection program, RBI programs can reduce both the risk in an operating unit as well as inspection costs.
- RBI programs can reduce the overall costs of the inspection program, affecting both turnaround and on-stream inspection activities.
The greatest value contribution of risk based inspection programs, is managing plant risk and improving reliability. A properly designed and implemented RBI
program will refocus the inspection plan to manage the risk contribution from all of the damage mechanisms by making sure the proper inspection tasks are performed on each piece of equipment. It will also eliminate inspection activities that do not make a contribution to a risk reduction.
Business challenge for the client
Our client, global manufacturer and marketer of differentiated chemicals, required a solution that could provide a dynamic means of determining when and where to expect in-service deterioration and effectively predict Corrosion Under Insulation (CUI) damage as well as chloride stress corrosion cracking and other damage mechanisms. A solution was required to support fitness for service evaluation and to develop an appropriate maintenance strategy to ensure safety, equipment reliability and uptime whilst reducing cost.
How we helped the client
Implemented RBMI, our fully integrated RBI software package, to promote and achieve safety, corporate and profit objectives.
- The project involved over 11,000 equipment items including fixed vessels, relief devices, piping circuits across multiple process units.
- It was scheduled for 32 months, including non-destructive examination (NDE) inspections that had to be completed as soon as possible, prior to a pending turnaround scheduled for month 16 following the RBMI project start date.
- The project involved data collection, reviewing inspection histories, corrosion studies, criticality analyses, prioritised NDE inspections which followed the inspection planning review process.
- The corrosion study provided key inputs for the RBMI program including potential damage mechanisms, corrosion types, and corrosion rates and predictable or potential locations, flow considerations to allow inspectable risk to be calculated.
- Cumulative risk curve used to illustrate a process unit’s overall risk by assets or risks by different damage mechanisms.
- Improved client’s ability to identify damage mechanisms resulting in prioritised inspection strategies.
- Eliminated inspection activities that do not make a contribution to a risk reduction.
- Corrosion Under Insulation (CUI) prediction found pitting, nozzle thinning and chloride stress corrosion cracking (CSSC).
- Identified that the contribution to cumulative risk for the example exchanger alone was almost half the risk of the all the assets associated with this process unit.
- The majority of risk was due to NO inspections previously conducted for CSSC as a damage mechanism for this asset.
- A number of exchangers showed high risk for CSSC.
- The potential for CSSC was determined from the corrosion study and made urgent by the criticality models for likelihood and consequence in the RBMI software.
- Repairing and replacing the damaged exchangers further reduced the risk dramatically to the facility.
- The significant findings in CUI and CSCC as a result of the RBMI study, have delivered significant value in lost production avoidance.
- Prioritised inspections revealed no damage in the asset resulting in a reduction in risk of over 70%.
- Focusing inspections on the higher criticality items resulted in a cumulative risk reduction of 80%.
- Achieved significant improvements in reliability leading to a 96.7% asset mechanical reliability.
- Systematic application of risk based inspection to all equipment types
- Carefully defined steps to improve plant performance
- Optimised inspection, test and maintenance work
- Eliminated unplanned equipment downtime
- Continuously improving equipment reliability
- Improved performance metrics
- Reduced costs
- Ensured community safety, personnel safety, and environmental protection while simultaneously improving equipment integrity and reliability
The full case study was delivered at the AFPM, Reliability and Maintenance Conference.