02/12/2016
WHEN CAN RBI BE USED TO EXTEND ENGINEERING INSPECTION INTERVALS?
Changing the inspection strategy through a Risk Based Inspection (RBI) could be a very powerful tool for organisations when implemented as part of a long-term strategy. An effective RBI that is managed correctly and is based on sound knowledge could lead to substantial cost savings, while at the same time increasing plant safety and reducing downtime.
When RBI is usually used
RBI is usually completed by companies that have high hazard pressure equipment at their sites. However, the RBI approach is being applied to a wider range of equipment that tends to be examined on a regular basis; in order to reduce the plant’s downtime and operational costs.
The justification for extended inspection periods, or modified inspection techniques needs to be based on a juxtaposition of the health and safety implications of carrying out prolonged internal inspections in relation to the benefits of risk reduction. A very important factor and part of the successful justification process is the company’s reporting culture and its ability to adapt to change. This needs to be supported by a comprehensive information management system of the operational history of the equipment. The transition towards extending intervals between inspections needs to comply with a number of regulations, such as the PSSR 2000, the fundamental principles of the Health and Safety at Work Act and COMAH regulations.
The First Step
Conducting a comprehensive RBI assessment is the first step towards effectively justifying the reasons for changing the inspection regime at your plant.
The RBI will involve people from different departments of your organisation, as well as external experts, that have the range of knowledge and experience developed from other sites that is needed to understand the potential degradation mechanisms and potential failure scenarios,
What follows next?
Following the risk based inspection, there are other factors that you may need to be aware of to justify a change in the inspection regime for your equipment.
RBM Assessment
When successfully completed, the RBI assessment should have correctly identified all the potential damage mechanisms. However, for internal examination to be deferred, or removed you will need to conduct further examination into the wider aspects within the Risk Based Management (RBM) of your plant. Some of the aspects of the examination that need to be included are:
Operating conditions
The number of shutdown cycles
The design and installation of internal fittings
Details about the ways of inspecting the gaskets and bolts of bolt connections, and
Whether the internal environment of the vessel could be jeopardised in any way by the maintenance of external fittings.
Previous Internal Examinations
The records of previous internal thorough examinations can play a significant role in building a strong justification for extending inspection periods. If your reports show a lack of degradation over a long period of time, this is a good indicator that an extended inspection is acceptable and will not put at risk the safe operation of the plant.
Non-invasive inspection
In certain circumstances conducting an external non-destructive (NDT) examination of the equipment could be the safest way to provide information about its internal condition without taking the risk of shutting down the plant and the potential risks from entry into confinrd spaces. There are several NDT techniques that can provide information about the thickness and the condition of the internal surfaces. These include ultrasonic testing, shearography and thermography.
In-service monitoring of process fluids
Certain fluids, such as petrochemical and chemical products, require close monitoring and are under stringent quality controls once refined, so that no contamination occurs before the product is distributed. This in-service process of monitoring the product’s composition brings extra confidence and security that the clean non-corrosive conditions are in place.
The RBI team
The RBI team’s range of experience and knowledge is the most crucial part of ensuring sound judgement in setting written schemes of examination and successfully justifying extending the inspection periods of your equipment.
The team needs to comprise competent and qualified people that have knowledge of:
The production processes
Failure consequences and safety management
Maintenance
Structural design and integrity
Materials
Corrosion
Welding
Non-destructive testing and production planning
It is also important to ensure independence between operation and the inspection of the plant in your evaluation. Many sites therefore utilise their in-house specialists whilst collaborating with external independent experts, who can offer a broader range of technical expertise.
