The inspection of plant and machinery has traditionally been based on statutary requirement backed up by local health & safety legislation. The type of equipment has determined inspection frequency, methods employed and locations examined - with little focus given to its age, specific duty or likely condition. Increased operational experience and a greater appreciation of the hazards are now leading some parts of industry to adopt a more informed approach to inspection planning, targeting the inspection required to reduce the risk as low as reasonably practicable.
Risk based inspection is the process of developing an inspection plan based on knowledge of the risk of failure of the equipment. The essential element is a risk analysis. This is the combination of an assessment of the likelihood (probability) of failure due to damage, deterioration or degradation mechanism with an assessment of the consequences of such failure.
The information gained from this process is used to identify
1.The type and rate of damage that may potentially be present and
2.The equipment or locations where failure would give rise to danger of different degrees.
Higher risk equipment may have active damage mechanisms or high consequences of failure, or a combination of the two. A suitable inspection scheme is then planned to increase confidence about the equipment's current and future condition, taking account of the potential damage mechanisms and the reliability of the inspection techniques used.
Risk based inspection may be applied in any industry, but there has been most interest from the power and petrochemical sectors. The American Petroleum Institute has published guidance for risk based inspection relevant to refineries. [1]
Industry sees RBI as a means of using inspection resources more effectively which can result in economic benefits from extended run lengths or from the use of advanced NDT or non-invasive schemes. Regulatory pressure will ensure that the process of RBI is carried out rigorously so that non-prescriptive inspection decisions are based on adequate information and expertise. .
Risk based inspection is the process of developing an inspection plan based on knowledge of the risk of failure of the equipment. The essential element is a risk analysis. This is the combination of an assessment of the likelihood (probability) of failure due to damage, deterioration or degradation mechanism with an assessment of the consequences of such failure.
The information gained from this process is used to identify
1.The type and rate of damage that may potentially be present and
2.The equipment or locations where failure would give rise to danger of different degrees.
Higher risk equipment may have active damage mechanisms or high consequences of failure, or a combination of the two. A suitable inspection scheme is then planned to increase confidence about the equipment's current and future condition, taking account of the potential damage mechanisms and the reliability of the inspection techniques used.
Risk based inspection may be applied in any industry, but there has been most interest from the power and petrochemical sectors. The American Petroleum Institute has published guidance for risk based inspection relevant to refineries. [1]
Industry sees RBI as a means of using inspection resources more effectively which can result in economic benefits from extended run lengths or from the use of advanced NDT or non-invasive schemes. Regulatory pressure will ensure that the process of RBI is carried out rigorously so that non-prescriptive inspection decisions are based on adequate information and expertise. .
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