RBI Assessment Planning
Getting Started:
— Why the RBI assessment is being done?
— How the RBI assessment will be carried out?
— What knowledge and skills are required for the assessment?
— Who is on the RBI team?
— What are their roles in the RBI process
Establishing Objectives and Goals of an RBI Assessment
General
An RBI assessment should be undertaken with clear objectives and goals that are fully understood by all members of
the RBI team and by management.
Understand Risks
From the understanding of risks, an inspection program may be designed that optimizes the use of inspection and
plant maintenance resources.
Define Risk Criteria
An RBI assessment will determine the risk associated with the items assessed.
Management of Risks
The results of managing and reducing risk are improved safety, avoided losses of containment, and avoided commercial losses.
Reduce Costs:
Reducing inspection costs is usually not the primary objective of an RBI assessment, but it is frequently a side effect of optimization.
a) ineffective, unnecessary or inappropriate inspection activities may be eliminated;
b) inspection of low-risk items may be eliminated or reduced;
c) on-line or noninvasive inspection methods may be substituted for invasive methods that require equipment shutdown;
d) more effective infrequent inspections may be substituted for less effective frequent inspections.
Meet Safety and Environmental Management Requirements:
Managing risks by using RBI assessment can be useful in implementing an effective inspection program that meets performance-based safety and environmental requirements.
Identify Mitigation Alternatives
The RBI assessment may identify risks that may be managed by actions other than inspection. Some of these mitigation actions may include but are not limited to:
a) modification of the process to eliminate conditions driving the risk;
b) modification of operating procedures to avoid situations driving the risk;
c) chemical treatment of the process to reduce deterioration rates/susceptibilities;
d) change metallurgy of components to reduce POF;
e) removal of unnecessary insulation to reduce probability of corrosion under insulation;
f) reduce or limit available inventories to reduce COF;
g) upgrade safety, detection or loss limiting systems;
h) change process fluids to less flammable or toxic fluids;
i) change component design to reduce POF;
j) process control and adherence to IOWs.
New Project Risk Assessment
An RBI assessment made on new equipment or a new project, while in the design stage, may yield important information on potential risks.
Facilities End of Life Strategies
Facilities approaching the end of their economic or operating service life are a special case where application of RBI can be very useful.
Initial Screening
General
The screening process focuses the analysis on the most important group of equipment items so that time and resources are more effectively utilized.
Establish Physical Boundaries of an RBI Assessment
The scope of an RBI assessment may vary between an entire refinery or plant and a single component within a single piece of equipment.
Facilities Screening
At the facility level, RBI may be applied to all types of plants including but not limited to:
a) oil and gas production facilities,
b) oil and gas processing and transportation terminals,
c) refineries,
d) petrochemical and chemical plants,
e) pipelines and pipeline stations,
f) liquified natural gas plants.
Process Units Screening
If the scope of the RBI assessment is a multi-unit facility, the first step in the application of RBI is screening of entire process units to rank relative risk.
Systems within Process Unit Screening
Block flow or process flow diagrams for the unit may be used to identify the systems including information about metallurgy, process conditions, credible damage mechanisms and historical problems. When a process unit is identified for an RBI assessment and overall optimization is the goal, it is usually best to include all systems within the unit. Practical considerations such as resource availability may require that the RBI assessment is limited to one or more systems within the unit.
Equipment Item Screening
An RBI assessment may be applied to all pressure containing equipment such as:
a) piping,
b) pressure vessels,
c) reactors,
d) heat exchangers,
e) furnaces and boilers,
f) tanks,
g) pumps (pressure boundary),
h) compressors (pressure boundary),
i) pressure-relief devices,
j) control valves (pressure boundary).
Utilities, Emergency and Off-plot Systems
a)The RBI assessment is being done for an overall optimization of inspection resources and environmental and business COF are included.
b) There is a specific reliability problem in a utility system. An example would be a cooling water system with corrosion and fouling problems. An RBI approach could assist in developing the most effective combination of inspection, mitigation, monitoring, and treatment for the entire facility.
c) Reliability of the process unit is a major objective of the RBI analysis.
Establish Operating Boundaries
General
The RBI assessment normally includes review of both POF and COF for normal operating conditions. Start-up and shutdown conditions as well as emergency and nonroutine conditions should also be reviewed for their potential effect on POF and COF.
Start-up and Shutdown
Process conditions during start-up and shutdown can have a significant effect on the risk of a plant especially when they are more severe (likely to cause accelerated deterioration) than normal conditions, and as such should be considered for all equipment covered by the RBI assessment.
Normal, Upset, and Cyclic Operation
a) operating temperature and pressure including variation ranges,
b) process fluid composition including variation with feed composition ranges
Operating Time Period
The unit run lengths of the selected process units/equipment is an important limit to consider. The RBI assessment may include the entire operational life, or may be for a selected period.
Selecting a Type of RBI Assessment:
Selection of the type of RBI assessment will be dependent on a variety of factors, such as:
a) is the assessment at a facility, process unit, system, equipment item, or component level;
b) objective of the assessment;
c) availability and quality of data;
d) resource availability;
e) perceived or previously evaluated risks;
f) time constraints.
Estimating Resources and Time Required
The resources and time required to implement an RBI assessment will vary widely between organizations depending on a number of factors including:
a) implementation strategy/plans,
b) knowledge and training of implementers
The estimate of scope and cost involved in completing an RBI assessment might include the following:
a) time and resources required for RBI assessment of data and information;
b) time and resources to evaluate RBI assessment results and develop inspection, maintenance, and mitigation plans.
