Best Practice RBI Technology Process by SVT-PP SIMTECH We define the best practice in RBI as a proactive technology process which is used to formally and reliably optimise the inspection efforts for each static equipment item of plant whilst minimising equipment failure risks caused by the relevant damage mechanisms. The technology is applied to all types of pressure vessels, piping, storage tanks and pipelines. Best practice RBI Technology brings immense benefits to plant sites. However, it is emphasised that there are no short cuts to effective implementation of best practices in RBI technology. For example, compromising the quality of the RBI team study by not providing sufficient study time in order to reduce project costs or project timescales will have a detrimental effect on the confidence that can be placed on the RBI study output. As such, the claimed outcomes in improvements of plant reliability, safety and financial benefits are questionable and so is the management decision to buy into this output and implement it in the hope that they are going to achieve these claimed benefits. It is crucial therefore that senior management at plant sites fully appreciate the minimum requirements outlined below and are committed to providing the required manpower and time allocation for the RBI team study.
For plant sites wishing to successfully embark on RBI implementation best practices, the following criteria must be met as a minimum:- The chosen RBI technology process must be robust and reliable in assessing damage mechanisms risks and optimum inspection interval for each item. The team study method applied to achieve this for each item must be structured and sufficiently comprehensive to deliver self assurance in the study output. The RBI study team composition must include inspection, process and operation engineers from the plant site, in addition to external consulting engineers such as RBI specialist and metallurgist (or corrosion specialist). Expertise must be available within the RBI study team to correctly identify items that require specific remaining life calculations (beyond corrosion allowance) or fitness-for-service assessments in order to reap the maximum benefit out of RBI. The supporting software for the RBI process (RBI data, team study and output) must be transparent and auditable. The RBI full implementation must be managed as a project in order to progress the team studies on a regular basis and to successfully embed the subsequent management process into site culture and practices. This fundamental criteria originated by PP SIMTECH formed the basis for the development of its RBI technology process in the late 1990 s and was later fine tuned in 2001 through a joint partnership with British Petroleum. It has over the years proved immensely successful in its application at various types of plant sites. Our proven RBI Technology is considered by our clients to be a reliable and unparalleled process incorporating leading edge of best-practice. It incorporates pertinent key guidance from API 580/581 and the Health & Safety Executive (regulatory body in the UK) which is integral to effective RBI implementation. Importantly however, and exceeding the guidance in API 580/581, our RBI methodology also includes a proven technology breakthrough, which provides an improved process to easily and reliably calculate or assess the consequence of
failure and in particular the probability of failure and the risk profile for each of the identified damage mechanisms applicable to an item (see * NOTE below). This in turn ensures that the resulting inspection interval is reliably optimized, thus providing the required confidence and self assurance to plant site staff responsible for equipment integrity and reliability assurance. *NOTE:- The inherent uncertainties in API & the resulting inconsistencies in the derived inspection interval for equipment items are due to the technique provided for the assessment of probability of failure using failure frequencies approach. In order for this approach to be valid, it requires sufficient and accurate failure frequency data for each type of equipment and each type of damage mechanism applicable to plant items in the oil & gas and petrochemical industry. In reality the required data is scarce, thus the Probability of Failure value selected by one RBI team in the assessment of damage mechanism risk profile has been found to be significantly dissimilar to that selected by a different RBI team. Noting that inspection interval is directly related to damage mechanisms risk profiles, this inconsistency has inevitably led to significantly different projections in inspection interval for an item, thus proving the technique is unreliable for applications in this particular industry. We are the only RBI service providing company to have taken the lead in 2000 in resolving these significant technical uncertainties in the API guidance. After having recognised the merits of our methodology used for damage mechanism risk assessment, British Petroleum (BP) provided further support in 2001 to finalise and verify this unique technique. PP SIMTECH owns this technology breakthrough, named RBI Breakthrough Technology TM which is only available for use by the clients of SVT-PP SIMTECH. It is worth noting that around the same time Shell Petroleum recognised the same inconsistencies in API and consequently developed its own RBI procedure. With respect to RBI software, we ensured that our technology process was reliable and robust before embarking on its development. Our fully auditable and
transparent software system rbiasyst TM (owned by PP SIMTECH) was also jointly developed with British Petroleum to support our technology process. Importantly, this Software captures the complete RBI study data, helps facilitate the RBI team study and records the key outputs required for successful implementation of RBI at a plant site. Clients at plant sites where PP SIMTECH RBI technology has been implemented have reported attaining benefits beyond their initial expectations in terms of improvement in reliability and safety and the net return on financial investment. 2.1. Our Deliverables (main Output from RBI Team Study).. A. Risk based inspection plan (RBI plan) for each equipment item of plant, as finalised by the RBI study team. For each item the RBI plan details.. 1) Optimised MAJOR Inspection interval for each item, based on next 3 desired TA interval and TA dates. Note:- the definition of MAJOR Inspection is where all the identified Damage Mechanisms (DMs) applicable to an item are inspected for at the optimum interval. 2) Inspection type: i.e. intrusive or non-intrusive; item on-line or off-line. Note:- Non-intrusive inspection is implemented as an INTERMEDIATE Inspection at a suitable date between MAJOR Inspections, for e.g., to inspect for a specific DM where its risk profile may not be acceptable up to the extended MAJOR Inspection date. By doing the inspection for that DM at a suitable intermediate date, the risk profile of that DM usually becomes acceptable. In most cases, this inspection can be carried out without entering the item, when the plant is on-line or off-line). 3) Inspection methods to match the identified damage mechanisms. 4) Inspection areas for each of the identified damage mechanisms. B. Operational limits are defined when relevant (e.g. temperature, flow rates, composition, etc) in order to prevent increase in damage rates or initiation of a new damage mechanism, thus ensuring validity of (A) above. C. NDT parameters are defined for the selected NDT methods when relevant (effectiveness & capability), this ensuring confidence in inspection results. D. Anticipated repairs and / or replacements at the next shutdown TA.
E. For critical items which are subject to complex deterioration or where the damage cause is unclear, recommendations are made on the scope of Root Cause Investigations or Fitness-For-Service assessments or special remaining life calculations to help make the correct decisions on run as is / monitor, or repair or replace or upgrade material or implement other risk mitigation measures. The results of these investigations and decisions are then fed back to the RBI study and the inspection intervals for the items adjusted accordingly. Unlike other RBI service providers, this unique output consisting of A to E above ensures that the identified risks are confidently managed within defined acceptance levels, thus providing best-in-class RBI driven safety & reliability achievement at optimum costs to the plant site. 2.2. RBI induced Safety & Reliability Improvements.. Positive evidence proves that our RBI technology process delivers significant improvement to current level of safety & reliability of equipment items at plant sites, as a direct result of our unique RBI study output, Section 2.1 A E above. How? - For EACH item, the combination of our RBI technology process and the thoroughness of our RBI team study method deliver.. 1. Better identification, understanding & knowledge of damage mechanisms (DMs) applicable to an item, including DM cause and susceptible areas for inspection for each of the identified DMs. 2. Latest inspection date for each DM, based on reliably acceptable Risk profile. 3. A reliably optimised inspection interval for the item, by considering 3 above + future desired scheduled plant shutdown (turnaround) dates + the use of suitable Non-Intrusive inspection techniques when relevant. 4. Inspection methods matched to the DMs, ensuring improved confidence in the methods used and inspection results & importantly ensuring detection of significant defects in the item. 5. Improved definition of operating limits to minimise increase in damage rates or prevent initiation of a new DM.
2.3. RBI induced Cash Benefit to plant site.. The following describes how the net cash benefit can be assessed by a plant site, based on our RBI study outputs. Cost of RBI implementation vs. Cash gained from the following.. 1. Savings from inspection related costs for items where current intrusive inspection intervals can be extended, for example, estimated over a period of say for the next 12 years. 2. Increased production (number of days) based on technically justified extension to plant run-length times between inspection turnarounds (estimated over a period of say for the next 12 years). For e.g. from 4 year run to a 6 year run, etc. 3. Increased production by minimising shutdowns caused by unexpected failures. This is achieved by improvement in reliability and safety, better understanding & knowledge of applicable damage mechanisms, causes and vulnerable locations. (the benefit assessment is generally based on comparison with past history). 4. Increased production due to better optimisation of turnaround time (projected over a period of say for the next 12 years). 5. Increased production due to avoidance of unexpected over-run of planned shutdown turnaround time through better knowledge and planning of anticipated repairs & replacements in advance, i.e. less unexpected shockers at TA shutdown. 6. Capital expenditure is optimised and better planned by ensuring maximum life is attained safely & reliably for items of plant which are suffering from greater deterioration than expected. Such deterioration can be either by thinning or cracking damage mechanisms.