Risk-Based inspection and maintenance

The concept of risk refers to an undesired event understood as the release of a substance due to loss of integrity of the containment walls of equipment and/or piping. In order to optimize plant inspections as effectively as possible, the best approach is undoubtedly to focus greater efforts on the inspection of those items associated with a higher level of risk. An RBI analysis is generally applied to a plant that can be generically defined as a set of equipment and piping forming part of a production unit intended for the manufacture of a specific product, using a given thermal, chemical, or other process. The objective of the analysis is to develop inspection and monitoring strategies that make it possible to keep the risk level of each item within its unit of belonging within an acceptable limit. The analysis consists of an initial phase dedicated to studying the process and the potential damage mechanisms (resulting from the interaction between the product/process and the material constituting the components) to which the various items are subjected. Possible damage mechanisms are numerous: wall thickness reduction due to generalized corrosion, localized corrosion (pitting), stress corrosion cracking, cracking due to wet H2S service, creep, etc. The inspection scheduling criterion according to the RBI methodology is particularly consistent with the founding principles of most regulatory requirements, and in particular with integrity inspections (normally required every 10 years), which are also inspired by the verification of component safety with respect to the structural integrity of pressure-containing parts. Thus, the RBI study appears to be the most appropriate tool to support, using shared and universally applied criteria, any requests for exemptions that may be necessary where, for certain equipment, statutory deadlines do not coincide with scheduled shutdowns, provided that it can be demonstrated that the level of risk remains within acceptable values (ref. Law no. 134/2012, art. 36, paragraph 5).

Identification of risks related to material degradation;
Optimization of inspection activities;
Compliance with regulatory requirements through increased safety;
Reduction of downtime.

Capabilities: Our team is composed of experts in Risk-Based Inspection, Fitness for Service methodology, Corrosion and Metallurgy, mechanical integrity, and Non-Destructive Testing.

Identification of Similar Damage Circuits

Similar Damage Systems (SDS) are characterized by homogeneity in materials, operating conditions, and damage mechanisms. This subdivision, following risk assessment, allows for the identification of the most critical plant areas and, within those areas, the most critical items. This makes it possible to optimize inspection activities, thereby reducing risk.
Damage Mechanism Identification

I meccanismi di danno vengono valutati sulla base dei materiali, condizioni operative e dei fluidi processati. Un singolo apparecchio può essere interessato da più meccanismi di danno.
Inspection Plan

Ha lo scopo di riportare nel dettaglio l’estensione e la tipologia di controlli non distruttivi da effettuare sui singoli componenti di un attrezzatura in base ai meccanismi di danneggiamento attesi. L’intervallo di ricontrollo sarà funzione dell’estensione e tipologia di controlli (efficacia del controllo).
Condition Assessment / Re-inspection Interval

The re-inspection interval is a logical consequence of the condition assessment derived from the analysis of inspection results carried out in observance of the specific "Inspection Plan" and based on the expected damage mechanisms. The re-inspection interval must be such as to guarantee the safe operation of the equipment.
Risk Matrix Assessment

The risk is quantified by the product of the Probability of Failure (Pf) and the relative Consequence (CA), expressed in terms of area per year: $R [m^2/year] = Pf [failures/year] \times CA [m^2]$. The risk matrix allows for the representation of risk in a semi-quantitative form. In the matrix, probability categories are defined by the calculated value of the damage factor, and consequence categories are defined by the extent of the damage area.
Subsequent Checks

Stability Checks, Fitness for Service (API 579), BS 9710