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The ageing challenge of hazardous installations

Author : Romualdo Marrazzo, ISPRA

04 July 2023

In this article, Romualdo Marrazzo from ISPRA (Italian National Institute for Environmental Protection and Research) presents examples of how organisations manage the issue of ageing asset problems through specific procedures oriented to “asset integrity management”. The article will also describe the results of Safety Management System (SMS) inspections, where weaknesses emerged with reference to ageing and asset integrity of the hazardous installations inspected.

Image: Shutterstock
Image: Shutterstock

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The Seveso III directive (2012/18/EU) is aimed at the prevention of major accidents involving dangerous substances. As part of the implementation of the Safety Management System for Prevention of Major Accident (SMS-PMA), the directive imposes an obligation to provide a plan for monitoring and control of risks related to ageing of equipment and systems that can lead to loss of containment of hazardous substances, including the necessary corrective and preventive measures.

It is important to understand that ageing is not strictly related to the age of the equipment, but to its changes over time, in terms of deterioration and/or damage degree. These factors are more likely to cause failures in the lifetime of the equipment but are not necessarily associated with it. In the case of equipment or installations, ageing can lead to significant deterioration and/or damage to initial conditions, which may compromise functionality, availability, reliability and safety.1,2

In Italy, the Seveso III directive has been implemented by the Legislative Decree n. 105/2015. In the decree, the national standards (i.e UNI 10617, UNI 10616, etc.) that provide users specific tools for the implementation of an effective SMS are mentioned as “state of the art” because they meet both the requirements of the law and the structure of the ISO standards. Furthermore, the Risk Based Inspection (RBI - i.e. API RP 581 “Risk-Based Inspection Technology”) and the Fitness For Service (FFS – i.e. API 579 1/ASME FFS-1 “Fitness for service assessment standard”) methodology are considered in the framework of the technical standards.

A method was finally implemented by a national working group, with criteria useful to address a qualitative assessment for ageing evaluation in the frame of the asset integrity management for site operators and SMS inspectors.3

Ageing mechanisms as potential contributors to accidents

In the following, the main outcomes of the analysis of some industrial accidents that recently occurred at Italian chemical and petrochemical establishments are presented, based on the results of inspections. In these events, ageing mechanisms have been identified as a significant cause, in terms of technical and organisational factors:

Refinery plant

a)  Date: 30/04/2006

b)  Title: Fire and explosions in piping

c)  Synthetic description: Release of crude oil from transfer pipe in the underpass of the road that crosses the plant, that developed a fire by accidental triggering which subsequently involved the adjacent piping belonging to different operators and then a series of explosions (Domino Effect)

d)  Causes: Age (over 25 years) and state of preservation of the pipe in relation to the progressive corrosion phenomena, which led to the pipe drilling

e)  Actions taken: Visual inspection and basic design of corrective actions. Necessary reconstruction activities

f)  Expected/Planned actions: Specific risk analysis. Planned and/or required compliances following Competent Authorities examination. Check of the pipeline inspection plan

Image: Shutterstock
Image: Shutterstock

Refinery plant

a)  Date: 01/05/2006

b)  Title: Leakage through the tank bottom

c)  Synthetic description: Leakage of oil through a large lesion at the bottom of a floating roof tank and subsequent release of the total amount of oil inside the containment basin

d)  Causes: High corrosion and deteriorated area

e)  Actions taken: Tank insulation. Transferring the product to another tank with temporary pipes

f)  Expected/Planned actions: Tank out of service. Carrying out the remediation and maintenance of the basin and the tank. Double bottom insertion.

The analysis of technical and organisational factors of such events highlights problems of asset integrity of hazardous installations. They are mainly connected to deterioration/degradation caused by corrosion, erosion, fatigue.

The corrective actions taken by the authorities and site managers concerned the Internal Emergency Plan, investigation and risk analysis, checks on installations and plants (pipeline, tanks, basins, pumps, etc.).

Among the methods used to assess industry’s response to ageing it is possible to identify activities of remediation and maintenance, updating management procedures and operational instructions, specific planning for critical technical systems.

Examples of good practices: the primary containment system

A possible approach is to define the main steps of good practices for maintenance activities in case of primary containment systems, in order to ensure sufficient mechanical integrity:

(i)  Defining the degradation mechanisms (related or not to corrosion). They depend on the type of tanks, on the nature of the stored fluids, which are the basis of the organisation of the inspection activities.

(ii)  Defining and personalizing inspection technologies. In addition to internal or external visual inspection, the degradation mechanisms affecting both atmospheric tanks and pressure vessels can be identified by the NDT (Non Destructive Test) common techniques.

Image: Shutterstock
Image: Shutterstock

(iii)  Determining the frequency of inspections, considering: Construction features; Repair techniques and materials; Nature of stored product; Conditions found at the previous inspection; Corrosion rates; Presence of corrosion prevention systems; Potential contamination of soil, water, air; Presence of double bottoms or other systems to prevent losses of containment; Leak detection systems with operating tanks.

It is possible to schedule targeted maintenance-planning, based on the RBI method, which consists of specific inspection activities according to the actual operating conditions of the equipment; while through the FFS method you can continue to maintain in operation, with accurate monitoring, equipment that has a structural degradation. It is important to highlight that the setting of these methodologies is well suited and integrated in the structure of a SMS already implemented.

In addition, the SMS element of "Management of Changes" is crucial, considering the difficulty of identifying new corrosion risks for process and plant design changes and the possibility that other modifications may also have a lesser impact on corrosion risk and therefore not recognised (i.e. changes in the source of crude oil supply or an increase in production, especially temporary).

It is important to keep records of the operating history and problems encountered during the life. For example, running hours, duty cycles, operational excursions and changes in duty or process. This means that to ensure the integrity of all plant containing hazardous substances, it is necessary to evaluate all the compliance requested (occupational safety, environmental safety, PMA, etc.).

The analysis of Safety Management System inspections

Based on Safety Management System inspections conducted in Italy in the last three years, it is possible to highlight these results: in 20% of the cases, problems with the correct management of mechanical integrity were found.

The following are some of the non-compliances found:

- Need to consider and analyse the problems of ageing (corrosion, erosion, fatigue) of equipment and installations that can lead to losses of dangerous substances, including, where relevant, a specific monitoring plan and control, and the subsequent corrective and preventive measures.

- No evidence of a plan for monitoring the risks associated with the ageing of equipment, unless it is in accordance with law obligations.

- Developed a well-structured Asset Integrity Management procedure, but partially implemented (no evidence).

- Lack of a specific procedure for monitoring and control of ageing.


Plants are subject to degradation phenomena based on the level of accumulation of static/dynamic stresses and the effect of changes of operating conditions. Knowing performance decay rates is useful for adequate scheduling maintenance interventions.

Romualdo Marrazzo, ISPRA
Romualdo Marrazzo, ISPRA

The site managers must consider the equipment changes over time in terms of deterioration and/or damage degree and understand damage mechanisms. This would allow identification of the best “non-destructive control method and test (NDT)” to apply in order to assess the equipment damage state.

It is important to control and maintain risk at acceptable levels through management of equipment maintenance activities. These activities are aimed at ensuring operational continuity and the stability conditions to prevent losses of containment of hazardous substances.

The safety management system should provide that each equipment and utility is subject to a program of inspections, testing and maintenance properly scheduled overtime to ensure that these components continue to meet safety requirements as long as they are in service.

The organisation should establish and formalize specific criteria for the determination of the defined maintenance regimes (preventive maintenance, condition-based maintenance, predictive maintenance).

It is important to establish a clear strategy, not just for periodic examination, but also for the whole plant lifecycle. This is especially relevant on sites storing and processing hazardous substances, where the consequences of integrity failure can be major. The RBI and FFS methodologies, meeting the criteria of a SMS adequately implemented, can constitute a valid response to the asset integrity management and the related problem of ageing.


1 OECD. AGEING OF HAZARDOUS INSTALLATIONS. Series on Chemical Accidents No. 29. ENV/JM/MONO(2017)9.

2 HSE. “Plant Ageing Study – A Summary Guide”. Research Report RR823. Health & Safety Executive, London UK.

3 MATTM. Valutazione sintetica dell’adeguatezza del programma di gestione dell’invecchiamento delle attrezzature negli stabilimenti Seveso. Coordinamento per l’uniforme applicazione sul territorio nazionale di cui all’art. 11 del decreto legislativo 26 Giugno 2015 n. 105 (

About the author:

Romualdo Marrazzo works at ISPRA (Italian National Institute for Environmental Protection and Research) in the Service for Risks and Environmental Sustainability of Technologies, Chemical Substances, Production Processes and Water Services and for Inspections. He holds a Master's degree in environmental engineering and is a national expert qualified as a Health, Safety, and Environment (HSE) Specialist. Romualdo provides technical and scientific support to the Environmental Ministry for the Seveso directives, and he is concerned with international implementation of Seveso directives on behalf of the European Commission Committee of Competent Authorities (EC-CCA). He also conducts inspections on various national industrial installations concerning Seveso and IPPC-IED directives, on a regular basis and after accidents.

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