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IIS SERVICE boasts an Engineering Division provided with the most advanced tools and expertise to take on complex problems of structural engineering, process engineering, material and corrosion engineering.

The integration within other Group departments, such as advanced NDT and Laboratory testing, allows us to supply our Clients with exceptionally powerful tools for the assessment of the reliability of components and plants, for Fitness for Service and Life Extension evaluations, and for structural integrity issues at large.

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Our services

Structural Integrity Assessment

Structural analysis and design of pressure vessels

The Engineering Department of IIS SERVICE is involved in the design and calculation for pressure vessels. In several contexts, from the sizing calculation to the life extension evaluation, from the assessment for equipment operating in the creep range, to the fatigue life evaluation, and, at last, where FFS (Fitness For Service) and ECA (Engineering Critical Analysis) assessments are required, the following activities may be carried out: Design "by formula" of pressure vessels in compliance with
ISPESL VSR/VSG codes; Design "by formula" of pressure vessels in compliance with
ASME Boiler & Pressure Vessel Code; Design "by analysis" of pressure vessels in compliance with
ASME B&PV Code, Sec. VIII, Div. 2, Part 5; Design "by analysis" of pressure vessels in compliance with
EN 13445, Part 3, Annex B & C; Assessment of fatigue life for pressure vessels in compliance with
EN 13445, Part 3, Chapter 17 & 18; Minimum Pressurizing Temperature (MPT) evaluation with reference to the start up phase for process plants.             

Assessment of fatigue life for civil structures, lifting appliances and mechanical components

IIS SERVICE, through its Engineering Department, is involved in assessments of fatigue life in the field of structures and structural components. Evaluations are generally carried out in ...


Repair / modification design of pressure equipment

IIS SERVICE is committed to design critical repairing operations such as removal and repairing of defects detected during periodic inspections, replacement of components, repairing on in-service equipment. Such a kind of intervention is crucial where the repair is deemed necessary and the component or the pressure equipment are installed within continuous process plant and, therefore, with short time for intervention or with the need of ensuring the equipment availability for operations. The IIS Group can support the User for pressure equipment which have to be subjected to important modifications that change their original design characteristics. In all these cases, the IIS Group is able to perform: Design of repairing / modification in compliance with ISPESL, ASME B&PV Code, EN 13445 according to national decree D.M. 01/12/2004 No.329; Temporary repair design in compliance with ASME PCC-2; Fulfillments with the national law requirements for the seismic action (NTC 2008 - D.M. 14/01/2008); Evaluation of the component resistance during provision of repair according to API 579-1 (repairs under applied loads) The IIS Group can provide in-field complete assistance for the supervision of the provisional works setting, for preparation and repair execution and for the final NDTs. Furthermore, the IIS Group is able to provide overall assistance in Italy for the fulfillments of the repair according to the D.M. 01/12/2004 No.329 or the CE marking of the pressure equipment, in case of important modifications.

Pipelines reliability assessment

IIS SERVICE has set up a in-house original procedure for the pipelines reliability assessment, based on the inspection results processing coming from: Smart Pig i...


Structural assessment of lifting appliances

For the lifting appliances, the Engineering Department of the IIS Group is able to provide the following engineering services: Supplementary analysis in compliance with the law requirements of the Italian decree D.M. 11/04/2011 Fatigue evaluation according to EN 1993-1-9, EN 1993-6 e EN 1999-1-3 Remaining life assessment according to ISO 12482 e ISO 9927. The IIS Group is able to provide an integrated service for the supply of all the investigations and evaluations required by the Ministerial Italian Decree D.M.11/04/2011, with the execution of non-destructive testing and assessments on the structural frames and the moving parts. Lastly, the IIS Group is able to carry out periodical inspections required by law for lifting appliances pursuant to Italian Legislative Decree No. 81.

Stress analysis of piping equipment

The Engineering Department of IIS SERVICE is able to perform the finite elements analysis of industrial piping equipment for different contexts: from the stress analysis, to the remaining life eval...


Structural analysis of atmospheric storage tanks

IIS SERVICE has a long and acknowledged experience in the management of any issues relating to stability analysis, inspection, control, maintenance of above ground atmospheric storage tanks. In the field of structural analysis IIS SERVICE is able to provide, through its Engineering department, the following services: Thickness Acceptability evaluation of the components according to API Std 653; Design and verification of atmospheric tanks by means of the software ETANK2014; Assessment of the components to new operating conditions according to API 579-1; Structural analysis for fixed roof according to API Std 650 and NTC 2008 (DM 14/01/2008); Structural analysis for floating roof according to API Std 650 and API Std 579-1; Evaluation of the conditions for exemption from the hydrostatic test according to API Std 653; Verification of calibration procedures according to ISO 7507. The IIS Group is also able to give full assistance to carry out inspection, testing, maintenance and inspection planning with criteria based on the API - Risk Based Inspection (RBI) technology.    

Fitness For Service (FFS) & Engineering Critical Assessment (ECA)

The Fitness For Service (FFS) assessments are the pride of engineering services of IIS SERVICE.
The IIS Group has taken on over the years, countless cases of FFS assessment in the sectors of the Oil & Gas, for pressure components and piping, in infrastructure and other steel structures. The multidisciplinary evaluations anyway involve material engineering expertise, fracture mechanics, thermal structural simulation analysis, skills in welding and non-destructive testing, skills in operational behavior of components and, of course, expertise in the field of design. The presence of all the required skills within our Group allow us to address the various problems through a comprehensive approach. The design and fabrication codes and standards for components and structures provide rules and regulations for the design, manufacture, inspection and testing of new components. These codes typically do not provide evaluation procedures aimed to verify and judge the acceptability of damage induced by the operating or manufacturing anomalies that can be detected during subsequent inspections. The main contexts in which the FFS techniques are required, are the stability analysis of defects, verification of fitness for purpose of components in which there are structural and morphological anomalies due to the service or to manufacturing, and in case where the fabrication procedures required by the reference codes have not been fulfilled. The IIS Group, supplied with the latest calculation tools to address this type of analysis of high scientific content, systematically is inspired to the most consolidated international regulatory references. Fitness For Service assessments, according to API 579-1/ASME FFS-1 Fitness For Service assessments, according to BS 7910, by means of the Crackwise software (TWI) Engineering Critical Assessment (ECA), according to BS 7910, by means of the Crackwise software (TWI) Engineering Critical Assessment (ECA), according to API 1104 Engineering Critical Assessment (ECA) according to API 579-1 o ASME B&PV Code, Sec. VIII, Div. 3 These assessments are used to support the decision making of "run-repair-replace"  for in-service components, but also to assess the suitability of the service for new components, in order to evaluate the risk of brittle fracture and fatigue. In the case of structural anomalies, adequate defect detection and characterization are a crucial factor in the reliability of the evaluation.
The IIS Group is able to provide a full inspection service for the defect detection and characterization, through the latest diagnostic non destructive techniques. The FEM analysis and laboratory testing of fracture mechanics often represent the strength and the worth for the reliability and effectiveness of the final evaluation. The IIS Group provides the opportunity to address all steps of the assessment internally, with his own skills and laboratory equipment.

Residual life assessment for pressure equipment

The residual life assessment for pressurized equipment in the creep range, in compliance with the technical specification UNI/TS 11325-2, is carried out through the following phases: Preliminary residual life evaluation Inspection, metallographic examinations and NDT planning and execution Residual life assessment and life extension evaluation Designer declaration for further service time for the legal obligations.

Repair / modification design of civil structures, lifting appliances and mechanical components

In the field of civil structures subjected to the law requirements (Ministerial Italian Decrees in law 1086 enforcement - today DM 14/1/2008, EN 1993, EN 1090) or other metal structures or machine elements and lifting equipment, the IIS Group provides technical advice and support in manufacturing engineering also in the stages of repair, reinforcement or functional and even substantial adjustment. With particular reference to: definition of the type of maintanance work or other operation and detailed study of the geometry of the concerned structure adjustment of the structure to new load conditions or to comply with most recent rules; for example when more stringent quality standards are required, or seismic susceptibility assessments are needed or when the compliance to standard and contractual specifications other than those European already mentioned above (e.g. AWS or GOST) is required design "by formula" or "by analysis" of the structural details definition of the methods of work and of welding sequences, consistent with the environmental conditions, the accessibility and the safety regulations critical assessment of adjustment works, in design phase and during the work, in order to ensure the final quality, the cost-effectiveness and the durability of the re-rated structure critical examination of the intermediate or final inspection and NDT The IIS Group can provide complete assistance to support the Manufactures, the Users or the Works Supervisors and the Final Design and Quality Controller, with unaltered competence and fairness (as indeed specifically requested by the Technical Standards on Construction DM 14/1/2008 for Third Parties), as well as in supervising the assembly, in providing technical support for preparation and execution of repairs, reinforcement and mantainance works, and in accomplishing final NDT, even to certify the work for the purposes of law or insurance.

Technical Specifications

Mothballing Operative Procedures for equipment and plants

In the chemical processing industry it is nowadays a fact that reduction of production or temporary production interruption are needed.
Although these capacity shifts can sometimes be anticipated, they are generally due to governmental or market events beyond a company's control.
Engaging in a well-planned process of deactivation/mothballing can be worthwhile either way, whether it should ever be reactivated or just sold for its second-hand value at some future point. By a multidisciplinary team of experts, IIS Group is able to support the end user for the damage mechanisms identification in the stand-by status, for the suitable strategy definition for equipment protection and degradation monitoring and in issuing the mothballing operative procedures.  

Piping Design Specifications

IIS SERVICE is able to draw up for its Clients piping design specifications (piping class) in compliance with: ASME B31.1 ASME B31.3 ASME B31.8 EN 13480 For a specific service, given the reference pressure and temperature, the piping specification defines: the reference codes and standards, the operative rating (maximum working pressure for the different operative temperatures), material type and the material specifications, the minimum design thickness, the corrosion allowance, the PED risk category according to the nominal diameter, welding and NDT reference specifications, the reference standards for applicable products as piping, fittings, gaskets and bolts, the admissible maximum free span, the specified tightening torque and the compensation required for openings.

Materials e corrosion

Evaluation of the damage mechanisms affecting pressure equipment and piping

IIS SERVICE is able to identify and evaluate the damage mechanisms that potentially affect specific equipment and / or plant section and, consequently, provide indications and recommended solutions targeted to prevent and mitigate the damaging.
Such a challenge is tackled through the establishment of a multidisciplinary team, made up of a panel of different professionals relating to process technology and to materials behavior with reference to corrosion resistance and to other degradation modes of components in different materials.

Material and corrosion engineering - Material Selection

The objectives of an activity of Material Selection require extensive knowledge in materials science, metallurgy, damage mechanisms that affect the various service conditions, weldability, corrosion and a long lasting experience on key issues of design, construction and operation for structures and industrial components. The IIS Group provides these skills and assists its Clients: in the design stages with the selection of the most suitable materials depending on the operating conditions for components and structures in the early stages of procurement, with the development of supply specifications containing additional requirements to ensure the expected performance for materials and components in the early stages of plant revamping for the identification of new materials suitable to ensure the required performance. IIS SERVICE, through its Engineering department, and IIS PROGRESS with Laboratory facilities, can offer the customer a full service for Material Selection, including characterization tests and analysis on the materials, as well as an advisory service for the activities of failure analysis.  

Asset Integrity Management

RBI (Risk Based Inspection) for road and railway infrastructures

This service provides an effective tool for inspection planning, consistent with the budget for the safely maintenance of the infrastructure efficiency. The IIS Group, particularly IIS SERVICE, gained a huge experience in RBI studies on industrial plants and is currently investing in developing RBI technology for infrastructures. Borrowed from the RBI Technology for the Oil & Gas Segment and transposed for civil road and railway infrastructures, the RBI appears as a powerful and effective tool for management control, specially developed by IIS SERVICE in order to correlate the planning budgetary costs with the inspection planning. It is therefore possible, given a reference budget, to evaluate the resulting level of risk or, vice versa, to define a limiting level of risk and get the resulting budget. This tool finds its natural application in the management of the maintenance of road and rail networks in order to target interventions where really necessary because of the risk worsening related to the consequences of any damage.  

RAMS Assessment (Reliability, Availability, Maintainability, Safety)

Reliability, Availability, Maintainability and Safety:
these aspects are mutually correlated, and related through a specific evaluation aimed at maximizing the efficiency of a plant, ensuring, for a given time interval and for each element, the performance of the expected function in the absence of unacceptable risks. Reliability: the ability of a system or component to perform its required functions under stated conditions for a specified period of time (mission time); Availability: the degree to which a system, subsystem or equipment is in a specified operable and committable state at the start of a mission, when the mission is called for at an unknown, i.e. a random, time; Maintainability: attitude of the entity in assigned conditions of utilization to be maintained or returned to a state of correct operation for the required function; Safety: absence of untolerable risks. It is noteworthy that the IIS Group, and particularly IIS SERVICE, is not only able to make a RAMS assessment for a specific plant, being it new or operating, but especially is able to ensure that its services are harmonized to the RAMS methodology, or conforming with the approach for efficiency optimization and the relating cost control.

RBI Assessments (Risk Based Inspection)

The IIS Group is the acknowledged leader in service and support for inspection planning and RBI studies according to the recommended practices API 580 and API 581 in Italy and...


Tailored Information Tools

Development of software routines and tailored information tools

IIS SERVICE, in a specific Engineering area, is able to develop dedicated supporting information tools, aimed at the completion and improvement of the main service provision.
The tools may range from the office automation, data entry/data storage and the design of specific algorithms. They are mainly addressed to improve data availability related to deliverings of our services, supporting data searching and analysis, and giving our Clients dedicated tools for browsing and filtering their data.

IPSE® - Inspection Planning by Structures Evaluation

IPSE® applicativo informatico sviluppato dal Gruppo IIS, pensato come strumento di supporto per Gestori delle infrastrutture e per le Amministrazioni Pubbliche sulla valutazione d’integrità di una struttura o di una famiglia di strutture. È onere dei gestori delle infrastrutture contemperare scelta, durata, estensione delle ispezioni con le risorse economiche e di personale disponibili sul territorio. Date le frequenze  ispettive nominali ad oggi richieste dalla legge, tali risorse sono spesso insufficienti per controllare in modo approfondito la totalità del patrimonio infrastrutturale esistente.
Una risposta innovativa nasce dalla definizione e dall’applicazione di criteri alternativi alle regole esistenti sulle frequenze ispettive, che prendono in considerazione “famiglie“ di
strutture e consentono di elaborare opportune classifiche di priorità o di rischio. Sulla base dell’esperienza maturata in svariati decenni di attività diretta nell’ambito delle costruzioni civili, IIS SERVICE (società del Gruppo IIS) ha elaborato una procedura capace di
coniugare una minore discrezionalità nella scelta del calendario delle ispezioni con una minore responsabilità diretta da parte del soggetto responsabile della programmazione. Tale procedura consente una prima valutazione su scala macroscopica finalizzata a dare un ordine di priorità alle strutture e pianificare nel tempo le valutazioni di secondo livello (ovvero
quelle di maggior dettaglio) finalizzate a programmare le campagne ispettive e le conseguenti attività di manutenzione.
L’applicazione della metodologia è resa più semplice attraverso l’uso dell’applicativo informatico IPSE® sviluppato dal Gruppo IIS e disponibile in cloud. IPSE® permette la registrazione di tutti i dati necessari ai due livelli di valutazione e ne restituisce il risultato in termini di indice di priorità o di classifica di rischio degli elementi strutturali principali. Sulla base di tali risultati IIS SERVICE può fornire al Gestore un piano d’ispezione di dettaglio ottimizzato in termini di modalità ed estensione. IPSE® consente diversi livelli di analisi.
>> In una prima fase, sulla base dei dati disponibili di tipo storico, topografico, ispettivomanutentivo e di parametri di tipo strategico, IPSE® consente di elaborare un primo indice di priorità per l'individuazione delle opere che richiedono approfondimenti di analisi o di indagine per pianificare nel tempo le valutazioni di secondo livello.
>> In una seconda fase, che può far seguito ad approfondimenti ispettivi, è possibile elaborare una vera e propria classifica di rischio delle principali parti strutturali di un specifico manufatto basata su una analisi di affidabilità.
A seguito della seconda fase è possibile definire un piano di ispezione mirato in termini di modalità ed estensioni e maggiormente indirizzato verso le aree risultate potenzialmente più critiche.

Welding Engineering

Technical support for welding

Our engineers are traditionally engaged in several services to support welding engineering: Conception and technological design of welding Technological design verification Drafting and revision of technical specifications for procurement, fabrication and repair Technical and scientific support.  

Technical support for the protection systems of industrial installations

SRMCR (Safety Related Measurement Control and Regulation) - PSV (Pressure Safety Valve)

The protection systems of industrial plants, against excessive pressure, are one of the key elements to ensure the safety of production processes for the population incolumity and health and for the environmental protection.
The protection of industrial plant is generally entrusted to devices for direct pressure limitation, the so-called safety valves (PSV - Pressure Safety Valve) or rupture discs (RD), or accomplished by systems / safety chains (SRMCR - Safety Related Measurement Control and Regulation) which, through the safety Instrumented systems (SIS - Safety Instrumented System) are able to ensuring the required safety levels. With reference to the devices for direct pressure limitation, IIS SERVICE provides the following services: PSV and RD sizing evaluation in compliance with EN ISO 4126, API 520/521, ISPESL Raccolta E Assistance for PSV shop check of operative set pressure in compliance with API 526/527 PSV in operation: check of operative set pressure by means of the PSV Monitor equipment (hydraulic jacks type) according to UNI 11513 PSV inspection and assistance for pre-pop test according to API 576 PSV relieving capacity evaluation, relating to modifications defined by HAZard and OPerability (HAZOP) analysis, or because of variations on base calculation assumptions or modification on the protected equipement PSV failure analysis PSV Risk Based Inspection analysis according to the API-RBI Technology with reference to the Recommended Practice 581. As far as the SRMCR (Safety Related Measurement Control and Regulation) is concerned, IIS SERVICE provides the following services: SIL (Safety Integrity Level) allocation, in compliance with IEC 61508/61511. IIS SERVICE carries out the evaluation of the integrated safety level required for the system or industrial plant, in order to mitigate the risk level to the tolerable value defined by an ALARP (As Low As Reasonably Practicable) approach. The most proper architecture for the system together with the definition of the reliability minimum requirements for each chain element are identified SIL (Safety Integrity Level) verification, in compliance with IEC 61508/61511. IIS SERVICE is able to verify the actual SIL level, based on the installed elements of each Safety Instrumented System (SIS).