Asset Integrity Management for steam generators, high-temperature creep

Safety considerations require stringent testing of the pressure components of a steam generator to rule out material issues and defects within the structures, which may cause permanent damage, unexpected shutdowns, dangerous incidents, and increased maintenance costs.

Our service can assess the safety and integrity of your equipment, helping to prevent catastrophic damage and ensure safe and reliable operation over time.

The fully integrated range of services we offer for assessing the condition of steam generators and HRSGs includes:

∙ Service life extension procedures, with respect to the design life and calculation of consumed life, for pressure equipment subject to high-temperature creep.
Italian regulations, according to ISPESL Circular 48/2003 and subsequent guidelines, as well as UNI 11325-1-2-4 (2013), require the mandatory execution—upon reaching 100,000 operating hours—of basic non-destructive testing combined with micrographic examination using replicas on steam generator components designed to operate in the creep regime, with repetition at intervals based on the results of previous inspections.

∙ Service life extension procedures for steam generators that have reached or exceeded 45 years of age.
Pursuant to ISPESL Circular 60/97, steam generators that are 45 years old must undergo specific non-destructive testing, as well as laboratory material analyses through chip sampling and metallographic examinations, in order to assess mechanical properties and allow continued safe operation.

∙ Specialized non-destructive testing to assess the structural degradation of welded joints
Fluorescent magnetic particle testing; TOFD and Phased Array tube weld scanning on HRSG evaporator and superheater headers.
Eddy current testing of shell-and-tube condensers.

∙ Targeted inspections and NDT for ten-year inspections, including the preparation of detailed inspection plans

∙ Field inspections and laboratory analyses for FAC monitoring

∙ NDE/NDT on P91-grade piping

∙ Repair strategies with WPS development; stability calculations; engineering consultancy and FFS assessment

∙ Metallurgical sampling of evaporator tubes
This destructive test is useful for providing, after prolonged periods of operation, in-depth information on what may be occurring inside the generator and on the condition of evaporator and superheater tube banks.
When several potential damage mechanisms are indicated (magnetite growth, under-deposit corrosion, FAC, etc.), reaching the correct conclusion and choosing the appropriate course of action is essential to save time and costs, minimize repeated failures, and protect the long-term health of the unit.

∙ Failure Analysis
Damage investigation and root cause analysis.
We effectively identify the underlying causes of damage and failures, providing knowledge and experience to enhance efficiency and operational safety in your steam generator.

∙ RBI Assessment
A primary function of the maintenance service, aimed at ensuring maximum productivity, is maintaining steam generators in full operating efficiency in order to limit unexpected shutdowns that may result from malfunctions or failures.
One of the methodologies used is RISK-BASED INSPECTION, as maintenance intervals are established based on the actual criticality of components, thereby optimizing maintenance costs.

The Donegani Anticorrosione team is able to provide steam generator operators with a practical and timely service capable of meeting all the above requirements.