Ageing Plants

A Presentation of

Prepared by Yousuf Memon

Yousuf Memon n As Plant & Equipment Integrity Professional, he has been in oil & gas exploration, petroleum refineries, petrochemical plants, chemical plants, fertilizer plants, power plants, desalination plants for last several years.  His working areas include Plant Inspection, NDT, Corrosion Monitoring, Corrosion Inhibitor Injection, Material Selection, Protective Coatings, Material Performance Evaluation, Cathodic Protection System, Risk-Based Inspection and Failure Analysis. He has received bachelor’s degree in chemical engineering from Dawood College, Karachi in 1975 and has previously served ARAMCO (Saudi Arabia), TOTAL E&P (UAE) and PARCO (Pakistan) in various disciplines of mechanical integrity. He delivers in-house and public seminars in Pakistan and abroad on relevant topics. He also heads operations of Reliance Swift Veritas (RSV) & Petrosult & Unimart (P&U).

Ageing Plants n Ageing is not about how old your equipment is; it’s about what you know about its condition, and how that’s changing over time

Ageing Plants

Presentation Summarysuf Memon Management of plant and equipment integrity begins with an awareness that ageing is not about how old the equipment is, but is about what is known about its condition, and the ageing equipment is equipment for which there is evidence or likelihood of significant deterioration and damage taking place since new, or for which there is insufficient information and knowledge available to know the extent to which this possibility exists. Significance of deterioration and damage relates to the potential effect on the equipment’s functionality, availability, reliability and safety. Just because an item of equipment is old does not necessarily mean that it is significantly deteriorating and damaged. All types of equipment can be susceptible to ageing mechanisms. Degradation mechanisms are multiple and depend on the type and quality of material of construction, the operating conditions, the process fluid, operating history, and time in service. It is, therefore, crucially required to develop countermeasures against the deterioration of equipment before it gets the critical condition. Countermeasures include understanding the degradation mechanisms and their detection by carrying out appropriate inspection and testing. Decision can be derived how to proceed taking into consideration the inspection and testing results for justify continued service, re-rating, repair, or scrapping the equipment.  

Ageing Plants n Ageing is not about how old your equipment is; it’s about what you know about its condition, and how that’s changing over time

Ageing Plants n This plant was only about 5 years old, but due to poor maintenance was stained in many locations from acid seepage

Ageing Plants n Ageing equipment is equipment for which there is evidence or likelihood of significant deterioration and damage taking place since new, or for which there is insufficient information and knowledge available to know the extent to which this possibility exists.

Ageing Plants n Just because an item of equipment is old does not necessarily mean that it is significantly deteriorating and damaged.

P

Ageing Plants n All types of equipment can be susceptible to ageing mechanisms, and it is worth drawing attention to some examples.  

Ageing Plants n By its nature, industrial equipment containing hazardous and/or pressurised fluids is exposed to conditions of stress and environment that ultimately will degrade the material fabric from its initial state.

Ageing Plants n Damage will accumulate until the equipment reaches a state in which it is judged to be no longer fit-for-service. Unless repaired or re-rated, the equipment may be said to have reached the end of its life.

Ageing Plants n As damage accumulates, failure becomes increasingly probable, and if not withdrawn from service, failure of some kind will eventually occur.

Ageing Plants n Identification of Ageing n Addressing Ageing n

Ageing Plants n Identification of Ageing n The type of equipment and characteristics of duty can significantly influence the life. It is not unusual for machines with moving parts to degrade rapidly and to have very limited tolerance to damage and deviations from the design conditions in terms of human error or variations in process conditions.

Ageing Plants n Identification of Ageing n Static equipment, such as process vessels and pipes, tend to have much greater tolerance, and under arising conditions, can remain in-service for many years.

Ageing Plants n Identification of Ageing n As damage accumulates, failure becomes increasingly probable, and if not withdrawn from service, failure of some kind will eventually occur.

Ageing Plants n Identification of Ageing n Stages of Equipment Life-Cycle Damage Types & Mechanisms Indicators of Ageing Inspection & Non-Destructive Testing  

Ageing Plants n Identification of Ageing n Equipment Life-Cycle n Four Stages of Equipment Life-Cycle: The Stage within the lifecycle can be determined and controlled from finding out about the degradation mechanisms, undertaking assessment, monitoring, maintenance, repairs and refurbishment.  

Ageing Plants n Identification of Ageing n Equipment Life Cycle n Four Stages of Equipment Life: Initial Revealing inherent weakness or fault in the design, materials or fabrication. Rapid degradation of the equipment early in life is possibleand it can progress quickly through the different Stages. Can be eliminated with appropriate quality assurance and control.  

Ageing Plants n Identification of Ageing n Equipment Life Cycle n Four Stages of Equipment Life: Maturity Equipment is predictable, reliable. Operating comfortably within its design limits. Examination and inspection, maintenance and NDT are generally to confirm the basis for these assumptions, and their scope and periodicity can be risk-based.

Ageing Plants n Identification of Ageing n Equipment Life-Cycle n Four Stages of Equipment Life: Ageing Equipment has accumulated some damage and the rate of degradation is increasing. Signs of damage and other indicators of ageing starts. A more proactive approach to equipment management, inspection and NDT is required.  

Ageing Plants n Identification of Ageing n Equipment Life-Cycle n Four Stages of Equipment Life: Ageing May no longer be possible to predict the current condition or future service life. Second hand equipment is assumed to be directly in ageing stage; unless there are sufficient historical evidence and records to demonstrate a lower risk.  

Ageing Plants n Identification of Ageing n Equipment Life-Cycle n Four Stages of Equipment Life-Cycle: Terminal Becomes clear that the equipment will ultimately need to be repaired, refurbished, decommissioned or replaced. Rate of degradation has become increasing rapidly and is not easy to predict.  

In

Ageing Plants n Identification of Ageing n Equipment Life-Cycle n Four Stages of Equipment Life-Cycle: Terminal Guaranteeing adequate safety between examinations while keeping the equipment in service as long as possible. Managed through making more use of on-line monitoring of the damaged areas.  

Ageing Plants n Identification of Ageing n Equipment Life Cycle n Four Stages of Equipment Life-Cycle: Terminal A reduction of the severity of the duty, for example reducing the pressure rating of the equipment may be another option to maximize the usefulness before decommissioning.  

Ageing Plants n Identification of Ageing n Damage Types & Mechanisms n Can be categorized into four main types: Wall thinning. Stress-driven damage, cracking and fracture. Physical deformation. Metallurgical / environmental damage.

Ageing Plants n Identification of Ageing n Damage Types & Mechanisms n Can be categorized into four main types: Stress-driven damage, cracking and fracture. Fatigue damage and cracking Creep Stress corrosion cracking (SCC) Stress influenced hydrogen cracking Brittle fracture Ductile failure

Ageing Plants n Identification of Ageing n Damage Types & Mechanisms n Can be categorized into four main types: Physical deformation: Dents and gouges Buckling Yielding  

Ageing Plants n Identification of Ageing n Damage Types & Mechanisms n Can be categorized into four main types: Metallurgical / environmental damage: Hydrogen Embrittlement  

Ageing Plants n Identification of Ageing n Indicators of Ageing n An indicator of ageing is a sign or evidence that some damage has already or is about to occur. Thought of as symptoms of ageing damage.

Ageing Plants n Identification of Ageing n Risk Factors n Conditions or circumstances that can promote or accelerate degradation, or a lack of control, but are not necessarily sufficient for ageing to occur.

 

Ageing Plants n Identification of Ageing n Inspection & Non Destructive Testing n Inspection for damage is a key activity for all equipment containing hazardous fluids and/or Pressure. Equipment deteriorates, but inspection is important at all stages of the life cycle. Approach to inspection will depend on the Stage of equipment life that has been reached.

Ageing Plants n Addressing Ageing n Assessment of Fitness-For-Service Remanent Life Repair & Modifications Revalidation of Equipment Financial Criteria for Determining the End of Equipment Life  

Ageing Plants n Addressing Ageing n Once the existence, extent and mechanism of damage in a component of equipment have been established, a range of options is available. These include: Scrap and decommission the equipment Remove the damage, with or without a repair. Repair the component, temporarily or permanently, with or without removing the damage.

Ageing Plants n Addressing Ageing n Once the existence, extent and mechanism of damage in a component of equipment have been established, a range of options is available. These include: Analyze the margin between the component condition and minimum code specification. Undertake a fitness-for-service and/or remanent life assessment (if defect size data exists).

Ageing Plants n Addressing Ageing n Once the existence, extent and mechanism of damage in a component of equipment have been established, a range of options is available. These include: Change operating practices, de-rate the duty, or make favorable modifications to process conditions or chemistry.

Ageing Plants n Addressing Ageing n Once the existence, extent and mechanism of damage in a component of equipment have been established, a range of options is available. These include: Monitor the component to ensure that the extent and rate of the damage do not change sufficiently to compromise safety limits.

In

Ageing Plants n Addressing Ageing n Once the existence, extent and mechanism of damage in a component of equipment have been established, a range of options is available. These include: Course of actions needed will usually depend on the nature of the damage, economic factors associated with the operation and repair/replacement of the equipment and the costs of assessment and monitoring.

Ageing Plants n Addressing Ageing n Once the existence, extent and mechanism of damage in a component of equipment have been established, a range of options is available. These include: An initial assessment of fitness-for-service can indicate the most cost effective and safest course to take. Sometimes defects in components and welds will be attributable to manufacturing, and may show no signs of further development.

Ageing Plants n Addressing Ageing n Once the existence, extent and mechanism of damage in a component of equipment have been established, a range of options is available. These include: The existence of stable pre-service defects does not necessarily mean that the equipment is sufficiently safe and fit for further service. Some further action is always needed to ensure that adequate margins against failure exist.

Ageing Plants n Addressing Ageing n Assessment of Fitness-For-Service (FFS) n Also known as Engineering Critical Assessment or ECA. Re-evaluation of the structural integrity of an item of equipment for further service, taking into account damage and deviations from design basis.

Ageing Plants n Addressing Ageing n Assessment of Fitness-For-Service (FFS) n Can be carried out: During design. During service before damage has been detected. Once damage has been detected.  

In

Ageing Plants n Addressing Ageing n Assessment of Remanent Life Some of the key factors for assessing the remanent life include: Original design life (specified in years or number of operating cycles). Current equipment age and condition. How long ago the damage initated and how fast it is accumulating.  

Ageing Plants n Addressing Ageing n Assessment of Remanent Life Key factors for assessing the remanent life include: Rate of degradation (whether constant, variable, or exponential). Expected operating regime and degradation mechanisms. Changes in material properties.  

Ageing Plants n Addressing Ageing n Assessment of Remanent Life Key factors for assessing the remanent life include: Corrosion life (determined from the corrosion rate, allowance and thickness limit) Limits determined from design. Safety margins  

In

Ageing Plants n Addressing Ageing n Assessment of Remanent Life Some of the key factors for assessing the remanent life include: Rate of degradation (whether constant, variable, or exponential). Expected operating regime and degradation mechanisms. Changes in material properties.

Ageing Plants n Addressing Ageing n Assessment of Remanent Life Some of the key factors for assessing the remanent life include: Fatigue life Corrosion life (determined from the corrosion rate, allowance and thickness limit).

Ageing Plants n Addressing Ageing n Assessment of Remanent Life Some of the key factors for assessing the remanent life include: Original design life (specified in years or number of operating cycles). Current equipment age and condition. How long ago the damage initated and how fast it is accumulating. Rate of degradation (whether constant, variable, or exponential). Expected operating regime and degradation mechanisms. Changes in material properties. Fatigue life (based on the S-N design or fracture mechanics). • Corrosion life (determined from the corrosion rate, allowance and thickness limit). • Limits determined from design or fitness-for-service assessment. • Safety margins.  

In

Ageing Plants n Addressing Ageing n Assessment of Remanent Life Some of the key factors for assessing the remanent life include: Original design life (specified in years or number of operating cycles). Current equipment age and condition. How long ago the damage initated and how fast it is accumulating. Rate of degradation (whether constant, variable, or exponential). Expected operating regime and degradation mechanisms. Changes in material properties. Fatigue life (based on the S-N design or fracture mechanics). • Corrosion life (determined from the corrosion rate, allowance and thickness limit). • Limits determined from design or fitness-for-service assessment. • Safety margins.  

In

Ageing Plants n Addressing Ageing n Assessment of Remanent Life Some of the key factors for assessing the remanent life include: Original design life (specified in years or number of operating cycles). Current equipment age and condition. How long ago the damage initated and how fast it is accumulating. Rate of degradation (whether constant, variable, or exponential). Expected operating regime and degradation mechanisms. Changes in material properties. Fatigue life (based on the S-N design or fracture mechanics). • Corrosion life (determined from the corrosion rate, allowance and thickness limit). • Limits determined from design or fitness-for-service assessment. • Safety margins.  

Ageing Plants n Addressing Ageing n Assessment of Remanent Life Some of the key factors for assessing the remanent life include: Original design life (specified in years or number of operating cycles). Current equipment age and condition. How long ago the damage initated and how fast it is accumulating. Rate of degradation (whether constant, variable, or exponential). Expected operating regime and degradation mechanisms. Changes in material properties. Fatigue life (based on the S-N design or fracture mechanics). • Corrosion life (determined from the corrosion rate, allowance and thickness limit). • Limits determined from design or fitness-for-service assessment. • Safety margins.  

In

Ageing Plants n Addressing Ageing n Assessment of Remanent Life Factors for assessing the remanent life include: Original design life (specified in years or number of operating cycles). Current equipment age and condition. How long ago the damage initated and how fast it is accumulating.  

Ageing Plants n Addressing Ageing n Repair & Modifications n Number of factors are considered for achieving a satisfactory result and the life expectancy (temporary or permanent) of the repair/modification are: Welding. Dimensional tolerances Material compatibility  

Ageing Plants n Addressing Ageing n Revalidation of Equipment n After temporary or permanent repairs are made, it is good practice to revalidate the equipment to ensure that the repairs have been carried out as specified and have not had any detrimental effect on integrity.  

Ageing Plants n Addressing Ageing n Financial Criteria Need for optimizing the cost of plant inspection and maintenance and repairs (IMR) and the decision of when best to replace equipment.

In

The End

In