What Is RLA ?
The remaining life assessment is a study which involves a detailed qualitative and quantitative examination and tests and interpretation of test results for every critical component. Various latest technologies available in Non-destructive and destructive tests will be used to assess the present status of each component. The purpose of RLA activity is not to continue the operation of a plant beyond its design life, but merely to ensure full utilization up to its useful life.
RLA - AIM
To improve the reliability / availability and operating efficiency of units
To plan to carry out modifications / replacements of affected components.
To ensure full safe utilization up to its useful life.
To avoid premature retirement of plant and plant components.
INPUT DATA REQUIRED FOR RLA
Drawings of the components.
Shop/site fabrication details.
Running Hours.
Failure data.
Details of modifications carried out.
No. of start up/ shut down details.
No. of forced outages.
Creep readings.
Past analysis reports if any.
Details of operation beyond allowable parameters
Results of performance test.
External piping support readings.
Expansion values.
Areas where modification / improvements required.
Operational parameters at different load conditions.
Metal temperature readings.
Major problems encountered.
History of components replaced in the past.
CAUSES FOR DETERIORATION OF BOILER COMPONENTS
Corrosion
Erosion
Creep
Quality of fuel
High temperature oxidation
Disturbances in chemical regime
More cycles of start up / shut down.
Rapid rate of heating / cooling.
Grid disturbances.
Poor initial design.
Steady state thermal stress.
Follow up of wrong repair procedure.
More forced outages.
Improper thermal expansion.
Thermal fatigue.
Usage of faulty materials
MECHANISMS INVOLVED IN TUBE FAILURES.
Creep
Fatigue
Erosion
Corrosion
Lack of quality control
TESTING TECHNIQUES FOR RLA
Visual examination.
Dimensional measurements
Liquid penetrant testing
Magnetic particles testing
Ultrasonic testing
Metallographic examination
Hardness measurements
Surface residual stress measurement
Oxidation thickness measurements
Endoscope examination.
Sample cutting and laboratory analysis
CLASSIFICATION OF BOILER COMPONENTS FOR RLA
Drum and its connections
Downcomer, up raiser and branch pipes.
Water walls.
Header and stubs.
Eco, super heater and reheater coils.
External critical pipings.
Miscellaneous parts
Drum and its connections
Drum longitudinal & circumference weld joints, feed tube connections, steam tap –off nipples are inspected by LPT, UT, Replica and deposit analysis for presence of any crack, pitting, and erosion damage.
Downcomer, up raiser and branch pipes
Downcomer, up raiser and branch pipe bends and welding are inspected by visual, LPT, MPT, and Thickness measurement for presence of any crack, pitting, and erosion damage.
Water walls
Water walls are inspected by visual, sample testing, and dimensional check for fatigue cracks, and corrosion damage.
Header and stubs
Header and stubs are inspected by visual, LPT, MPT, and Thickness measurement, replica, and fiber optic inspection for presence of any debris, crack, creep and fatigue damage.
Eco, superheater and reheater coils
Eco, superheater and reheater coils are inspected by visual, sample analysis, deposit analysis and dimensional check for creep, erosion, pitting, corrosion, and fatigue damage.
External critical pipings.
External critical pipings ECO inlet /out let, CRH, HRH, MST and desuperheater cross pipe line weld joints, heat affected zone, and parent metal at bends are inspected by visual, UT, OD / thickness measurement, replica, and hardness for creep and fatigue damage.
Miscellaneous parts
Miscellaneous parts like desuperheater nozzles, flow meter orifices are to be tested by UT and fiber optic inspection for pitting, blockage and integrity of the components.
ADVANTAGES OF RLA STUDY
To avoid unplanned forced outages.
To improve PLF.
To avoid unnecessary repair.
To increase operational, availability and reliability.
To procure and stock necessary spares in advance.
To avoid any accidents / damages for the equipment /personnel working near by.
To plan to replace defective components during scheduled plant overhaul.
To improve availability.
To plan execution proposals in advance.
To know the integrity of the equipment.
Reduction in fuel oil consumption.
It gives a proper inspection schedule, maintenance and operating procedure.
To plan for LEP.
Outage of the plant can be planned as per grid demand.
Thank you so much for sharing valuable information with us. We also have articles related to this. We will be glad if you just have a look into it.
ReplyDeletehttps://tinyurl.com/yckfwm35
Great Blog, Although this is my first remark on this site, I just wanted to say hello and tell you how much I like reading your articles about . Boilers are intricate bits of machinery, as far as I know. The experts should handle their maintenance and repair with the help of your blog.Can you recommend any other blogs/websites that deal with the same subjects? Thanks.
ReplyDeleteGreat Blog, Although this is my first remark on this site, I just wanted to say hello and tell you how much I like reading your articles about boiler repair service. Boilers are intricate bits of machinery, as far as I know. The experts should handle their maintenance and repair with the help of your blog.Can you recommend any other blogs/websites that deal with the same subjects? Thanks.
ReplyDeleteRemaining Life Assessment (RLA) for boilers involves a comprehensive evaluation of the current condition of a boiler to estimate its remaining operational life. This assessment is crucial for ensuring the safe and efficient functioning of the boiler system. When conducting RLA for boilers, various factors are considered, including material degradation, corrosion rates, operating conditions, and maintenance history.
ReplyDeleteLeak repair is a critical aspect of RLA, as boiler leaks can lead to significant safety hazards, reduced efficiency, and unplanned downtime. Identifying and addressing leaks promptly is essential to extend the operational life of the boiler. Regular inspections and non-destructive testing methods, such as ultrasonic testing and visual inspections, play a crucial role in detecting leaks and assessing their severity.
In the context of RLA, leak repair involves not only fixing the immediate issue but also understanding the root cause of the leak. Common causes of leaks in boilers include corrosion, erosion, and mechanical damage. Proper repair strategies should be implemented to address the specific type of leak and prevent its recurrence. Additionally, measures such as applying protective coatings, upgrading materials, or implementing corrosion inhibition strategies may be part of an effective leak repair plan.
By incorporating leak repair into the overall RLA process, operators can enhance the reliability and safety of boiler systems. This proactive approach helps in identifying potential issues before they escalate, reducing the likelihood of major failures and minimizing the risk of accidents. Implementing a robust RLA program with a focus on leak repair ensures that boilers remain in optimal condition, maximizing their operational life and contributing to a more sustainable and cost-effective operation.