Residual Life Assessments and Condition Monitoring

Name: Samir Kumar Nath

Organisation: Central Power Research Institute, Nagpur

Designation: Joint Director

Education: Bengal Engineering College (Calcutta University), IIEST (BE & ME), IIT Madras (PhD)

Specialized in solving operation and maintenance problems of power plants by developing new and novel inspection techniques in the area of non-destructive evaluation (NDE). Has more than 28 years of experience in both Research & Development and Engineering Services. Professionally qualified in ASNT/ISNT Level-II/I in UT, MT, PT, RT, and ET. 

As an expert and experienced professional in remnant life assessment (RLA) and NDE-based condition assessment of plant components has rendered many field engineering & consultancy services, carried out many R&D projects, published many research papers in national & international journals of repute, coordinated many seminars/workshops/training program, guided many UG/PG scholars and delivered many invited technical lectures in industries and academic institutions. 

  • Received “Shri B M Naidu Award for Best Research Paper” of CPRI in the year 2015.
  • Received a patent in 2021 (Patent No. 380101) 

Name: Rajesh Ranjan

Organisation: Central Power Research Institute, Nagpur

Designation: Joint Director

Education: B.E (Mech.), M.E (Material Science), ASNT Level-II, Auditor ISO/IEC 17023:2017

Working In Central Power Research Institute, Thermal Research Centre, Nagpur. Expert in the field of metallurgy, Non-Destructive tests, taken up many failure analyses of various power plant components and condition assessments of boilers and turbine components including pressure parts, Chemical and elemental analysis of materials, and deposit analysis. 

26 years of experience in the field of non-destructive tests and metallurgical analysis. Expert in guidance to minimise the frequent boiler tube failures in various Thermal Power plants and Process Industries of India.

  • 4 technical papers in International Journals
  • 12 technical papers in national journals and conferences
  • Training provided too many officials of Power sectors on failure analysis of power plant components.
  • Expert guidance to many power sectors for solutions to minimise the premature failure of power plant components.

Working in CPRI for 26 years. Testing, evaluation, and consultancy for CPRI in the field of material characterisation, failure analysis, condition assessment of power plant components, RLA study of boiler and turbine, and life prediction of plant components through metallurgical analysis.

Remnant life and Condition assessment of Boiler Pressure Parts and Role of Boiler Inspectorate during Assessment.

Abstract:

Boilers are made up of a large amount of tubing and pipes of different materials which will have to withstand high pressure and temperature. The pressure parts undergo aging due to various reasons and subsequently start failing to lead to outages of the plant. These aging boiler pressure parts are required to be monitored and assessed through condition assessment and Remnant life assessment. Indian boiler regulation act has been discussed in article 391A (b) of IBR -1950 and made mandatory to assess these components through a non-destructive and destructive test to find the life span and present conditions of the pressure parts components. Life estimation of all the components of the boiler is a very important maintenance tool for predictive mainten

Introduction:

Boiler, a steam generator is an integrated system of a thermal power plant. In addition to the utility boilers, there are large numbers of process steam boilers. The components of boiler mainly the pressure parts are continuously subjected to high temperatures and pressure throughout the service life. Failure of any components not only leads to the loss of power generation; it poses threat to the safety of the surrounding working environment. Thus, the safe running of a boiler is of prime importance. The healthiness of a boiler with respect to its fitness for the purpose is monitored by the Government statutory body-inspectorate of boilers on a regular basis. Remnant life assessment and condition assessment of boiler pressure parts is carried out and is mandatory to ascertain the health status of all pressure parts and other related components of boilers.

RLA & Condition assessment of boiler components using non-destructive techniques provides the healthiness of the components at the present condition which ensures and prevents premature failures. The condition assessment also ensures its full utilization up to its useful life. It will also result in enhancing the original rated capacity by utilizing earlier conservative design considerations. The industrial growth and improved living standard for the Indian population have exceeded the available supply of power in this country and the need for huge additional power to fulfil the target of power on demand and to achieve these requirements required to install of new power generating units. In addition to installing new power plants, generating power from the existing aged power stations to the maximum extent possible has gained importance.

Augmentation of the power generating capacity of the old power plants by renovation and modernization can significantly contribute to achieving the target.

The quicker, cheaper, and more practical solution to increase the existing available power supply is to carry out condition assessment and life extension programs for the operating power plant components. 

It is necessary to evaluate the condition of the boiler which had to withstand fatigue stress, creep damage, oxidation, corrosion attacks, etc.

Some of the non-destructive techniques are discussed herewith.

The components of boilers like headers and tubes of different zones are subjected to high temperatures and pressure during steam generation. The tubes and other related components may fail due to several regions without alarming any symptoms. This leads to huge generation loss. The reasons for failure are very much important to analyze to minimize premature failure in the future so that the losses due to unforeseen causes may be controlled. The tubes and other related components in the boiler may fail due to various reasons like short-term and long overheating, corrosion, fatigue, creep, erosion, oxidation, scale deposits, etc. Hence failure analysis of power plant components is a very vital investigation to minimize premature failure.

Dynamic structures like TG decks are subjected to continuous cyclic loading, various operational loads, vibrations, etc results distress and the formation of cracks in hardened concrete structures. The operation loads like mechanical imbalance and sudden impact due to various reasons like electrical shocks, temperature conditions, and aging effects create abnormal conditions in the concrete structures.

The condition assessment and routine inspection of hardened structures are very important for continuous operation. It is essential to determine the distress and deterioration that occurred in the structures.

RLA of Boilers – Role of Indian Boiler Regulation

Article 391A (b) of IBR 1950 states that the boilers which are operating at a temperature of 400℃ (main steam outlet temperature) and above including utility and industrial boilers and all boiler parts operating in the creep range shall be tested non-destructively as per the table-1(391A (b)) after they are in operation for 1,00,000 hours for assessment of remnant life of parts.

The boilers which are operating at a temperature less than 400℃ (main steam outlet temperature) on completion of a life of twenty-five years are to be tested for the remnant life of its components as per table 2. (391A (b))

However, the boilers working at a pressure less than 50kg/cm2 and temperature less than 400℃ (main steam outlet temperature), such elaborate remnant life assessment is not mandatory but in such cases, drums and headers of such boilers shall be inspected by non-destructive tests like the ultrasonic test, Magnetic particle test, and Dye penetrant test.

Heat recovery steam generators (HSRGs) that are operating at a temperature of 400℃ (main steam outlet temperature) and above shall be non-destructively tested by the Remnant Life Assessment organization for their components as per Table 3 (391A (b)).

If results are acceptable as per the standard laid down by Central Boiler Board, a certificate shall be issued by the Chief Inspectorate of Boilers for extending the life of the boiler for a period of further period not exceeding six years or fewer periods as recommended by the Remnant Life Assessment Organization. This assessment shall be carried out thereafter every six years.

The assessment of remnant life shall be carried out thereafter by the organizations working in the field of boilers and remnant life and extension thereof after such organization is approved by the Central Boilers Board. Such an organization shall work in close coordination with the office of the Chief Inspectorate of boilers in the field of remnant life assessment and extension.

Non-Destructive Evaluation (NDE)

Various NDE techniques for detection of cracks, effects of corrosion/erosion, etc. in addition to commonly adopted techniques such as Ultrasonic thickness gauging, Ultrasonic flaw detection, Dye Penetrant testing, Fluorescent magnetic particle testing, specialized techniques such as assessment of hydrogen damage by Ultrasonic, measurement of steam side oxide scale by in-situ ultrasonic, video probe examination of critical components are employed. Metallurgical tests such as in-situ metallography using replica method, in-situ chemical analysis by metal spectroscope / X-ray fluorescence method, in-situ hardness measurement, etc. 

NDE techniques adopted in the residual life assessment of plant components can be broadly classified as conventional and specialized techniques. Conventional techniques include Visual examination & Dimensional measurement using appropriate tools, Ultrasonic thickness gauging, penetrant testing, and Magnetic particle inspection using the wet fluorescent method.

Specialized NDE techniques include video probing using fiber optics to assess the damage on the internal surfaces especially for corrosion, erosion, cracks, and the presence of foreign materials, in-situ replica technique to study the material degradation and the presence of micro cracks, ultrasonic testing using high-frequency pulse transducer for measurement of oxide scale on the steam side, ultrasonic attenuation measurement to detect hydrogen damage.

Advanced Ultrasonic Techniques

Failures of superheater and re-heater tubes and other related components can be considered one of the most prevalent causes of unforeseen outages of a thermal power plant. The failures are often attributed to creep deformations which can lead to rupture. Such premature failures are caused by the steam side build-up which can cause an increase in the operating temperature of the tube. Using a high-frequency Pulse-Receiver and using specially designed high-frequency transducers operating in the frequency range (20 – 50 Hz), it is possible to measure the oxide scale thickness on the steam side.

Hydrogen damage failures of water wall tubes are generic for some utilities where condenser leaking occurs for prolonged periods. Since the damage is initiated from the waterside surface of the tubes, the same cannot be revealed on the outside surface. Ultrasonic examination using a 5 MHz longitudinal wave transducer and measuring the attenuation characteristics can indicate the regions where micro-fissuring due to hydrogen damage has occurred. Replacement of tubes can be done in time to avoid unplanned outages.

Micro Structural Damage Evaluation

Engineering materials are subjected to several damage mechanisms while in service. Before the damage becomes perceptible to the unaided eye, the microstructure would have responded to the degradation of the material.

In high-pressure and high-temperature components, the consequential damage mechanism is a creep, which manifests itself in the form of cavities in the microstructure. The morphology (shape characteristics and orientation) of the cavities lends a clue to the status of the component.

The phenomenon of creep is guided by the following factors: Temperature, Stress, Time, and Material Properties

Given a material is subjected to constant temperature and stress (pressure), creep damage evident in the microstructure will be a function of time (expended life fraction). 

Neubauer and Wedel related the creep-life consumption of plant components to cavity classification as shown in the table given below:

They characterized cavity evolution in steel at five stages – i.e., undamaged, isolation cavities, oriented cavities, linked cavities (micro-cracks), and macro-cracks. They also formulated recommendations corresponding to the different stages of cavitation. For undamaged & class-A damage, no remedial action would be required. For class B damage, consisting of oriented cavities, re-inspection within1 ½

To 3 years would be required. For class C damage, repair or replacement would be needed within six months. For class D damage, the immediate repair would be required. 

Structural ClassificationMicrostructure featuresAction neededExpended life fraction
UndamagedFerrite & PearliteNone0.12
AIsolated cavitiesNone until next major scheduled maintenance outage.0.46
BOriented cavitiesReplica test at specified interval preferably within 1 ½ to 3 years0.50
CLinked cavities (micro-cracks)Limited service until repair and better to inspect within 6 months0.84
DMacro-cracksImmediate repair1.00

Test Procedures:

Visual Examination

Visual examination is carried out to assess material wastage due to oxidation, erosion/corrosion, fouling of heat transfer surfaces. This includes inspection of drum internals to ensure proper steam/water separation. Visual inspection of the observations made with reference to the discoloration of coils, and prior evaluation of pressure part condition based on experience and design knowledge from similar plants make sample selection more rational. Samples from the regions thus determined are most susceptible to failures. Such samples from each component are selected for an evaluation of the metallurgical condition.

Ultrasonic Testing

By using high-frequency sound waves, the surface and sub-surface flaws in the components are detected. Cracks, laminations, shrinkages, cavities, flakes, pores, etc. that act as discontinuities in the components are detected. 

Magnetic Particle Inspection

The technique is adopted for locating surface and sub-surface discontinuities like seams, laps, quenching, grinding cracks, and surface rupture occurring on welds. This method is also used for detecting surface fatigue cracks developed during service. 

Magnetic Particle Inspection helps to detect cracks and discontinuities on the surface of ferromagnetic materials. Magnetizing at least two mutually perpendicular directions ensures the detection of flaws in all possible orientations. 

In-Situ Oxide Scale Thickness Measurement

Ultrasonic equipment with high-frequency probes is used for in-situ oxide scale thickness measurement for the specific coils/tubes exposed to high temperatures. The measured oxide scale thickness becomes an important input for determining the extent of degradation. In-situ evaluation of SH/RH tubes by Non-Destructive evaluation (Ultrasonic) for steam side oxide scale gives a clear indication of average tube metal temperature since the growth of the oxide scale is a function of time and temperature.

The ultrasonic technique using high-frequency probes is employed for the measurement of the thickness of the steam side oxide scale. The ultrasonic method used is based on transmitting a sound wave through the tube thickness. The thickness is calculated by measuring the time difference between the signals reflected from the metal/scale interface and the tube ID surface. The outer surface of the tube under inspection region is made free of fireside oxide deposits and polished to expose the base metal. The ultrasonic energy of high frequency (25 MHz) from a specially designed focused beam-type transducer is transmitted through the sample tube. With the knowledge of working hoop stress and metal temperature, it is possible to determine the time to creep rupture failure from the ISO data of specific tube material.

Dye Penetrant Inspection

This technique is adopted primarily for the detection of the discontinuities that are open to the surface of a part, like surface porosity, pitting, pinholes, etc. In principle, the dye/liquid (Penetrant) is applied to the surface to be examined and allowed to enter into discontinuities. All excess penetrant is then removed; the surface is dried and the developer is applied. The developer serves both as a blotter to absorb the penetrant and as contrasting background to enhance the visibility of the indication.

In-situ Metallography

Power plant components that operate at high temperatures creep is a major cause of cracking especially on the highly stressed brittle regions. Creep damage occurs in different stages and is the first sign in the formation of microscopic cavities at grain boundaries. Application of an NDE technique using a plastic film replica on the metal surface can assess the creep damage and the presence of micro cracks. The findings of this examination have recommended the replacement of the header at the first available opportunity. 

The process involves preliminary preparation of the metal surface using polishing equipment. When the spot is ensured free from rust and scale polishing is carried out using abrasive paper of varying grits from 120, 200, 400, and 600 in sequence. Subsequently, diamond paste lapping is done followed by etching to reveal the microstructure. 

The microstructure of the component is transferred to a film and this is called replication. The microstructure is further examined in the laboratory with magnification up to 500X and more to assess the metallurgical damages like creep cavitation etc.

Hardness Measurement

A portable hardness tester is used for in-situ hardness measurement of various critical components like steam drums, high and low-temperature headers, pipelines, etc. Hardness measurement aids in the assessment of the metallurgical status/condition of components.

Dimensional Measurement and Thickness Measurement

Outside diameter measurements are generally employed to determine the swelling (bulging) due to creep. Diameter measurements are made using digital Vernier calipers and bow gauges. Thickness measurements at critical areas give a measure of thickness loss over the years due to erosion and corrosion. The thickness measurements are made using an ultrasonic thickness gauge.

Video probing using fibre-optics Fibroscopic Inspection

The internal condition of many power plant components needs examination. High-temperature headers may develop cracks due to creep or fatigue or a combination of both. Video probing using fiberoptic can detect the presence of these cracks in time for further evaluation. In addition, the presence of corrosion pitting and foreign particles may also be detected by this examination. Based on the above finding, chemical cleaning off the boiler may be recommended. This inspection reveals valuable information about the internal condition of the components. 

Deposit Analysis

Deposit samples were carefully collected after the visual inspection from critical components like drums (internal), external deposits on high and low-temperature coils, etc. Those samples are subsequently analyzed in a laboratory for elemental analysis by conventional chemical methods/atomic absorption spectrometer. 

Mechanical Properties:

The selected tubes from various zones of boilers have to be collected. These tubes are tested for the Creep rupture test, Tensile and flattening test to assess their present conditions of available strength.

Improved Suggestions for Conducting RLA of Boilers

The following improvements are suggested while conducting RLA of boilers:

A) Location details of all the weld joints of the pressure piping namely main steam line (MSL), hot reheat (HRH) line, cold reheat (CRH) line, feed water line should be well documented by the owner. With the availability of such a document, a particular weld joint of interest based on the findings of the analysis of the piping or any other analysis can be exactly bared open (de-insulated) for conducting various tests with not much loss of time and more reliably during RLA study at the site. 

B) Detected weld defects in thick section components e.g., headers, pipelines, etc should be reassessed by the ultrasonic time of flight diffraction (TOFD) method.

C) Leakage points causing ash accumulation in a penthouse should be identified and repaired. A clean penthouse immensely helps in better NDE of all the critical pressure parts e.g., headers, link pipes, etc located there within the short shutdown period. 

D) In-situ replication for assessing microstructural degradation is carried out during the RLA study. Location details specific to a particular pressure part where the replica of the microstructure is taken should be marked and documented and included in the report. Given an opportunity subsequently, replication at the same location can be conducted to reassess the damage accumulation with respect to creep, a high-temperature damage mechanism in boilers. This will help in obtaining a trend analysis of the microstructural damage of the part and better prediction of the life remaining. 

E) Failure investigation of each boiler tube leakage (BTL) should be arranged to be conducted by the owner. A consolidated report of all such leakages and investigation conclusions should be made available to the assessment organization since it will serve as an important technical input for the RLA study. 

F) In-situ material mix-up survey should be conducted during the RLA study. Especially appropriateness of the material grades of the new tubes going as a replacement should be confirmed. This may reduce certainly forced outages due to BTL subsequently.

Conclusions:

The RLA Study and condition assessment of boiler pressure parts and their components helps in a recommendation for safe operation and maintenance practices and also in RUN / REPAIR / REFURBISH / REPLACE OR MODIFICATION / REINSPECTION based on the thorough analysis with close guidance and monitoring of inspectorate of boilers 

CPRI has successfully conducted the RLA and condition assessment study of more than 150 boilers of different capacities ranging from 50MW to 500 MW in both utility and non-utility category as per the stipulated guidelines of IBR throughout the country.

Residual Life Assessment (RLA) and Condition Monitoring of Boiler

Boiler

Operational Effects on Boiler Components

  • High temp. effects (ageing)
  • High temp. corrosion (ash attack)
  • High velocity flue gas with particulate burden (erosion)
  • Thermal cycling (crack)
  • Water chemistry effects
  • Maintenance repairs (weld, foreign materials entrapment)
  • Material mix-up during repair

Manifestation

  • Mechanical
    • Material loss, wall thinning
    • Weld defect
    • Crack
    • Swelling
    • Slagging, fouling
    • Loss of material strength
  • Metallurgical
    • Hydrogen embrittlement
    • Creep life
    • Structural integrity
  • Steam Starvation
    • Sudden rupture

Various damage mechanisms and suitable NDE methods (Boiler)

Damage MechanismNDE Methods for detection
ErosionVisual Examination (VE), Ultrasonic Thickness Survey
Blockade in water circuitFibroscopy
Welding defectsUltrasonic Test (UT), Magnetic Particle Test (MPT), Dye Penetrant Test (DPT), Radiographic Test (RT)
Hydrogen EmbrittlementUltrasonic Test (UT),
CreepIn-situ Metallography, Hardness Measurement
Oxide Scale growthUltrasonic Test (UT)
Crack detection and sizingUltrasonic Time of Flight Diffraction (TOFD) inspection, Phased Array Ultrasonic Test (PAUT)
Short Term overheatingIn-situ Metallography, Hardness Measurement
SwellingDimensional Measurement (OD)

Header

Areas of Inspection:

  • Parent body
  • Weldments
  • Stub and opening joints
  • Inter-opening ligament area
Pre-existingPost-operative
Slag
Sidewall lack of fusion (look for whether these are active or not)
Cracking (weld, ligament)
Oxide scale built-up
Foreign material entrapment

Selection criteria for NDE methods

NDE Methods
Dye Penetrant Test (DPT)Time of Flight Diffraction (TOFD)
Magnetic Particle Test (MPT)Phased Array (PA)
Fibroscopy (FIB)Oxide Scale Measurement (OT)
Ultrasonic Test (UT)Radiographic Test (RT)

Outlet Header (Secondary Superheater)

Failure MechanismAssessment Method
Creep
Fatigue
Corrosion
Replica
Internal Inspection
Dimensional Measurement
Dye Penetrant Test
Ultrasonic Flaw Detection
Magnetic Particle Inspection
Stub tube Magnetic Particle Inspection

What is Creep?

The time dependent, thermally assisted deformation of components under load (stress) is known as creep. 

Structural ClassificationMicrostructure featuresAction neededExpended life fraction
UndamagedFerrite & pearliteNone0.12
AIsolated cavitiesNone until next major scheduled maintenance outage0.46
BOriented cavitiesReplica test at specified interval preferably within 1.5 to 3 years0.50
CLinked cavities (micro cracks)Limited service until repair and better to inspect within 6 months0.84
DMacro cracksMacro cracks1.00

Residual Life Assessment (RLA) & Renovation & Modernisation (R&M)

Objectives

Health Check-up

Safety to Continue Operation

Scientific tool for Design Options

  • Run
  • Repair
  • Refurbish/ Retrofit
  • Replace
  • Operational Improvements

Methodology

  • 1A – Past History Review
    • Interview with Plant Personnel
  • 2A – Present Condition Assessment
    • Hot walk down Survey
    • Tests/ Inspection in Running Condition
    • Hot/ Cold Spots, Leakages 
    • Cold Walk down Survey
    • Tests/ Inspection in Cold (Shutdown) Condition
      • NDT
      • Sampling & Further Laboratory Analysis
    • Pre-light up Study
      • Cold Air Velocity
  • 3A – Home Office
    • Compilation & Data Analysis
    • Recommendations
      • Component Level
      • Sub-System Level – System Level

Condition Assessment

  • Destructive Test (on samples)
    • Creep life (quantitative)
    • Tensile strength – Bend test
    • Flattening test
    • Corrosion products
    • Metallurgical structure of cross section
  • Non-destructive Test (in-situ/field)
  • Visual
    • DPT
    • MPT
    • UT
  • RT
    • TOFD
    • LEFT
    • Replication and Hardness
    • In-situ oxide scale measurement

RLA Calculation Criteria

  • Neuber’s Structural Classification
  • Stress Rupture Test 
  • Oxide scale thickness
Structural ClassificationMicrostructure featuresAction neededExpended life fraction
UndamagedFerrite & pearliteNone0.12
AIsolated cavitiesNone until next major scheduled maintenance outage0.46
BOriented cavitiesReplica test at specified interval preferably within 1.5 to 3 years0.50
CLinked cavities (micro cracks)Limited service until repair and better to inspect within 6 months0.84
DMacro cracksImmediate repair1.00

Residual Life Assessment Studies

Remaining life prediction

Creep Base

Assess accumulated Creep Damage

  • Metallography (Replication)
  • Accelerated Creep Rupture Test on Post-service sample

Oxide Scale Base

  • Oxide Scale Thickness

Accelerated Creep Rupture Test Method

Collection of Specific sample from the identified area

Test under accelerated Conditions (Iso-Stress)

P = T (20 + log t) T= Temperature (oR)

 t = Time (hrs.)

P = Larsen-Miller parameter

An illustration of conducting such a confirmatory test is explained below:

Given that data are as follows:

  1. Material: 1 ¼ Cr _ ½ Mo _ Si Steel
  2. Working Stress: 8 ksi
  3. Working temperature: 900°F

Calculate LMP at working temperature (900°F) for rupture time of 10 years, say 105 hours

P = 1360 (20 + log 105) = 34000

Using LMP = 34000 calculate for higher temperature the time of the rupture which corresponds to a rupture time of 105 hours at 900°F (working temperature)

Following table gives a calculated data temperature in °C for convenience

LMP 3400Temp °C540550560570580590
Time in Hours167587546525013776

Conduct the accelerated creep test under iso-stress condition at any of the elevated temperatures in the above table and confirm if the sample passes the test for the duration of time as per the above table. 

Sample passes, for example, 465 hours in Iso-stress Creep Rupture test conducted at 5600°C, the life extension can be recommended for 10 years. 

Under the above condition the sample ruptures at say 300 hours.

The LMP corresponding to this time and temperature is P = 33715

Using P = 33715 calculate rupture time at working temperature (900°F) 

33715 = (900 + 460) (20 + log tr) trupture 

(at 9000 F, 8 ksi) = 61722 hours

Recommended extension of life = 61722 hours (7 years)

Oxide Scale Thickness Method

Oxide Scale Thickness Measurement

  • Optical Microscope
  • Non-Destructive Technique (Ultrasonic Method)

Log X = 0.00022 P – 7.25 X= Oxide Scale Thickness in Mils

P = T (20 + log t) P= Larsen-Miller Parameter

T= Temperature in °R

t = Time in hrs.

Name of the component: Convection Super heater

Oxide scale measured: 2.8 mils

Running Time t – 1,00,000 hours (approximately)

Stress = 4.6 Kg/mm

Calculation of equivalent temperature exposed:

Log 2.8 = 0.00022 P – 7.25

P = 34987

P = T (20 + log t)

34987 = T (20 + log 105)

T = 1399.48°R

= 504°C

LMP rupture at working stress (4.6 Kg/mm2) is

P =37500 (from standard data curves)

Using the formula P = T (20 + log t)

37,500 = 1399.48 (20 + log tr) tr

504°C = 62.5 x 105

Remaining life using life fraction rule

trem = tr – texp

= 62.5 x 105 – 105 hours

= 61.5 x 105 hours

The remaining life (trem) = 61.5 x 105 hours

Boiler tubes

MSL (RHS)

Major Findings

Crack In Boiler Piping

Field trial: TOFD inspection of weld in feed water pipe line of thermal power plant

Equipment:

  1. Image analysis system for metallurgical evaluation
  2. In-situ (field) Metallography (Replication) Test Facility
  3. In-situ (field) Hardness Test facility
  4. In-situ Chemical Analysis / Material Grade Identification Test Facility.
  5. In situ Oxide scale measurement facilities
  6. Ultrasonic test facility (Pulse-Echo, TOFD, Phased Array)
  7. Dye penetrant test facility.
  8. Magnetic Particle Inspection.
  9. Dimensional measurement test facility.
  10. Video Image scope for remote visual inspection for boiler, turbine, and other components.

    Leave Your Comment

    Your email address will not be published.*

    eighteen + 7 =