Recent Completed Project on Metallography, Accelerated Rupture Testing and Remaining Life Assessment of Superheater & Reheater Tubes

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ETD is pleased to announce the successful recent completion of a metallography, accelerated rupture testing and remaining life assessment project of superheater & reheater tubes.

It is reported by the client that they had hired a sub-contractor to perform accelerated rupture testing and remnant life assessment work for 1 superheater and 1 reheater tubes (of T91 materials). This contractor had completed the creep test and RLA based on an iso-thermal basis with reference to Manson-Haferd curve. Recently, the client hired a second contractor to do the same job. This second contractor had done the creep test and RLA based on an iso-stress basis. The actual service stress in this case is relatively low. The client had found that the results from these two contractors differed greatly; the results of second contractor showed unrealistically high remaining life and they did not consider progressive wastage.

Therefore, ETD was approached with a request to perform the same work (accelerated rupture testing and RLA) again for these two coal-fired tubes to provide an estimate for the remaining life of the components.

The scope of the work carried out included the following tasks:

i.  Metallography - Metallography of two tube samples were carried out to establish the creep damage (i.e. creep cavitation & microstructure degradation) levels. The microstructure and any degradation characterised using damage classification for creep damage of the relevant materials. Specific scope in this task included:

  • Visual examination of the tube samples including internal and external appearance;

  • Assessment of condition of internal and external surfaces including identification of inclusions/ contaminations, scale/ deposits, welding defects etc (if any exists) and obtain photos of evidence;

  • Dimensional examination - OD measurement at 12-6 and 3-9 O’clock positions at fixed length intervals throughout the entire tube length.

  • Tube wall thickness measurements for all aforementioned clock positions.

  • Metallographic examination of the tube samples using optical microscopy to assess the condition of internal and external surfaces, to identify phase changes in microstructure / material degradation/ precipitations and also to identify the damage mechanism(s);

  • Estimation of tube operating temperature based on measurements of steam-side oxide thickness;

  • Hardness testing and evaluation to determine the equivalent tensile strength values (using published hardness/ UTS correlation tables) to assess the mechanical strength or softening of the materials.

ii.  Accelerated Stress Rupture Testing - A programme of isothermal rupture testing was then performed comprising three specimens from each of the two tube samples to be tested. The tests were performed at conditions designed to achieve target durations of 500, 1000 and 3000 hours as proposed by ETD. After reviewing the design and operating parameters, the test conditions (i.e. temperature, stress etc) was selected by ETD based on previous experience and reference database to give failures at the above number of hours.

All these tests will be conducted by ETD’s collaborative accredited laboratory in Europe and according to the international and ECCC specifications.

iii.  Analysis of Creep Test Results and Remaining Life Calculations - The results from the above rupture testing programme were compared with standard data for the relevant steel grade to establish where, within the upper and lower bounds, the material creep properties lie. Hence an equation describing the actual creep strength of the ex-service material being modelled. This equation was then used to estimate the creep life at the service conditions.

Provided that the as-installed tube wall thickness and service hours to date are known, then the corrosion rate (wall thinning rate) can be calculated using the thickness measurements from the first task. This corrosion rate was used to determine the combined effect of creep and corrosion on the component remaining life at the effective operating temperature estimated in the first task.

A final report, detailing the findings of the tasks undertaken, was issued for comments by the client. It will include photographic records from the metallographic study and provide details of the remaining life estimate based on accelerated rupture testing. Any possible causes for concern will be highlighted. The influence of material degradation and other microstructural changes were also discussed in this report.

For more information about our life assessment services please click here.

Recent Completed Project on Inspection, Fitness for Service and Life Assessment of T-piece Welded Piping

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ETD is pleased to announce the successful recent completion of an inspection, fitness for service and life assessment project for a European based plant.

In October 2017, microcracks were observed on a welded T-piece of main steam balancing pipe connections. Defect/ crack assessment was performed by the plant engineers and the results showed that the component will be fit for service for another 4 years with the repair of cracks by burring techniques. However, these results were not acceptable by the owners and insisted further analysis would be performed. The results of the second assessment showed that the component should be replaced as early as possible. Due to the disagreement between the owners and plant management, a decision was made that further analysis would be performed by an independent third party and then make appropriate decision for run/repair/replacement of the component. Therefore, ETD were asked to submit a proposal to perform further inspection and analysis to assess fitness for service and predict remaining life and of the component.

ETD proposed to carry out the project in the following two phases. The objectives and scope of work for each phase are:

Phase 1:

(i) Review two previous reports - defect assessment and life assessment reports completed by the client.

(ii) Perform onsite inspection. This will include the followings:

  • On-site replication at 4 clock positions for the affected T-piece of the balancing pipe connection;

  • On-site hardness testing at the same locations as the replication spots;

(iii) Review design and operating parameters, previous failure and maintenance history;

(iv) Perform condition assessment and fitness for service assessment based on the damage classification.

(v) Report covering the results of the investigations & provide recommendations on whether the component is fit for service.

Phase 2:

(i) Perform pipeline stress analysis of the piping system to obtain line loads and bending stresses which will be used in Finite Element (FE) analysis. This will include the following Tasks:

  • Review of design/ isometric drawings clearly showing all dimensions and piping connections of the piping system.

  • Review and analysis of inspection data/ information of hangers and supports collected during hot and cold condition inspection.

  • Perform pipeline stress analysis of the piping system using CAESAR II software.

(ii) Perform Finite Element (FE) analysis to obtain accurate stress levels at the affected T-piece location of the balancing pipe.

(iii) Perform remaining life assessment using the stress values obtained from FE analysis.

A report was then issued detailing the findings with photographic records including results of stress analysis & life assessment and highlighting any possible causes for concern regarding the pipe integrity. Furthermore, the report included recommendations for possible remedial actions that may improve component integrity.

For more information on our life assessment services, please click here.

On-site Inspection and Remaining Life Assessment for Boiler Pressure Parts *Using our ‘Smart Sleeve’ commercially on a power plant for the first time*

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The client contacted ETD to submit a proposal on Remaining Life Assessment (RLA) for boiler pressure parts by performing on-site inspection, analysis and assessment on tubes, T-piece nozzles, stub tube weldments and hot reheat pipe weldment for final superheater (FSOH) & reheater (ROH). The work involved performing on-site inspections - ultrasonic thickness measurements (UT) of tubes (wall thickness & bore oxide scale), EMAT (Electromagnetic Acoustic Transducer), replication and hardness measurements of selected locations. The inspection data was then used to estimate effective tube metal temperature and identify material degradation which could be used for damage assessment and predicting the remaining life of outlet headers and tubes of the FSOH & ROH.

The objectives and scope of the work to be carried out were:

  • Reviewing the drawings of FSOH & ROH, tube banks of the boiler to be studied and identify accessible test locations for on-site inspections;

  • Performing on-site ultrasonic thickness (UT) measurements of tube wall thickness and bore oxide scale for FSOH & for ROH tubes;

  • Performing on-site EMAT (Electromagnetic Acoustic Transducer) testing of tube wall thickness for FSOH & ROH tubes;

  • Performing on-site replication and hardness measurements on straight tubes, T-piece nozzle weldments, stub tube weldments and hot reheat pipe weldment for FSOH & ROH for the first time, using our newly developed ‘Smart Sleeve’ Hardness Tester commercially on a power plant;

  • Assessing all replicas by using OM (optical microscope) to confirm the damage condition. Further assessment was also made of selected P/T/F91 & T23 replica(s) by using SEM (Scanning Electron Microscope), if necessary, to confirm the damage condition;

  • Assessing the damage and material degradation of FSOH & ROH outlet headers, tubes, T-piece nozzle weldments, stub tube weldments and hot reheat pipe weldments based on the replication and hardness measurements data;

  • Reviewing & analysing UT inspection data and estimation of wall thickness loss & tube metal temperature;

  • Assessing the remaining life of FSOH & ROH components based on estimated tube metal temperature and other inspection data;

  • Reviewing & analysing previous failures, inspection and maintenance data for other pressure parts (i.e. economiser, etc) of the boiler to complete the life assessment study;

  • Preparing a full report including results of on-site inspections, analysis results of damage & life assessment study and make recommendations for any further actions to be taken for safe and reliable operation of the boiler.

For more information about of Remaining Life Assessment & Extension services please click here.

Offer of Unique P91, P92 Services for New & Running Plants

In this P91/P92 Services Brochure you will find useful and interesting information on ETD’s unique P91, P92 Services for New & Running Plants. These include:

a) Inspection, Monitoring, Assessment & Life Extension Services: Over the last decade through its collaborative research programmes, with its international industry partners, involving large pipe testing ETD has developed a suite of specialist inspection and monitoring techniques and life assessment methodologies that it offers to plants worldwide. These are offered in addition to the conventional NDE techniques for the detection and sizing of defects, together with replication and portable hardness testing for component condition and remaining life assessment. ETD carries out code-based calculations of creep life using either deterministic or probabilistic (another of ETD specialities) methodologies. Examples of these techniques include: Scanning Force Microscope (SFM) for early stage damage detection, Miniature sample removal (boat sampling) for quality checks and life/condition assessment, Precision Portable Hardness Tester (known as ‘Smart sleeve’), ‘Obikou’ for Pipe Strengthening and Life Extension and Defect/Crack Assessment.

 b) Root Cause Failure Analysis: Over the years ETD has developed an expertise in the root cause failure investigation of P91 and P92 components/welds. In the recent past, ETD has investigated a range of failures of T91 tube components and welds, and cracking in P91 pipes and drain-line components in conventional boilers and HRSGs. In these investigations, ETD identifies the root cause of the damage, and proposes remedial actions and solutions to the problem.

c) Consultancy & Guidelines on Materials & Welding: ETD provides P91 and P92 users with advice and guidance on the metallurgy, welding and heat treatment of these steels. This service includes reviewing weld procedure specifications (WPS) for similar and dissimilar metal welds, inspection of NDE records, and guidelines for repair welding of P91. The advice is provided to both the plant operators and designers/ manufacturers. This advice is based on ETD’s P91 experience in a number of Group Sponsored Projects including its running of the International P91 Users Group (Int. P91UG) for international industry over more than a decade and its involvement as consultants to many a power plants worldwide.

For further details of our P91/P92 services and opportunities being offered, please click on the image above.

Recent Completed Project on ‘Accelerated Rupture Testing and Integrity/Life Assessment of HP Steam Header Material’

In a recent outage in a process plant in the Middle East, damages (i.e. misalignment, bulging, graphitisation etc.) were observed on certain welds of HP steam header. The scope of study involved metallographic examination, including microstructure analysis and hardness testing, and accelerated rupture testing for material samples removed from respective sections. This allowed assessment of the remaining life of the service-exposed header material, enabling improved remaining life predictions for the components within the HP steam header system.

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For more information about our life assessment services please click here.

On-site Inspection and Remaining Life Assessment for Boiler Pressure Parts for an Asian Power Plant

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The client contacted ETD to submit a proposal on Remaining Life Assessment (RLA) for boiler pressure parts by performing on-site inspection, analysis and assessment on tubes, T-piece nozzles, stub tube weldments and hot reheat pipe weldment for final superheater (FSOH) & reheater (ROH). The work involved performing on-site inspections - ultrasonic thickness measurements (UT) of tubes (wall thickness & bore oxide scale), EMAT (Electromagnetic Acoustic Transducer), replication and hardness measurements of selected locations. The inspection data was then used to estimate effective tube metal temperature and identify material degradation which could be used for damage assessment and predicting the remaining life of outlet headers and tubes of the FSOH & ROH.

The objectives and scope of the work to be carried out were:

  • Reviewing the drawings of FSOH & ROH, tube banks of the boiler to be studied and identify accessible test locations for on-site inspections;

  • Performing on-site ultrasonic thickness (UT) measurements of tube wall thickness and bore oxide scale for FSOH & for ROH tubes;

  • Performing on-site EMAT (Electromagnetic Acoustic Transducer) testing of tube wall thickness for FSOH & ROH tubes;

  • Performing on-site replication and hardness measurements on straight tubes, T-piece nozzle weldments, stub tube weldments and hot reheat pipe weldment for FSOH & ROH;

  • Assessing all replicas by using OM (optical microscope) to confirm the damage condition. Further assessment was also made of selected P/T/F91 & T23 replica(s) by using SEM (Scanning Electron Microscope), if necessary, to confirm the damage condition;

  • Assessing the damage and material degradation of FSOH & ROH outlet headers, tubes, T-piece nozzle weldments, stub tube weldments and hot reheat pipe weldments based on the replication and hardness measurements data;

  • Reviewing & analysing UT inspection data and estimation of wall thickness loss & tube metal temperature;

  • Assessing the remaining life of FSOH & ROH components based on estimated tube metal temperature and other inspection data;

  • Reviewing & analysing previous failures, inspection and maintenance data for other pressure parts (i.e. economiser, etc) of the boiler to complete the life assessment study;

  • Preparing a full report including results of on-site inspections, analysis results of damage & life assessment study and make recommendations for any further actions to be taken for safe and reliable operation of the boiler.

For more information about of Remaining Life Assessment & Extension services please click here.

Recent Completed Project on 'On-Site Inspection and Remaining Life Assessment of a Boiler' for a European Power Plant

ETD is pleased to announce the successful recent completion of a remaining life assessment project.

A European based power plant approached ETD to submit a proposal on Remaining Life Assessment (RLA) of one of their boilers. The work involved performing on-site inspections - ultrasonic thickness measurements (UT) of tubes (wall thickness & bore oxide scale), replication, hardness measurements of selected components from FSOH and ROH. The inspection data was then used to estimate tube metal temperature and identify material degradation which could then be used for damage assessment and predicting the remaining life of outlet headers and tubes of final superheater & reheater.

The scope of the work included:

  1. Reviewing the drawings of FSOH & ROH, tube banks of the boiler to be studied and identify accessible test locations for on-site inspections;
  2. Performing on-site ultrasonic thickness (UT) measurements of tube wall thickness and bore oxide scale considering ~40% of total tubes for FSOH & for ROH;
  3. Performing on-site replication and hardness measurements on straight tubes, T-piece nozzle weldments, stub tube weldments and hot reheat pipe weldment for FSOH & ROH;
  4. Assessment of all replicas by using OM (optical microscope) and to confirm the damage condition, further assessment of selected P/T/F91 & T23 replicas by using SEM (Scanning Electron Microscope) and if necessary, to confirm the damage condition, further assessment of selected P/T/F91 replicas by using ETD’s SFM (Scanning Force Microscope) at ETD lab;
  5. Assessment of damage and material degradation of outlet headers, tubes, T-piece nozzle weldments, stub tube weldments and hot reheat pipe weldments for FSOH & ROH based on the replication and hardness measurements data;
  6. Review & interpretation of UT inspection data and estimation of wall thickness loss & tube metal temperature;
  7. Assessment of the remaining life of FSOH & ROH components based on estimated tube metal temperature and other inspection data;
  8. Review & analysis of previous failures, inspection and maintenance data for other pressure parts of the boiler to complete the life assessment study;
  9. Preparing a full report including results of on-site inspections, analysis results of damage & life assessment study and make recommendations for any further actions to be taken for safe and reliable operation of the boiler.

 For more information on our remaining life assessment services, please click here.

Launch of a new Group Sponsored Project on Aberrant P91 Inspection, Repair and Life Extension

ETD Proposal No: 1558-gsp-prop17

To read the GSP Outline please click on the Proposal Image.

ETD has launched a new proposal for a Group Sponsored Project. The proposal is entitled 'Early Stage Damage Inspection, Repair & Life Extension of Aberrant P91 Components'. This newly launched proposal is aimed at testing some of the NDE techniques, tried and established in the earlier project, on the P91 aberrant microstructures, It is also looking at testing some newer NDE techniques developed since the start of the earlier project, and, also look at new ideas and technologies for the strengthening and life extension of P91 components which have either developed creep damage or contain aberrant microstructures.

As this is a Group Sponsored Project (GSP) costs are shared between a number of sponsors so each pays only a fraction of the total project cost. 

If you would like to obtain the full proposal or would like to discuss this Group Sponsored Project in more detail, please don't hesitate to contact us

Recent Completed Project on ‘Risk Based Inspection and Remaining Life Assessment of a Boiler for an Asian Power Plant’

ETD were approached to submit a proposal on ‘Risk Based Inspection (RBI) and Remaining Life Assessment (RLA) of one of the client’s boilers by performing on-site inspection, analysis and assessment on tubes, T-piece nozzles, stub tube weldments and hot reheat pipe weldment for FSOH and ROH.

The work involved performing on-site inspections - ultrasonic measurements (UT) of tube wall & bore oxide scale thickness, replication, hardness measurement, wet fluorescent magnetic particle test and advance UT phased array of selected components from FSOH and ROH. The inspection data was then used to estimate tube metal temperature and identify material degradation. This was then used for damage assessment and predicting the remaining life of outlet headers and tubes of final superheater and reheater. The previous inspection and maintenance data for other pressure parts (i.e. economiser, etc) were also reviewed and analysed to complete remaining life assessment of the boiler.

For more information about ETD’s Remaining Life Assessment services, please click here.