Bids Are Invited For Custom Bid for Services - PHASED ARRAY ULTRASONIC TESTING PAUT for Tube Weld Joints of BOILER Unit 8 during Overhauling - CONSULTANCY_ SERVICES_PAUT - PHASED ARRAY ULTRASONIC TESTING OF TUBE WELD JOINTS OF BOILER DURING OVERHAULING OF UNIT#8 CTPS. SCOPE OF WORK: (A) JOB DESCRIPTION: Phased Array Ultrasonic Testing of Tube Weld Joints of Boiler at CTPS UNIT 7&8. 1. Phased Array Ultrasonic Testing for circumferential weld joint inspection of Boiler Tubes (Waterwall, Super heater, Reheater, Economiser, LTSH & other zones as identified by EIC) is to be carried out for assessment of the weld joints. For old waterwall tubes covered by insulation, only portion of weld on fireside will be tested with probes/wedges dismantled from the scanner. 2. The agency has to quote for each weld joint to be inspected. For mobilization during overhaul, separate charges shall be paid for mobilization during each visit. 3. No extra payment shall be made for tube sample calibration, testing of reference tubes or inspection on any other tube pieces (on sample basis) with known defects for verification of reliability of test set up. 4. For reliability of calibration, 5% of the test results of PAUT in each type of tube dimension and thickness will be cross checked by DVC through radiography. If any defect is observed in radiography and same is not observed in PAUT M/c, Calibration & test set up of PAUT M/c are needed to be rechecked and PAUT to be repeated. However, defect noticed in PAUT but not detected in radiography will be treated as defect. 5. PAUT TEST SYSTEM: For PAUT inspection of boiler tubes, service provider agency has to bring the PAUT equipment & accessories with following or higher capability: a) PAUT Equipment: 16:68 or higher configuration having i. Weld Inspection features including setting up of weld profile. ii. Multi Grouping Capability. iii. Capability of using two PAUT probes simultaneously. Necessary adapter/splitter (if required) for attaching two probes for simultaneous working should be available for inspection. iv. Operation with battery. v. A-Scan, B-Scan, C-Scan, S-Scan, Linear Scan, Sectorial Scan vi. Calibration: Velocity, Wedge Delay, Sensitivity, TCG, DAC, Encoder Calibration features. vii. Data Analysis and Report Building. viii. Encoder Recognition. b) Probes: At-least two numbers of low profile suitable PAUT probes for (MS and Alloy Steel) of 7.5 – 10.0 MHz frequency, 16-32 element with more than 2 meters of cable length. The probes shall have couplant supply mechanism for passage of couplant (water to be used in this case) to test surface. A water irrigation channel along with water storage container & pressure mechanism for providing continuous couplant (water) to the probe during testing. Suitable probe for SS will be required for inspection of SS Joints. c) Wedges: Specially designed wedges to fit in the above probes and having refractive angle of 50 to 60-degree shear wave in steel. Wedges should have suitable contour to fit with around 25-100 mm OD of boiler tubes. d) Scanner: A manual/automated scanner capable for scanning of around 25-100 mm OD of boiler tubes. The scanner shall have encoder with it for precise data acquisition. The scanner shall be able to hold two low profile phased array probes and wedges, as mentioned above for complete inspection of the weld in one rotation of the scanner. The design of scanner, probe and wedges shall allow complete inspection of circumferential weld on tube having minimum spacing of 15 mm with any adjacent tubes, support and structures etc. 6. Manpower: Inspection/service provider agency shall depute two persons with minimum UT Level-II qualification/certification from PCN, CSWIP, ASNT, ISNT. Also at least one person should have sufficient training in PAUT for operation, data analysis and interpretation of signal/data acquired. The necessary document/ certificate in support of the above requirements are to be produced to station. Interpretation of certain number of joints is to be carried out immediately after scanning & report to be given so that there shall not be any delay in work execution. The final comprehensive report shall be handed over after completion of total joints. In case repeated wrong interpretation by the deputed expert is detected during the course of work, the firm has to provide alternate substitute expert having desired qualification within two days. 7. Test Plan: a) The agency shall submit the written inspection procedure for PAUT of boiler tube weld joints. Scan Plan (linear/sectorial) shall cover the entire volume of the weld for inspection and should mention parameters like thickness, OD, Index Offset, Weld Profile, Probe, Wedge, Scan Angles etc. There shall be minimum one sectorial scan for one probe. Total minimum two groups for two probes, positioned at 90 & 270 degree. Angle step shall be 0.5 degree. b) Calibration: Velocity, Wedge Delay, Sensitivity, TCG, Encoder Calibration shall be performed before inspection. Reference block: Tubes with similar diameter & wall thickness (within 10%) and circumferential notches/grooves (detailed below) shall be used as reference block. The reference block should have length not less than 200 mm. It should have two circumferential grooves/notches (one each on ID & OD) having depth of 10% wall thickness. 1 to 1.5 mm width and length between 25 to 50 mm. These two grooves should be located at opposite ends of the tube. The notches should be separated from adjacent tube edge by about 50 mm. The length of reference block and location of reflectors (notches/grooves) should comply the requirement of calibration for angle beams. c) The agency shall be provided with tube samples in advance so that calibration of machine work can be completed before start of overhauling. The tube samples are to be returned to DVC and kept in safe custody by DVC for future reference. d) Data Storage: The calibration data and inspection data should be stored in the equipment and should be available for verification by DVC Personnel. Inspection data file is to be stored by giving identifiable marking for reporting and inspection. Soft copy of all the data & interpretation to be provided on daily basis to DVC on next day of scanning. e) Test Results: The test results for each tested tube should provide information on type of defects (i.e. - lack of penetration, porosity, lack of fusion etc), their location, length, height, depth etc. The final report with above information to be given in an excel sheet along with PAUT inspection data file & images for all the tested tubes. f) Surface Preparation & Access to Test Area: DVC shall provide suitable arrangement (scaffolding etc) for safe access to test locations. Also surface cleaning/buffing on weld regions of tube, lighting (hand lamps etc as required) would be in the scope of DVC. g) The dimensions of the boiler tubes to be tested by PAUT is from OD 44.5 mm to 76.1 mm and the thickness range varies from 4.5 to 10.0 mm. The material is carbon steel, alloy steel and SS 347. The firm has to arrange all necessary probes for completing the job. h) Representatives of DVC will be allowed to check the test set-up, examine the test procedure and the test results. i) The agency has to abide all the safety regulations of DVC without any exception. 1. PAUT PAUT FOR BUTT WELD BOILER TUBE JOINTS 2. Travelling Charges Travelling Charges from vendor site to CTPS & back Total Quantity :
