Cracking of Heavy Wall Steam Separators During Fabrication: An Investigation

2012 ◽  
Author(s):  
Dilip Kumar ◽  
Luis Ganhao
Keyword(s):  
Cross Section ◽  
High Hardness ◽  
Radiographic Testing ◽  
Weld Defect ◽  
Section Viii ◽  
Carbon Arc ◽  
Recent Project ◽  
Weld Area ◽  
Non Destructive

On a recent project, four high pressure steam separator vessels were received from overseas after fabrication. There was suspicion on the quality of fabrication when non destructive examination (NDE) reports were reviewed. There were major concerns with the quality of radiographic films as they did not meet the ASMe Section VIII Div. 1 Code requirements as well as client specifications. Subsequent examination of welds using radiographic testing (RT) revealed crack-like features around nozzles in the region adjoining (but outside) the weld metal. Macro etching at the surface around nozzles showed that the weld area was extended beyond the apparent weld/base metal interface. Further examination of a cross section cut out from one vessel nozzle confirmed the initial doubts that weld repairs had been performed that were not reported. Metallography of the cross section indicated evidence of significant cracking associated with carbon contamination and very high hardness (up to 365 HV; in one particular case 609 HV) in affected areas. This was believed to be due to improper and incomplete cleaning by grinding after performing carbon arc or, flame gouging to remove a weld defect. Further detailed NDE was carried out using advanced ultrasonic testing (UT), i.e. phased array UT and time of flight diffraction (TOFD) and all defects (many new that were undetected by RT) were repaired per ASME Section VIII Div. 1 Code and client specification. This experience was a lesson for the design office and helped make a decision to be much more vigilant and to ask for greater quality surveillance on overseas fabrication of critical equipment for all future projects. The paper discusses the detailed investigation as well as findings.

Digital Radiographic Image Enhancement for Weld Defect Detection using Smoothing and Morphological Transformations

2012 ◽  
Vol 9 (1) ◽  
pp. 15
Author(s):  
Suhaila Abdul Halim ◽  
Arsmah Ibrahim ◽  
Yupiter Harangan Prasada Manurung
Keyword(s):  
Defect Detection ◽  
Test Method ◽  
Radiographic Image ◽  
Radiographic Image Enhancement ◽  
Radiographic Images ◽  
Weld Defect ◽  
Different Types ◽  
Morphological Transformations ◽  
Non Destructive

Accurate inspection of welded materials is important in relation to achieve acceptable standards. Radiography, a non-destructive test method, is commonly used to evaluate the internal condition of a material with respect to defect detection. The presence of noise in low resolution of radiographic images significantly complicates analysis; therefore attaining higher quality radiographic images makes defect detection more readily achievable. This paper presents a study pertaining to the quality enhancement of radiographic images with respect to different types of defects. A series of digital radiographic weld flaw images were smoothed using multiple smoothing techniques to remove inherent noise followed by top and bottom hat morphological transformations. Image quality was evaluated quantitatively with respect to SNR, PSNR and MAE. The results indicate that smoothing enhances the quality of radiographic images, thereby promoting defect detection with the respect to original radiographic images. 

Weld defect inspection based on machine vision and weak magnetic technology

2021 ◽  
Vol 63 (9) ◽  
pp. 547-553
Author(s):  
Jing Ye ◽  
Guisuo Xia ◽  
Fang Liu ◽  
Ping Fu ◽  
Qiangqiang Cheng
Keyword(s):  
Machine Vision ◽  
Average Height ◽  
Defect Inspection ◽  
Welding Seam ◽  
Inspection Method ◽  
Weld Formation ◽  
Weld Defect ◽  
Inspection Process ◽  
Weld Area

This study proposes a weld defect inspection method based on a combination of machine vision and weak magnetic technology to inspect the quality of weld formation comprehensively. In accordance with the principle of laser triangulation, surface information about the weldment is obtained, the weld area is extracted using mutation characteristics of the weld edge and an algorithm for identifying defects with abnormal average height in the weld surface is proposed. Subsequently, a welding seam inspection process is developed and implemented, which is composed of a camera, a structured light sensor, a magnetic sensor and a motion control system. Inspection results from an austenitic stainless steel weldment show that the method combining machine vision and magnetism can identify defect locations accurately. Comprehensive analysis of the test results can effectively classify surface and internal defects, estimate the equivalent sizes of defects and evaluate the quality of weld formation in multiple dimensions.

RADIOGRAPHIC TESTING BY COMPUTED RADIOGRAPHY (RT-CR) OF THE HELIUM INLET WELDS (HI) OF THE POLOIDAL FIELD COIL (PF1), PRODUCED BY JSC NIIEFA (SCIENTIFIC RESEARCH INSTITUTE OF ELECTROPHYSICAL APPARATUS) WITHIN THE FRAMEWORK OF THE INTERNATIONAL THERMONUCLEAR EXPERIMENTAL REACTOR (ITER) PROJECT

2019 ◽  
pp. 38-43
Author(s):  
K. A. Bagaev ◽  
T. M. Gurieva ◽  
A. A. Mednikov ◽  
I. Yu. Rodin ◽  
I. V. Sokolov
Keyword(s):  
Computed Radiography ◽  
Non Destructive Testing ◽  
Poloidal Field ◽  
Destructive Testing ◽  
Radiographic Testing ◽  
Imaging Plates ◽  
Non Destructive ◽  
Weld Seams ◽  
Iter Project

The manufacturing and non-destructive testing of the superconducting poloidal coil PF1 is one of the tasks of NIIEFA, the member of the international ITER project. Radiographic films were traditionally used for the purposes of radiation non-destructive testing. The technology of computed radiography was used to substitute films. It improved the quality of testing and increased productivity. Comparisons of testing results were carried out using films and imaging plates. The “Test Measurement for Qualification of Computed Radiography method for HI PF1 Weld Seams testing” was developed. It allowed to do testing using imaging plates without installing a duplex wire indicator. Compliance with the standards requirements for unsharpness is confirmed using certified specimens.

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