OBJECTIVES To study the airway response and its mechanism to welding fumes in six welders with respiratory symptoms. METHODS Methacholine and welding challenge tests were carried out. The concentration of welding fumes during the exposure test was measured. On two subjects who developed bronchoconstricition to welding challenge, additional tests were carried out including prick, patch, and in...

In the first European Community Respiratory Health Survey (ECRHS I), an excess asthma risk was associated with high exposure to gases and fumes, mineral and biological dusts. In a 9-year follow-up study (ECRHS II), the aim was to study if welding at work increases the risk of asthma symptoms, wheeze and chronic bronchitis symptoms. The study also aimed to identify specific welding risk factors....

Hydrogen enrichment induced by pipeline welding residual stress is a key issue affecting the safe service of hydrogen pipelines. In order to explore influence on diffusion and effect heat treatment, an X80 model with six-layer girth weld was established using ABAQUS software, coupling analysis temperature field, carried out. The distribution in area local inclusion analyzed, relationship betwee...

For an arbitrary (3,L) QC-LDPC code with a girth of twelve, a tight lower bound of the consecutive lengths is proposed. For an arbitrary length above the bound the resultant code necessarily has a girth of twelve, and for the length meeting the bound, the corresponding code inevitably has a girth smaller than twelve. The conclusion can play an important role in the proofs of the existence of la...

Laser beam welding is becoming widely used in many industrial applications. This paper reviews recent research conducted on the performance, potential and problems of thick section butt joint laser welding. Common defects that occur in laser beam welding with high power laser welding are discussed and possible solutions proposed. Methods of welding process efficiency improvement are analyzed.

Graph G is the square of graph H if two vertices x, y have an edge in G if and only if x, y are of distance at most two in H . Given H it is easy to compute its square H, however Motwani and Sudan proved that it is NP-complete to determine if a given graph G is the square of some graph H (of girth 3). In this paper we consider the characterization and recognition problems of graphs that are squ...

For the long-term service of X65/Incoloy 825 bimetallic composite pipe girth welds in H 2 S environment, corrosion damage behavior was investigated. Characterizations welded joints were conducted by OM, SEM, XRD, and EDS. The pitting corrosion’s 3D surface morphology NACE-B solution saturated with results show that composition segregation occurs welding process, Laves phase appears between dend...

1 ATE-80212044©Asian-Transactions September 2012 Study the Effect of Welding Joint Location on the Fatigue Strength and Fatigue Life for Steel Weldment Dr.Ali Sadiq Yasir Kufa University / Faculty of Engineering Mechanical Engineering Department IRAQ E-mail:[email protected] / [email protected] Abstract: The welding process is one of the oldest joining processes between the ma...

Abstract The gas tungsten arc welding process is an uncertain nonlinear multivariable system. In order to control the welding process, the nonlinear dynamic relationship between the weld pool geometry reflecting the weld quality and the welding parameters must be developed. A three-dimensional numerical model is developed to investigate the dynamic characteristics of the weld pool geometry when...

Laser welding has been widely used in various industry fields. In order to further alter and broaden its applicability, a novel technology of laser welding under vacuum is introduced. The combination of high power laser and low ambient pressure provides an excellent welding performance and quality. In this paper, an overview on laser welding under vacuum is presented. It begins with a short int...