Experimental results show that the acoustic emission technique can effectively detect heavy weld active flaws and the accurate size and location of flaws can be measured by the ultrasonic phased array technique.

Laser welding volume energy and its influence on weld penetration in laser deep penetration welding;

Activating TIG welding (A - TIG) can greatly improve the weld penetration and thus enhance the process efficiency in comparison with the conventional TIG welding.

The article analysed and described in detail the TOFD technology for thick-wall weld of thermal walled-hydrogenation reactors,and has a certain guiding significance.

The result shows that the ring weld has weld defects and under alternating stress it will crack,which will finally cause breaking of the urea synthetic tower.

Effect of simulated welding parameters on pipe girth weld residual stresses;

In order know the size and the distribution of residual stresses of mill welding seam,this paper uses blind-hole method to test the girth welds between round plate and the cylinder body of the mill produced by CBMI CONSTRUCTION CO.

The mechanical properties testing and metallography testing of girth welded joints were carried out.

Ductile tearing assessment of surface flaw in circumferential weld of pipe-line based on J integral parameter;

This paper consider the influences of materials,stress,process and diffusion hydrogen etc on the circumferential weld cracks in steel cylinders,analyzes the microstruture and fracture appearance by scanning electron microscope and metallography microscope,and finds out the main reasons why cracks emerge and also the prevention measures.

In order to solve this problem , "automatic welding system for circumferential weld of large diameter penstock" is especially developed .