THE CORROSION BEHAVIOR OF WELDED LINE PIPES IN WET H 2 S ENVIRONMENT

ABSTRACT The corrosion behavior of over-bending and under-bending formed Spiral Submerged Arc Welded (SSAW) steel pipes in NACE solution has been investigated by use of the selfdesigned full-scale corrosion test unit. It indicates that the H 2 S damage of welded pipes characteristics Blister and Stress Corrosion Cracking (SCC). The blister number, diameter, and crack number is increasing as the increasing of applied stress. The residual stress of welded pipes has a large effect on the H 2 S corrosion resistance, the tensile residual stress has a detrimental effect, and while the compression residual stress is beneficial to H 2 S corrosion resistance. The damage mechanism of the welded pipes in H 2 S containing solution under the presence of applied stress and residual stress has not only Hydrogen Induced Cracking (HIC), but also Stress Corrosion Cracking, and the applied stress and residual stress promote not only Stress Corrosion Cracking, but also Hydrogen Induced Cracking. The test results reveal that improving pipe's weld surface quality, lowering tensile residual stress, and also control the operating stress are the key measures for controlling the wet H 2 S corrosion of welded steel pipes. Suggestions for selection of line pipes in different service conditions have been made

IPC02-27155 DEVELOPMENT OF LARGE DIAMETER X70 HIGH TOUGHNESS HSAW LINEPIPE FOR GAS TRANSMMISION

ABSTRACT X70 large diameter linepipe with helical seam SAW were developed, with1016mm OD and 14.6mm WT. Acicular ferrite type linepipe steel is adopted for the base material, which was found having high toughness and low yield strength loss after pipe forming. The very stringent requirements for toughness, i.e. 190J/140J for average/minimum for pipe body and 120J/90J for average/minimum for weld and HAZ were meet successfully. The yield strength loss due to Bauschinger effect was found lower than 20 MPa, which benefited

Comparison and Analysis on Specification of X80 Line Pipe for 2nd West-East Gas Transmission Pipeline Project

Specification of X80 line pipe for 2nd West-East Gas Transmission Pipeline Project has referenced in context to the latest edition of international standards like ISO 3183 and API Spec 5L. Some complementarities have been made to achieve the balance between the safety and economy of the high-pressure gas transmission system, such as in the chemical content, tensile strength, arrest toughness, etc. The line pipe specification was analyzed combining with the properties of the practically manufactured pipe in this paper. It’s shown that the pipe manufactures have established the steel design process for X80 pipes and the pipeline designers have been developing the design method of high-pressure gas pipelines with X80 line pipe. As the collaboration between the pipe manufactures and pipeline designers, X80 line pipes are applicable in 2nd West-East Gas Transmission Pipeline Project commercially.</jats:p

STUDY ON THE MISMATCHED GIRTH WELDS OF X80 LINEPIPES

ABSTRACT X80 linepipes are going to be widely used for gas transmission pipelines in China. The welding procedure for girth weld is very critical to the safety of the X80 pipeline. In The level of mismatch shouldn&apos;t be too high because too much weld seam strength will not only be a way of waste, but also decrease weld resistance to HIC cracks