Specified Minimum Yield Strength

Abstract: In recent decades, the ductility and weldability of structural steels has improved considerably. Also, the developments in modern welding technology have led to a decrease in the fabrication costs of steel structures, especially when higher strength steels are used. This has created new opportunities for more economical applications of steel in the construction industry. The choice of higher strength steels has become increasingly attractive, eg grade S355 (specified minimum yield strength 355 N/mm2) instead of S235 or S275, or grade S460 instead of S355. This review surveys the possibilities for the cost-effective application of high strength steels in buildings, bridges, cranes, etc. Some developments in research and drafting of codes are also highlighted. The review focuses mainly on developments in Europe, but in other parts of the world, such as Japan and the USA, similar trends can be observed.

Abstract: A new high-strength steel with a specified minimum yield strength of 120 ksi has been developed for linepipe applications Because existing specifications were not originally intended for the X120, and no service experience exists for this grade, fullsize pipe tests and finite element analyses were conducted to evaluate structural performance The full-size testing included burst, pure bending, collapse, bending + collapse, ring expansion, curved wide plate and crack arrest tests In addition to these tests, bending trials were performed on the X120 using commercial pipeline construction equipment to verify cold deformability This paper presents the burst and fracture arrest studies Results from burst tests and analyses demonstrate sufficient pressure containment capacity For crack arrest, full-size tests were conducted to evaluate the intrinsic arrestability of the material and the effectiveness of crack arrestors Although the X120 pipe did not have sufficient toughness for intrinsic arrest for the prescribed test conditions, tight-fitting sleeve crack arrestors were shown to be effective in stopping propagating fractures

Abstract: Hydrostatic testing is one method to confirm the integrity of pipelines containing colonies of stress corrosion cracks. Although this technique is widely used, a concern of the pipeline industry is the potential for ductile tearing damage of subcritical flaws. Objectives of the current study were to evaluate the influence of hydrostatic testing on the crack tip morphology and to determine the amount of ductile tearing that may occur for different hydrostatic testing conditions. Stress corrosion cracks were grown in compact tension specimens of X-65 line pipe steel in a near-neutral-pH stress corrosion cracking (SCC) environment. Simulated hydrostatic tests were performed at loads that corresponded to hoop stresses at and above the specified minimum yield strength (SMYS), resulting in applied J-integral values near to and above the J(Q) fracture toughness value of the material. Some specimens ruptured; some did not fail. Crack tip blunting occurred and the tearing extent was small and proportional...