employs the full wall/plate thickness of the weld joint for specimens. Charpy V-Notch and CTOD fracture toughness information is available by means of weld codes/standards and ASTM E23 (Ref. 3), ASTM A370 (Ref. 4), and ASTM E1820 (Ref. 5). Hardness, Hardenability, and Hydrogen-Induced Cracking In the utilization of carbon and low-alloy steels in cold climate regions and/or when materials are utilized in a H2S sour service environment, weld deposit/heat-affected zone (HAZ) cracking is a major concern. More specifically, the steels are at risk of hydrogen induced cracking (HIC), which is also referred to as “hydrogen-assisted A B cracking” (HAC) or “cold cracking.” For HIC to occur, three conditions must be satisfied simultaneously, the availability of 1) a susceptible microstructure; 2) tensile stress acting upon the weld; and 3) hydrogen in the weld. A susceptible microstructure exhibits hardness and hardenability traits. That is, as the alloying content increases and/or as the carbon content increases, the hardenability of the weld deposit/HAZ increases. Material hardness and hardenability both increase as the carbon content increases. Hardness is inversely proportional to weldability, whereby, the potential for HIC increases as the weld deposit/ HAZ hardness and hardenability in- Project Materials 74 WELDING JOURNAL / JUNE 2016 Fig. 3 — A — 48-in.-diameter flange spool tie-in weld; B — pipe welding in a snow trench. Pipeline and pipework fabrication involves utilizing a range of pipe sizes from 1 to 60 in. of various wall thicknesses, ranging from Schedule 10 to 160, including API 5L (Ref. A) Grades X52, X60, and X65; ASTM A333 Grade 6; and ASTM A335 chromiummolybdenum alloys: Grades P5, P9, P11, P22, and P91. In addition, pipe alloys consisting of duplex stainless steels (i.e., 2205, 2507), austenitic stainless steels (e.g., TP 304L, TP 316L, and copper-nickel (i.e., 90/10) are employed. Materials for oilfield well construction comprise: API 5CT (Ref. B) Grades L80, N80, J55, K55, and P110. Structural frames, pipe supports, and oil storage tanks encompass carbon and lowalloy steel structural shapes and plate: ASTM A1011, A516, A633, A36, and A572.
Welding Journal | June 2016
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