Four low carbon steels with different Cr and Cu concentrations were prepared to investigate the effect of alloying elements on their corrosion behavior in 3.5% NaCl solution diluted hydrochloric acid and dilute sulphuric acid (pH=1.4-1.5) respectively. Electrochemical measurement and immersion test at room temperature characterized the corrosion behavior and evaluated the corrosion rate.
To investigate the role of Cr and Cu in steels in different solutions, four kinds of low carbon steel with different Cr and Cu concentrations were prepared to investigate the effect of alloying elements on their corrosion behavior. Solutions of 3.5 wt.% NaCl, diluted hydrochloric acid and diluted sulphuric acid (pH=1.4-1.5) were used.
A quantitative assessment of remnant cold deformation and effectiveness of post deformation treatment (PDT) on sour resistance and mechanical properties of a C110 grade by reproducing uniform deformation with tensile/compressive tests followed by heating/soaking/cooling cycles representing induction PDT
High-strength low-alloy steel bar stocks with 110ksi (758MPa) and 125ksi (862MPa) specified minimum yield strength (SMYS) are in demand for temporary and permanent downhole tools for sour service. NACE MR0175/ISO15156 currently allows the use of low-alloy steel bar stocks without any environmental restrictions up to 22HRC, which, by most specifications, corresponds to 80ksi (552MPa) SMYS. At higher SMYS, and with exclusions of API and proprietary sour tubular grades, NACE MR0175/ISO15156 does not address solid bar stocks, a gap and opportunity addressed by this investigation. Specifically, in this paper, the sulfide-stress cracking (SSC) of commercial UNS G41xxx (41xx) alloys, including 41xxMod (i.e., carefully selected or mill modified) is investigated following a series of NACE TM0177 Method A tests in either Solution B or A (NACE Region 3). Domain diagrams for 41xx alloys are disclosed, all demonstrating that 41xx solid bar stocks are SSC resistant above 150°F (66°C) when under a new and improved specification. When SMYS is raised to 125ksi (862MPa) with 34HRC max, a safe minimum temperature of 175°F (79.5°C) is confirmed for hollow bars, well in line with current NACE MR0175/ISO15156. The metallurgical and hardness requirements of 41xx alloys are also briefly discussed, along with opportunities for further modifications of 41xx bar stocks.
This paper details with the unexpected cracking encountered in the outlet nozzles of all three reactors for Platformer unit, during a scheduled shutdown. The unit was commissioned in 1957 and the reactors metallurgy is as per withdrawn ASTM standard, A301 Gr. B (1Cr-1/2Mo). The isolated cracks were located at the upstream edge of the inset nozzle and running vertically down. The cracking in the high-pressure fixed bed reactor outlet nozzles was successfully repaired in-situ. This paper reviews the circumstances which led to these failures and highlights the lessons learned from each failure.
Proper design and fabrication, heat treatment and inspection practices play a vital role in achieving good quality and performance of low alloy steel piping. These materials have narrower fabrication windows as the alloy content goes up and non-adherence to correct execution practices may lead to leakage by delayed hydrogen cracking, stress corrosion cracking or fatigue resulting in unplanned shutdowns and costly repairs.
This paper describes details about strengths and weaknesses of support design and fabrication practices for such attachment welds. The paper discusses various precautions to be taken during the design and fabrication stages for low alloy steel supports attachment welds. It will discuss heat treatment cycles viz. preheat, interpass, dehydrogenation treatment (post heating) and post weld heat treatment (PWHT). The control of consumables, welding environment conditions, and the weld heating cycle is essential to prevent hydrogen assisted cold cracking in high hardness microstructures in weld and HAZ, and for achieving successful relief of residual welding stresses.