Abstract: The present disclosure provides a method for calculating wellbore friction resistance of a foam drainage gas production well. It is based on the conversion of the parameters of the gas-liquid two-phase flow Mukherjee & Brill model, it defines the liquid film reversal point as the zero friction resistance point, ignores the influence of the negative value of friction resistance, and uses this as a starting point to predict the change of friction resistance. The influence of liquid phase parameters and foaming agent concentration is taken into account in the friction resistance coefficient. An effective calculation method is obtained by combining the experimental data fitting and optimization. The present disclosure better characterizes the wellbore flow condition of the foam drainage gas production well, and provides important theoretical support for the prediction of the wellbore pressure drop of the foam drainage gas production well.

Abstract: A semi-closed local low-vacuum laser welding device and welding method is provided. The semi-closed local low-vacuum laser welding device includes a local low-vacuum cabin, a dynamic sealing structure, a mechanical pump, and a laser welding mechanism. The local low-vacuum cabin includes a primary vacuum chamber, a secondary vacuum chamber and a tertiary vacuum chamber which are arranged in sequence, and a plate to be welded is arranged at a bottom of the primary vacuum chamber. The dynamic sealing structure is arranged at the bottom of the primary vacuum chamber, and the dynamic sealing structure is configured for connecting the primary vacuum chamber with the plate to be welded. The mechanical pump is in communication with the primary vacuum chamber and the secondary vacuum chamber. The laser welding mechanism is arranged corresponding to the local low-vacuum cabin, and is configured for welding the plate to be welded.

Abstract: Disclosed are a narrow gap laser-TIG arc hybrid welding apparatus and method. The welding apparatus includes a welding gun body, a swing welding gun assembly, a welding wire feeding and heating assembly, and a gas conveying assembly; the swing welding gun assembly includes a welding gun rotating shaft, a stepper motor, a large gear, a pinion, an upper insulating sleeve, a lower insulating sleeve, a tungsten electrode clamp, and a tungsten electrode; the stepper motor is mounted on a motor connection seat; the pinion is mounted on the output shaft of the stepper motor; the large gear is mounted on the welding gun rotating shaft; the pinion is engaged with the large gear; the welding gun rotating shaft is mounted and positioned on the welding gun body; the tungsten electrode is mounted at the tail end of the welding gun rotating shaft by means of the tungsten electrode clamp.

Abstract: Disclosed are a flux-cored welding strip and a welding flux used in combination for submerged arc welding of a duplex stainless steel, and preparation methods and use thereof. The flux-cored welding strip is composed of a stainless steel shell and a flux core powder, the flux core powder consisting of the following components: in percentages by mass, ferrochrome nitride: 0.70% to 1.0%, a chromium powder: 26% to 27%, a nickel powder: 4.5% to 5.5%, a molybdenum powder: 3.7% to 4.2%, a manganese powder: 2.55% to 2.65%, a copper powder: 1.45% to 1.55%, a ferrosilicon powder: 1.1% to 1.2%, a tungsten powder: 1.0% to 1.15%, a niobium powder: 0.25% to 0.35%, an aluminum powder: 0.35% to 0.55%, a rhenium powder: 0.35% to 0.40%, a lanthanum powder: 0.1% to 0.15%, and a balance being an iron powder.