In a trial peening step, a shot peening process is applied to a back face 40B of a mold 40 in which an opening of a closed-end water cooling hole 42 is formed. Next, in an evaluation step, compressive residual stress and surface roughness of a region shot-peened in the trial peening step are measured and an extent of shot peening treatment in the trial peening step is evaluated based on measurement results. Next, in a peening step, a surface of the water cooling hole 42 in the mold 40 is shot-peened under peening conditions set based on peening conditions for the trial peening step and on evaluation results produced in the evaluation step.

For the shot peening of a pipe inner wall of a curved workpiece (200) having a workpiece bore (201), use is made of a flexible blasting abrasive feed hose (10) having blasting nozzle head (20). The latter is guided through a supporting element (30) which is applied to one workpiece end (203). The blasting abrasive feed hose (10) together with the blasting nozzle head (20) is introduced into the workpiece bore (201) and advanced along a blasting treatment section therein, and subsequently retracted into the supporting element (30) again. The blasting abrasive is emitted during the advancing movement and/or during the retraction movement. A blasting nozzle unit (100) suitable for carrying out the method comprises a flexible blasting abrasive feed hose (10) and a blasting nozzle head (20) connected to the blasting abrasive feed hose (10). The blasting nozzle head (20) has a plurality of nozzle openings (21) distributed around the circumference. The outer circumference of the blasting nozzle head (21) is smaller than the inside diameter of the workpiece bore (201) in a workpiece (200) to be processed. The blasting abrasive feed hose (10) is guided in a supporting element (30) and this element (30) is guided in a displaceable manner in a stationary bearing element (40).

This relates to a method for manufacturing a lens element including: a refraction area having first curvature; a plurality of optical elements located on at least part of the refraction area, wherein the method includes a step of using an abrasive-filled fluid jet to manufacture the lens element.

A pipe-cutting tool, which can be independently pumped down to cut a wellbore pipe or casing, is disclosed. When the tool is lowered into the wellbore, a pump down ring, included in the tool, remains flush with the inner surface of the pipe. To power the tool's descent, high-pressure fluid is pumped into the wellbore. On reaching the target location, a swellable sleeve included in the tool, on being exposed to fluid in the wellbore, expands to push against the inner surface of the pipe, lodges the tool at the location, and seals any fluid flow path bypassing the tool. Thereafter, high-pressure abrasive fluid is pumped through the tool to eject in the form of high-pressure abrasive fluid jets, which cut through the wellbore pipe at the target location.

This application relates to the technical field of coal-fired boilers, and provides a method and an apparatus for improving steam oxidation resistance of a small-diameter boiler tube in a coal-fired boiler. The method includes the following steps: cutting a boiler tube panel from a ceiling of the boiler, vertically hoisting and fixing the boiler tube panel, and cutting out a section from a bottom portion of a lower bend of the boiler tube panel; cleaning an inner tube wall of each tube body in the boiler tube panel; performing oxidation resistance coating sintering on the inner tube wall of each tube body in the boiler tube panel; and performing a welding repair on each tube body in a sintered boiler tube panel. All construction processes of this method can be completed in a furnace during shutdown and maintenance, production efficiency is high, and maintenance duration can be significantly reduced. In addition, a steam oxidation resistance layer can be formed on an inner wall of the small-diameter boiler tube, so that a steam oxidation resistance capability of a small-diameter boiler tube in a service coal-fired boiler can be greatly improved.