Problems of weld overlay of seating surfaces of pipe fitting and solutions

Introduction. A problem of providing the necessary functions of pipe fitting for blockage, control, distribution of the working medium flows under the most adverse operating conditions of oil and gas pipelines associated with abrasive particles, mechanical impurities, hydrogen sulfide, carbon dioxide and organic acids with sulfate-reducing bacteria, is considered.Materials and Methods. High performance properties of seating surfaces of pipe fittings are provided through anticorrosive plating of alloyed and high-alloyed metals based on iron with the addition of chromium, nickel, cobalt and niobium. The basic weld overlay methods are analyzed: metalarc welding, nonconsumable and consumable-electrode weld facing in shielding gases, submerged arc surfacing. Advantages and disadvantages of surfacing methods implemented in recent years are noted: laser, plasma-powder and plasma-arc methods.Research Results. Taking into account the automation capabilities, a high-tech process of robotic anticorrosive surfacing using a consumable electrode with an additional filler metal feed to the front welding puddle for shielding the thermal effect of the arc, is proposed...