Investigation of welded joints of long-term operated gas pipeline controllable rolled X70 steel

The complex properties (mechanical, microstructure, and electrochemical) of controllable rolling X70 steel pipes of the main gas pipeline with a diameter of 1420 mm after an operation for 20 years and emergency reserve pipe after a similar period of storage were studied. Taking into account specified heterogeneity caused by the technological effect on X70 steel of controllable rolling, it is difficult to draw unequivocal conclusions about the effect of operational work on changes in the condition of welded joints of investigated pipes. It was established that operating loads did not significantly affect the characteristics of base metal and welded joints. Electrochemical properties (corrosion potential, hydrogen recovery potential, anodic curves slopes) of long-term operated pipes of different manufacturers (Ukraine, France) and stock pipes in NS4 solution are similar. Due to the high reserve of impact viscosity at standard temperature conditions, investigated pipes are characterized by satisfactory resistance against breaking

Improvement of the Installation with an Extended Barrel of Cranked Type Used for Fire Extinguishing by Gel-forming Compositions

Extinguishing fires with gel-forming compositions was found to be a promising direction of increasing the extinguishing efficiency, especially at multi-storey buildings and facilities for different functional purposes, because it makes it possible to prevent unintended damage from flooding the lower floors.To extinguish fires at residential and industrial buildings rapidly, the new installation for fire extinguishing by gel-forming compositions was proposed. The rational use of the fire-extinguishing capacity of gel-forming compositions in it is achieved through the application of a cranked extended barrel with a special mixer and a sprayer. This new installation enables extinguishing by gel-forming compositions from the distance of 3–5 m to the fire site, ensuring safety of a firefighter-rescuer.The full-scale sample of the original two-cranked barrel-sprayer of the portable installation was constructed, manufactured, and tested. By performing experimental research, it was proven that its use, due to its compactness in the folded state and the ease of unfolding into operating position, provides convenience of transportation and operation efficiency under rapidly changing conditions of a fire, especially in high-rise buildings.Feeding gel-forming compositions in the finely sprayed form decreases their consumption for extinguishing fires by 1.5 times, compared with the previously proposed technical solutions.To determine the effective value of dispersion and intensity of spraying gel-forming compositions in mathematical models of consumption for extinguishing the simulated fire and the time to extinguish it, we used second degree polynomials. Unknown coefficients were determined by the standard least square method. As a result, the rational values of the diameter of droplets (1 mm) and intensity of feeding (0.6 l/s) of gel-forming compositions were determined, which ensured the technical optimum of their use. Thus, it was found that the parameters of extinguishing the simulated fire 1A by the finely dispersed gel-forming compositions correspond to the total consumption of 2.5 kg, which is 3.5 times less compared with wate