Generally speaking, the diameter of spiral steel pipes can be divided into outer diameter, inner diameter, and nominal diameter. The outer diameter of the spiral steel pipe is represented by the letter D, followed by the size of the outer diameter and wall thickness. For example, a seamless steel pipe with an outer diameter of 108 and a wall thickness of 5MM is represented by D108*5. Plastic pipes are also represented by outer diameters, such as De63. Others such as reinforced concrete pipes, cast iron pipes, and galvanized pipes are represented by DN. Nominal diameters are generally used in design drawings. The nominal diameter is a standard artificially stipulated for the convenience of design, manufacturing, and maintenance. It is also known as the nominal bore, which is the specification name of the pipe (or pipe fitting).
The nominal diameter of a pipe is not equal to its inner or outer diameter. For example, spiral steel pipes with a nominal diameter of 100MM may have several options such as 1025 or 1085. Here, 108 represents the outer diameter, and 5 represents the wall thickness. Therefore, the inner diameter of this steel pipe is (108-2*5)=98MM, but it is not exactly equal to the difference between the outer diameter and twice the wall thickness. In other words, the nominal diameter is close to but not equal to the inner diameter, serving as a specification name for pipe diameters. The reason for using the nominal diameter in design drawings is to determine the structural and connection dimensions of pipes, fittings, valves, flanges, gaskets, etc. based on the nominal diameter. The nominal diameter is represented by the symbol DN. If the outer diameter is used in the design drawings, a pipe specification comparison table should also be provided, indicating the nominal diameter and wall thickness of a particular pipe.
To achieve energy saving in fluid transportation through spiral steel pipes, measures are taken to reasonably start and stop the operation of cooling tower fans and axial flow fans in the pump room for cooling, taking advantage of the seasonal drop in temperature in late autumn. This effectively reduces electricity consumption. According to calculations by professional management departments, this measure alone can reduce costs by nearly 100,000 yuan per month.
In daily production operations, 15 sets of cooling tower fans operate simultaneously at full capacity, with a total power consumption of up to 1600kW per hour, making them a significant consumer of electricity. Due to the special requirements of the steelmaking and continuous casting systems for water medium supply, especially when refining high-quality steel grades, the control of water medium temperature difference plays a crucial role in stabilizing product quality and developing new steel grades.
Taking full advantage of seasonal changes and the decrease in outdoor temperature at night, on-duty personnel conduct real-time tracking and monitoring of water medium temperature changes at the production site, and promptly adjust the operating fans to minimize the number of operating fans. Over the past week, the number of operating fans has been halved, and electricity consumption has also been reduced by half.
