High Pressure Boilers

A PAPER on high pressure boilers read to the Institution of Electrical Engineers on December 15 by C. H. Davy and C. H. Sparks gives an interesting account of the development of the use of very high pressure steam in modern boilers. Prior to 1918, no plants had been placed in commercial service with steam pressures exceeding 350 lb. per sq. in. In 1923 the Edison Company at Boston ordered the first boiler unit suitable for a pressure of 1,200 lb. per sq. in. The construction of this boiler was made possible by the use of the first seamless forged steel boiler drum. Recent developments of X-ray technology have given the manufacturer of welded drums the long sought non-destructive test. A definite proof of the satisfactory condition of a metallic arc fusion weld can now be given by radiographic examination. By means of scientifically controlled welding, drums can be produced which are more suitable for working conditions than the riveted structures used in the past. The drums forming part of the 1,400 lb. per sq. in. pressure sectional boilers at present being installed at the Dagenham plant of the Ford Motor Co. are 45 ft. long, 48 in. in internal diameter, 5 in. thick and weigh 62 tons. The production of such forgings reflects great credit on the forge-masters. Whilst the trend of invention has been definitely towards higher final steam temperatures, it is probable that these will be limited, at least for the present, to below 850° F. This is due to the fact that the cost of ‘special’ steels is still very high and so it is not economical to use them. The Philip Carey Works at Ohio, which started last year, use a steam pressure of 1,800 lb. per sq. in. The demand for high pressures and consequently high temperatures continues for power stations but super-pressure boilers are mainly used in industrial work.