Boiler Pipes Research Articles

Laser Surface Cladding with Wire Feeder for Boiler Piping

Laser Surface Cladding with Wire Feeder for Boiler Piping

Diagnostics of corrosion fatigue damage in components of equipment of thermal electric power stations

The complicated service conditions of components of steam boilers operating at moderate temperatures (bends of nonheated boiler pipes, drums, etc.) lead in some cases to premature damage in these components. The identification of this damage in metallographic and fractographic investigations is a complicated problem because this type of damage is caused by the combined effect of a number of factors. This problem can be solved efficiently be comparing service failures with those obtained in tests in testing units. However, this method is not as yet used extensively because it is difficult and complicated to reproduce service damage in the laboratory conditions and there is insufficient experience with these experiments.

Monitoring the Service-Induced Damage in Utility Boiler Pressure Vessels and Piping Systems

Electric utilities are becoming more concerned about extending the life of older fossil-fueled power plants. Of particular interest are methods for estimating the remaining useful life of steam headers and main steam piping. This paper discusses different methodologies for determining exhausted and remaining life of these components. An example of a header which was found to have exhausted its useful life is also presented.

Low-cycle fatigue and cracking resistance of power plant boiler pipes and steam lines of 12Kh1MF steel

This paper examines the low-cycle fatigue and cracking-resistance characteristics of 12Kh1MF steel by testing specimens and full-size sections of steam lines produced from a single industrial batch of pipes with an external diameter of 194 mm and a wall thickness of 36-39 mm. The steel was also subjected to standard long-term strength tests and its chemical composition and mechanical properties were determined. The results of the investigation satisfied the technical requirements on the supply of steam lines and varied on the level of mean grade values.

Silencing boiler blowdown for pipe cleaning operations

Prior to startup, many fossil fueled power stations clean the boiler piping to the turbine generator with high pressure steam. The steam is vented to the atmosphere in a series of several minute “blows” over a several week period. Steam conditions of up to 900 psi and 5000000 lb/hr are not unusual and sound levels from this activity can easily exceed 100 dBA at property lines. The traditional approach to the community noise associated with the blow has been to warn the neighbors, but the community reaction to the noise is still often significant. This paper describes the methodology and equipment used for quieting the blows. Sound level measurements of a number of steam blows, both silenced and unsilenced are presented and the resultant benefits are discussed.

Characteristics of the recrystallization of pipe steel Kh18N12T

o 1.On recrystallization of cold-rolled pipe of austenitic steel Kh18N12T one observes a substantial difference in grain size, reaching 3\2-4 grades in a single field of view. The difference in grain size is not eliminated by any combination of the strain and heat treatment conditions investigated. 2.The difference in grain size through the cross section of the pipe wall is due to uneven plastic deformation through the cross section and is most pronounced at low deformation close to the critical strain. With increasing strain the difference in grain size through the cross of the wall decreases somewhat but is not completely eliminated. 3.After all degrees of deformation in the supercritical range (up to 48%) the structure is fine grained after heating to high temperatures. Only on heating at 1200\2-1220\dgC does one observe uneven grain growth, which is due to the beginning of the solution of dispersed phases. To obtain grain sizes of grade 7-3 boiler pipes of Kh18N12T steel must be heat treated at 1200–1220°C with rapid heating. 4.The strain leading to critical grain growth depends on the subsequent recrystallization temperature.

Influence of the time and temperature of heating on the grain size of Kh18N12T steel

1. Heating in a tunnel furnace (10 m long, pipes moving through at the rate of 0.4 m/min) at 1200–1230°C ensures the desired grain size (grades 3–7) in steam boiler pipes of Kh18N12T steel. 2. An increase in the heating rate during heat treatment decreases the difference in the grain sizes. 3. At lower heating temperatures the grains in steel containing titanium are smaller, while at higher temperatures they are larger, than in the steel without titanium. 4. At the same temperature the microstructure of Kh18N12T steel containing 0.44% Ti consists of larger grains than that of steel with 0.65% Ti.