Boiler Shell Research Articles

Photoelectronic system for checking the cross section of boiler shells during their correction

Photoelectronic system for checking the cross section of boiler shells during their correction

Nonsteady thermal stresses at the edges of holes in boiler shells

Nonsteady thermal stresses at the edges of holes in boiler shells

Buffeting Excitation of Boiler Tube Vibration

The origin of the vibration generated within an extensive bank of tubes that run transverse to the direction of gas flow through a boiler shell and whose movement is small enough in amplitude to have no perceptible effect on the motion of the gas, is examined on the supposition that, sufficiently deep inside the bank, the flow is essentially turbulent and, except for a general drift through the bank, exhibits no regular feature. Conditions of this kind are thought to be appropriate to certain types of heat exchanger used in nuclear power stations and operating at large Reynolds numbers. The source of vibration, either structural or gaseous, is associated with the randomly fluctuating forces imposed on the tubes by the turbulent eddies, and a simple argument is put forward to account approximately for the length scale of the most energetic of these eddies and consequently the frequency with which they encounter the tubes. It is further argued that the tubes are aerodynamically discriminating in their force response which is thereby narrowed spectrally and confined to the neighbourhood of the frequency corresponding to the energetic eddies. The subsequent structural or acoustic response is even more sharpened spectrally, owing to the small damping inherent in the system. A relation between the dominant frequency of the force fluctuations, the gas velocity and the geometrical arrangement of the tubes, that emerges from the argument, agrees in form with published observations of the sound emission from boilers under resonant conditions. A disposable constant appearing in the relation is also satisfactorily predicted in order of magnitude. The analysis applies to only one possible form of the vibration phenomenon; other forms, aero-elastic and vortex-excited, may appear under suitable conditions dependent upon Reynolds number, structural stiffness and damping.

On the stresses due to thinning of boiler shells

水管式汽罐の罐胴に於て管板の部分と然らざる部分との板の厚さを異にする場合に、罐胴の外側のみに段を付けるのが普通であるが、この形状では罐胴を完全円筒と看做したる場合の計算に比し段付部附近に著しく大なる應力を発生することを指摘し、全然段付を施さないか又は内外面共段を付けて板の中立面が眞円筒となる如くすれば、内圧に依る應力は完全円筒の場合と大差なきことを述べる。

SOME OBSERVATIONS CONCERNING METAL CRACKING IN NAVAL BOILERS

During the past fifteen years there has been much published concerning the intercrystalline cracking of toiler steel. The volume of published information on this subject has directed thought toward caustic embrittlement whenever cracks are encountered in boiler shells. While the author recognizes the importance of investigative work in this field, he considers other factors which are often responsible for boiler metal failures. Thus, he correlates causes according to their relative importance from his wide experience of phenomena observed and recorded on the subject. He presents his findings and conclusions in an available form.

Discussion: “Tests of the Resistance to Repeated Pressure of Forged, Riveted, and Welded Boiler Shells” (Moore, H. F., 1931, Trans. ASME, 53(3), pp. 55–60)

Discussion: “Tests of the Resistance to Repeated Pressure of Forged, Riveted, and Welded Boiler Shells” (Moore, H. F., 1931, Trans. ASME, 53(3), pp. 55–60)

Discussion: “Tests of the Resistance to Repeated Pressure of Forged, Riveted, and Welded Boiler Shells” (Moore, H. F., 1931, Trans. ASME, 53(3), pp. 55–60)

Discussion: “Tests of the Resistance to Repeated Pressure of Forged, Riveted, and Welded Boiler Shells” (Moore, H. F., 1931, Trans. ASME, 53(3), pp. 55–60)

Tests of the Resistance to Repeated Pressure of Forged, Riveted, and Welded Boiler Shells

Abstract Data regarding the performance of welded joints in resisting repeated stresses are very important in any consideration of the adoption of welded construction for power boilers, and it is the object of this paper to present such data. Comparative tests were made on (1) a standard A.S.M.E. riveted drum, (2) manganese-steel riveted drum, (3) forged seamless-steel shell, (4) two forge-and-hammer-welded shells, and (5) eight fusion-welded (metallic-arc) shells, each drum or shell being subjected to applications of pressure well above the allowable working pressure. The results indicate that under repeated stress properly made welded joints are stronger than the plates themselves when weakened by “stress raisers” such as small holes or surface defects. The tests also give useful data on the strength of drum heads when subjected to intermittent pressures.

Discussion: “Tests of the Resistance to Repeated Pressure of Forged, Riveted, and Welded Boiler Shells” (Moore, H. F., 1931, Trans. ASME, 53(3), pp. 55–60)

Discussion: “Tests of the Resistance to Repeated Pressure of Forged, Riveted, and Welded Boiler Shells” (Moore, H. F., 1931, Trans. ASME, 53(3), pp. 55–60)

Discussion: “Tests of the Resistance to Repeated Pressure of Forged, Riveted, and Welded Boiler Shells” (Moore, H. F., 1931, Trans. ASME, 53(3), pp. 55–60)

Discussion: “Tests of the Resistance to Repeated Pressure of Forged, Riveted, and Welded Boiler Shells” (Moore, H. F., 1931, Trans. ASME, 53(3), pp. 55–60)

Closure to “Discussions of ‘Tests of the Resistance to Repeated Pressure of Forged, Riveted, and Welded Boiler Shells’” (1931, Trans. ASME, 53(3), pp. 60–63)

Closure to “Discussions of ‘Tests of the Resistance to Repeated Pressure of Forged, Riveted, and Welded Boiler Shells’” (1931, Trans. ASME, 53(3), pp. 60–63)

Discussion: “Tests of the Resistance to Repeated Pressure of Forged, Riveted, and Welded Boiler Shells” (Moore, H. F., 1931, Trans. ASME, 53(3), pp. 55–60)

Discussion: “Tests of the Resistance to Repeated Pressure of Forged, Riveted, and Welded Boiler Shells” (Moore, H. F., 1931, Trans. ASME, 53(3), pp. 55–60)

Discussion: “Tests of the Resistance to Repeated Pressure of Forged, Riveted, and Welded Boiler Shells” (Moore, H. F., 1931, Trans. ASME, 53(3), pp. 55–60)

Discussion: “Tests of the Resistance to Repeated Pressure of Forged, Riveted, and Welded Boiler Shells” (Moore, H. F., 1931, Trans. ASME, 53(3), pp. 55–60)

Discussion: “Tests of the Resistance to Repeated Pressure of Forged, Riveted, and Welded Boiler Shells” (Moore, H. F., 1931, Trans. ASME, 53(3), pp. 55–60)

Discussion: “Tests of the Resistance to Repeated Pressure of Forged, Riveted, and Welded Boiler Shells” (Moore, H. F., 1931, Trans. ASME, 53(3), pp. 55–60)

Working Stresses for Steel at High Temperatures

Abstract Certain of the published results for the stress to produce creep at higher temperatures have led to apprehension in the employment of stresses that have been used, and it is the object of the paper to dispel such apprehension for the particular stresses which are discussed. The results secured in practical experience are used for setting the maximum working stresses for drums and superheater headers up to temperatures of 800 deg. fahr., and for temperatures above 800 deg. fahr., the working stresses are scaled down in proportion to the falling off of the stresses that produce creep. The first curve of creep stresses published by Mr. H. J. French of the Bureau of Standards was used, and the working stresses for a given temperature are taken at 2/3 the creep stress. The effect on the stress of piercing a boiler shell with holes and of transmitting heat through the shell is discussed, as well as the tendency toward equalization of stress through extension of the most-strained fiber. The tendency of the creep to equalize the stresses is also brought out. The method of extrapolation used by different authorities is discussed, and the conclusion is reached that more exact results are obtained by using the method employed by Prof. F. H. Norton in his book on the “Creep of Steel at High Temperatures” than by some other methods.

Riveted Joints in Boiler Shells

Riveted Joints in Boiler Shells

Riveted joints in boiler shells

Riveted joints in boiler shells

Riveted joints in boiler shells

Riveted joints in boiler shells