This section is from the book "Welding And Cutting Metals By Aid Of Gases Or Electricity", by L. A. Groth. Also available from Amazon: Welding and cutting metals by aid of gases or electricity.
Fig. 118. - Test Pieces from Oxy-Acetylene Welded Plates.
After the repairs were carried out on the boilers, the usual hydraulic pressure test was applied, when the results were found satisfactory. The steam pressure on the boilers is 200 lbs.
The illustrations (Figs 117 to 119) show the depressions in the furnaces, also the work done by the oxy-acetylene process, and test pieces from welded plates.
The publication in various parts of Dingier's Polytech-nisclies Journal, 1908, by Dr. Hilpert, of repairs on marine boilers made by L. Chatelier in Marseilles, has aroused the German Steam Boilers' Associations to vigorous action, so far as Germany is concerned, in the direction of providing that kind of safety which the public has a right to demand.
In the United Kingdom, where autogenous welding is still in its infancy, scarcely known even in its most simple elements, much less in the serious and responsible application to repairs on steam boilers, and more particularly marine boilers, it is safe to assume that the British Steam Users' Associations, headed by Lloyd's, will take steps in a similar direction, so as to regulate that such repairs shall only be made under the most vigorous restrictions.
It must not be forgotten that the industry of compressed gases, more so their application to welding, is an entirely new industry, and that the present knowledge is not sufficient to advise, either as to the mixture of the gases employed, the best means of keeping a proper mixture, when ascertained, constant or without decomposition, more so as it always must differ according to the nature and thickness of the welding metal, or as to the right temperature of the flame.
Much less is there evidence, so far as marine boilers are concerned, to show the faults or defects of the welds executed. It may be easy to schedule the number of repairs and the names of the steamship companies; but it is difficult, if not impossible, to say how many of the accidents which so repeatedly occur are, more often than not, caused by a bad weld, which seemed to have been properly executed.
Fig. 119. - Repairs by Oxy-Acetylene Process.
The more the advantages of boiler repairs appear, the greater becomes the number of those who, in self-confidence, are willing to undertake such jobs, as they evidently are of a lucrative nature ; but it is apt to be forgotten that such repairs are often required on the most sensitive organs of the boiler, by which, therefore, certain conditions are required, and which have been duly denned; the greater will also be the responsibilities of those undertaking to execute the job, and perhaps more so of those authorising the same to be done, knowing that there is no means of controlling the work, the only guarantee being left to ocular inspection and to the repute of the welder. Happily enough, the place of the weld will in many instances offer difficulties to the unskilled, securing thereby a certain safety.
Although welding with compressed gases has given satisfactory results, there are many instances to prove that the industry is still in its infancy, as even leading firms, which are entitled to inspire confidence, fail sometimes in producing a satisfactory weld.
Far from wishing to discourage the application of autogenous welding to repairs on steam boilers, a disclosure of its extreme difficulty, often combined with great peril, will assist in finding means for overcoming the obstacles and to gain knowledge; but until that has been done such repairs should be entrusted, under most restricted conditions, to persons only who are intimately conversant with the construction and building of steam boilers.
 
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