1030 



TUBES 



compressible tools or dies. In 1 826, Harvey and Brown used a long-ended mandril 

 with bit attached thereto, corresponding to the internal diameter of the iron tube 

 which was to bo welded. Bussell in 1836 attempted to expedite the production of 

 iron tube by turning up the end of the skelp to a tube-like form, and when the iron 

 was at welding heat, on being drawn through the tool, the entire length of the skelp 

 was turned up, and welded by one operation or heating, either by means of rollers or 

 bell-mouthed plyers, as already described. Prosser in 1840 followed in intention 

 the last-described process, using, however, a tool composed of four pulleys, operated 

 upon by pinions, and a long-shanked mandril with a thick end : the end of the skelp 

 was in this process turned up to enter the combined roller die ; it was heated ancl 

 welded, passing over the thick part of the mandril when being welded. A united 

 patent of Eussell and Whitehouse, taken out in 1842, and specially adapted for the 

 production of locomotive- and marine-engine boiler tubes, consisted in introducing a 

 mandril of smaller diameter into the turned-up tube, the edges of which were 

 thinned ; the mandril lay immediately under the overlapping edges of the joint : the 

 tube being heated, was then passed under rollers, which pressed the laps or edges of 

 the skelp together on the internal support and produced a firm, strong, and substantial 

 joint or weld. In 1844-5, Eussell, instead of passing the tube through the tools, used 

 a moveablo bed on which the tube to bo welded was laid ; the mandril in this 

 process was either placed in the interior of the tube, or was held stationary' at the 

 point of welding, or immediately at the point of contact or pressure of the rolls, and 

 the tube passing under it was welded : the tube in this process required two heatings to 

 weld it into its entire length. It will be evident that the majority of these patents 

 ring the changes on the roller alternating with the 'plyer' mode of welding; the 

 former method having been used by Mr. Bush in 1780, not for welding purposes as 

 regards tubes, but for the production of lead-tube, being used by him for rolling down 

 the thick billet of lead in order to elongate and reduce it in its external diameter. 

 Of the patents noticed, the majority depend on the use of rollers as a means of 

 welding in connection with an internal mandril, pointing to the conclusion that, 

 previous to the introduction of the amended Patent Law in 1852, such arrange- 

 ment of tools or welding machines included therein must have formed, as they did, 

 fertile sources of litigation. A somewhat ingenious process for making tubes to be 

 applied for locomotive and marine-engine boiler purposes was carried into execution 

 by the late Mr. Kichard Prosser in the years 1852-3. In this process the welding of 

 tie tubes was attempted to be got rid of altogether by a process dependent entirely on 

 the accuracy of the preparation of the skelp, and the closing of its edges ; the skelp, 

 being placed on the bed of a planing machine, had its two outer edges planed down to 

 half the thickness on the opposite sides of the sheet, thus; see *.,fig. 2037, a stationary 



2039 



cast-iron grooved bed die, the entire length of the intended tube, with corresponding 

 convex tool, which descended and converted the flat metal into the form represented at 

 n,fig. 2037. In this condition a concave die, descending in a similar manner, turned over 

 the edges of the metal, which was eventually forced down, and assumed the cylindrical 

 form as represented at c, as the tightness of the tube was dependent on the accuracy 

 of the planing of the edges of the skelp and the closeness with which these edges were 

 brought together, the only means of retaining these firmly being the cohesion of the 

 joints arising from the pressure of the water in the interior of the boiler. Perfect as 

 these joints were made, the vibration of the engine speedily opened them, and the tube, 

 it is almost unnecessary to add, was not a success. 



The manufacture of welded ' edge and edge ' or ' butt ' and ' lap ' jointed iron tube 

 is practised as follows: The iron of which the tube is made is received from the manu- 

 facturer of iron in the form, thickness, and breadth required for the tubes of the 

 various diameters and thicknesses of metal necessary for the purposes intended : it is 

 cut into lengths, and then heated to a red heat in a revcrberatory furnace of sufficient 

 length to heat the iron at one operation. This furnace is similar in construction to a 

 soldering stove, shown at./?//. 2047; the heat is also regulated by dampers ; it can, 

 hfnvover, be raised to ;i higher temperature. When heated the ' skelp ' at its end is 

 be-.tcn into a semi-tubular form, and after passing it through the tool, it is taken hold 



