Boiler Construction
(B) is often adopted at the former point. The hole is
drilled and then elongated to suit the tube by inserting
and bending over a piece of sleel rod of the same diameter
as the tube.
Fig. 246. Single-tube Boiler.
In all soldering work absolute cleanliness must be observed at all joints. All oxides must be removed by scraping. When silver-soldering is to be followed by soft- soldering pickling for a few hours in a weak solution of sulphuric acid (1 to 20), warming the work to hand-heat before plunging, in addition to the scraping is essential. The work in either soft- or hard-soldering must not be raised to a temperature much above that of the melting point of the solder used. This is important in using tin- man's solder, as it is so easily "burnt" and the surfaces oxidised and rendered unclean. When this happens the scraping process will again be necessary and the parts require re-soldering together.*
- Brazing temperatures are 1,400 to 1,500° Fahr.
Silver solder ,, ,, 1,100° to 1,130° ,, } Flux for both, Borax
Tinman's.. ,, ,, 380° to 650° ,, Flux, Zinc Chloride199
