WELDING AND BRAZING
Counterboring is required for jobs that need a harsh yet
Use of Welding Tips with MAPP GAS
stable flame. Table 4-2 lists the counterbore drill
number for each tip drill size. In every case the depth
If you use a standard acetylene tip with MAPP gas and
of counterbore is 1/16 in.
introduce enough oxygen to create what appears to be a
neutral flame, it is actually an oxidizing flame. Although
The counterboring schedule (Table 4-2) is for use with
unsuitable for welding, this type of flame is
welding tips only. Because of different flame
recommended for most brazing operations. For brazing,
requirements, different counterboring schedules are
the performance and consumption of MAPP gas has been
used for flame hardening heads and other equipment.
determined to be generally equivalent to that of
acetylene. MAPP gas has a slower flame propagation
rate, so, to accommodate the same amount of fuel it is
necessary to increase tip size by about one number.
A tip that overcomes the oxidizing effects of flames
adjusted to the neutral position has been perfected. It
consists of a flame curtain around the primary flame cone
to protect it from atmospheric gases. This tip design is
shown in Figure 4-1.
A tip that works well with MAPP gas is one or two sizes
larger than a tip designed for acetylene (Table 4-1).