Figure 4-16.MAPP gas cutting tips.
flames are too short, the orifices are still partially
blocked. If the flames snap out when you close the
valves, the orifices are still distorted.
If the tip seat is dirty or scaled and does not properly
fit into the torch head, heat the tip to a dull red and
quench it in water. This will loosen the scale and dirt
enough so you can rub it off with a soft cloth.
MAPP GAS CUTTING TIPS. Four basic types
of MAPP gas cutting tips are used: two are for use with
standard pressures and normal cutting speeds, and two
are for use with high pressures and high cutting speeds.
Only the standard pressure tips, types SP and FS, will
be covered here since they are the ones that Steelwork-
ers will most likely use. SP stands for standard pressure
and FS for fine standard.
The SP tip (fig. 4-16, view A) is a one-piece standard
pressure tip. It is used for cutting by hand, especially by
welders who are accustomed to one-piece tips. SP tips
are more likely to be used in situations where MAPP gas
is replacing acetylene as the fuel gas.
The FS tip (fig. 4-16, view B) is a two-piece, fine
spline, standard pressure tip. It is used for cutting by
hand as well as by machine. Welders accustomed to
two-piece cutting tips will use them in hand cutting,
especially when MAPP gas is replacing natural gas or
propane as the fuel gas. The FS tips will produce heavier
preheating flames and faster starts than the SP tips;
however, two-piece tips will not take as much thermal
or physical abuse as one-piece tips. But in the hands of
skilled Steelworkers, they should last as long as one-
Recommended tip sizes and gas pressures for use in
cutting different thicknesses of steel using MAPP gas as
a fuel are given in table 4-1.
Table 4-1.Recommended MAPP Gas Tip Sizes and Oxyfuel Pressures