Page 86 - Air and Gas Drilling Manual

3-14 Air and Gas Drilling Manual
diameter concave bit. The smaller bit (laying on its side) is a 6 inch diameter
concave bit.
There are five air hammer bit cutting face designs. Figure 3-12a shows the
profile of the drop center bit and Figure 3-12b shows the profile of the concave bit.
Figure 3-13a shows the profile of the step gauge bit and Figure 3-13b shows the
profile of the double gauge bit. Figure 3-14 shows the profile of the flat face bit.
These five bit cutting face designs are applicable for a variety of drilling applications
from non-abrasive, soft rock formations to highly abrasive, very hard rock
formations. The application of these five face designs are shown in Figure 3-15.

Figure 3-12: Air hammer bit face profile designs, a) drop center bit, and b) concave bit
(courtesy AB Sandvik Rock Tools).

Figure 3-13: Air hammer bit face profile designs, a) step gauge bit, and b) double gauge
bit (courtesy AB Sandvik Rock Tools).

Figure 3-14: Air hammer bit face profile design, flat face bit (courtesy AB Sandvik Rock
Tools).
In the past the air hammer manufactures have provided the air hammer bits for
their specific air hammers. This practice insured compatibility of bit with hammer
housing. The increased air hammer use in drilling deep oil and natural gas recovery
wells has attracted traditional oil field drill bit manufacturers to fabricate air hammer