Page 106 - Air and Gas Drilling Manual
P. 106
3-34 Air and Gas Drilling Manual
tube of the dual wall pipe (see Chapter 8). Therefore, the velocity of the air flow in
the annulus is slow. The flow in the annulus at each connection is somewhat
obstructed and therefore not suited for direct circulation. The inside tube, however,
has no obstructions at the connections and allows free flow of the compressed air
with entrained rock cuttings.
Figure 3-27a: Pin threaded shouldered connection for dual wall pipe (courtesy of Holte
Manufacturing Company).
Figure 3-27b: Box threaded shouldered connection for dual wall pipe (courtesy of Holte
Manufacturing Company).
