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enlarging the opening. This operation is called “pre-reaming”. Drill pipe is
attached to the far side of the reamer so that it can be pulled back from the
near side, once the pre-reaming operation is complete. The line pipe string
to be installed has been welded; NDT inspected, tested and is supported
by steel cradles that incorporate rollers, allowing the line pipe string to
slide. This string of pipe may be very long, depending on the width of the
crossing. Multiple strings may be required for the widest crossings and
when the first string has been nearly pulled through the crossing, the next
string will be lifted and placed on the cradles and manually welded to the
last pipe in the first string. For installing the line pipe, a cap incorporating
a swivel joint is connected to the leading end of the pipe string. The
swivel joint is connected to the reamer and the drilling rig again pulls the
reamer back through the hole from the pipe side to the rig side, along with
the pipe string connected to the reamer. This final operation is the pull
back and installs the line pipe under the river.
Keys:
1. N, 2. C, 3. A 4. K, 5. H, 6. M, 7. J, 8. E, 9. B, 10. I, 11. D, 12. L, 13. F,
14. O, 15. G.
Exercise 26. Which steps in 22 do these diagrams show?
1. Meanwhile, Horizontal Directional Drilling (HDD) is easy and
understandable. The unit of directed drilling is placed in a point of
pipeline entry (on a river bank, on the one side of the road). It drills a
pilot borehole on the predetermined path and comes out on the other
side of the obstacle with high accuracy.
2. Widening of the well is made in several stages subject to needed
diameter of the well for one or more pipes or pipe-cases. Needed
pipes are pulled into the well with the help of special drilling agent,
which works as an oiling and forming a pipe material.
3. Advantages of work of drilling facilities are unquestionable. They
pass all the ground and underground obstacles: city districts, highways,
railways, rivers, dams, channels. The equipment won’t be stopped
neither by rocks, nor ravines or broken country. The construction
volume, which is performed in some months with trench method, is
made just in a few days with Horizontal Directional Drilling.
Environmental protection is also very important: untouched plants and
lay of land, preserved fertile soil. The usage of this technology
considerably raises operating efficiency. As a rule only one drilling rig