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Table 14.1 – Parameters of boring towers

Derrick size Height A Ft.–In. Nominal base Water table
No. square B Ft.–In. opening D Fl.–In.
10 80-0 20-0 5-6
11 87-0 20-0 5-6
12 94-0 24-0 5-6
16 122-0 24-0 5-6
18 136-0 26-0 5-6
18A 136-0 30-0 5-6
19 140-0 30-0 7-6
20 147-0 30-0 6-6
25 189-0 37-6 7-6

Tolerances: A ± 6 in. , B ± 5 in., D ± 2 in.

The water table opening dimension D is the inside or the
clear dimension of the opening in the water table.
The gin pole structure is used to lift crown components from
the derrick floor to the top of the derrick and through the water
table. It extends across the center of the water table opening.
Minimum clearance between the horizontal header of the gin pole
and the tops of the water table beams is 8 ft for derricks under
122-ft high; 10 ft for 122-ft derricks: 12 ft for 136-ft derricks and
17 ft for 140-ft and 189-ft derricks. Usually higher gin poles may
be obtained on special order.
A safety platform is usually placed around the crown which
conforms to the various safety codes.
Horizontal members are called girts and the cross bracings
are called diagonals. Cross bracing comes in several forms
depending on manufacturer. Typical examples are X bracing, K
bracing and diamond bracing.

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