Pile Design and Construction Practice, Fifth edition

Equipment of the type described in Section 3.3 is used to drill-out the soil from within a
tubular pile. Where rotary methods are used centralizers are required to keep the drilling
pipes in line with the pile axis. A Calweld drill was used to clean out the soil from within
the 2000 and 2200 mm outside diameter steel tubular piles used for the breasting and
mooring dolphins of The British Petroleum Company’s tanker terminal in the Firth of Forth.
To install the vertical piles, a rotary table and guide frame were mounted on top of the pile
as shown in Figure 8.16. A full-face drilling bit was used and the cuttings were removed by
air–water reverse circulation up the 200 mm drilling pipe. The drill bit was maintained in
correct alignment by centralizers and a heavy collar was provided to maintain pressure on

420 Piling for marine structures

Figure 8.16Drilling soil from within 2200 mm ODpiles using reverse-circulation drill (Forth

Tanker Terminal,The British Petroleum Co.).

Guide frame

Water and air swivel

Rotary table

200 kN-m at 12 r.p.m.

Centralizer

200 drill pipe

2200 O.D. steel

tubular pile

Guides Deck of jack-up

barge

Barge leg

Weight collar

1 829 dia.×6 706

Drilling bit

Sea bed

Sea level

Water delivery

to pile