NSW Resources Regulator 26th annual Mechanical Engineering Safety Seminar

1. Remote Removal of Damaged
Steel Liner From Vent Shaft
Angus Place East Mine Expansion
Vent Shaft 1

2. Australian Shaft
Drilling
ASD was formed in 2003 and proceeded to design
and build a blind bore drill rig to service the
Bowen Basin mines.
The company won its first contract for
Moranbah North to drill a 2.2m finished
diameter shaft to a depth of 275m.
The Shaft was completed in June 2005 and
was quickly followed by a 4.5m diameter shaft
drilled to 230m for the same mine.

3. Since that time ASD have expanded operations, built three new drill rigs and have at
times managed four drilling projects concurrently.
Some of the projects include
Kestrel Coal – Drill 3.8m diameter to 230m depth – lined with steel
Carborough Downs – Drilled 5.4m to 150m
Kestrel Mine Extension – Drill 5.5m diameter to 230m
Narrabri No 1 Vent Shaft – Drill 5.5m diameter to 200m deep
Lady Loretta Vent Shaft – Drilled at 5.4m diameter to 148m
Moranbah North Vent shafts – two shafts drilled at 2.6m diameter to depths up to 345m
Grosvenor Mine Shafts – 3 vent shafts, two at 2.6m Diameter and one at 6m Diameter to
170m

4. Angus Place East Mine
Extension Site
ASD was contracted to Centennial
Coal’s Angus Place Colliery for the
installation of the new Ventilation
Shafts for Angus Place East which is
a proposed extension of the Angus
Place mine workings
The Drill site is located on the
Newnes Plateau approximately 15
minute’s from Lithgow

5. Vent Shaft Details
Vent Shaft 1
Total Lined Depth 393m
Finished Lined Diameter 3.5m
Initial Drill Depth 75m @ 5m Dia
Lined with Dia 4.6 Steel casing
Final Drill Depth 396m @ 4.5 Dia
Lined with Dia 3.5 Steel casing

6. Liner Breakdown
Lower Section
108m is made up of 9 x
12m sections of 20mm
G350 Plate 230PFC
stiffening rings at 1m
spacing's
Middle Section
108m is made up of 9 x
12m sections of 16mm
G350 Plate 230PFC
stiffening rings at 1.2m
spacing's
Upper Section
177m is made up of 15 x
12m sections of 12mm
G350 Plate 230PFC
stiffening rings at 1.5m
spacing's

8. Floating of Liners
Floating of Liners is undertaken when
the weight of the liner is too large to
handle with the Drill Rig and shaft is
straight
The Rig being used in this instance
was the SDR6500 this rig has a WWL
of 300t. The Total liner weight to be
installed was 615t
The process is to seal the bottom
liner with a water tight bulkhead.
This turns the liner tube into a sealed
unit which floats. As each section is
welded on to the top, fluid is
pumped into the liner to equalize the
buoyancy to allow controlled sinking
of the liner sections. There is always
a slight negative buoyancy

9. Bottom Liner Segment
20mm PlateBulk Head
Multiple Reinforcement RingsUB Beams Reinforcement
Valves to allow drainage
when holing in from Mine

13. Loss of Liner (November 2014)
• When Floating down section 29
of Liner we had an unexpected
change in buoyancy which
caused the liner to sink
• The lifting equipment broke
away from the liner as designed
to do to save the rig from
damage
• The liner sank to the bottom of
the shaft approximately 45m
below the collar
• Initial investigations pointed to a
failure in the liner wall which
allowed an uncontrolled influx of
water into the liner
• There is some conjecture over
what caused the split
• External damaged during sinking
• Design fault due to the liner being
out of round reducing the F.O.S

14. Australian
Standards
for amount of
deformation of
Pressure Vessels
1% difference
between Min and
Max Dia
Deviation of 0.3%
over Chord Length
of .25 D
Chord Length
875mm
Deviation
10.5mm

15. Deformation in Liner
In Manufacture

16. Diameter 3.5Liner
Weights Installed
Liner Sections Number Off Weight (t) Length (m) Total lenghts (m) Quanity Length (m) Mass (t)
1x 9m @ 12mm 1 12 9 0 0
14x 12m @ 12mm 14 14.7 12 168 11 132 161.7
9x 12m @ 16mm 9 19.6 12 108 9 108 176.4
8x 12m @ 20mm 8 24 12 96 8 96 192
1x 12m @ 20mm +Bulkhead 1 31 12 12 1 12 31
Diameter 3.5m 9.62 m2
393 29 348 561.1 t
Pressure Force 572.11 Kpa
Differential Fluid Height 53.0 m
(SG1.1)
Liner Sank 45m
Water level inside Liner approximately 50m Below Collar
Water level outside liner is level with collar

17. Damage
Investigation
Fluid was pumped out of the shaft
to reveal what the damage to the
steel liner was
First Picture is with water pumped
to 87m below the collar
The Liner above this is still
reasonable circular

18. Damage at
section 87 to
93m

19. Liner stays a kidney shape down to
141m and below
During the pumping of fluid out for
the initial investigations the liner tore
open at 141m due to pressure
difference and the liners weakened
state
Another small split developed in the
wall at 155m
There is no video of the liner shape
after this depth. Due to having to
pump internally and externally to
keep the fluid levels balanced so not
to propagate any more damage
So only split in liner before pumping
was at 93m Liner below that was
intact but deformed in the classic 2
lobe failure mode of thin walled
cylinders

20. Sonic Calipier
As the damage to the liner in the
upper sections was too great to use
our usual measuring instruments.
We researched what instruments
would be able to internally measure
the diameter of a steel liner
immersed in fluid.
The Sonic Caliper is a profiling sonar
device specially adapted to function
in drilling fluid.
Each 360 degree pass with the Sonic
Calipier generates up to 120
individual echo returns.
A geometric shape is fitted to the data points using the non-linear least
squares technique. The plots indicated that below 180m the liner was round
and not damaged. This depth coincided with the change in liner wall from
12mm to 16mm plate.

21. 180 to 210m 290 to 317m

22. Decision to Proceed with Removal of
Damaged Liner
• ASD developed a methodology for the reclaim of the liner which was
submitted to Centennial Coal for consideration and risk analysis; the
methodology involved the cutting of the liner using a High Pressure
Water Jet Cutter, then lifting of the cut sections to the shaft collar,
followed by the removal of the damaged sections.
• Following the Risk Assessment process the methodology was
additionally peer reviewed by an independent engineering party with
the consensus being that the reclaim was achievable. Australian Shaft
Drilling commenced the reclaim work in early 2016 and is ongoing.

23. Basic Methodology for Liner Removal
• The first section of liner to be removed started at 45m below shaft
collar
• Method was to cut two windows at top of liner section to be removed
• Cut the separation cut. This could be 12m or longer sections
• Install the lifting grapples or Lifting Beam
• Raise to the surface
• Lift out of shaft and remove from work area

24. Water Jet Cutter
• Two types of water jet cutters
• Garnet added at Nozzle (venturi mix)
• Garnet added upstream (slurry mix)
• Chose second type Due to no access to the
hopper.
• Pressure at nozzles is 1500 Bar
• Nozzles 0.8mm
• Garnet 80mesh - 177 microns
• 13L per minute water usage
• 60kg of garnet per hour (50% mix)

25. Cutting Tool No 1
This Cutting tool had telescopic
arms in both directions
Idea behind design was front arm
carried the high pressure cutting
nozzles and the back arm was used
to push against the opposite wall to
keep the head steady during the
cutting process.
Cameras where positioned at
several different points to obtain
views of the cutting nozzles and
other areas.
Two cutting nozzles where fitted for
redundancy

26. Rotation and Vertical Lift
while Cutting

27. Good Cutting

28. Cutting at
Distance

29. Camera Vision

30. Damage to Camera
lens

31. Cutting Tags due
to poor visibility

32. Window Cutting

33. Grapple Installed in Window
ready for lifting of Section
Crane Lift Grapple

34. Separation Cut

35. Chairing of Liner
Section on Collar
Welding of Lift
Lugs

36. Removal of Liner
Section from Shaft

37. First Three Sections
Removed

38. Tear at 93m

39. Robot Cutting Arm

40. Robot
Cutting
Arm
Nozzle Tip

41. Lowering Cutting
Arm through
Highly Damaged
area to cut depth
at 93m

42. Highly Damaged section area removed

43. Top of Liner at 93m

44. Pressing of Liner to reshape to allow better access for cutting and
lifting. First 6m below the 93m edge

45. Liner Reformed at
top section to allow
lifting beam
insertion

46. Windows Cut at 97m

47. Tear at 141 m

48. Liner Shape at
141m

49. Cutting of Separation at 141m

50. Pushing of
Separation cut to
check actual
separation of Liner

51. Lift Beam inserted into windows ready for lifting of liner section

52. Top Risk from RA
Monitor Shaft Wall
for collapse

53. Shaft Wall Erosion