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Non-magnetic
Drill Collars
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Materials
of the Non--magnetic drill collars
are
from chrome manganese, low carbon austenific alloy obtained
by combining a proprietary chemical analysis and a rotary
hammer forging process. The material is resistant to stress
corrosion cracking, with high mechanical properties, low
magnetic permeability, excellent machineability and no tendency
to galling.
Magnetic
permeability (when MPS=l x l0£µ/4?Nm)
* Relative Max: 1.010.
* Average: Uµr 1.005.
Magnetic Field Gradient (hot spots)
* Max: B 0.05 micro Tesla/100mm.
Mechanical Properties
The non--magnetic drill collars exhibit the mechanical properties
indicated below along their entire length. This table is
derived from test samples of steel taken from a point 1"
below the surface.
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Mechanical
Properties
Yield
strength
(at 0.2%)
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Tensile
strength
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Elongation
%
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Reduction
of area %
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Charpy
impact value
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Min
Mpa
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Min
psi
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Min
Mpa
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Min
psi
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25
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50
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Min.50ft.1b
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689
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99,000
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823
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118,000
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Chemical
Composition
Grade
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C
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Mn
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Ni
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Cr
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Mo
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N
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Nb
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N1310
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0.1
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18
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1.4
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13
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0.9
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0.3
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0.2
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The
non--magnetic drill collars are of a Cr--Mn type.
The chemical composition is strictly controlled in order
to ensure high strength and low permeability.
On inquiries and orders please specify:
* Outside diameter.
* Length.
* Connection Style.
* Stress relief grooves.
* Elevator and slip recess.
* Special features (magnets, scribe--line, top landing
device, spiral grooves.)
Note: Other non--magnetic products also include: Short collars,
integral HWDP, subs, stabilizers, etc.
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Copyright 2002
© Unitech Asia Pacific Limited
All rights reserved.
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