Non-magnetic Drill Collars


M
aterials 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 l05/4?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.


Mechanical Properties

Yield strength
(at 0.2%)
Tensile strength
Elongation
%
Reduction of area %
Charpy impact value
Min Mpa
Min psi
Min Mpa
Min psi
25
50
Min.50ft.1b
689
99,000
823
118,000


Chemical Composition

Grade
C
Mn
Ni
Cr
Mo
N
Nb
N1310
0.1
18
1.4
13
0.9
0.3
0.2


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.

 

 
 


Copyright 2002 © Unitech Asia Pacific Limited
All rights reserved.