N850

1. CHEMICAL COMPOSITION

„N850“ is a special nonmagnetic, nickel chromium molybdenum alloy.

C Cr Mo Fe Co Ni
max. 0,01 20,00 - 22,00 15,00 - 18,00 max. 2,0 max. 1,0 remainder

 

2. MECHANICAL PROPERTIES

Following mechanical properties (tested at room temperature) are achieved by a special cold-working process over the full length of the collar:

TEXT OD KSI N/MM
Yield Strength (min.) 0,2%-offset method: OD up to 10“ 150 ksi 1035 N/mm²
Tensile Strength (min.):   160 ksi 1104 N/mm²
Elongation (min.):   15% 15%
Reduction of area (min.):   50% 50%
Impact energy (min.):   100 ft.lb 135 J
Endurance Strength / N=10⁵ (min.):   ± 90 ksi ± 620 N/mm²
Hardness Brinell: (min.):   300-430 HB 300-430 HB

 

3. MAGNETIC PROPERTIES

Relative permeability: ≤ 1,005.

 

4. CORROSION RESISTANCE

Superior corrosion properties compared to other Ni-based alloys are given.
The material specified conforms to ANSI/NACE MR0175 / ISO 15156.
This alloy can be used in environments containing 1000 psia (7000 kPa) H2S at a chloride concentration of 180000 mg/L and any in situ pH up to 550°F (288°C). It can be used also in enviroments containing 500 psia (3500 kPa) H2S at a chloride concentration of 180000 mg/L, at any situ pH and in the presence of elemental sulfur up to 400°F (204° C)

 

5. NON-DESTRUCTIVE TESTING

• Magnetic inspection: Drill collars are 100% tested by a proprietary probe-testing process using a Förster Magnetomat 1.782. (“Hot Spot“-test).

• Ultrasonic inspection: Each collar is ultrasonically inspected over 100% of the volume according to ASTM E 114, last edition as a minimum level.