Drilling Stabilizer (Integral Blade & Non-Magnetic)
A drilling stabilizer is a drill stem element with blades that centralize the bottom hole assembly in the wellbore, controlling deviation and improving hole quality. Integral blade stabilizers are machined from a single forged bar of AISI 4145H Mod steel — or P550 non-magnetic steel for MWD zones — with spiral or straight blades dressed with tungsten carbide inserts or hardfacing.
| Blade OD | 5-7/8" – 26" (149 – 660 mm), gauge to drawing |
|---|---|
| Type | Integral blade (IBS); near-bit or string placement |
| Blade form | Spiral (open/tight) or straight, 3–4 blades |
| Hardfacing | Tungsten carbide inserts (TCI), crushed carbide, or smooth |
| Connections | API NC / REG, box × box or box × pin per API 7-2 |
| Inspection | UT, MT, blade gauge check, thread gauging, MTC 3.1 |
Materials
- · AISI 4145H Mod alloy steel
- · P550 non-magnetic steel (non-mag version)
RFQ Checklist
Include this in your inquiry for a fast, accurate quote
- 01Hole size (blade gauge OD) and fishing neck OD
- 02Near-bit or string type; connection sizes and box/pin arrangement
- 03Standard or non-magnetic body material
- 04Blade form (spiral/straight) and hardfacing option
- 05Quantity and delivery requirement
- 06Certificates required (API monogram, MTC 3.1, NDT reports)
Role in directional control
Stabilizer gauge and placement set the side forces on the bit. A full-gauge near-bit stabilizer with an undergauge string stabilizer builds angle; the reverse drops angle. Because the stabilizer touches the borehole wall continuously, blade material and dressing determine service life in abrasive formations.
One-piece integral construction
Blades are milled from the parent forged bar — no welded-on blades — so there is no weld zone to fatigue. After machining, blades are dressed, connections threaded and gauged per API Spec 7-2, and the finished stabilizer is UT/MT inspected with a full documentation package.
- What is the difference between a near-bit and a string stabilizer?
- A near-bit stabilizer sits directly above the bit (box × box) and controls bit side force; string stabilizers are placed between drill collars (box × pin) to keep the BHA centralized. Placement and gauge determine build, hold or drop tendency.
- When is a non-magnetic stabilizer required?
- When the stabilizer sits within the non-magnetic zone of the BHA near MWD/LWD instruments, it must be machined from P550-class non-magnetic steel so directional surveys stay unaffected.
- What blade dressing options are available?
- Tungsten carbide inserts pressed into the blade face for abrasive formations, crushed-carbide hardfacing for general service, or smooth dressed blades where formation damage must be minimized.
- What HS code applies to drilling stabilizers?
- Drilling stabilizers for oil and gas wells are classified with drilling tool parts under HS 8431.43, consistent with published customs rulings.