Project Description
P550 Non Magnetic Drill Collar for Directional Drilling
The P550 non magnetic drill collar is a premium austenitic Mn-Cr stainless steel specifically engineered for the most demanding directional drilling environments. As a high-nitrogen, low permeability component, the P550 exhibits exceptional mechanical strength and a relative magnetic permeability of less than 1.005. This makes it the ideal non magnetic drill string component for MWD and LWD applications where magnetic interference must be strictly minimized.
Its advanced chemical composition control system, combined with a specialized cold-working process over the full length, guarantees superior fatigue resistance, high yield strength, and excellent pitting corrosion resistance. ShunFu Metal, a trusted non magnetic drill collar manufacturer, utilizes precision machining and rigorous inspection protocols to ensure every collar delivers uncompromising downhole performance. You can explore our complete range of drill collars to find the right fit for your bottom hole assembly.
Applications and Use Cases
The P550 non magnetic drill collar is critical for maintaining directional accuracy in complex well trajectories. By eliminating magnetic interference, it allows downhole sensors to operate with maximum precision. Primary applications include:
- MWD (Measurement While Drilling) non magnetic collar assemblies
- LWD (Logging While Drilling) non magnetic drill string components
- Non magnetic drill collars for directional drilling
- Stabilizers and custom non magnetic drill collar OD NC50 configurations
- BHA components in oil and gas exploration
- Mining and rock drill steel applications requiring low magnetic permeability
- Drill string components for horizontal and deep well drilling
Proper selection of non magnetic materials directly impacts wellbore placement accuracy. When combined with our high-strength drill pipe, the P550 collar ensures a robust and magnetically stable drilling system.
Specifications and Equivalent Grades
Equivalent Grades
| Grade / Trademark | Category | Standard / Origin |
|---|---|---|
| P550 | Austenitic Mn-Cr Non-Mag Steel | Proprietary / API Spec 7-1 |
Applicable Specifications and Standards
- API Spec 7-1 – Rotary Drill Stem Elements (Drill Collars)
- ASTM A262 – Standard Practices for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels (Practices A & E)
- ASTM E114 – Standard Practice for Ultrasonic Pulse-Echo Straight-Beam Examination
Available product shapes include solid round bar, hollow bar, and precision machined drill collars. Our hollow bar materials provide an excellent starting point for custom deep-hole drilling requirements.
Chemical Composition
| Element | P550 (%) |
|---|---|
| Carbon | max. 0.06 |
| Manganese | 20.00 - 21.60 |
| Chromium | 18.30 - 20.00 |
| Molybdenum | min. 0.50 |
| Nitrogen | min. 0.60 |
| Nickel | min. 2.00 |
The high manganese and chromium content, combined with a minimum of 0.60% nitrogen, ensures the structural stability of the austenite phase. This precise composition prevents magnetic transformation even under severe downhole stress and temperature variations.
Mechanical Properties and Strength
The mechanical properties of the P550 non magnetic drill collar are achieved via a special cold-working process over the full length of the collar. This process guarantees consistent yield and tensile strength throughout the entire component, preventing weak points near the connections or middle joint.
| Property | OD up to 9 1/4" | OD 9 1/2" and larger |
|---|---|---|
| Yield Strength (min.) | 140 ksi / 965 N/mm² | 130 ksi / 900 N/mm² |
| Tensile Strength (min.) | 150 ksi / 1035 N/mm² | 150 ksi / 1035 N/mm² |
| Elongation (min.) | 20% | 20% |
| Reduction of Area (min.) | 50% | 50% |
| Impact Energy (min.) | 60 ft.lb / 82 J | 60 ft.lb / 82 J |
| Endurance Strength (N=10⁵ min.) | ± 80 ksi / ± 550 N/mm² | ± 80 ksi / ± 550 N/mm² |
| Hardness Brinell | 350 - 430 HB | 350 - 430 HB |
These strength levels ensure the P550 non magnetic drill collar can withstand extreme torsional and axial loads encountered during directional drilling operations.
Melting Routes and Manufacturing Processes
Flexible Melting Routes
ShunFu Metal offers flexible melting routes for P550 austenitic stainless steel to match your specific downhole requirements. Standard production utilizes EAF + AOD + LF + VD to ensure high purity and precise carbon control. For enhanced structural integrity and nitrogen retention, we can integrate ESR or PESR (Pressurized Electroslag Remelting). For the most demanding applications, a VIM + VAR route is available. Clients can negotiate with our metallurgical team to select the optimal melting solution.
Heat Treatment and Surface Hardening
Proper heat treatment is critical to prevent sensitization and ensure long-term downhole reliability. Our processes include:
- Warm Forging & Quenching: Warm forging followed by immediate quenching prevents material sensitization and intergranular SCC.
- Cold Working: A special full-length cold-working process achieves the required high yield strength (130-140 ksi) and mechanical properties uniformly.
- Surface Hardening: Hammer peening, roller burnishing, and shot peening induce compressive residual stress, preventing transgranular SCC and significantly enhancing fatigue life.
Precision Machining and Surface Finish
ShunFu Metal delivers precision machined non magnetic drill collar products through our comprehensive in-house capabilities. We perform BTA boring, CNC lathe and milling, and long distance gunhole drilling to achieve strict dimensional tolerances compliant with API Spec 7-1. Surface finishes include turning, milling, and roller burnishing, ensuring precise internal and external profiles.
To further enhance fatigue life and prevent transgranular SCC, connections undergo specialized shot peening and hammer peening. Advanced 6-axis laser cladding is also available for custom surface protection. These processes guarantee optimal surface roughness and exacting tolerances required for high strength non magnetic drill collar applications.
Quality Assurance and Inspection Protocols
Quality is rigorously controlled at ShunFu Metal across pre-production, in-process, and post-production stages. 100% ultrasonic inspection (UT) is executed according to ASTM E 114 over the entire volume of every P550 non magnetic drill collar. Magnetic permeability is strictly verified using a Forster Magnetomat 1.782 ("Hot Spot" test), certifying relative permeability below 1.005.
We conduct comprehensive chemical analysis, mechanical testing, dimensional checks, and metallographic exams. Corrosion resistance is validated via ASTM A262 Practice A & E for intergranular attack, alongside pitting corrosion assessments. Certified to API Q1 and ISO 9001, ShunFu Metal issues EN 10204 3.1 certificates (3.2 available upon request) and welcomes third-party inspections by SGS or TÜV.
Available Sizes, Lead Times, and MOQ
ShunFu Metal provides a comprehensive range of sizes for P550 non magnetic drill collar material, encompassing forged round bars, rolled flat bars, and hollow bars. We accommodate ODs up to 9 1/2" and larger, tailored to custom specifications. Our manufacturing capabilities are supported by API-standard calibrated heat treatment furnaces and advanced precision machining equipment.
- Ready Stock
- Standard high strength API Spec 7 nonmagnetic drill collars available with single piece MOQ, delivery in approximately 7 days.
- Custom Forged/Rolled Material
- MOQ typically 3 tons, delivery in approximately 30 days.
- Small Batch Special Grades
- Smelted via our small induction furnace, 3-5 tons MOQ.
- Large Volume Orders
- Processed via 30-60 ton EAF for fast delivery.
Packing and Shipping Protocols
Proper packing ensures the integrity of P550 non magnetic drill collar deliveries. For black skin (as-forged) products, heavy steel wire strapping secures the material, preventing any shifting or damage within the container during transit. For bright surface and precision machined components, we offer multiple protective packaging materials—including custom crates and caps—to safeguard surface roughness and strict dimensional tolerances.
Anti-rust oil is uniformly applied to all products, guaranteeing complete protection against corrosion throughout long-distance ocean shipping to global destinations.
Frequently Asked Questions
Can you supply P550 non magnetic drill collar to API specification?
Yes. Our P550 non magnetic drill collars fully meet all requirements of API Spec 7-1, and we can provide custom non magnetic drill collar with API thread configurations.
What is the minimum order quantity for P550 non magnetic drill collar?
For standard sizes from our ready stock, we support a single piece MOQ with a 7-day lead time. For custom forged requirements, the MOQ is typically 3 tons with a 30-day lead time. Small batches of 3-5 tons can also be smelted via our induction furnace.
How do you ensure the low magnetic permeability of the P550 drill collar?
We utilize high-purity austenitic stainless steel and a specialized manufacturing process. Each collar is 100% tested using a Forster Magnetomat 1.782 ("Hot Spot" test) to verify and certify that relative permeability remains below 1.005.
What surface treatments are applied to prevent stress corrosion cracking (SCC)?
Transgranular SCC is prevented by applying hammer peening, roller burnishing, and shot peening on connections. Intergranular SCC is prevented by quenching immediately after warm-forging, and verified through ASTM A262 testing.