Drill Collar

‌API SPEC 7-1 Drill Collars: High-Strength Chromium Molybdenum Alloy for Demanding Drilling.‌ ‌Engineered for Extreme Downhole Conditions‌ API SPEC 7-1 drill collars are precision-manufactured from ‌AISI 4145H chromium molybdenum alloy steel‌ via rotary forging or rolling processes. With controlled trace elements (S≤0.015%, P≤0.020%), these collars deliver ‌1,200–1,400 MPa tensile strength‌ and ‌HRC 28-32 hardness‌ (ISO 6508-1), making them ideal for directional drilling, geothermal wells, and ultra-deep oil/gas reservoirs (up to 25,000 ft TVD).

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Product Introduction

‌API SPEC 7-1 Drill Collars: High-Strength Chromium Molybdenum Alloy for Demanding Drilling.‌

‌Engineered for Extreme Downhole Conditions‌

API SPEC 7-1 drill collars are precision-manufactured from ‌AISI 4145H chromium molybdenum alloy steel‌ via rotary forging or rolling processes. With controlled trace elements (S≤0.015%, P≤0.020%), these collars deliver ‌1,200–1,400 MPa tensile strength‌ and ‌HRC 28-32 hardness‌ (ISO 6508-1), making them ideal for directional drilling, geothermal wells, and ultra-deep oil/gas reservoirs (up to 25,000 ft TVD).


‌Certifications & Key Advantages‌

  • ‌API 7-1 & SY5144-2007 Certified‌: Compliant with ISO 11961 for sour service (H₂S ≤15 ppm).
  • ‌Precision Machining‌: OD tolerance ±0.005″, ID ±0.003″ (ASME B94.55M).
  • ‌Bending Strength Ratios‌: 2.38:1 to 2.58:1 for optimized weight-on-bit (WOB) transfer.
  • ‌Customization‌: NC23 to NC60 tool joints, 30–31 ft standard lengths.

‌Technical Specifications‌

‌Mechanical Properties‌

Property Value Test Standard
Yield Strength 965–1,100 MPa ASTM E8/E8M
Impact Toughness ≥50 J @ -20°C ISO 148-1 (Charpy V)
Fatigue Resistance 10⁷ cycles @ 550 MPa ASTM E466

‌Material Composition‌:

  • ‌Chromium (Cr)‌: 0.80–1.10%
  • ‌Molybdenum (Mo)‌: 0.15–0.25%
  • ‌Carbon (C)‌: 0.42–0.48%

‌Dimensional Tolerances‌

Model OD (in.) ID (in.) Weight (lb/ft) Bending Ratio
‌NC 23-31‌ 3-1/8 1-1/4 22 2.57:1
‌NC 38-50‌ 5 2-1/4 54 2.38:1
‌NC 44-60‌ 6 2-1/4 83 2.58:1

‌Thread Connections‌:

  • ‌API Regular/Full Hole‌: 4 TPI to 5 TPI (threads per inch).
  • ‌Torque Capacity‌: 12,500–35,000 ft-lbs (API RP 7G).

‌Applications‌

  1. ‌Directional Drilling‌: Maintains trajectory in 12–25° dogleg severity.
  2. ‌HPHT Wells‌: Stable in 400°F/30,000 psi environments.
  3. ‌Geothermal‌: Resists chloride stress corrosion (Cl⁻ ≤150,000 ppm).
  4. ‌Mining‌: Core barrel stabilization in hard rock formations.

‌Quality Assurance‌

  • ‌NDT Testing‌: Ultrasonic (ASTM E317) + magnetic particle (ASTM E1444).
  • ‌Straightness‌: ≤0.005″/ft (API 7-1 Sect. 8).
  • ‌Surface Finish‌: 125–250 µin RA for reduced friction.

‌Competitive Edge‌

  • ‌Lead Time‌: 20–35 days (MOQ 10 collars).
  • ‌Wear Resistance‌: 15% harder than 4140 steel.
  • ‌Traceability‌: Full heat treatment records (quench & tempered at 1,200°F).

‌Logistics & Compliance‌

  • ‌Packaging‌: VCI-coated wooden crates with RFID tracking.
  • ‌Certifications‌: API Q1, NACE MR0175, ISO 9001:2015.
  • ‌Export Docs‌: Mill test reports, NDE certificates, material traceability.

‌Performance Comparison‌

Model Max Torque (ft-lbs) Dogleg Severity Key Markets
‌NC 23-31‌ 12,500 ≤15°/100 ft Geothermal, Coalbed
‌NC 38-50‌ 25,000 ≤20°/100 ft Offshore Oil
‌NC 44-60‌ 35,000 ≤25°/100 ft Ultra-Deep Gas

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Supplier of various types of carbon steel

Luo Kaiwei Steel Company is a comprehensive steel supplier that produces a variety of carbon steel plates, carbon steel pipes, galvanized steel, carbon steel coils, and steel profiles.

Luo Kaiwei Steel Company is a multi-ISO certified steel manufacturer specializing in carbon steel plates, pipes and galvanized coils since 2010. Competitive prices and ASTM/JIS compliant. Get instant quotes for bulk orders and global shipping support.

Tel: +86 15635685959

E-mail: [email protected]  

WhatsApp: +86 18912200505

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