INDUSTRY COMPONENT

Internal Bore

Internal bore is a precision-machined cylindrical cavity within the Kelly Bar that facilitates fluid transfer and structural integrity in drilling operations.

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Component Specifications

Definition
The internal bore is a critical cylindrical passage machined through the length of the Kelly Bar, designed to allow the flow of drilling fluid (mud) from the surface to the drill bit. It maintains precise dimensional tolerances to ensure efficient fluid dynamics, structural support under torsional and axial loads, and compatibility with mating components in rotary drilling systems.
Working Principle
The internal bore operates by providing a sealed conduit for high-pressure drilling fluid transmission, which cools the drill bit, removes cuttings, and stabilizes the borehole. Its smooth, concentric geometry minimizes fluid friction and pressure loss while maintaining the bar's torsional rigidity during rotation.
Materials
High-strength alloy steel (e.g., AISI 4140 or 4340), heat-treated to 28-32 HRC, with optional internal coatings (hard chrome plating or tungsten carbide) for wear and corrosion resistance.
Technical Parameters
  • Diameter 50-200 mm (standard range)
  • Tolerance H7/h6 (ISO)
  • Straightness ≤ 0.1 mm/m
  • Surface Finish Ra ≤ 1.6 μm
  • Pressure Rating Up to 35 MPa
Standards
ISO 286-2, DIN 7154, API RP 7G

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Internal Bore.

internal bore Kelly Bar drilling component fluid transfer precision machining industrial engineering Internal Bore in Machinery and Equipment Manufacturing

Parent Products

This component is used in the following industrial products

Kelly Bar

A hollow, square or hexagonal steel bar that transmits torque and vertical force from the drilling rig's rotary table to the drill string in foundation drilling operations.

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Engineering Analysis

Risks & Mitigation
  • Bore wall erosion from abrasive fluids
  • Misalignment causing seal failure
  • Fatigue cracking under cyclic loads
FMEA Triads
Trigger: Abrasive particle accumulation in drilling fluid
Failure: Progressive bore wall erosion leading to leaks
Mitigation: Implement fluid filtration systems and use wear-resistant coatings
Trigger: Improper machining tolerances
Failure: Seal incompatibility and fluid leakage
Mitigation: Adhere to ISO H7/h6 tolerance standards and conduct dimensional inspections

Industrial Ecosystem

Compatible With

Interchangeable Parts

Compliance & Inspection

Tolerance
Geometric tolerances per ISO 1101, diameter tolerance H7/h6
Test Method
Ultrasonic testing for wall thickness, pressure testing per API RP 7G

Buyer Feedback

★★★★☆ 4.5 / 5.0 (23 reviews)

"Impressive build quality. Especially the technical reliability is very stable during long-term operation."

"As a professional in the Machinery and Equipment Manufacturing sector, I confirm this Internal Bore meets all ISO standards."

"Standard OEM quality for Machinery and Equipment Manufacturing applications. The Internal Bore arrived with full certification."

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Frequently Asked Questions

What is the primary function of the internal bore in a Kelly Bar?

It transmits drilling fluid to the drill bit while providing structural integrity under operational loads.

How does bore diameter affect drilling performance?

Larger diameters reduce fluid pressure loss but may compromise torsional strength; optimal sizing balances flow efficiency with mechanical requirements.

Can I contact factories directly?

Yes, each factory profile provides direct contact information.

Get Quote for Internal Bore

Internal Baffles/Fins Internal Bore Surface