Concentric Casing System

Your Professional Concentric Casing System Manufacturer

A concentric casing system—commonly known by the trade name Symmetrix—is a casing advancement method designed for drilling through the most challenging overburden formations where eccentric (ODEX) systems cannot perform. As a leading manufacturer in China, MSD (Zhuzhou Jingde Machinery Co., Ltd.) has spent over two decades perfecting the design and production of these critical tools. Unlike ODEX which uses a single-sided eccentric reamer, Symmetrix employs a ring bit that cuts a full 360-degree circle around the pilot bit. Our expertise ensures every Symmetrix system we produce delivers superior hole straightness, exceptional reliability, and complete project certainty in the most demanding geological conditions.

What Is a Concentric Casing System?

A concentric casing system is a casing advancement method designed for drilling through the most challenging overburden formations where eccentric (ODEX) systems cannot perform. Unlike ODEX which uses a single-sided eccentric reamer, Symmetrix employs a ring bit that cuts a full 360-degree circle around the pilot bit. This concentric cutting action delivers balanced forces, superior hole straightness, and the ability to penetrate massive boulders that would instantly destroy an eccentric reamer. The system enables simultaneous drilling and casing installation to depths exceeding 100 meters. When target depth is reached, the pilot bit is retrieved through the casing while the ring bit remains permanently attached to the casing shoe at the bottom of the hole.

MSD Concentric System Components

A complete MSD Symmetrix system consists of five integrated components: Casing Tubes—steel tubes with threaded (left-hand thread) or welded connections that remain permanently in the hole to stabilize the borehole wall. Drill Rods—connect the rig to the hammer, transmitting rotation, thrust, and compressed air. Thread options include API REG, IF, and NC. Stabilizer—keeps the drill string centered within the casing. Thread specification matches the drill rod. DTH Hammer (Impactor)—provides percussive energy to drive the pilot bit assembly. API REG threaded connection. Concentric Drill Bit Assembly—the core component consisting of three parts working together: casing shoe (welded to the casing bottom, drives the casing forward and houses the drill bits), reamer bit or ring bit (enlarges the hole in a full 360° circle, allowing the casing to advance), and pilot bit (drills the guide hole and transmits impact energy from the hammer).

How Concentric System Works: Operating Sequence

Step 1 - Drill Through Overburden: The pilot bit breaks rock at the center while the ring bit simultaneously cuts a full circle around it. The balanced concentric forces enable penetration through massive boulders without the deviation or tool damage that plagues eccentric systems. The casing advances directly behind the cutting assembly.

Step 2 - Retrieve the Pilot Bit: At target depth, the pilot bit is unlocked and pulled up through the casing. The ring bit and casing shoe remain permanently at the bottom of the hole, attached to the casing string.

Step 3 - Switch to Conventional Drilling: With the casing securing the unstable overburden, continue drilling into stable bedrock using conventional DTH tools through the cased hole.

MSD Symmetrix Design Advantages

Heavy-Duty Interlocking Bayonet Design: The most catastrophic concentric system failure is ring bit shear-off when impacting massive boulders. MSD has completely redesigned the force-bearing interface between the pilot bit and ring bit casing shoe. Instead of standard point-contact or simple step-contact designs, MSD employs a precision-machined large-area interlocking bayonet mechanism. This increases the torque distribution area by over 30%, dramatically reducing localized stress concentration. The result: complete elimination of the ring bit shear-off risk that destroys conventional systems when drilling through granite boulders.

Dual-Grade Carbide Configuration: The outermost gauge buttons on a ring bit endure the most extreme abrasive wear. MSD ring bits feature a dual-grade carbide setup: high-toughness buttons on the inner cutting face for rock-breaking impact resistance, and proprietary YK05 premium wear-resistant buttons on the outer gauge positions. This configuration reduces OD wear rate by 25% even in highly abrasive quartz-gravel formations, ensuring the casing advances smoothly to design depth without binding.

Superior Hole Straightness: The inherent stability of concentric 360-degree cutting minimizes hole deviation, ensuring consistently straight holes even in varied and complex geological structures—critical for foundation piling where verticality tolerances are strict.

Full Multi-Angle Capability: Engineered for maximum operational flexibility, MSD Symmetrix systems perform reliably at any angle—vertical, horizontal, or inclined. This multi-angle capability meets the demanding requirements of slope anchoring, tunnel support, and horizontal directional drilling applications.

Low-Disturbance Operation: The smooth, balanced rotation of concentric systems significantly reduces operational vibration and noise compared to eccentric methods. This makes Symmetrix the ideal choice for urban construction, hospital expansions, and other noise-sensitive or vibration-restricted project sites.

Concentric System Application Scope

Foundation Piling: Symmetrix is the preferred system for bridge foundations, building piles, and infrastructure projects requiring large-diameter holes (>325mm) in boulder-laden or deep unconsolidated ground. The superior hole straightness ensures every pile meets verticality specifications.

Anchoring & Ground Support: Slope stabilization, rock anchoring, and tunnel support applications often require drilling at non-vertical angles through difficult mixed ground. Symmetrix multi-angle capability delivers reliable performance regardless of inclination.

Deep Water Wells & Geothermal: When aquifers lie beneath 50+ meters of unstable overburden, or when drilling through karst formations with voids and cavities, Symmetrix provides the depth capability and hole integrity that ODEX cannot achieve.

Geotechnical Investigation: Site investigation drilling in complex geology benefits from the precise, straight holes that concentric systems produce, ensuring accurate sampling and reliable borehole logging.

When Concentric System Is Required

MSD believes in honest technical guidance. Symmetrix is essential—not optional—when: Massive Boulders Present—the full 360-degree ring bit distributes impact forces evenly, enabling penetration through granite boulders that would instantly shear off an ODEX eccentric reamer. Overburden Exceeds 50 Meters—the balanced concentric cutting action eliminates the spiral deviation inherent in eccentric drilling, allowing reliable casing advancement to 100 meters and beyond. Large Diameter Required (>273mm)—at large diameters, eccentric rotation creates severe centrifugal forces and vibration that damage equipment. Concentric systems maintain smooth, balanced operation at any diameter. Strict Hole Straightness Required—foundation piling specifications often demand precise verticality. Only concentric systems can guarantee the hole straightness that eccentric drilling inherently cannot provide. Multi-Angle Drilling Required—anchoring, tunneling, and horizontal drilling applications require systems that perform at any inclination. ODEX is limited to vertical operation; Symmetrix works at any angle.

MSD Symmetrix Product Range

Small Diameter (R114-R146): Casing OD 114-146mm, for COP34/DHD3.5/TH3.5 to COP44/DHD340/SD4/QL40 hammers. Weight 10-22kg. Suitable for micropiling and light anchoring.

Medium Diameter (R168-R273): Casing OD 168-273mm, for COP54-COP84/DHD350-DHD380/SD5-SD8/QL50-QL80 hammers. Weight 27-135kg. Most popular range for foundation piling and water well applications.

Large Diameter (R325-R610): Casing OD 325-610mm, for COP84/DHD380/SD8/QL80 to QL200/SD18/NUMA180/TH18 hammers. Weight 135-710kg. Heavy-duty applications for bridge foundations, large-diameter piling, and infrastructure projects requiring maximum hole stability.

Custom Capability: MSD has verified delivery capability for 800mm and 1000mm concentric systems for specialized bridge foundation projects in Southeast Asia.

Proven Field Performance

Taiwan Highway Bridge Foundation Project: MSD Symmetrix 500mm system (with SD15 DTH hammer) was deployed for a major highway bridge foundation piling project facing extreme ground conditions—30 meters of highly unstable loose sand, abrasive riverbed cobbles, and scattered massive granite boulders, all with a high water table. The contractor's previous attempts using rotary drilling and vibratory pile driving failed repeatedly when encountering boulders, causing severe project delays. Results: 100% success rate across all 24 foundation piles drilled to 45-meter design depth. Zero ring bit failures despite continuous heavy boulder impacts. Overall drilling efficiency improved by 40% compared to the client's original methods, recovering weeks of schedule delay. The client confirmed that MSD Symmetrix delivered the same project certainty as European tier-1 brands while reducing their tooling investment by over 35%.

Why Drilling Contractors Trust MSD Symmetrix

In deep foundation piling and boulder-laden overburden, a collapsed hole costs ten times more than the casing system itself. MSD Symmetrix systems are engineered as your ultimate project insurance. We deliver the 100% project certainty and OEM-grade reliability of premium European brands, but with a 30-40% lower capital investment. Trusted by 500+ drilling contractors in 40+ countries, MSD delivers OEM-grade quality at China factory pricing. Our manufacturing base in Zhuzhou—China's tungsten carbide capital—provides direct access to premium carbide materials and ensures responsive delivery on standard sizes, with proven custom capability up to 1000mm diameter for major infrastructure projects.

Why Partner with MSD?

Beyond manufacturing, we provide complete drilling solutions. Our engineers analyze your project's geology and objectives to recommend the ideal Symmetrix system configuration, DTH hammer, and bit combination. By optimizing the entire drilling system, we help you achieve the lowest possible cost per meter and maximize project certainty. With a massive inventory and agile production, we ensure your project stays on schedule. Trust MSD for reliable tools and expert support that deliver your project on time and on budget.

Technical content reviewed by MSD Engineering Team. | About MSD: Zhuzhou Jingde Machinery Co., Ltd. — 23+ years of DTH drilling tools manufacturing expertise | ISO 9001 Certified | Serving 500+ contractors in 40+ countries