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Three Shield Heavy Duty
Screw Anchor
Mechanical expansion anchor with three symmetrically arranged shields providing balanced 360-degree grip. Combines high load capacity with easier installation than four-shield designs. Ideal for general heavy duty anchoring in concrete and solid masonry.
Three Shield Expansion Technology for Reliable Heavy Duty Anchoring
The Three Shield Heavy Duty Screw Anchor represents a refined balance between expansion uniformity and manufacturing efficiency. Unlike four-shield anchors that require precise assembly of four components, the three-shield design uses three expansion shields spaced at 120 degree intervals around the internal cone. This configuration provides excellent load distribution while simplifying manufacturing and reducing cost. The three-shield anchor is the preferred choice for general heavy duty applications where reliability is required but the extreme demands of four-shield redundancy are not necessary.
The operating principle of the three-shield screw anchor follows standard mechanical expansion logic with a twist. The anchor body features a conical expansion section. Over this cone ride three individually formed shields. When the anchor is driven into a pre-drilled hole and the nut is tightened, the cone is drawn upward, forcing the three shields outward against the concrete hole wall. The three-point contact creates a stable, tripod-like grip that resists off-axis loading better than wrap-around clips. The 120-degree spacing ensures that no matter how the load is applied, at least two shields are effectively engaged.
The three-shield design offers several practical advantages over both wrap-around clips and four-shield anchors. Compared to wrap-around clips, the three independent shields provide better tolerance for slightly oversized holes and more uniform load distribution. Compared to four-shield anchors, the three-shield design has fewer components to assemble, lower manufacturing cost, and less risk of shield misalignment during production. The three-shield anchor also requires slightly less embedment depth than four-shield designs because the shields are typically shorter. For these reasons, three-shield anchors are widely used in industrial construction, commercial building projects, and infrastructure applications.
The screw anchor designation refers to the threaded body of the anchor. Unlike through-bolt configurations that require driving through a fixture, the three-shield screw anchor is typically installed directly into concrete with the fixture placed over the protruding threads, or it can be used as a through-bolt with the nut and washer assembled. The anchor is available in both Grade 5.8 and Grade 8.8 carbon steel, with electro-zinc plating as standard. For corrosive environments, hot-dip galvanized and A4 stainless steel three-shield anchors are available upon request.
The shields themselves are manufactured from hardened spring steel, typically 50CrV4 or equivalent. They are stamped from coil stock, heat treated to achieve hardness of 45 to 50 HRC, and then assembled onto the anchor cone. The shield geometry includes a slight taper to facilitate insertion into the hole and a serrated outer edge to increase friction against the concrete. When properly expanded, the shields embed slightly into the concrete surface, creating a mechanical interlock that supplements the friction grip. This interlock provides additional safety margin under dynamic loading conditions.
For contractors and engineers seeking a reliable, cost-effective mechanical anchor for heavy duty applications, the three-shield screw anchor delivers excellent performance. It is easier to install than four-shield anchors, more forgiving of hole quality issues than wrap-around clips, and provides immediate load capacity without chemical curing. The three-shield design has been proven in millions of installations worldwide across industrial plants, commercial buildings, bridges, and infrastructure projects. When the application requires high load capacity but not the extreme redundancy of four-shield anchors, the three-shield heavy duty screw anchor is the optimal choice.
Three Shield Design
Three expansion shields spaced at 120 degrees provide tripod stability. Balanced grip with fewer components than four-shield designs. Easier assembly and lower cost.
Screw Anchor Configuration
Available in standard screw anchor configuration for direct concrete anchoring or through-bolt configuration with permanent washer and nut for fixture-first installation. Fully threaded or partial thread options available.
Wide Material Selection
Available in Grade 5.8, Grade 8.8 carbon steel, hot-dip galvanized, A2 stainless, and A4 stainless. Match anchor material to environmental exposure.
Three Shield Heavy Duty Screw Anchor Specifications
| Parameter | Grade 5.8 Three Shield | Grade 8.8 Three Shield | A4 Stainless Three Shield |
|---|---|---|---|
| Diameter Range | M8 through M24 | M8 through M24 | M8 through M20 |
| Anchor Body Material | Medium carbon steel | Medium carbon alloy steel | A4 stainless 316 |
| Shield Material | Hardened spring steel | Hardened spring steel | Hardened stainless spring steel |
| Tensile Strength MPa Minimum | 500 MPa | 800 MPa | 700 MPa A4-70 |
| Yield Strength MPa Minimum | 400 MPa | 640 MPa | 500 MPa |
| Shield Hardness HRC | 45 to 50 | 45 to 50 | 40 to 45 |
| Standard Lengths | 50mm to 300mm | 50mm to 300mm | 50mm to 250mm |
| Minimum Embedment | 5 times diameter | 5.5 times diameter | 6 times diameter |
Ordering and Availability
Three Shield Technical Support
Need load tables or three shield recommendations for your heavy duty project? Our engineering team responds within 24 hours.
Request Three Shield DataThree Shield Heavy Duty Screw Anchor Applications
Commercial Construction
Steel column base plates, parking garage equipment, mechanical room anchors, and building expansion joint hardware.
Industrial Facilities
Conveyor systems, storage racks, processing equipment, and utility supports in manufacturing plants and warehouses.
Infrastructure
Traffic signal poles, highway sign structures, tunnel lighting, and railroad signal equipment foundations.
Machinery Anchoring
Pumps, compressors, generators, and industrial fans where moderate vibration isolation is required.
Core Advantages of Three Shield Screw Anchors
Tripod Stability
Three-point contact provides inherent stability. Resists tilting and off-axis loading better than wrap-around clips or two-point expansion systems.
Cost Effective
Less expensive than four-shield anchors while providing excellent performance. Balance of reliability and affordability for general heavy duty use.
Forgiving Installation
Three independent shields accommodate slight hole irregularities better than single-piece clips. Less sensitive to drill bit wear than wrap-around designs.
Standard Tooling
Installs with standard hammer drill and torque wrench. No special tools or training required beyond basic wedge anchor installation procedures.
Yuyao Nanshan Development Co., Ltd.
Yuyao Nanshan Development Co., Ltd. was established in 1999 and is located in Ningbo with elegant and charming environments and enjoys convenient transportation.
Yuyao Nanshan Development Co., Ltd. is China Three Shield Heavy Duty Screw Anchor Manufacturers and Wholesale Three Shield Heavy Duty Screw Anchor Factory, specializes in producing Wedge Anchor with professional production equipment. Nanshan has strong technologies with advanced facilities and imported automatic production machines and inspection equipment. Nanshan also is using the ERP to control the production process line and has set up a research & development center for continued innovation and to meet the requirements of more and more customers from all over the world.
Our products extensively are used in steel high constructions, tunnel projects, bridges, railways, airport stations, high way, sea ports, nuclear power plants, and so on.
Yuyao Nanshan Development Co., Ltd. adheres to the principle of "quality the eternal base, credit forever pursuit", we will spare no effort to provide our customers with more stable quality and more wonderful service.
Three Shield Screw Anchor Installation Procedure
Drill Hole
Using hammer drill with carbide-tipped bit matching anchor diameter exactly. Drill hole to depth equal to required embedment plus 15mm for dust accumulation. Maintain perpendicularity within 2 degrees of surface.
Clean Hole Thoroughly
Use two complete blow and brush cycles minimum. Three cycles recommended for critical applications. Dust is the primary cause of reduced anchor performance.
Insert Anchor
Assemble washer and nut flush with top of anchor threads. Insert anchor into hole. Drive using hammer until washer contacts fixture surface or concrete face.
Torque to Value
Using calibrated torque wrench, apply torque in three increments: 30 percent, 70 percent, and 100 percent of final torque. Three shield anchors use same torque values as standard wedge anchors of equivalent diameter and grade.
Three Shield Installation Tips
- Minimum embedment 5.5 times diameter for Grade 8.8 three shield anchors.
- Minimum edge distance 6 times diameter from any free edge.
- Minimum spacing 10 times diameter center to center for groups.
- Apply torque smoothly — jerky torque application may cause uneven shield expansion.
- Three cleaning cycles recommended for heavy duty or vibratory applications.
- Do not reuse anchors — shields permanently deform during expansion.
Tools Required
Three Shield vs. Four Shield vs. Wrap-Around Anchors
Three Shield Anchor Quality Control Program
Shield Hardness
Sample shields from each batch tested to 45 to 50 HRC for consistent expansion force without deformation.
Shield Alignment
100 percent visual inspection confirms all three shields evenly spaced at 120 degrees and seated correctly on cone.
Tensile Testing
Destructive testing per ISO 898-1. Grade 8.8 minimum 800 MPa tensile strength verified each batch.
Salt Spray Testing
Zinc plated samples tested to ASTM B117 72 to 96 hours without red rust.
Three Shield Anchor Design Parameters
Minimum Embedment
Grade 8.8 three shield anchors require 5.5 times diameter minimum embedment. Grade 5.8 anchors may use 5 times diameter for non-critical applications. Shallower embedment reduces pull-out capacity.
Edge Distance
Three-point expansion distributes load effectively. Minimum edge distance 6 times diameter for full capacity. Reduced edge distance requires load reduction factors per ACI 318.
Anchor Spacing
Three shield anchors in groups perform well. Minimum spacing 10 times diameter center to center for full group efficiency. Closer spacing requires group reduction factors.
Concrete Strength
Minimum concrete strength for three shield anchors is C25/30 for Grade 8.8, C20/25 for Grade 5.8. Lower strength concrete may result in concrete breakout failure before anchor steel yields.
Environmental Responsibility in Three Shield Manufacturing
Three shield anchors manufactured with sustainable practices and full environmental compliance.
RoHS and REACH Compliance
Zinc plating Cr6+ free. Spring steel from recycled content mills.
100 Percent Recyclable
Steel anchor and shields fully recyclable at end of life.
Reduced Manufacturing Energy
Three shield design requires fewer components and less assembly energy than four-shield anchors.
Three Shield Screw Anchor Production Process
Cold Heading Body
Anchor body cold headed from wire. Integral cone formed in same operation. Threads rolled after forming.
Shield Stamping
Spring steel coil stamped into shield shape. Induction hardened to 45 to 50 HRC. Three shields per anchor assembled.
Three Shield Assembly
Shields placed onto cone at 120 degree spacing. 100 percent visual inspection confirms correct shield position before plating.
Three Shield Production Process Flow
Three Shield Anchor Ultimate Load Capacity Grade 8.8
Values shown for Grade 8.8 three shield heavy duty screw anchors in solid non-cracked concrete C25/30. Minimum embedment equals 5.5 times anchor diameter. Safety factor of 4 to 1 applies for working loads in general structural applications. For Grade 5.8 anchors, reduce tensile and shear values by approximately 30 percent.
| Diameter mm | Min Embedment mm | Ultimate Tensile kN | Ultimate Shear kN | Recommended Torque Nm | Min Concrete Thickness mm |
|---|---|---|---|---|---|
| M8 | 44 | 13.8 | 10.8 | 28 | 95 |
| M10 | 55 | 22.0 | 17.0 | 52 | 120 |
| M12 | 66 | 32.0 | 25.0 | 90 | 145 |
| M16 | 88 | 56.0 | 45.0 | 220 | 195 |
| M20 | 110 | 87.0 | 67.0 | 450 | 240 |
| M24 | 132 | 126.0 | 96.0 | 720 | 290 |
Professional Three Shield Anchor Installation Checklist
Pre-Installation Verification
- Confirm concrete strength minimum C25/30 for Grade 8.8 three shield anchors.
- Verify edge distance at least 6 times anchor diameter from any free edge.
- Verify anchor spacing at least 10 times diameter center to center for groups.
- Inspect each anchor before installation. All three shields must be evenly spaced and move freely on cone.
- Ensure drill bit is carbide-tipped and exact diameter. Worn bits cause oversized holes.
- Calibrate torque wrench within 6 months.
Installation Execution
- Drill hole to depth equals embedment plus 15mm minimum for dust accumulation.
- Clean hole using two complete blow and brush cycles minimum. Three cycles recommended for heavy duty applications.
- Assemble washer and nut flush with anchor top.
- Insert anchor into hole ensuring all three shields enter without catching.
- Drive anchor using hammer until washer contacts fixture surface.
- Apply torque in three increments: 30 percent, 70 percent, 100 percent.
- Record torque value for quality documentation.
Shield Inspection Before Installation
- Check that all three shields are present. Three shield anchors have exactly three shields.
- Verify shields are evenly spaced at approximate 120 degree intervals.
- Shields should move slightly when pressed. They should not be stuck or frozen in place.
- Shield tips should be at approximately same height.
- Shield edges should be smooth without burrs.
Critical Warning: Do not install three shield anchors without inspecting shields. Damaged or misaligned shields will not expand properly and will reduce anchor capacity below design values.
Standards and Approvals for Three Shield Screw Anchors
European Standards
EN 1992-4 for mechanical anchors. EN ISO 898-1 for fastener mechanical properties. EN 10204 Type 3.1 certification available.
ASTM Testing Methods
ASTM F606 mechanical testing. ASTM B117 salt spray. ASTM A153 zinc coating. ASTM E8 tensile testing.
ISO Standards
ISO 9001:2015 certified manufacturing. ISO 898-1 property class compliance. ISO 4042 for plating requirements.
ICC-ES Evaluation
Evaluation report available for three shield anchors. Contact engineering team for current report number.
Recommended Torque for Three Shield Heavy Duty Screw Anchors
| Diameter mm | Dry Threads Nm | Lubricated Threads Nm | Torque Multiplier Required | Verification Torque Required |
|---|---|---|---|---|
| M8 | 28 | 22 | No | Recommended for critical anchors |
| M10 | 52 | 42 | No | Recommended for critical anchors |
| M12 | 90 | 72 | No | Recommended for critical anchors |
| M16 | 220 | 176 | No for M16 | Yes for heavy duty applications |
| M20 | 450 | 360 | Yes | Yes for heavy duty applications |
| M24 | 720 | 580 | Yes | Yes for heavy duty applications |
Safety Factors for Three Shield Heavy Duty Anchors
| Application Category | Example | Steel Failure | Concrete Breakout | Recommended Working Factor |
|---|---|---|---|---|
| Non-structural | Signage light fixtures | 3.0 | 3.5 | Use 4.0 |
| General structural | Steel columns equipment | 4.0 | 4.5 | Use 5.0 |
| Moderate vibration | Pumps compressors fans | 4.5 | 5.0 | Use 5.5 |
| Safety critical | Overhead cranes fall protection | 6.0 | 7.0 | Use 7.0 |
Payment and Shipping for Three Shield Anchors
Payment Methods
Shipping Ports
Packaging
Three Shield Heavy Duty Screw Anchor Frequently Asked Questions
Corrosion Protection for Three Shield Heavy Duty Anchors
| Environment Description | Recommended Coating | Service Life Years | Special Considerations |
|---|---|---|---|
| Dry indoor heated no condensation | Electro-zinc 5 micron | 50 plus | No corrosion expected |
| Indoor with occasional condensation | Electro-zinc 8 micron yellow | 30 to 40 | Yellow passivation provides higher corrosion resistance |
| Sheltered outdoor under roof | Electro-zinc 12 micron with sealer | 15 to 20 | Shield tips may show first corrosion |
| Outdoor rural direct rain | Hot-dip galvanized | 20 to 30 | HDG recommended for outdoor use |
| Outdoor urban deicing salts | A4 stainless steel | 30 plus | Stainless required for salt exposure |
| Coastal within 1 kilometer | A4 stainless steel | 30 plus | A2 stainless not sufficient for coastal |
Chemical Resistance of Three Shield Carbon Steel Anchors
| Chemical | Concentration | Carbon Steel Body | Spring Steel Shields | Recommendation |
|---|---|---|---|---|
| Fresh water | Any | Good | Good | Suitable for indoor use. Inspect periodically if immersed. |
| Seawater or brine | 3.5 percent | Poor | Poor | Not suitable. Use A4 stainless three shield anchors. |
| Hydrochloric acid | Any | Very Poor | Very Poor | Do not use in acid environments. |
| Sulfuric acid dilute | Up to 10 percent | Very Poor | Very Poor | Not suitable. Severe corrosion. |
| Sodium hydroxide | Up to 10 percent | Fair | Fair | Limited exposure only. Stainless recommended. |
| Chlorine gas wet | Any | Very Poor | Very Poor | Not suitable. |
Three Shield Anchor Case Studies
Three shield anchors for 40 foot high steel storage rack anchoring.
M16 Grade 8.8 three shield anchors were specified for row end rack anchors. Over 12000 anchors installed in C30/37 concrete floor. After 5 years of operation with daily forklift traffic and rack impacts, no anchor failures or loosening were observed. The three shield design provided cost savings over four shield anchors while delivering required performance.
Key learning: Three shield anchors are ideal for high-volume rack anchoring where reliability is required but extreme vibration is not present.
A4 stainless three shield anchors for corrosive environment in aeration basin equipment.
M12 A4 stainless three shield anchors were installed in concrete aeration basins. The environment includes hydrogen sulfide, humidity, and periodic chemical washdown. After 4 years of service, anchors show no corrosion. Standard carbon steel anchors previously required replacement every 2 years.
Key learning: For corrosive environments, A4 stainless three shield anchors provide long service life at lower cost than A4 four shield anchors.
Glossary of Three Shield Anchor Terminology
Three Shield Anchor
Mechanical expansion anchor with three expanding shields spaced at 120 degrees. Provides balanced grip and tripod stability.
Screw Anchor
Anchor configuration where the fixture is placed over protruding threads after anchor is set. Contrast with through-bolt design.
Shield
Individual expansion element that contacts concrete hole wall. Three shield anchors have three shields.
120 Degree Spacing
Equal spacing between the three shields. Provides symmetrical expansion force distribution.
Tripod Stability
Inherent stability from three-point contact. Resists tilting and off-axis loads better than wrap-around clips.
Shield Hardness
Spring steel shields hardened to 45 to 50 HRC. Provides wear resistance without brittleness.
Partial Redundancy
If one shield fails to expand properly, the remaining two shields still provide some holding capacity.
Expansion Ratio
Three shield anchors expand 1.5 to 2.0mm depending on diameter and concrete strength.
Three Shield Anchor Documentation Package
For heavy duty industrial and commercial projects, we provide comprehensive documentation including shield hardness verification and tensile test results. Third-party inspection is available upon request. All records are maintained for minimum 10 years.
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Need Three Shield Anchors for Your Project?
Three shield anchors provide the perfect balance of performance and cost for most heavy duty applications. Contact our team for technical data and competitive quotations.
