I. Product Overview

1.1 Product Positioning

FRP nuts are high-performance fasteners specifically engineered to pair with FRP rock bolts, serving as critical load-bearing components in rock bolt support systems. Reinforced with high-strength fiberglass and molded from weather-resistant resin via high-temperature compression or pultrusion curing, they are seamlessly compatible with the full-thread specifications of FRP rock bolts. Widely used in coal mine roadway support, traffic slope protection, tunnel and bridge reinforcement, water conservancy slope stabilization, and building foundation strengthening, these FRP nuts represent a modern non-metallic alternative to traditional metal nuts and standard nylon nuts.

Role of 1.2 products in the support system

As a core component of the rock bolt support system, the fiberglass nut works in tandem with the fiberglass bolt rod and the fiberglass (or reinforced nylon) plate to form a complete non-metallic anchorage support system. Its specific functions include:

• Lock Anchoring Force:Thread-lock the anchor rod body to transfer anchorage force to the plate, compressing the surrounding rock surface and ensuring the anchor system achieves its designed performance.
• Load Transfer and Dispersion:Effectively transfers the tensile load from the anchor rod to the bearing plate, which then distributes the force uniformly across the surrounding rock surface, significantly increasing the reinforcement area per anchor.
• Apply Preload:Acts as the anchor point for applying preload. Tightening applies the required initial tension to the anchor rod, actively restraining surrounding rock deformation and bonding multiple soil/rock layers into a single unit, significantly enhancing the ground's self-bearing capacity.

1.3 Industry Development Background

In traditional bolt support systems, matching nuts are typically made of carbon steel or alloy steel. However, metal nuts are highly susceptible to rust and corrosion in humid underground environments and corrosive rock conditions, leading to seized threads, inability to disassemble, or loss of anchoring force. This severely compromises the long-term safety of the support system. With the increasing adoption of fiberglass bolts in mining and tunneling projects, demand for non-metallic matching nuts has grown significantly. Currently, industry-standard fiberglass bolt nuts fall into two main categories: nylon nuts and fiberglass nuts. Leveraging superior strength, durability, compatibility, and high safety factors, fiberglass nuts are gradually replacing traditional nylon and metal nuts, emerging as the preferred solution for high-end anchorage support engineering and operations under complex, harsh conditions.

2. Product Categories and Specification System

2.1 by Material

Currently, fiberglass anchor bolts are primarily paired with two types of nuts on the market. These products differ significantly in performance and are suited to different applications:

2.2 by specification and model

Current mainstream products feature a complete specification system designed to perfectly fit the full range of fiberglass anchor bolts, including Φ16, Φ18, Φ20, Φ22, Φ25, Φ28, and Φ32. Detailed specifications are listed below:

Threaded connection capacity exceeds 14 kN; overall joint capacity fully covers the 50–120 kN range and meets or exceeds the yield load of the equivalent rod.

2.3 by structural design

• Hex Nut:Standard hex shape; installable with a regular wrench, pneumatic wrench, or torque wrench. Suitable for most conventional construction scenarios.
• Lock Nut:Circular design, typically used with dedicated installation tools. Ideal for projects with space constraints or specific aesthetic requirements.

2.4 Classified by Flame Retardancy and Antistatic Rating

• Standard:Meets general engineering requirements for insulation and corrosion resistance; suitable for tunnels, slopes, excavations, and other projects without special explosion-proof needs.
• Flame Retardant and Anti-StaticEngineered with a flame-retardant and antistatic compound, surface resistivity meets underground coal mine safety standards (≤3×10⁸Ω), making it suitable for high-risk environments such as high-gas mines that require stringent explosion-proof and antistatic protection.

3. Core Materials and Manufacturing Processes

3.1 Raw Material System

FRP nuts are manufactured using high-quality raw materials to ensure mechanical and durability performance meet design requirements:

• Reinforcement Material:Constructed with premium E-glass fiber yarn, with fiber content maintained between 50% and 70% to deliver exceptional tensile strength and impact resistance.
• Matrix Resin:Uses high-performance unsaturated polyester resin, vinyl ester resin, or epoxy resin as the matrix. Select the resin system based on the operating environment:
  • Unsaturated Polyester Resin: Cost-effective; suitable for standard operating conditions.
  • Vinyl Ester Resin: Superior corrosion resistance for harsh acidic/alkaline and high-humidity environments
  • Epoxy: Best mechanical performance for ultra-high load critical engineering applications.
• Functional Fillers:Scientifically introduce wollastonite needle fibers as reinforcing fillers to effectively enhance wear resistance and creep performance.
• Additive System:Improve processability with fumed silica and enhance fiber-resin interfacial adhesion using silane coupling agents.
• Functional Additives:Add flame retardants and antistatic agents in specified proportions to ensure the product meets underground safety requirements.

3.2 Manufacturing Process

This product is manufactured using advanced prepreg molding or pultrusion processes:

1. Prepreg Manufacturing:Blend glass fiber yarn with resin matrix, fillers, and additives according to a precise formulation to produce uniform prepreg. Strictly control fiber and resin content consistency across batches to ensure product quality stability.
2. Molded:Weigh the prepreg precisely according to the design weight and place it into the precision mold cavity. After closing the mold, apply high temperature (typically 140°C–180°C) and high pressure (10–25 MPa) to heat, pressurize, and cure the part. During this process, the resin flows thoroughly and impregnates the reinforcement material, then undergoes cross-linking and curing reactions under high temperature to form a three-dimensional network structure.
3. Pressure curing:Hold at the specified temperature and pressure for a set duration (typically 3–10 minutes, depending on product thickness) to ensure complete resin curing, resulting in a dense internal structure free of bubbles and clear, complete thread profiles.
4. Demolding and Trimming:After curing, remove the product from the mold. Trim flash and burrs, then inspect with a thread gauge to ensure precise, clean threads with tight engagement and no stripping.
5. Post-processing (optional):Surface finishing or secondary processing per customer requirements.

3.3 Process Advantages

Compared to simple manual processing, molding and pultrusion offer significant advantages:

• Uniform product density:Molded under high temperature and high pressure; free of bubbles, cracks, or delamination defects.
• High dimensional accuracy:Precision-machined molds ensure accurate thread profiles, with the clearance between the bolt body threads controlled within an optimal range.
• Consistent batch quality:Process parameters are fully controllable, ensuring minimal batch-to-batch performance variation and quality stability that far exceeds industry standards.
• High production efficiency:Short molding cycle; ideal for high-volume continuous production.

IV. Core Performance Advantages

5. Material Comparison and Selection Analysis

5.1 Fiberglass Nut vs. Traditional Steel Anchor Nut

Conclusion:In conventional geotechnical projects without special explosion-proof requirements, steel nuts are still used. However, in coal mine underground environments, damp conditions, or projects requiring insulation or explosion-proofing, fiberglass nuts offer irreplaceable advantages.

5.2 Fiberglass Nut vs. Nylon Nut

Conclusion:For core engineering applications with stringent support safety requirements—such as permanent mine roadways, deep-level mining, high-stress zones, and highly corrosive environments—fiberglass nuts are the superior choice. Nylon nuts are suitable only for low-load, short-term scenarios like face protection and temporary support.

5.3 Selection Recommendation

VI. Application Areas

VII. Technical Specifications Overview

8. Installation and User Guide

Pre-installation check for 8.1

• Inspect nut thread integrity; confirm absence of cracks, missing threads, broken threads, burrs, or other defects.
• Verify that the nut thread specification fully matches the anchor bar body thread; ensure smooth rotation without binding.
• Check that the matching tray is intact and matches the specifications.

8.2 Installation Steps

1. Step 1: Install Anchor Bolts

   Install the fiberglass anchor rod and mix the resin cartridge according to design specifications. Allow the resin to fully cure and reach the specified strength.

2. Step 2: Tray Installation

   Place the tray (FRP or reinforced nylon) firmly against the surrounding rock surface, ensuring the center hole aligns with the anchor rod. The tray must be flush against the rock face with no gaps or tilting.

3. Step 3: Install Nut

   Manually thread the fiberglass nut onto the threaded end of the anchor rod until it contacts the plate. The manual insertion should be smooth without any binding. If resistance is encountered, check for thread mismatch or damage.

4. Step 4: Apply preload

   Apply the design preload torque to the nut using a pneumatic impact wrench or a torque wrench. The preload torque must be strictly controlled within the design range: insufficient torque fails to effectively restrain surrounding rock deformation, while excessive torque may cause thread overload damage to the nut or yield failure of the anchor rod body. Reference values for common preload torque: For Φ20 anchor rods with matching nuts, the recommended torque is 80-120 N·m; however, always refer to the engineering design documents for specific requirements.

5. Step 5: Quality Check

   After installation, verify that the nuts are tightly seated against the tray with no looseness. If necessary, perform spot checks using a torque wrench to confirm that preload requirements are met.

8.3 Installation Notes

• Do not apply lubricants or any substances that may reduce the coefficient of friction to the nut threads, as this could cause loosening under dynamic loads.
• Avoid using impact tools with excessive torque to prevent thread damage or sudden overload failure.
• For projects requiring flame retardancy and antistatic properties, do not use tools or auxiliary materials that may contaminate or damage the product surface during installation.
• If a nut shows cracks, damage, or thread defects during installation, replace it immediately. Do not force its use.
• In coal mining faces, fiberglass nuts can be cut directly with the anchor bolts without requiring dedicated removal prior to extraction.

8.4 Storage and Handling Requirements

8.5 Safety Precautions

• Although FRP nuts are made of flame-retardant and anti-static materials, prolonged exposure to open flames or extreme heat sources should still be avoided.
• Dispose of discarded fiberglass nuts in accordance with industrial solid waste regulations, using landfill or incineration methods. Do not discard them indiscriminately.
• Dust may be generated during product cutting or grinding. Operators must wear protective masks and safety goggles.

9. Custom Services

Anhui Send New Material Technology Development Co., Ltd. provides comprehensive customized services tailored to meet diverse customer operating conditions:

10. Quality Assurance and Service System

10.1 Quality Control System

Anhui Sende New Material Technology Development Co., Ltd. operates standardized production workshops and is equipped with a full suite of automated compression molding and pultrusion machinery, backed by a comprehensive quality control system.

• All products strictly adhere to scientific material formulations, utilizing premium alkali-free glass fiber and high-temperature resistant, corrosion-resistant resins.
• Every batch undergoes sampling tests for compressive strength, torsional strength, thread load capacity, and corrosion resistance.
• One-piece molded, uniform density, bubble-free, crack-free, and precisely threaded.
• Strictly adheres to industry standards such as MT/T 1061-2008, ensuring no defective products leave the factory. Product stability and consistency far exceed industry averages.

10.2 Pre-sales Technical Support

Our dedicated technical team provides comprehensive pre-sales services, including product selection, application-specific solutions, and technical parameter consulting. We help you identify the optimal product solution to prevent safety risks and cost overruns caused by incorrect selection.

10.3 After-Sales Guarantee

Ample production capacity and stable inventory enable us to fulfill large-volume orders, ensuring on-time delivery without project delays. Our rapid after-sales response is backed by a dedicated team that supports your project from start to finish, promptly resolving any procurement or usage issues—so you can purchase with confidence and use with peace of mind.