As the core storage facility for temperature-controlled goods such as fresh produce and pharmaceutical products, cold-chain warehouses maintain a low-temperature environment—typically - 30℃ to 10℃ ) Special requirements are put forward for the material performance of heavy-duty shelving —— It must simultaneously withstand multiple challenges, including low-temperature embrittlement, condensation corrosion, and load fluctuations. According to the China Federation of Logistics & Purchasing’s… 2024  According to data from the "Annual Cold Chain Warehousing Equipment White Paper," shelf failures caused by improper material selection account for a significant portion of cold chain warehouse safety incidents. 38% , direct economic losses average over 20  Billions of yuan. This article systematically examines the material selection logic for heavy-duty cold-chain racking from three perspectives: environmental challenges, material requirements, and selection practices, providing enterprises with a scientific reference.

I. The Special Challenges Posed by the Low-Temperature Environment of Cold-Chain Warehouses to Heavy-Duty Racks

The cold-chain warehouse's “ Low temperature +  High humidity ”  The complex environment differs fundamentally from ambient-temperature storage, requiring shelf materials to withstand issues such as degraded physical performance, accelerated corrosion, and diminished structural stability. Additionally, the intensity of challenges varies significantly across different low-temperature ranges.

1.1 Low-Temperature Zone Division and Differences in Environmental Characteristics

Cold-chain warehouses can be classified by temperature into refrigerated warehouses ( 0℃ to 10℃ ), freezer ( -18℃ to -25℃ )、Deep Freezer ≤ -30℃ ) Three categories— the lower the temperature, the more stringent the material performance requirements:

• Refrigerated storage room 0℃ to 10℃ ） : The core challenge is “ Temperature Difference Condensation Water “—— The temperature difference between inside and outside the warehouse causes moisture in the air to condense on the shelf surfaces, creating a persistently humid environment that accelerates oxidative corrosion of metal materials.
• Freezer -18℃ to -25℃ ） : Besides condensation water (which repeatedly freezes and thaws after turning into ice), low temperatures can cause materials like steel to “ Decreased toughness, increased brittleness ” , easily fractured when impacted;
• Deep Freezer ≤ -30℃ ） Under extreme low temperatures, material molecular activity slows down, significantly reducing impact toughness, and increasing the risk of fracture in ordinary steel compared to ambient conditions. 4 to 6 Multiple (Data source: GB/T 25800-2023 Appendix to "General Technical Specifications for Storage Racks" C ）。

1.2 The Core Risk of Shelf Material Failure in Low-Temperature Environments

Low-temperature environments through “ Physical degradation +  Chemical corrosion ”  Dual effects lead to the failure of shelf materials, specifically manifesting as three types of risks:

• Brittleness Fracture Risk : The properties of metallic materials at low temperatures “ Yield strength increases, while impact toughness decreases. ” , such as ordinary Q235 Steel in - 20℃ Impact energy at the moment AKV ) Is merely at room temperature 50% , if the cargo collides (e.g., due to forklift operation errors), the columns or beams are likely to break directly;
• Corrosion and Wear Risk : Condensation water, combined with residual cold-chain materials (such as fresh-juice liquids and pharmaceutical reagents), forms an acidic environment. / In alkaline corrosive environments, ordinary galvanized coatings can corrode at a rate of up to per year in freezer warehouses. 5~8 μm ， 3 to 5 Rust-through appeared as early as then (refer to the "Technical Specification for Corrosion Protection of Cold-Chain Storage Equipment") WB/T 1125-2023 ));
• Risk of Structural Loosening : Low temperatures exacerbate the difference in thermal expansion and contraction coefficients between shelf connectors (such as bolts and pins) and the main material, making them prone to issues after prolonged use. “ Cold-shrink loosening ” , shelf load stability has declined. According to statistics from an e-commerce cold-chain warehouse, shelves that do not use low-temperature-compatible connectors require maintenance as often as once a year. 8  Next time /  The group is the compliant shelf. 3  Twice.

(Cold Storage Shelving)

II. Core Material Requirements for Heavy-Duty Racks in Low-Temperature Environments

Given the unique characteristics of the cold-chain environment, the materials for heavy-duty shelving must be carefully selected. “ Low-temperature toughness, corrosion resistance, and structural compatibility ”  The three major dimensions meet clear standards, while the requirements for different components—such as the main frame, connectors, and coatings—show nuanced distinctions.

2.1 Primary frame material: Prioritize low-temperature tough steel.

The shelf structure—consisting of upright posts and crossbeams—as the core load-bearing components, must be made from materials that possess “ Low-temperature impact toughness ”  The steel must meet the following key specifications:

• Material Model Refrigerated storage room 0℃ to 10℃ ) Available options include Q355B Steel; freezer -18℃ to -25℃ ）Needs to be upgraded to Q355D (Applicable to - 40℃ Low temperature); Deep freezer ( ≤ -30℃ ）Needs to adopt Q355ND (With superior low-temperature toughness), it is in - 40℃ The impact energy at the time ( AKV ） ≥34J , far higher than the average Q235 Steel -20℃ Time AKV ≤ 20 J );
• Mechanical Properties : Yield strength deviation under low temperatures must ≤±5% , Tensile strength ≥470MPa , avoid load imbalance caused by intensity fluctuations;
• Grain Control : Steel must undergo “ Grain Refinement Treatment ” , Grain diameter ≤50μm , reducing the risk of intergranular fracture at low temperatures, such as those produced by Baosteel Q355ND Steel, through controlled rolling and controlled cooling processes, achieves a grain refinement rate of 92% , Enhanced low-temperature toughness 30% (Data source: Baosteel's "Technical White Paper on Low-Temperature Shelf Steel") 2024 ）。

2.2 Connector material: Dual standards for cold-shrink resistance and corrosion protection

Although connecting components—such as bolts, nuts, and crossbeam pins—are small in size, they directly affect the structural stability of the shelving system, so their material must meet specific requirements. “ Low-Temperature Anti-Loosening +  Corrosion-resistant ”  Dual requirements:

• Bolt material : Prioritize the selection 316L Stainless steel (with superior corrosion resistance to 304  Stainless steel) or low-temperature alloy steel bolts (such as 20MnTiB Steel), which is in - 40℃ The elongation at break at the time ≥15% , avoid thread stripping caused by thermal contraction;
• Anti-Loosening Design : Requires adoption “ Double-nut lock washers ”  Or “ Low-Temperature Adaptive Elastic Washer ” (Such as hydrogenated nitrile rubber gaskets, with a temperature resistance range of - 40℃ to 120℃ ), preventing loosening caused by temperature changes, testing at a pharmaceutical cold-chain warehouse showed that the connectors employing this design achieved an annual loosening rate of 12% Drop to 1.5% ；
• Surface Treatment : The connector must undergo “ Dacromet Coating ”  Handling (Salt Spray Test) ≥1000 Hours), superior to ordinary galvanized steel (salt spray resistance ≤500 Hours), capable of resisting corrosion from condensation and residual materials.

2.3 Surface coating material: Resistant to low-temperature cracking and corrosion

The shelf surface coating must remain stable at low temperatures. “ Strong adhesion, crack-free, and corrosion-resistant ” , the core technical indicators must meet the following standards:

• Coating Type : Prioritize the selection “ Low-temperature curing epoxy powder coating ” , Solidification temperature ≤180℃ To avoid high-temperature curing that could lead to a decline in the mechanical properties of steel, the coating thickness must reach 60–80 μm (Standard storage racks are 40–60 μm );
• Low-temperature performance : At - 40℃~50℃ During the cyclic temperature test, the coating showed no cracking or peeling (meeting the requirements of GB/T 1732-2020 "Method for Determining Impact Resistance of Coatings"), Adhesion ≥5MPa (Grid Method Test);
• Corrosion resistance : Neutral Salt Spray Test ≥1200 Hours ( GB/T 10125-2021 ), corrosion area of the coating after salt spray ≤5% , ensuring long-term durability even in condensation environments.

2.4 Cold Chain Shelf Core Material Performance Comparison Table

III. Practical Considerations for Cold-Chain Shelving Selection Based on Material Requirements

Considering the characteristics of low-temperature environments and material standards, the selection of heavy-duty cold-chain shelving must adhere to “ Environmental Assessment → Material Verification → Performance Testing → Scene Adaptation ”  A four-step process that simultaneously avoids common pitfalls, ensuring the shelf system operates smoothly and reliably over the long term.

3.1 The Four-Step Selection Process: End-to-End Control from Requirement to Implementation

3.1.1 Step 1: Precise Assessment of Environmental Parameters

First, clearly define the core parameters of the cold-chain warehouse, including:

• Temperature range (e.g., - 25℃ Freezer), humidity (usually 60% to 85% );
• Storage material types (such as fresh produce—includes liquids—and pharmaceuticals—require protection against chemical corrosion);
• Payload requirements (e.g., static load per layer) 1.5 tons , Dynamic Load 0.8t );
• Assignment frequency (e.g., average daily forklift operations) 50 Next time /  Group, consider the impact frequency).

A case study of a fresh-food cold-chain enterprise shows that shelves selected after precise environmental assessment have significantly lower failure rates compared to those chosen blindly. 62% (Data source: China Chain Store & Franchise Association’s “ 2024  Cold Chain Warehousing Operations Report》.

3.1.2 Step 2: Strict Verification of Material Qualifications

Require suppliers to provide the following material certification documents to avoid “ Passing off inferior goods as superior. ”：

• Steel Material Certificate (including the low-temperature impact toughness test report, if applicable) Q355ND Of the - 40℃ AKV Test data);
• Corrosion Resistance Test Report for Salt Spray of the Connector (Required ≥1000 Hours);
• Coating Low-Temperature Cycle Test Report -40℃ to 50℃ No cracking.)

Key Verification “ Low-Temperature Adaptation Label ” , such as Q355ND Steel must have “ND” Use low-temperature grade markings—avoid using standard ones. Q355B Steel impersonation.

3.1.3 Step 3: On-site Performance Simulation Testing

Conduct on-site testing of critical components, including:

• Low-temperature impact testing: Using a falling-weight impact tester (compliant with GB/T 229-2020 ) Test the beam, -40℃ No cracks after the impact test indicate qualification;
• Coating adhesion test: After scoring with a grid cutter, no coating detachment was observed when the tape was peeled off.
• Connector cold-shrink test: At - 30℃ Standing still in the environment 24  Hours, bolt torque decay ≤5% Qualified.

3.1.4 Step 4: Scenario-Based Structural Adaptation

Optimize shelf structures based on storage scenarios, and enhance stability by leveraging material properties.

• Freezer: Adopting “ Double-column +  Diagonal bracing reinforcement ”  Structure that minimizes deformation at low temperatures;
• Deep Freezer: Selected “ Lightweight crossbeam ” (As for Q355ND Thin-walled steel sections, reducing the self-weight load on the main frame;
• Fresh Food Storage: Added beneath the shelf shelves “ Condensate Drain Channel ” , reduce coating corrosion.

3.2 Common Selection Pitfalls and Avoidance Strategies

3.3 Typical Scenario Selection Case Study: A Practical Guide from Requirements to Outcomes

3.3.1 Case 1： -25℃ Fresh and Frozen Food Storage (Meat Storage)

• Environmental characteristics: Low temperature, high humidity, and materials containing oily juices (which are highly corrosive);
• Shelf material selection:
  • Main framework: Q355ND Steel -40℃ AKV = 42J );
  • Connector: 316L Stainless steel bolts (salt-spray resistant) 1200  Hours);
  • Coating: Low-temperature epoxy powder (thickness 75μm , Salt Spray Resistance 1500  Hours);
• Running result: Using 3 No coating corrosion over the years, connectors remain secure, and failure rate is low. 0.3%/ Year.

3.3.2 Case 2： -35℃ Pharmaceutical Deep-Freezer (Vaccine Storage)

• Environmental features: Extreme low temperatures, low humidity ( 40% to 50% )、No chemical corrosion;
• Shelf material selection:
  • Main framework: Q355ND Steel (grain refinement treatment, -40℃ AKV = 45J );
  • Connector: 20MnTiB Steel bolts (Dacromet-coated, salt-spray resistant) 1000  Hours);
  • Coating: Low-temperature epoxy powder (thickness 80μm ， -40℃ to 50℃ Cyclic, no cracking);
• Running result: Using 5 This year, the shelf structure remained free of deformation, and the impact test still met the standards.

Conclusion

The choice of material for heavy-duty shelving in cold-chain warehouses essentially comes down to... “ Matching Engineering for Low-Temperature Environments and Material Performance “—— The key indicators should include low-temperature toughness, corrosion resistance, and structural compatibility. By conducting precise assessments, rigorous verification, and scenario-specific adaptation, we can effectively mitigate the risk of material failure. As the cold-chain industry moves toward “ Deep cryogenics, high turnover ”  Upgrade (e.g., - 40℃ The proportion of ultra-low-temperature cold storage facilities has decreased from 2020  Year's 8% Rise to 2024  Year's 15% ), material standards will be further enhanced, as the application of technologies such as new low-temperature alloy steel and nano-ceramic coatings will drive cold-chain shelving toward “ More durable, lower-carbon ”  Directional development. For enterprises, scientifically selecting equipment not only reduces the risk of safety incidents but also extends shelf life—ranging from 5 to 8 The year is extended to 10 to 15 year), ultimately achieving cost reduction and efficiency improvement in cold-chain warehousing.