As the core supporting structure of warehouse systems, the stability of shelving directly determines storage safety and operational efficiency. Meanwhile, the verticality of column installation serves as the "lifeline indicator" for shelving structures—once deviations exceed allowable limits, it not only leads to uneven load distribution and increases the risk of goods tipping over, but may also shorten the shelf's service life and even trigger safety incidents. This article explores the critical value of verticality, clarifies detection standards and methods, and proposes comprehensive lifecycle management strategies, helping companies establish a scientific system for shelving installation and maintenance.

(Shelf Post)

I. The Core Value of Shelf Column Installation Perpendicularity: The Cornerstone of Stability and Safety

The upright posts are responsible for supporting the weight of the shelf. “ Skeleton ” , its vertical deviation can amplify risks through structural transmission, creating cascading effects on warehouse safety, operational costs, and compliance. The China Warehousing and Distribution Association ( CWDA ）《 2024  The "Annual Report on Warehouse Rack Safety Accidents" reveals that rack collapses and cargo damage incidents caused by不合格立柱垂直度 account for a significant proportion. 35% , far surpassing other installation issues such as loose connectors and ground subsidence, highlighting the necessity of verticality control.

1.1 Directly determines load-bearing safety: Avoiding the risk of structural instability

Shelf columns must vertically transfer the weight of the goods to the ground; if there is any tilting deviation, it will cause the force to shift from “ Axially Uniformly Loaded ”  Transform into “ Eccentrically Loaded ” , significantly reducing structural load-bearing capacity:

• Load-bearing attenuation data : According to the "Warehouse Rack Structure Design Code," GB/T 27924-2021 ) Calculation shows that when the column's vertical deviation exceeds 1‰ At that time, the rated load capacity of a single column will decrease. 15%-20% ; If the deviation reaches 3‰ , the load-bearing capacity will directly decrease 40% Above all, irreversible damage such as column bending and beam deformation is likely to occur.
• Accident case evidence ：2023 A certain e-commerce logistics park due to 2  Heavy-duty rack columns are tilted (with deviations up to 4.5‰ ), in storage 1.2  Tonnes /  When handling the layered goods, the upright post suddenly bent, causing the entire row of shelves to collapse, resulting in 20  Over millions of yuan worth of goods were damaged, and operations have been halted for rectification. 3  Heaven, indirect losses exceed 50  Ten thousand yuan.

1.2 Extend shelf lifespan: Reduce structural fatigue and wear.

Verticality deviation can cause the shelf to remain continuously in a tilted position during daily use. “ Subhealth ”  Status: Accelerating Structural Fatigue

• Fatigue Damage Mechanism :倾斜的 columns will cause the beam-to-column connectors to endure additional shear forces over time, reducing the fatigue life of standard bolted connections below their normal levels. 8-10 The year is shortened to 3-5 Year; when combined with collisions during forklift operations, the probability of connectors loosening increases. 60% (Data source: "Shelf Structure Maintenance Technical Guide.")
• Life Span Comparison Cases : In a manufacturing enterprise, within the same workshop, two sets of heavy-duty shelving units with identical specifications (rated load capacity 2 Tonnes /  Layer), a set of vertical deviation controlled within 0.5‰ Within, use 8  After the Lunar New Year, the structure showed no significant deformation; meanwhile, another group exhibited deviations of 2.3‰ , using only 4  Cracks soon appeared at the base of the pillars, requiring a complete replacement and increasing costs by approximately 12  Ten thousand yuan.

1.3 Meeting compliance requirements: Adhering to industry standards and safety regulations

Both domestically and internationally, mandatory or recommended standards have been established for the verticality of shelf columns; compliance is a fundamental prerequisite for enterprises to ensure safe production.

• Domestic standards "General Technical Specifications for Storage Racks" GB/T 25800-2023 ) Clearly stipulates that the height of a single column is ≤10m At that time, the perpendicularity deviation must not exceed 10mm ; Height > 10 meters At that time, the deviation must not exceed the height of 1‰ (And no more than 15mm ）。
• International Standards : European Material Handling Association Standard FEM 10.2.02 ) Requirements are stricter—verticality deviation of the columns must be controlled within a tolerance of the height. 0.8‰ Within this limit, and the parallelism deviation between any two adjacent columns must not exceed 5mm/m。
• Compliance Implications : Shelves that fail to meet standards cannot pass the safety production inspection, and in some industries—such as food and pharmaceuticals—their non-compliant storage facilities may even lead to regulatory issues. GMP 、 HACCP System certification issues led to business disruptions.

(Shelf Post)

II. Detection Standards and Quantitative Methods for Shelf Column Verticality

A scientific testing system is the core of controlling verticality and must be clearly defined. “ Standard based on -  Tool Selection -  Operation Procedure -  Deviation Determination ”  Four steps ensure accurate and traceable testing results.

2.1 Analysis of Core Testing Standard Systems at Home and Abroad

Standards vary across different countries and regions in terms of deviation thresholds and detection ranges. Companies need to select the appropriate standard based on their shelf usage scenarios—such as domestic warehousing or export projects.

Data Source: China Warehousing and Distribution Association CWDA ）、International Material Handling Association FEM ）

2.2 Mainstream Detection Tools and Operational Procedures

The accuracy of detection tools directly affects the reliability of results, so it’s essential to select appropriate tools based on shelf height and installation stage. Common tools and key operational points are outlined below:

2.2.1 Basic tool: Laser line projector (suitable for 10 meters The following shelves)

• Precision parameters : Level / Vertical accuracy ±0.3 mm/m , Range ≥20m , supporting 360° Projection;
• Operating Procedure ：
  1. Place the instrument directly in front of the base of the column. 1-2 meters Here, calibrate the level (ensure the bubble tube is centered);
  2. Project a vertical laser line to align the line with one side of the column;
  3. Use a feeler gauge to measure the gaps between the top, middle, and bottom of the column and the laser line; the maximum value obtained will be the deviation.
  4. Rotating Column 90° , repeat the measurement on the other side, ensuring there is no “ Tilt and Twist ”。

2.2.2 Professional tool: Total station (suitable for 10 meters The above-mentioned high shelves and large-scale warehousing

• Precision parameters : Angle Measurement Accuracy ±2″ , Distance measurement accuracy ±(2 mm + 2 ppm × D) , capable of simultaneously detecting multiple columns;
• Operating Procedure ：
  1. Set up outside the shelf area 2-3 A reference point to establish a coordinate system;
  2. Collect coordinate data for the key points at the top and bottom of each column (at least 2 A high point);
  3. By using software to calculate the angle between the column axis and the plumb line, and then converting it into verticality deviation;
  4. Generate a bias heatmap to visually highlight the locations of columns that exceed the standard.

2.2.3 Simple tool: Plumb line (suitable for temporary rechecks and low-precision requirements)

• Precision limitations : Deviation ±1-2mm (Affected significantly by wind conditions and operational techniques);
• Operating Procedure : Suspended from the top of the pillar 5kg After the plumb bob stabilizes, measure the horizontal distance between the bottom post and the plumb line—this value represents the verticality deviation (multiple measurements should be taken and averaged).

2.3 Quantitative Determination of Deviation Thresholds and Risk Categorization

Based on the magnitude of deviation, the column verticality risk can be categorized into “ Security -  Early warning -  Danger ”  Level 3 corresponds to different handling measures:

Example: Someone 12 meters High shelves (permissible deviation ≤12mm ), if the detection deviation is 9mm ( 80% × 12 mm = 9.6 mm , approaching the warning threshold), needs to be included in early warning management; if the deviation reaches 13mm , it is deemed hazardous and must be immediately deactivated.

(Shelf Post)

III. Construction and Maintenance Strategies to Ensure the Verticality of Shelf Columns

Verticality control must be implemented throughout. “ Before construction -  Under Construction -  Maintenance Period ”  Throughout the entire cycle, ensure long-term stability through source prevention, process calibration, and regular monitoring.

3.1 Before Construction: Foundation Preparation and Risk Assessment

3.1.1 Ground Levelness Control

• Requirements : The floor where the shelf is installed must meet the requirements. GB 50209-2010 "Code for Acceptance of Construction Quality of Building Flooring Works," Levelness Deviation ≤2mm/m ；
• Measures : Usage 2 meters Use a straightedge to inspect the floor; apply epoxy resin mortar to level out any depressions, and sand down any raised areas. If the floor is concrete, proper curing is required. 28  More than a day, to prevent later settlement.

3.1.2 Quality Inspection of Column Components

• Inspection Items : Column straightness (deviation per meter ≤1mm )、Cross-sectional dimension deviation ±0.5mm ）、Coating thickness（ ≥60μm , to prevent rust-induced deformation);
• Data Requirements : The random inspection rate shall not be lower than 3% , non-conforming components must be returned to the manufacturer and are prohibited from installation (one case revealed that the column itself exceeded the allowable straightness tolerance). 3mm , the vertical deviation after installation directly reaches 5‰ ）。

3.2 Construction in Progress: Phased Calibration and Quality Control

3.2.1 Installation Sequence Optimization (Key Steps)

• Correct order ： “ Single-column positioning → Temporary Fix → Column Group Calibration → Permanently fixed → Overall Re-inspection ”；
• Taboos : Do not install all columns first and then perform unified calibration, as this can easily lead to widespread exceedances due to accumulated errors; instead, install each column 3-5 The base column requires a localized re-inspection to prevent deviation from propagating.

3.2.2 Calibration Techniques and Detail Control

• Bottom adjustment : Use adjustable anchor bolts (adjustment range ±10mm ), adjust the column height based on the detection results to correct any vertical deviations;
• Top fixed : High shelving (> 10m ) Additional top tie rods are required, connecting to the building structure to minimize the impact of horizontal displacement on verticality. After installation, the tie rods must be re-inspected to prevent column tilting caused by excessive tensile force.

3.2.3 Acceptance Testing (Mandatory)

• Detection Rate ： 100% Full-coverage inspection (no sampling allowed); each column must be inspected at least. 2  One direction;
• Qualification Standards ： 100% Column deviation ≤ Allowed values, with the proportion of warning-level deviations ≤5% ; If it fails to meet the standards, a corrective action plan must be provided. Delivery and use can only proceed after passing the re-inspection.

3.3 Maintenance Period: Regular Testing and Deviation Correction

3.3.1 Inspection Cycle and Content

• Routine Inspection : Monthly 1 Next, use a laser line projector to inspect key areas (such as the pillars on both sides of aisles where forklifts frequently operate), and record any deviations or changes.
• Comprehensive Testing : Every year 1 Next, use a total station to inspect all columns, generate a "Verticality Inspection Report," and file it for future reference.
• Special circumstances After forklift collisions, earthquakes, or cargo overloading 24 An urgent re-inspection is required within the hour, as a logistics park previously experienced a forklift collision with a pillar due to failure to conduct a timely re-check. 3  Months later, the deviation from 1.2mm Increased to 8mm , ultimately leading to the beam's fracture.

3.3.2 Common methods for correcting biases

Conclusion

The verticality of shelf column installation is not “ Single-use detection indicators ” Instead, it is the core control point that runs through the entire lifecycle of the shelf—from pre-construction ground preparation, to phased calibration during installation, and finally to regular monitoring during the maintenance phase. Each step must be data-driven and guided by established standards. Companies need to establish “ Detection -  Record -  Rectification and Improvement -  Re-examination ”  The closed-loop management mechanism keeps the vertical deviation within a safe range. —— This is not only a necessary measure to prevent accidents, but also a critical investment for reducing operational costs and extending the shelf life of products. As warehouse automation continues to evolve—such as AGV , with high-frequency operations of stacker cranes, the requirements for shelf stability will further increase, and the importance of verticality control will become even more prominent.