Container Loading Operation Standards: Loading Sequence, Center of Gravity Control, and Securing & Lashing

Container loading is a technical skill. With the same container and the same cargo, good loading means more cargo loaded, stable transport, and low cargo damage; poor loading can lead to container collapse, cargo damage, or even safety incidents. This article systematically explains the core technical requirements for container loading operations.

I. Preparation Before Container Loading

1.1 Developing a Loading Plan

The loading plan is the "construction drawing" for container loading and should be completed at least 1 day before container loading:

1.2 Tools and Materials Preparation

II. Basic Principles of Container Loading

The five basic principles of container loading are the foundational rules for all container loading operations:

The above five principles are all cited from the Code of Safe Practice for Cargo Stowage and Securing (CSS Code), which are container loading operation standards recommended by the International Maritime Organization (IMO).

III. Detailed Loading Sequence

3.1 Standard Container Loading Sequence (Top View)

20GP Standard Loading Layout (Viewed from Above)

┌──────────────────────────────────────────┐
│  Row 1 → Row 2 → Row 3 → Row 4 → Row 5 │
│                                        │
│  ██████ ██████ ██████ ██████ ██████    │
│  █Heavy█ █Mixed█ █Mixed█ █Mixed█ █Light█    │
│  ██████ ██████ ██████ ██████ ██████    │
│                                        │
│  ██████ ██████ ██████ ██████ ██████    │
│  █Heavy█ █Mixed█ █Mixed█ █Mixed█ █Light█    │
│  ██████ ██████ ██████ ██████ ██████    │
└──────────────────────────────────────────┘
     ↑ Truck Head (Front)    ↑ Container Door (Rear)
       Heavy cargo forward    Light cargo near door

3.2 Standard Loading Steps

Step 1: Start loading from the deepest part (container head), arranging sequentially along the container length Step 2: Arrange each row neatly, leaving no gaps between rows Step 3: After completing one row, separate with dunnage air bags to prevent forward/backward sliding during transport Step 4: Stagger arrangement between layers (brick-wall pattern) to increase stability Step 5: Load the last row flush with the container door position, and perform final securing

3.3 Loading Methods for Different Packaging Types

IV. Center of Gravity Control Techniques

4.1 Three-Dimensional CG Standards

                  ┌──────────┐
                  │  TOP     │
                  │   CG     │ ← Height: Below 50% of container height
                  │  ↓       │
   ───────────────┼──────────┼────── Fore-Aft: 40%-60% of container depth
   ←  Truck Head  │    CG    │ →  Container Door
                  │          │
                  │  BOTTOM  │
                  └──────────┘
                  ←── Centerline ──→ Lateral: Within ±5% of centerline

4.2 Practical CG Control Methods

Method 1: Even Weight Distribution

20GP Container Weight Distribution Example:

┌──────────────────────────────────┐
│  ████  ████  ████  ████  ██    │
│  █3t █  █2t █  █1t █  █1t █  ██    │
│  ████  ████  ████  ████  ██    │
│  ████  ████  ████  ████  ██    │
│  █3t █  █2t █  █2t █  █1t █  ██    │
│  ████  ████  ████  ████  ██    │
└──────────────────────────────────┘
 Total 18t  Truck Head← First 4 rows 12t → Last row 6t → Container Door
 CG Position ≈ 40% container depth ← ✅ Pass

Method 2: Heavy Cargo Priority

Prohibited Practices:

• ❌ Strictly prohibited: Concentrating all heavy cargo on one side of the container — rollover probability during turns increases by 300%
• ❌ Strictly prohibited: Concentrating more than 50% of cargo weight at the container tail — cargo impacts container doors during emergency braking
• ❌ Strictly prohibited: Exceeding container floor rated load (typically 3-4 tonnes per axle pair)

V. Gap Filling and Securing

5.1 Comparison of Common Securing Methods

5.2 Dunnage Air Bag Usage Specifications

Dunnage air bags are the most effective filling and securing method inside containers, but must be used correctly:

Air Bag Placement Illustration:

┌──────────────────────────────────┐
│ █████ █████ █████ │ █████ █████ │
│ █Cargo█ █Cargo█ █Cargo█ │ █Cargo█ █Cargo█ │
│ █Heavy█ █Heavy█ █Heavy█ │ █Light█ █Light█ │
│ █████ █████ █████ │ █████ █████ │
│          ↑Air Bag   ↑Air Bag     │
│  Fill gaps between groups  Fill gap with door │
└──────────────────────────────────┘

5.3 Securing and Lashing Standards

VI. Container Loading Quality Inspection Checklist

After completing container loading, verify the following items item by item:

• □ Cargo arranged neatly, no tilting
• □ Center of gravity within safe range
• □ All gaps filled and secured
• □ Lashing straps tightened, edge protectors in place
• □ Container doors open and close normally
• □ Seal locked, seal number recorded
• □ Container number photographed and archived
• □ Loading photos taken (before/during/after loading)
• □ Loading manifest completed (including details of cargo in each row)

Regulatory Basis: Loading principles cited from IMO Code of Safe Practice for Cargo Stowage and Securing (CSS Code). Securing and lashing standards reference industry-standard operational practices. Data as of July 2026.

📖 Extended Reading:

• International Maritime Operations Handbook Part 19: Trailer and Container Loading Operation Standards — Step-by-step operational procedure version (complements the technical standards in this article)
• Cargo Stowage and Securing — In-depth interpretation of CSS Code regulations

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