Containers must be securely fastened to withstand strong winds, heavy waves and vessel movement at sea. Without reliable locking equipment, containers can shift, collapse or fall overboard, endangering the vessel, cargo and crew. The twist lock is the core component that keeps containers stable and safe during maritime transport.

Why Twist Locks Are Critical

In December 2020, a large container vessel encountered severe weather near Kyushu, Japan. Improperly secured containers resulted in 36 units falling into the sea and 21 collapsing on deck. Such accidents prove that high‑quality fastening equipment is essential for safe shipping.

The main container securing tools include:

• Twist lock

• Bridge fitting

• Stack cone

• Base

• Cone plate

• Lashing bar

• Height compensator

Among these, the twist lock is the most widely used and critical safety component.

What Is a Twist Lock?

A twist lock (also called an angle locking device) is used to:

• Fix containers to the ship’s deck base

• Secure stacked containers together

• Prevent sliding, tilting and overturning under rough sea conditions

Basic Operation

1. Place the twist lock into the corner casting of the lower container or deck base.

2. Lower the upper container into position.

3. Push the handle to lock the mechanism.

4. To unload: return the handle to unlock, then lift the upper container.

Types of Twist Locks

1. Manual Twist Lock

Commonly used to fix the first‑layer container to the deck base. Requires full manual operation.

2. Semi‑Automatic Twist Lock

The lock head automatically rotates and locks under the weight of the container.
Unlocking is done by pulling a release cable.
Widely used for medium‑to‑high stack layers.

3. Full‑Automatic Twist Lock

Locks automatically when the container is placed, using gravity and special latch design.
No manual action needed during loading.

Note: Under extreme conditions, full‑automatic twist locks may disengage. For maximum safety, they are often combined with manual or semi‑automatic types.

Safety Importance in High Stacks

On large container ships, stacks can reach 6 layers or higher. Each twist lock bears enormous weight. Strong waves or sharp turns can cause:

• Container collapse

• Cargo damage

• Structural damage to the vessel

• Loss of ship stability

• Vessel capsizing

Strict on‑site supervision is required during loading and unloading. Missing or incorrectly installed twist locks must be corrected immediately to ensure navigation safety.

CIMC Equilink – Full Range of Container Securing Parts

CIMC Equilink supplies high‑quality twist locks and complete container components trusted by global customers:

• Twist locks (manual, semi‑automatic, full‑automatic)

• Container corner casting

• Container floor

• Container locking device

• Lashing equipment

• Container corner post

• Container cross member

• Container gasket

• ISO tank parts

We provide reliable, durable and certified parts to support safe and efficient container operations worldwide.

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