So, what even is a double-girder semi-gantry crane?

In places like steel mill auxiliary material zones, precision workshops, port transshipment yards, and small-to-medium-sized precast plants, you'll often see a special lifting device. One side of it rests firmly on outriggers along tracks, while the other side leans against the factory crane beam or wall structure for support. This crane can lift really heavy stuff, like components weighing dozens of tons, without taking up too much space. It's called a double-girder semi-gantry crane.

I. The Essence of Double-Girder Semi-Gantry Cranes

Double-girder semi-gantry cranes are a big deal in the world of gantry crane technology, and they're defined by their core feature: It's got a dual main girder structure with semi-gantry support. They use two parallel box-type main girders as the load-bearing core. One side has rigid outriggers and runs along ground tracks, while the other side connects to the factory's crane girders, corbels, or dedicated support structures via end beams, so you don't need any extra outriggers. This design has the same high load capacity and operational stability as double-girder cranes, but doesn't need the same width as full-gantry cranes. It's great for "connecting indoor and outdoor areas" or "narrow sites with heavy loads."

Double-girder cranes can lift over 50% more than single-girder ones. They can handle loads of between 10 and 100 tons. It's smaller than full gantry cranes, taking up 30% less space, which makes it perfect for tight spots like workshop-open area transitions or narrow-space installations. Basically, when you've got a "space-constrained yet high-load" environment to deal with, the double-girder semi-gantry crane is the best option.

II. There are lots of different types of double-girder semi-gantry cranes. You can categorise them based on how they're built, how much weight they can hold, and what they're used for. This means they can be used in lots of different situations, which is the main reason why they're so versatile.

1. So, let's take a look at how these cranes are sorted based on their structure.

For example, we've got the L-type double-girder semi-gantry crane. The end beam on the non-outrigger side has an L-shaped design, which means you can install it flush against factory walls or crane girders. The main girder runs along the same lines as the factory structure, which makes the most of the space along the building's length. It's perfect for precision workshops, like heavy-duty production line lifting in electronics factories, because it stops equipment and factory columns from colliding while making the most of existing structures to save outrigger space.

C-Type Double-Girder Semi-Gantry Crane: The non-outrigger side has an open C-shaped structure, which makes it easy to use around large equipment or racking systems. This design makes it easier to manoeuvre and lift lateral components more accurately. C-Type Double-Girder Semi-Gantry Cranes are often used for equipment maintenance, like steel mill rolling mill inspections. The boom can extend from the equipment's side, so you can replace a component without moving the main machinery.

Hybrid Double-Girder Semi-Gantry Crane: It's a combo of the best bits of L-type and C-type designs. The non-outrigger side can be easily adjusted based on the conditions on site, and can be used with both factory interface zones and temporary work areas. Multi-scenario hybrid double-girder semi-gantry cranes are used a lot in port transshipment yards, handling both container transfer and equipment maintenance.

2. Classification of lifting capacity

Light-duty double-girder semi-gantry crane: It can lift 10-20 tons. It's pretty lightweight, so it's great for moving stamped parts around in car component factories or putting together medium-sized equipment. It's quick to lift and works really efficiently.

Medium-duty double-girder semi-gantry cranes: It can hold 20-50 tons. This is the most common type of market, and it strikes the right balance between load capacity and flexibility. 50-ton double-girder semi-gantry cranes are used a lot in precast yards for moving small beams and in ports for handling bulk cargo, handling both heavy loads and being able to adapt to different sites.

Heavy-duty double-girder semi-gantry crane: It can lift 50-100 tons. It's got double main girders made from high-strength steel with reinforced outriggers. It's perfect for heavy-duty jobs in steel mills and for lifting big equipment, like billet transfer and shield machine component lifting. It'll give you stable load-bearing and precise positioning.

3. Classification by Drive Type

Manual double-girder semi-gantry crane: Just so you know, there are manual hoisting and travel mechanisms. These cranes are only suitable for lifting capacities of up to 15 tons and are perfect for extremely low-frequency operations, such as small warehouse manual double-girder semi-gantry cranes. They're great for inventory checks or temporary equipment relocation, but not for regular use. It's really cheap, but not that efficient.

Electric Double-Girder Semi-Gantry Crane: Motor-driven core mechanisms with variable frequency speed control make for smooth lifting and movement, so it's the current mainstream choice. The electric double-girder semi-gantry crane has a variable frequency, which means you can adjust the speed to be really precise. For example, when you're lifting something, you can slow the speed right down to 0.5m/min to avoid any damage to the equipment. Some of the models are smart enough to allow remote operation, so there's no need to have an operator on-site.

Hydraulic Double-Girder Semi-Gantry Crane: It uses a hydraulic drive system, which gives it a better lifting capacity and makes it more stable. It's perfect for heavy-duty load hydraulic double-girder semi-gantry cranes, like lifting steel components over 50 tons. The hydraulic system's buffering effect reduces the impact on the main girder, meaning the equipment will last longer.

4. This is a special-purpose explosion-proof double-girder semi-gantry crane. It's got explosion-proof motors, control panels and sensors, making it perfect for places like chemical plants and oil depots where there's a risk of fire or explosion. It stops electrical sparks from causing accidents and has explosion-proof ratings of up to Ex d IIB T4 or higher.

High-Temperature Resistant Double Girder Semi-Gantry Crane: It's got heat-insulated main girders and outriggers, with hooks made of heat-resistant alloy steel. It can be used in steel mills and glass factories because it can handle temps over 300°C without melting.

The corrosion-resistant double-girder semi-gantry crane is perfect for… It's got a sprayed anti-corrosion coating and galvanized leg-to-rail connections. These cranes are perfect for use in port corrosion-resistant double-girder semi-gantry cranes and aquatic processing area double-girder semi-gantry cranes. They can handle corrosion from sea salt or humid environments. The equipment is now able to last for more than 15 years.

The Precision Positioning Double-girder Semi-Gantry Crane is pretty cool. It's got laser positioning and visual recognition systems, so it can be really precise, like millimetre-level accuracy. This is usually used for installing precision equipment, like when you're hoisting stuff during chip production, and it can control errors within 2 mm.

III. Why are double-girder semi-gantry cranes the go-to?

Double-girder semi-gantry cranes are great for tight spots and heavy loads, and they're exactly what industrial companies need. Compared to full-gantry or single-girder cranes, their benefits are really obvious.

1. How the crane is used

By attaching it to one side of the factory building, the double-girder semi-gantry crane means you don't need to use the space on both sides. This saves 30%-40% of the floor space compared to full-gantry cranes. Even in narrow workshop areas, where the width is only 8 metres, you can install a 10-metre span model, which allows for cross-area lifting operations. You just can't put full-gantry cranes in such tight spots.

2. Superior load capacity

The box-type structure of the dual main girders makes them more stable than single-girder designs. This ensures that the stress is spread evenly and that they can resist deformation better. For identical spans, double-girder semi-gantry cranes can lift over 50% more than single-girder ones. A 20-ton double-girder semi-gantry crane is even more stable than a 25-ton single-girder model, which makes it perfect for situations where you need a lot of heavy-duty support.

3. More flexibility in how they work

By swapping lifting attachments (like electromagnetic chucks, grabs and special lifting beams), double-girder semi-gantry cranes can handle all kinds of materials, like steel, bulk cargo, precision equipment and prefabricated components. This means the equipment can be used more than 80% of the time. For example, a multi-functional double-girder semi-gantry crane can lift steel billets in the morning and transport coal in the afternoon by simply switching to a grab attachment, meaning you don't need any extra specialist equipment.

4. These cranes are great value for money. Compared to full-gantry cranes, double-girder semi-gantry cranes mean you don't need to spend as much on one set of outriggers and rails, cutting prices by 20%-30%. Compared to truck cranes, their fixed operating range means you don't have to keep redeploying them, which saves over 40% in annual maintenance costs. If you've got a small or medium-sized business, high-value double-girder semi-gantry cranes are a great way to get the job done at a lower cost.

5. We've got you covered with our comprehensive safety protection. Reliable operation in complex conditions

It's got overload protection, collision prevention, limit switches and emergency braking as standard. Some of our specialised models are also explosion-proof, high-temperature resistant and corrosion-resistant. When it comes to underground workshops, explosion-proof and anti-electric leakage designs are essential for safety in humid, poorly ventilated environments.

IV. Here are some typical ways you'd use double-girder semi-gantry cranes:

Steel Mill Auxiliary Material Area: It uses a 50-tonne heavy-duty double-girder semi-gantry crane to move materials like steel billets and coke. It's attached to the factory crane beam, so it saves outdoor space, and its high-temperature design can handle the intense heat of steelmaking workshops.

Precision Equipment Workshop: It uses a 20-ton precision positioning double-girder semi-gantry crane to lift machine tools, robotic production lines and other precision equipment. Millimetre-level positioning stops the equipment from colliding, and the L-shaped structure aligns with workshop layouts.

Port Transfer Yard: It uses a 30-ton corrosion-resistant double-girder semi-gantry crane for handling containers and maintaining equipment. The anti-corrosion coating can withstand sea air erosion, and the tyre-mounted design allows for flexible relocation.

Prefab Beam Yard: It uses a 40-tonne medium-duty double-girder semi-gantry crane to move small T-beams and precast tunnel segments. Its C-shaped design makes it easy to lift components from the side, which is great for the tight storage spaces in yards.

V. Core things to think about when choosing double-girder semi-gantry cranes

Work out what you need the crane to do and how much it can lift Then you need to measure the site width, height and operational span. To work out the maximum weight you can lift, just add 15% to the maximum lifting load. For example, when you're lifting 30-ton materials regularly, picking a 35-ton model makes things safer.

Match Type to Operating Conditions: When it comes to chemical zones, go for explosion-proof models. For hot areas, high-temperature resistant models are the way to go. And for delicate lifting tasks, precision positioning models are the perfect choice. Try not to go overboard with the engineering or under-specification.

Check out Reputable Manufacturers: Just to let you know, we've selected suppliers who hold a Special Equipment Manufacturing Licence. Focus on vendors who can show you their experience in your industry – for example, if you're looking for steel mill double-girder semi-gantry cranes, go for companies that have worked with steel enterprises before. Just so you know, the after-sales coverage includes installation, commissioning, and maintenance.In a nutshell, picking the right double-girder semi-gantry crane lets you handle heavy loads even in tight spaces.The big selling point of these cranes is that you can "trade space for load capacity" because of their unique semi-gantry design. This lets you do heavy-duty operations in confined spaces, which is great for businesses that have a lot of space but not a lot of load capacity. There are all kinds of double-girder semi-gantry cranes, from L-type to C-type and from light-duty to heavy-duty models. They're great for all sorts of different scenarios. If you pick the right model for your site, load and operating conditions, it'll become your "trusted assistant" for boosting operational efficiency.If you're unsure which double-girder semi-gantry crane is right for you or want to get local manufacturer quotes, feel free to give us a shout. We'll provide personalised selection solutions tailored to your specific needs, helping you choose the most suitable equipment.