Mast Crane Design and Installation Acceptance per GB/T 26558-2011
GB/T 26558-2011 "Mast Cranes" is the product standard governing the design and manufacturing of mast cranes. Also referred to as derrick masts or A-frames, mast cranes are fixed-base jib cranes widely used in heavy equipment lifting and building installation works. The standard specifies the classification, design calculation, manufacturing and installation, and test methods for mast cranes.
GB/T 26558-2011 is a dedicated product standard for mast cranes (also known as derrick cranes or gin poles), published and implemented in 2011. A mast crane is a fixed-base jib crane comprising a mast (main column), a jib (boom), guy ropes (guy lines), and a hoisting mechanism. The mast is anchored to the foundation via guy ropes, and lifting operations are carried out through the slewing and luffing of the jib. Mast cranes offer a simple structure, high load-bearing capacity, and low cost, making them particularly suitable for heavy lifting projects such as large equipment installation, power plant construction, and petrochemical plant erection. Kelude can design and manufacture non-standard mast cranes to meet specific project requirements.
Mast Crane Classifications and Structural Configurations
The standard classifies mast cranes into three types based on mast structural configuration. Single-mast type (independent mast) — a suspension system consisting of one main mast and guy ropes, with the jib hinged at the mast base and the boom angle adjusted via the luffing wire rope. The single-mast type has the simplest structure, with a maximum lifting capacity generally not exceeding 100 t. A-frame type — two masts arranged in an A-shape configuration, offering better stability than the single-mast type while requiring fewer guy ropes; suitable for lifting capacities ranging from 100 t to 500 t. Derrick-mast type — both the mast and the jib can luff independently, providing the greatest operational flexibility. Key structural parameters for mast cranes include mast height (typically 10–50 m), jib length (10–40 m), maximum lifting capacity (50–500 t), and maximum working radius (10–30 m). The mast and jib are typically fabricated from Q345B or Q420B high-strength low-alloy structural steel, with main chord members available in seamless steel tube or built-up angle steel cross-sections.
The guy rope system is a safety-critical component unique to mast cranes. The standard specifies the number, diameter, and anchoring requirements for guy ropes. At least six guy ropes shall be provided at the mast top, evenly spaced around the circumference, with the included angle between the guy rope and the ground kept within 30°–60°. Guy ropes shall be wire ropes with a safety factor of no less than 3.5, and rope end terminations shall be made using wire rope clips or alloy swaged terminations. The preload in the guy ropes shall be such that the mast remains vertical under no-load conditions, with the preload value determined by design calculation. Each guy rope shall be equipped with an independent turnbuckle or adjusting screw for tension adjustment. Ground anchors for guy ropes shall be constructed of concrete blocks or steel pipe pile foundations, with an uplift resistance of no less than twice the maximum working tension of the guy rope. The standard also requires that the supporting foundation at the mast base provide adequate load-bearing capacity and anti-sliding resistance, and that the foundation design be verified and confirmed by a qualified civil engineer.
Design Calculation Requirements
Design calculations for mast cranes are more complex than for general-purpose cranes, because the statically determinate nature of the structure makes the internal forces in each member highly sensitive to guy rope tension and the position of the suspended load. The standard requires that design calculations for mast cranes include load analysis covering dead load, lifting load, wind load (calculated separately for working and non-working conditions), inertia load, and guy rope preload. Load combinations are executed in accordance with the principles of GB/T 3811 and GB/T 22437; however, the unique aspect of mast cranes is that the elastic deformation of the guy ropes affects the overall load distribution in the structure, and therefore a geometric nonlinear analysis shall be performed. Stability calculations for the mast include overall stability (considering combined compression and bending) and local stability (with the stability factor of each member not less than the specified value).
The standard also specifies the anti-overturning stability factor for mast cranes: not less than 1.5 under working conditions (calculated with the most unfavorable load combination) and not less than 1.8 under non-working conditions (considering maximum wind load). The horizontal anti-sliding stability factor at the mast base shall be not less than 1.5. The uplift safety factor for guy rope anchoring shall be not less than 2.0. Since mast cranes are typically assembled on site for single-use or multiple re-erection cycles, the standard permits the use of the allowable stress method under specific conditions, with safety factors that may be appropriately reduced but shall not fall below 90% of the values specified in GB/T 3811. Upon completion of fabrication, a no-load trial run and a rated load test (100% SWL) shall be carried out to verify the correctness of the design calculations. Design documentation shall include the structural calculation report for the mast and jib, the guy rope system layout drawing, foundation load parameters, and the installation plan description.
Erection and Load Testing Requirements
The erection and dismantling of a mast crane are high-risk operations, and the standard specifies strict requirements for these procedures. Prior to erection, a detailed installation plan must be prepared and approved by the technical manager. The installation site must be leveled and compacted, and erection may only proceed after the foundation concrete has reached 100% of its design strength. The mast may be raised using either the overall lifting method or the sliding method, with guy ropes and auxiliary support plates used throughout to prevent tipping. Guy ropes must be installed in a specific sequence—back-side ropes first, followed by windward-side ropes—with the initial tension of each rope individually adjusted to the design value. Boom erection may only begin after the mast is fully raised and secured. Following erection, a comprehensive inspection must be carried out to confirm that all connections are secure and all mechanisms operate correctly.
Load testing is the ultimate verification of a mast crane's safety performance. The test loads are categorized as follows: No-Load Test—each mechanism operates at rated speed for no less than 30 minutes. Rated Load Test (100% SWL)—the rated load is lifted at each typical working radius to verify the braking and luffing functions of all mechanisms. Dynamic Load Test—1.1 times the rated load is lifted, with hoisting, lowering, and luffing operations each performed no fewer than 5 times. Static Load Test—1.25 times the rated load is lifted and held stationary for 10 minutes while mast perpendicularity and guy rope tension variations are measured. The horizontal displacement of the mast top must not exceed 1/100 of the mast height. Upon completion of testing, a Test Report must be issued documenting all measured data. The mast crane's Operation Manual must specify the maximum lifting capacity and corresponding load-radius curve, the procedure and interval for adjusting guy rope tension, and the items and acceptance criteria for Periodic Inspection.
Safe Use Requirements for Mast Cranes
The standard sets out clear requirements for the safe use of mast cranes. Before a mast crane is put into operation, a detailed Lifting Plan and safe operating procedures must be developed. The Lifting Plan must be approved by the technical manager, and a Pre-Work Safety Briefing must be delivered to all personnel involved in the lifting operation. A restricted zone must be established at the worksite, and unauthorized personnel are not permitted to enter. The operator and the crane operator in charge / signal person must maintain reliable communication at all times, and hand signals must be standardized and unambiguous. The standard specifies that the hoisting and luffing mechanisms of a mast crane must not be operated simultaneously. Luffing operations should be performed under no-load or light-load conditions; when luffing under load, the load must not exceed 70% of the rated lifting capacity. Hoisting must be carried out smoothly at a steady speed, with emergency stops and sudden starts strictly prohibited. After the load is lifted off the ground, the operator must pause to verify brake reliability and load balance before continuing the hoist. Lifting operations are prohibited in winds of Beaufort Force 6 or above, heavy rain, dense fog, or when nighttime lighting is insufficient. During operation, a designated person must monitor guy rope tension changes and ground anchor stability, and work must stop immediately if any abnormality is detected.
Mast Crane Design Parameter Comparison Table
The comparison table below lists the core parameter configurations for mast crane design, for reference by selection and operation personnel.
| Parameter Item | technical requirements | design basis | Description |
|---|---|---|---|
| Rated Lifting Capacity | ≤design Lifting Capacity | GB/T 3811 Crane Design Standard | Includinglifting accessories and slings Weight |
| mast Length | Perlifting height+safety margin | stability calculation | slenderness ratio≤120 |
| guy rope Quantity | Main guy wire≥4Pcs | Stability calculation | Symmetrical arrangement |
| Basetype test | Hinged/Fixing | force analysis | Satisfy Anti-overturning |
| winchrope capacity | ≥Maximum Hoisting / Lifting Length×3 | safety margin | Wire Ropenumber of winding layers≤4 |
FAQ: Mast Crane vs. Tower Crane & More
Q: What is the difference between a mast crane and a tower crane?
A: A mast crane is anchored to the ground or a building structure using guy ropes. It offers a simpler design and lower cost, but installation is more complex and the slewing angle is limited. A tower crane, by contrast, stands independently or is attached to the structure via its tower mast, provides 360° slewing, and can climb and add sections on its own. It is more versatile but comes at a higher cost.
Q: How should guy rope tension be checked and adjusted?
A: Guy rope tension should be checked before every hoisting operation using a tension meter or the vibrating-wire method. If the tension deviation exceeds ±10% of the design value, adjustment shall be made via the turnbuckles. Tension should be uniform across guy ropes on the same level, with the maximum difference between individual ropes not exceeding 15% of the average value.
Q: What are the key safety precautions for mast crane operation?
A: Overloading is strictly prohibited, as is any operation other than luffing under load. Operations shall be stopped when wind speed reaches Force 6 or above. If the mast verticality deviation exceeds H/200, work must be paused for inspection. Guy ropes must not come into contact with sharp edges of the building; protective sleeves should be fitted where necessary.
Q: Does a mast crane require periodic inspection?
A: Yes. Mast cranes fall under the category of special equipment (lifting appliances). A newly installed mast crane shall only be put into service after passing a supervision inspection. After each dismantling and re-erection, a full inspection and test must be carried out. In-service inspections shall be performed in accordance with the relevant parts of GB/T 31052.
