Crane Safety Signs: ISO 22986:2018 Standard Interpretation

Safety Sign Classification and Color Coding

ISO 22986:2018 categorizes crane safety signs into four types based on function and color. Prohibition signs — white background with a red circle, red diagonal slash, and black graphical symbol — indicate actions that are not permitted (e.g., no overload, no standing beneath suspended loads, no operation by unauthorized personnel). Warning signs — yellow background with a black border and black graphical symbol — alert to potential hazards (e.g., high-voltage danger, swinging loads, rotating parts). Mandatory signs — blue background with a white graphical symbol — indicate requirements that must be followed (e.g., wear a hard hat, wear protective footwear, use a safety belt). Emergency information signs — green background with a white graphical symbol — indicate safe conditions or escape routes (e.g., emergency stop location, safety passage, first-aid kit location).

The standard specifies chromaticity coordinates for each color — red (RAL 3020), yellow (RAL 1003), blue (RAL 5017), and green (RAL 6018) — ensuring visual consistency and recognition across all signage.

Sign Content and Design Principles

The standard sets clear requirements for the content and design of safety signs, which consist of three components: a graphical symbol, a text label, and a border. The graphical symbol must be simple, clear, and easily recognizable, using the standardized crane safety sign symbol set. Text labels must be bilingual in Simplified Chinese and English (with additional local language versions for exported equipment), with a minimum text height of 10 mm when the viewing distance is ≤5 m, ensuring legibility from the operator's position. The border color corresponds to the sign type — red for prohibition signs, yellow for warning signs, blue for mandatory signs, and green for emergency information signs.

Design principles for safety signs include: prioritizing graphical symbols to reduce reliance on text; using standard symbol styles from the designated library; sizing signs according to viewing distance (minimum size of 50 mm × 50 mm for viewing distances ≤5 m); and selecting materials that offer weather and corrosion resistance (film-coated aluminum or engineering-grade reflective film for outdoor use, self-adhesive polyester for indoor use). All safety signs must pass type testing, including weather resistance testing for ≥1,000 hours, corrosion resistance testing for ≥72 hours (salt spray), and adhesion testing at ≥5 N/cm.

Installation Position and Mounting Requirements

The Standard specifies where safety signs must be placed. The operator's cab must display a no-overload sign and the Safety Operating Procedures sign. The slewing area requires a warning sign for rotating parts and a no-entry sign. Near the hoisting mechanism, a sign warning against standing under suspended loads and a falling-object hazard warning must be posted. The Electrical Cabinet must carry a high-voltage danger warning and a sign restricting access to authorized personnel only. The Jib and Counterweight must be fitted with a falling-hazard warning sign.

As for installation height, safety signs should be mounted with their center distance 1.5–1.8 m above floor level, aligning with typical eye level. Signs must be mounted flat and securely, without tilting or obstruction. Outdoor signs should be positioned in sheltered spots or protected with a waterproof cover. Where multiple signs are grouped in one area, they must be arranged top-to-bottom in the order of prohibition, warning, mandatory action, and advisory. The Standard also requires that all safety signs be fully installed before the crane is delivered, and that Factory Acceptance Test includes a check of sign completeness.

Maintenance and Replacement Interval

For routine maintenance, the Standard calls for a monthly inspection of sign integrity and legibility. Signs that show fading, cracking, peeling, or soiling must be replaced promptly. The typical Replacement Interval is 2–3 years for outdoor signs and 3–5 years for indoor ones. After an Overhaul or Retrofit, the crane's safety signs must be re-checked; if the structure or function of the crane has changed, the relevant signs must be updated accordingly.

Kelude supplies a safety sign inventory and an installation position drawing with every crane shipped from the factory, so customers can verify and maintain signs against the reference. Replacement signs are made with the same materials and processes as the originals, ensuring consistent service life and legibility. The Standard emphasizes that safety signs must not be arbitrarily covered or removed, and that Operator Training must include safety sign Identification.

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