An operator at a control console beside plate-cutting equipment in a manufacturing workshop.
Steel fire protection needs a coordinated specification, a measurable inspection plan and a complete record trail. Zhonghengfeng’s October 6, 2026 guidance reviews fireproofing coating selection, thickness checks, connection details and common defects. For buyers arranging steel fabrication and supply, the first decision is where workshop coating ends and the appointed local fireproofing contractor’s responsibility begins.
Select a tested system for the actual members
Intumescent and non-intumescent coatings protect steel through different mechanisms. The older descriptions “ultra-thin,” “thin” and “thick” remain familiar in practice, but a nominal thickness category does not guarantee a particular fire-resistance period. Selection must follow the fire design, the product’s approved test or assessment scope, member conditions and exposure environment. Indoor products must not be assumed suitable for outdoor or semi-exposed use.
China’s GB 51249-2017 includes a recommendation against selecting intumescent coatings for members requiring fire resistance above 1.50 hours. This is a provision within that Chinese standard, not a universal international prohibition. The responsible designer should resolve product suitability and the applicable project requirements before procurement.
As checked on October 23, 2026, GB 14907-2018 remains the effective Chinese product standard. GB 14907-2026 has been published but takes effect on September 1, 2027. Product selection should identify the applicable edition rather than assuming a newly published version is already effective.
Plan thickness inspection before application
The inspection plan should identify the coating system, specified thickness, measuring method, instruments, member sampling and locations. Use an appropriate dry-film gauge for suitable thin systems or the specified probe method for thicker materials. Cover faces, edges, ends, joints and difficult corners; establish additional checks for long members and complex details through the approved plan.
Under China’s GB 55006-2021 provisions, intumescent coating thickness must meet the design requirement. For non-intumescent coatings, at least 80% of the area must meet the design requirement, and the minimum thickness must be at least 85% of that requirement. These provisions must be read with the project specification and governing acceptance procedure; local overbuild must not disguise widespread under-thickness.
GB 51249-2017 also contains thickness-deviation provisions. Do not combine different clauses into an improvised allowance to reduce specified protection. The GB 55006-2021 publication notice gives the mandatory general code priority where other provisions conflict. Record actual readings and the disposition of failed areas.
Detail connections and concealed areas
Beam-to-column joints, bolt heads, nuts, washers, member ends and splice areas need deliberate coverage. Follow the approved fire-protection details for each connection, including any sealing or reinforcement requirements. Avoid exposed steel and thin spots in inaccessible corners. Do not assume that one generic coating detail suits every connection or movement condition.
Complete the specified inspections before ceilings, wall finishes or equipment conceal protected members. Keep photographs and location-linked thickness records, and agree who releases concealed work. Later damage or changes should trigger the approved repair and reinspection process.
Separate documents, inspection and fire-performance evidence
Check the product’s applicable approval and test documentation, model, intended use, coating thickness and stated performance against the approved design. Match delivery batches to manufacturing certificates and inspection records. Also confirm compatibility between the steel substrate, shop primer, fireproofing material and any finishing coat.
A completed-site thickness survey does not independently prove a member’s fire-resistance rating. Product testing or assessment, material verification, field thickness inspection and appearance checks serve different purposes. GB 51249-2017 Section 9.2 includes witnessed material-testing requirements for specified circumstances. Arrange qualified inspection or testing where required, without presenting a generic site survey as a fire test.
Prevent defects and agree the supply interface
Hollow areas, cracking, detachment and uneven coverage call for investigation of substrate cleanliness, moisture, compatibility, application thickness, mixing and curing. Follow the approved product instructions rather than adding water or material informally. Protect curing work against damage and unsuitable exposure, and verify repaired areas before release.
Zhonghengfeng’s stated role is to carry out the contractual workshop coating and provide corresponding manufacturing records. Site fireproofing, installation and local acceptance remain with qualified parties appointed for those tasks. Confirm interfaces during design and contracting so that supplied members arrive with the agreed surface condition and documentation.
Technical editorial note: This English edition removes fixed thickness-to-fire-rating shortcuts and clarifies standard precedence and inspection limits. It is a coordination checklist, not a project-specific fire design or application method statement.
Archive source: Zhonghengfeng’s original Chinese company article, published 6 October 2026. Technical wording clarified during English archive migration on 24 October 2026.