In commercial space, public buildings and high-end residential buildings, steel-framed glass doors have become mainstream due to their transparency and structural stability. As the core component of door, the safety of glass is directly related to the safety of pedestrian access and the reliability of buildings. China has set up a complete system of glass material safety standards for steel-frame glass doors, including material selection, performance indicators, certification specifications and so on, and has built a solid defense line for building entrance safety.
The glass material of steel frame glass door must choose safety glass that accords with the national standard first, strictly forbid to use ordinary floating glass. According to the Building Safety Glass Regulations, glass used indoors must meet the core requirements of "breaking without serious injury and with a℃of impact resistance." Mainstream compliance materials include tempered glass, laminated glass and tempered-laminated composite glass. Their selection must be guided by the principle of scenario suitability:
-As a basic safety material, -Tempered glass must meet the criteria GB 15763.2 "Safety Glass 2: tempered glass". By quenching at high temperature, uniform compressive stress is formed on the surface of glass, which is 3-5 times the mechanical strength of ordinary glass. The thickness of tempered glass used for single-leaf steel-framed glass doors shall not be less than 8mm and that for double-leaf glass doors shall not be less than 10mm. The edges of the glass must be ground to eliminate the danger of sharp angles. The size of small blunt angle particles formed after fragmentation must be controlled to avoid cutting damage.
Laminated glass is manufactured in accordance with GB15763.3 "Building Safety Glass Part 3: Laminated Glass" and consists of two or more laminated glass and a PVB, EVA or SGP laminates. Its core safety feature lies that even after damage, the debris is firmly glued together by a the interlayer, maintaining the door intact and preventing debris from falling and hurting people. For shopping malls, hospitals and other crowded areas, laminated glass should be the preferred material for steel-framed glass doors, laminated glass an interlayer thickness should not be less than 0.76mm. In special cases, multiple interlayers can be used to improve protection performance.
-Tempered laminated glass combines the high strength of tempered glass with the scattering advantages of tempered glass and is the preferred material for tempered glass doors. The material must meet the dual criteria of tempered and laminated glass and be verified by drop impact stripping tests and bullet bag impact tests to ensure that no sharp fragments are broken up and to prevent laminar stripping. Suitable for banks and office buildings with high security requirements.
The safety performance of steel-framed glass doors and materials must be verified by a number of mandatory indicators, including mechanical properties, thermal stability, durability, and other key indicators:
Percussion resistance is the core safety indicator of doors and windows. According to national standards, a drop ball impact test is required: a steel ball of specified weight falls from a height of 1.2 metres and hits the centre of the glass. A test is considered合格 (qualified) if the glass tube that drips three times without breaking is called a pass test. In the case of laminated glass, there is also a need for a bag impact test to ensure that the interlayer does not break or penetrate on impact and to prevent penetration by external forces. Bending strength must meet the requirements of withstanding the weight, wind pressure and daily impact of the door. The bending strength of tempered glass shall not be less than 250 MPa to ensure that the tempered glass is not prone to deformation or fracture during large spans or frequent use.
Warmth and shock resistance are equally important. Glass must be able to withstand temperature differences of more than 100℃ without breaking, adapt to changes in temperature differences indoors and outdoors, and sudden high temperatures. For steel doors with laminated glass, the bonding strength between the laminated glass and the original glass plate must be verified by boiling water and radiation resistance tests to ensure that layering and yellowing do not occur during long-term use, thus maintaining structural integrity. In addition, the light transmittance of glass must be uniform, and the difference in light transmittance between the same steel-frame glass doors should not exceed 5%, both to ensure clear visibility and to meet the optical design requirements of the building.
In response to the risk of spontaneous breakage of tempered glass, the standard specifies that tempered glass is used for glass doors and can be homogenized (commonly known as "bursting") to reduce the rate of spontaneous combustion breakage of tempered glass. The probability of spontaneous breakage after treatment must be kept to a very low level. At the same time, manufacturers are required to include spontaneous breakage risk warnings and protection measures in the product certificates and to allow reasonable expansion gaps during installation to prevent stress concentration that could lead to breakage.
Compliant materials must be combined with standardized certification processes and installation techniques to achieve complete security, and our country has a mandatory 3C certification system for safety glass used on doors. Glass used for steel glass doors shall have a a clearly identifiable 3C certification mark, which shall be easily located for inspection. It is forbidden to use glass without 3C certification in door manufacturing. In addition, glass manufacturers must provide quality documents such as impact test reports and size deviation inspection reports to ensure that products meet standard requirements.
Technical specification during installation is the key to ensure glass safety performance. According to the Technical Specification for Safety Glass Engineering in Buildings, the depth of glass embedded in the bottom rail of the steel frame glass door shall not be less than 12mm. Neutral silicone sealant must be used to fill the gap between the glass and steel frame. The sealant must be uniformly continuous, free of bubbles and cracks, and have good compatibility with glass and steel to prevent corrosion and damage. Anti-collision signs must be installed on the glass within 60cm of the ground and pedestrians can be alerted by using collision strips or coloured warning panels.
For steel-framed glass doors of more than 1.5 square metres, regardless of material type, a laminated process and wind pressure simulation tests are required to ensure sufficient structural stability in extreme weather conditions. After installation, the glass must be dynamically tested: a hard sphere with a diameter of 500g will fall freely from a height ℃ 1.2m; three impacts will not break, indicating eligibility (eligibility); and, in order to check the firmness of the equipment, there will be no vibration when pushed by hand and no bounce when pressed against the seal.
To ensure the safety of steel-frame glass doors and glass materials, covering the entire life cycle of the management process, acceptance and maintenance of strict standards. Upon acceptance, the consistency of the glass material's 3C certification certificate, performance test report and design documents of the glass material must be verified. Glass must be free from cracks, scratches and bubbles, and size deviations must conform to GB/T2680 ``Building Glass-Solar and Optical Performance Test Method ''.
The construction company must provide not less than five years of warranty period, the first two years of comprehensive maintenance responsibility, the last three years of material quality responsibility. The user unit shall establish a quarterly inspection system, focusing on stress cracks of glass surface, aging of the sealant, stress condition of glass hardware connections, etc. If damage to the edges, yellowing the interlayer film or cracks are found, the glass must be removed and replaced immediately. Replacement glass must still meet the original safety standards.
Whoever uses non-safety glass without authorization shall be fined not more than 5% of the contract price in accordance with the provisions of theRegulations on Quality Management of Construction Projects. Failure to set up anti-collision signs or falsify inspection data as required shall result in corresponding administrative punishment and joint and several liability shall be borne by the design and construction units. This penalty mechanism ensures the strict enforcement of safety standards in the system.
Steel frame glass doors safety standard system is an important component of building safety. Its core value lies in the scientific material selection, the strict performance indicators and standardized certification processes, realizes the ``anti-breakage, anti-dispersal, anti-injury"triple security protection. With the improvement of safety performance requirements in the construction industry, safety glass standards are also being optimized to promote material technology innovation and application standards upgrading. In practical application, the steel frame glass doors can only play its transparent and beautiful building function and become a reliable line of defense for the safety of personnel if it strictly abides by all safety standards.
