Because of its high strength, tempered glass may be used in curtain wall, large window and window wall systems to resist high wind pressure or horizontal imposed loads specified in Table 3 of Regulation 17(3) of the B(C)R. However, tempered glass is susceptible to spontaneous breakage induced by nickel sulphide inclusions. Extreme care and considerations to minimize the spontaneous breakage should therefore be taken in the manufacturing process of tempered glass prior to application in the construction of buildings, all tempered glass panes should be heat soak treated. It is widely recognized that heat soak process accelerates the expulsion of the nickel sulphide inclusions in tempered glass and that heat soak process is the most effective means of eliminating tempered glass with nickel sulphide.

Under item 6 in Section 17(1) of the BO, a condition will be imposed, when giving approval of plans, to require the submission of a quality supervision plan by the RSE and the RC for the quality supervision of manufacturer’s heat soak process of the tempered glass to be used in the works shown in the approved plans. The RSE should assign a quality control supervisor to supervise a certain number of tempered glass panes undergoing the heat soak process. The RC should assign a quality control supervisor to provide full time continuous supervision of the heat soak process of all tempered glass panes in the factory.

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