The experimental apparatus of corrugated flame-retardant system was shown in Fig. 9.1. The main part had been detailed in the previous work. Only a detailed explanation was introduced for the corrugated flame-retardant system. It consisted of the flame-retardant element shell, the flame-retardant element, the flame-retardant pressure plate, and four threaded support rods. The flame-retardant system was made of 304 stainless steel and its thermal conductivity was 16.3 W m−1 K−1. Multilayer flame-retardant elements were tightly stacked inside the flame-retardant element shell and was fastened by bolts, and placed inside the upper and lower flame-retardant pressure plates. The flame-retardant pressure plates with four through-holes at the diagonals were installed on the support rod with a determined height (H = 650 mm). By changing the length of flame-retardant element shell and the number of flame-retardant element, the structural parameters for different corrugated flame-retardant systems were achieved. To ensure a tight joint between the flame-retardant system and the inner wall surface, the gaps was sealed by the high temperature explosion-proof sealing mud. Two visualization windows were installed at the front and rear ends of explosion vessel to capture the transient transformation process of flame structure obstructed by the flame-retardant system and the propagation change after passing through the narrow channel.