GB/T 4513.4 - 2017 is the fourth part of the standard for amorphous refractory materials, focusing on the determination of the flowability of castables. It specifies special test equipment, such as truncated cone round molds, etc. Detailed sample preparation and test steps, the stirred castable is placed in a specific mold, and after removing the mold, the flowability is quantified by measurement of the expanded diameter of the castable. The standard provides a key basis for manufacturers to control the mass of the castable and the construction unit to evaluate the construction performance. It ensures that the castable can flow and fill smoothly in high temperature industrial construction, and guarantees the mass of the project and the subsequent use effect.