Which of the following statements about Type B Vent pipe is true?

The statement about Type B Vent pipe being composed of an inner aluminum pipe and an insulating outer layer accurately reflects its construction and purpose. Type B vents are specifically designed for venting gas appliances, offering critical safety features to handle high temperatures and corrosive gases. The inner aluminum pipe indeed allows for efficient venting, while the insulating outer layer prevents heat loss and protects surrounding materials from high temperatures, ensuring both efficiency and safety.

The other statements do not correctly represent the characteristics of Type B Vent pipe. For instance, being solely composed of PVC would not be true; Type B pipe requires significant structural integrity and heat resistance that materials like PVC cannot provide. Additionally, it is not exclusively for high-efficiency appliances; instead, it is suitable for a range of gas appliances. Lastly, stating that it functions as a single wall vent pipe is misleading, as Type B is a double-wall vent system designed to offer additional protection and efficiency compared to single-wall options.