Type B vent pipe must be kept at least ________ from combustible materials.

Type B vent pipe must be kept at least 1 inch from combustible materials to ensure safety and to comply with building codes and standards. This distance is crucial as it helps prevent the possibility of combustion caused by the heat generated by the vent pipe during the operation of gas appliances. Maintaining the specified clearance allows for proper airflow around the vent, which facilitates efficient operation and reduces the risk of overheating adjacent materials.

This regulation is established to mitigate fire hazards while ensuring the venting system functions effectively. While other clearances might apply in different contexts or for different types of venting, the 1-inch clearance is a widely accepted standard specifically for Type B vents, which are commonly used for gas appliances.