Exceptions to markings apply to piping designed to carry more than one gas and what type of plants?

The correct response is based on the specific nature of gas-manufacturing plants and how they handle multiple gases. In gas-manufacturing facilities, there is often a complex system that deals with various types of gases, including those that might not be classified as flammable or hazardous. The regulations recognize that such plants have unique operational characteristics that might not necessitate the same rigorous marking requirements as other types of facilities.

It is important to highlight that gas-manufacturing plants often produce, blend, or process different gaseous substances, which could include non-flammable gases, necessitating a distinct approach to their piping and markings due to the varied nature of the substances involved.

On the other hand, while manufacturing plants, food processing plants, and chemical plants may also have complexities in their operations, their regulatory environments concerning gas handling and marking do not have the same specific exemptions that apply to gas-manufacturing plants.