What must the manufacturer do to indicate the service ratings on the valve body?

The correct approach for manufacturers to indicate the service ratings on the valve body is to stamp or mark the information directly onto the surface. This method ensures that the information is durable and resistant to wear, which is essential in maintaining clarity and legibility over the valve's operational life.

Stamping or marking is often used because it creates a permanent identification that can withstand the conditions typically faced in the field, such as exposure to chemicals, temperature fluctuations, and mechanical wear. This permanence is crucial for safety and compliance, as operators need to easily verify service ratings to ensure they are using components correctly and safely.

While engraving is another method that provides a permanent mark, it is often more labor-intensive and not the most common practice for indicating service ratings on valve bodies, especially in high-volume manufacturing contexts. Painting, on the other hand, can wear off over time and may not provide the same level of durability. Labeling could also become detached or damaged, compromising the clarity of the information.

In summary, stamping or marking is the preferred method due to its lasting nature and ability to provide essential safety information that operators need to ensure valves are used within their intended service ratings.