Final answer:
An inservice process pipe should be classified as Class 1 when the % of H2S exceeds a certain threshold. The threshold is typically determined by industry standards and regulations, such as the API Recommended Practice 571.
Step-by-step explanation:
An inservice process pipe should be classified as Class 1 when the % of H2S exceeds a certain threshold. This threshold is typically determined by industry standards and regulations, such as the American Petroleum Institute (API) Recommended Practice 571.
For example, according to API RP 571, if the % of H2S in a process pipe exceeds 0.1%, it should be classified as Class 1. This is because H2S is a highly toxic gas that can cause corrosion and other safety issues in the pipe. It's important to note that different industries and regions may have their own specific classification criteria, so it's always best to consult the relevant standards and guidelines for accurate information.