Which document serves as a guideline for evaluating various forms of degradation in pressure vessels?

The document that serves as a guideline for evaluating various forms of degradation in pressure vessels is API 579, also known as the Fitness-For-Service (FFS) standard. This standard provides a comprehensive approach to assessing the structural integrity of pressure vessels that may have experienced degradation due to factors like corrosion, fatigue, cracking, or other influences related to operational stresses.

API 579 outlines methodologies for analyzing the condition of vessels and delineates the steps necessary for determining if a vessel is still fit for service. It incorporates assessments based on the type and extent of the degradation identified and offers guidelines on repair and remaining life evaluation to ensure safety and operational reliability.

Other documents listed do provide important information relevant to pressure vessels but serve different functions. For instance, API 510 focuses on the inspection, repair, alteration, and re-rating of in-service pressure vessels, while ASME Section VIII covers the design and fabrication of pressure vessels. The National Board Inspection Code, on the other hand, is primarily concerned with the criteria for the inspection of boilers and pressure vessels post-construction. Each of these documents plays a critical role in the industry, but API 579 specifically targets the evaluation of degradation.