What is the ligament efficiency used for the maximum operating pressure calculation of the SA-515-70 steel drum?

The selected answer of 0.66 for the ligament efficiency in the maximum operating pressure calculation of an SA-515-70 steel drum is based on established standards and practices in the engineering field, particularly concerning the design and structural integrity of pressure vessels.

Ligament efficiency is a critical factor that signifies the effectiveness of the effective cross-sectional area in resisting pressure. In the context of the SA-515-70 carbon steel, which is widely used in pressure vessels and boiler applications, an efficiency rating of 0.66 indicates that the design incorporates certain structural considerations that account for losses in strength due to openings for nozzles or other features.

This specific value of 0.66 is often derived from codes that regulate pressure vessel design, such as the ASME Boiler and Pressure Vessel Code. It reflects the balance between maximizing the strength of the metallic material while acknowledging the presence of stress concentration points that may arise from machining processes and design features.

Understanding the appropriate ligament efficiency is vital when assessing the maximum operating pressure, as it directly impacts how pressure vessels are designed and secured for safe operation. In practical applications, adhering to the correct value helps ensure that a vessel can withstand its intended operational conditions without risking structural failure.