How often should diameter measurements of a vessel skirt be taken to check for distortion?

Taking diameter measurements of a vessel skirt at periodic intervals is essential for identifying any distortion or out-of-round conditions that may jeopardize the integrity of the pressure vessel. Measuring every 60 degrees allows for a thorough assessment of the skirt's condition while maintaining a balance between resource efficiency and comprehensive coverage of the structure.

This choice is based on standard practices that recommend measuring at regular angular increments to ensure that the entire circumference is assessed without excessive expenditure of time or resources. A 60-degree interval offers a reasonable number of measurement points—six around the vessel—that can effectively highlight changes without over-complication.

In contrast, measuring at smaller intervals, such as 30 degrees, could potentially lead to unnecessary work and may not provide significantly more useful data. On the other hand, larger intervals like 90 degrees would likely miss critical areas of distortion, making the assessment less reliable and could increase the risk of undetected issues. Therefore, measuring at 60 degrees strikes a balance that aligns with best practices in pressure vessel inspections.