Which material is specified for the thickness calculation of the seamless, blank unstayed dished head under 1650 kPa?

The correct material for the thickness calculation of seamless, blank unstayed dished heads under a pressure of 1650 kPa is SA-299. This specification is particularly suited for pressure vessels and provides the necessary mechanical properties and thickness standards required for high-pressure applications.

SA-299 is a specification for carbon steel plates intended for use in pressure vessels. It delineates the chemical composition and mechanical properties that ensure the steel can maintain its integrity under the expected pressure conditions. In the context of dished heads that need to support internal pressure, the strength, ductility, and other related properties of SA-299 make it ideal for such applications.

Other materials listed, while they may be used in different contexts, do not have the same combination of properties required for a seamless, blank unstayed dished head under such significant pressure. For instance, SA-285 is designed for lower-pressure applications, and its grades (A and C) vary slightly in terms of yield strength and tensile strength, further impacting their suitability for high-pressure conditions compared to SA-299. Therefore, when considering the specific requirements for thick-walled components in pressure vessels, SA-299 is the preferred choice for this condition.