Which of the following is a reference recommended within API 936?

The reference recommended within API 936 is ACI 547R - Refractory Concrete: Stage-of-the-Art Report. This document is acknowledged for its comprehensive overview of the advancements and practices in refractory concrete, which makes it particularly relevant for professionals working with refractory materials. It covers key aspects, including composition, properties, testing methodologies, and applications in various industrial environments.

In the context of API 936, which primarily focuses on the certification and guidelines for refractory personnel, having a reference that addresses the specifics of refractory concrete is crucial for understanding best practices and current trends in the industry. This directly supports the training and certification process by ensuring that personnel are informed of high-quality standards in refractory applications.

Resources like API Std 780, ISO 9001, and ASTM C95, while valuable in their own right, do not specifically focus on the nuances of refractory materials and their application, which is why they are not recommended as references within API 936 for this particular context.