In API 936, it is specified that as-installed specimens of gunned refractory linings are to be cut from the installation using adiamond saw. This ensures precision and avoids thermal or mechanical damage to the specimen, which could otherwise alter the properties being tested such as density or strength.
This practice is consistent with ASTM standards (e.g., ASTM C133, ASTM C704) referenced in API 936 for the preparation of physical specimens.
Reference:API Std 936, Section 6.4.4 - "Cutting of test specimens shall be performed using a water-cooled diamond saw to avoid thermal damage."