The correct answers are A (Borescope) and C (Hydrostatic test) because these are commonly accepted and practical methods for inspecting the condition and integrity of heat exchanger tubes under the Mechanical Integrity element of RBPS.

Borescope inspection (A) allows direct visual examination of the internal surfaces of tubes. It is particularly useful for identifying corrosion, fouling, pitting, cracking, and blockages . CCPS recognizes visual inspection tools as important non-destructive examination (NDE) techniques for assessing internal equipment condition.

Hydrostatic testing (C) is used to verify the pressure integrity and leak tightness of the exchanger tubes. By pressurizing the system with a liquid, operators can detect leaks or weaknesses that could lead to failure during operation.

Option B (Dye injection) is not a standard or recognized method for internal tube inspection in heat exchangers. While dye penetrant testing exists, it is typically used on surfaces—not for internal tube integrity in this context.

Option D (Radiography) is generally impractical for inspecting individual tubes in shell-and-tube exchangers due to geometry, access limitations, and effectiveness concerns.

CCPS emphasizes selecting appropriate, proven inspection techniques that effectively assess degradation mechanisms and ensure continued safe operation of critical equipment.