Final answer:
New boilers or extensively replaced pressure parts are usually required to undergo a hydrostatic test to ensure structural integrity and safety. This is different from an alkaline test, which is used for chemical treatment of the boiler water, not for testing pressure parts.
Step-by-step explanation:
When new boilers or pressure parts of a boiler are extensively replaced, they must typically undergo a hydrostatic test. This test is conducted to verify the integrity of the boiler and ensure it is safe to operate at the designated pressure. The hydrostatic test involves filling the boiler with water, which is then pressurized to a higher level than normal operating pressure to check for leaks and weaknesses in the boiler structure. This is a critical safety measure and is required by various safety standards around the world, one of which being the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code.
An alkaline test, by contrast, is not typically used for testing pressure parts after replacement but for the chemical treatment of the boiler water to prevent corrosion and scaling. Therefore, for testing the structural integrity of new or repaired boiler components, the hydrostatic test is the relevant procedure. In summary, the hydrostatic test is essential for ensuring the safety and proper functioning of new or repaired boiler pressure parts.