Question 52 1AE01 - First Assistant Engineer

The Correct Answer is C **Why option C ("an ptfe/glass fiber reinforced gasket") is correct:** In industrial pumping applications (like those depicted in standard pump illustrations such as GS-0012, which typically shows a centrifugal pump assembly), maintaining a static seal between major casing components—like the suction cover (or pump casing cover) and the volute (the main pump body)—is crucial for preventing leakage and maintaining efficiency. This static seal is most reliably achieved using a dedicated, high-quality gasket material placed between the two bolted flanges. A PTFE/glass fiber reinforced gasket is a high-performance material commonly used in chemical and industrial pumps because it offers excellent chemical resistance (from PTFE) and structural strength and dimensional stability (from the glass fiber reinforcement), ensuring a durable and leak-proof joint under high pressure and temperature. **Why the other options are incorrect:** * **A) good metal-to-metal contact:** While highly machined surfaces can achieve a seal (e.g., in hydraulic systems), relying solely on metal-to-metal contact for a large, flanged pump casing joint is impractical for industrial equipment. Tolerances are too difficult to hold, and thermal cycling or slight imperfections would inevitably lead to leakage. A soft, compliant element (a gasket) is required to fill microscopic gaps. * **B) sealant between the two parts:** Sealants (like RTV silicone or thread compounds) are generally used for minor joints, pipe threads, or as a dressing *on* a gasket. They are not typically used alone to create the primary static seal for the main high-pressure joint between the suction cover and the volute in industrial centrifugal pumps; a robust, dimensionally stable gasket is necessary for this purpose. * **D) compressing the packing rings:** Packing rings (or mechanical seals) are used to maintain a dynamic seal around the rotating shaft where it passes through the pump casing (the stuffing box). They have no function in sealing the static joint between the non-moving suction cover and the volute casing.