Question 1 CEL01 - Chief Engineer - Limited

The Correct Answer is B ### Why Option B is Correct Option B, **"descaled by using a pickling solution,"** is the primary and essential step for newly fabricated steel piping intended for use in a hydraulic system, especially high-pressure systems. 1. **Contamination Source:** New steel piping often retains mill scale (a flaky iron oxide layer formed during hot rolling), weld slag, flux residue, rust, and other contaminants. 2. **Hydraulic Sensitivity:** Hydraulic systems operate with tight clearances (e.g., in pumps and valves) and rely on clean fluid. If mill scale or rust flakes off during operation, it will cause catastrophic damage, component failure, and filter clogging. 3. **The Process:** Pickling is a chemical cleaning process (using acidic solutions) specifically designed to dissolve and remove these metallic oxides (scale and rust) from the internal surfaces of the pipe, making the surface clean and passive. This step is critical for ensuring the cleanliness standards required by modern hydraulics. ### Why Other Options Are Incorrect **A) hydrostatically tested to 100% of maximum working pressure:** * While pressure testing (proof testing) is a crucial quality assurance step *after* cleaning and *before* final installation (or commissioning), it is **not** the necessary cleaning step mentioned in the question. Performing a hydrostatic test on uncleaned piping can introduce water, rust, and contaminants that are difficult to remove later, potentially negating the effects of future pickling or flushing. The *cleaning* must precede the *testing*. **C) cleaned using a water-based detergent:** * Detergents are effective for removing oils, grease, and superficial dirt. However, they are **ineffective** at removing the hard, chemically bonded mill scale, weld flux, or heavy rust. Mill scale requires a strong chemical reaction (acid pickling) to be dissolved. Furthermore, using a water-based solution requires extensive and immediate drying/purging afterward to prevent internal flash rusting, which can recontaminate the piping. **D) all of the above:** * This option is incorrect because the steps must be performed in a specific sequence, and the critical cleaning requirement (B) is not functionally equivalent to the testing requirement (A) or the inadequate cleaning method (C). Descaling (B) is the mandatory **prior** step to prepare the pipe for service, making it the most appropriate answer for what must be done "prior to installation."