ASME B31.8, 831.3.7 A __________ is a pressure-containing component used for repeated access to the interior of a piping system. A) Quick Opening Closure B) Pup Joint C) Blind Flange D) Relief Valve

The question asks to fill in the blank for a definition: "A __________ is a pressure-containing component used for repeated access to the interior of a piping system."

Let's evaluate the given options:

• A) Quick Opening Closure: This is a device specifically designed to allow rapid and repeated access to the interior of a pressure vessel or piping system without the need for extensive bolting or tools. This perfectly matches the description.
• B) Pup Joint: A short length of pipe used to make up specific lengths in a pipeline. It does not provide access to the interior.
• C) Blind Flange: A solid disc used to block off a pipeline or vessel opening. While it contains pressure, it is not designed for repeated access as it requires unbolting.
• D) Relief Valve: A safety device that opens to release excess pressure. It does not provide access to the interior of the system.

Therefore, the term that fits the definition is "Quick Opening Closure."

The correct option is A).

$$\boxed{\text{A) Quick Opening Closure}}$$