Abstract: The present invention provides a valve which makes it possible to reduce the diameter of the vacuum exhaustion pipings for making the facility for the vacuum exhaustion system small, as a result lowering the costs, and making the vacuum exhaustion time short, and also which can prevent the corrosions, cloggings, and seal leakages inside the piping system caused by the accumulation of substances produced by the decomposition of the gas. Specifically, the aluminum passivation is applied on the piping parts, i.e. the valve and others, used in the vacuum exhaustion system to inhibit the gas decomposition caused by the temperature rise at the time of the baking so that components for the reduction in the diameter size in the vacuum exhaustion system are provided. The corrosions, cloggings and seat leakages caused by the gas decomposition are prevented.