Which solution is commonly used to locate leaks in gas piping?

The use of a soapy solution is common for locating leaks in gas piping due to its effectiveness in creating bubbles at the site of a leak. When the soapy mixture is applied to a potential leak area, if there is any escaping gas, it will rise through the liquid and form visible bubbles. This method is both simple and economical, making it a preferred choice for technicians, as it allows for quick visual identification of gas leaks.

In contrast, the other solutions mentioned are not suitable for this purpose. Saline solutions could corrode certain materials over time and are not designed for detecting gas leaks. Alcohol solutions might evaporate too quickly to be effective and do not provide clear indicators of gas escape. Oil solutions may not create bubbles effectively and could leave a residue that complicates further inspections or repairs. Therefore, the soapy solution provides the optimal combination of ease of use and clear visibility in detecting gas leaks.