The pipe joint mostly used for pipes carrying water at low pressures is

Solution (By Examveda Team)

For pipes carrying water at low pressures, the most commonly used pipe joint is the Socket joint.

A Socket joint is simple to make and provides a tight connection suitable for low-pressure applications.

- Option A: Socket joint is widely used in plumbing for water supply lines at low pressure.
- Option B: Nipple joint is typically a short piece of pipe used to connect two fittings but is not a joint type by itself.
- Option C: Union joint is used where frequent dismantling is required, more suitable for maintenance purposes.
- Option D: Spigot and socket joint is similar to the socket joint but generally used for higher pressure or different pipe types.

Hence, the correct answer is Option A: Socket joint.