Disclosed is an apparatus for connecting a pressure gauge to a pipe. The apparatus includes a cylinder, a joint/valve unit and a clip. The cylinder includes a space defined therein for receiving the pressure gauge, an aperture in communication with the space and a slit in communication with the aperture. The joint/valve unit includes a section for connection to the pipe and another section inserted in the aperture and formed with two grooves. The clip is inserted in the grooves through the slit, thus keeping the joint/valve connected to the cylinder.