Here stove pipe should always be installed with the "male-end-down". Installing the pipe male-end-down allows creosote drippings to go back down into your stove instead of running down your pipe onto the stove or floor.The pipe connected to a wood or pellet stove should not need sealing unless it has a hole or leak in it. When conditions are right, the negative pressure and natural draw of the stovepipe causes the hot smoky air to rise through the pipe and out the chimney. including gas pipe , electric cable , liquid pipe for more details download this file.