Horizontal or Underhand Joints.
—For making a successful wiped joint, the ends to be joined must be a good fit and the temporary fixing must be sufficiently strong so that the joints will not be broken in the process of wiping. These two points should be always strictly attended to. Service pipes should be tightly pressed home one in the other, the cupped or female end shaved inside with a knife, but not close in as is the case with soil or waste pipe; this allows the solder to fill up the cavity, which effectually prevents any tendency to sweat. This principle is followed up by some plumbers with branch joints on small size service pipes, the male end being worked in with a twisting motion, to prevent any solder getting into the pipes. All other pipe joints should be closed, the female end being tightly worked in round the male end of pipes as an extra precaution against the solder getting inside. It is a good plan to black the inside of waste and soil pipes, so that the solder will not adhere if any should get through when making the joint. [Fig. 50] shows the wiping of an underhand joint.
Beginners often spend a lot of time practising “rolling” underhand joints. This is bad practice, and will be of no use in wiping fixed joints. Little advice can be offered with regard to the actual wiping, constant practice being the essential thing. See that the solder is at the correct heat. This is readily found by dropping a piece of newspaper into the pot, and, if it quickly browns, the solder is ready for use. If the solder is used too hot it will quickly burn holes in the pipe, and if not hot enough a heat cannot be properly worked up, and the cloth may get torn trying to move hard metal. For underhand joints pour on steadily with a circular motion on to the sides of the joint, and on to the soil at the ends of the joint, until sufficient solder in a molten condition can be brought up to cover the top of the joint with the cloth, which is held underneath it; then pour steadily all over the solder until it runs back again. Repeat this continuously until the solder can be worked in a substantial body all round the joint without any hard solder being left at the underneath edges. Give the joint a last pour on, and wash all the solder into the cloth. Bring the solder smartly on to the top, and quickly work it all round the joint with the wiping cloth, using two fingers of one hand for the top and back edges, and the index fingers of both hands for the underneath part. The top of the joint should be roughly shaped first and the surplus metal brought over the back to the underneath; this should be worked into the bottom of the joint with a slight sideways motion. The extra body of metal should be used to warm up any hard edges, the surplus being brought up again to the top and quickly thrown off to the back.
Fig. 50.—Pipes Supported and Secured on Bench for Joint Wiping
Fig. 51.—Finished Wiped Joint