Collar for joining branch pipe to main - has internally or externally threaded coupling boss receiving drill

摘要

Each collar consists of two half clamps (1, 2-8, 9) and layers of jointing material (3, 10). The clamps are bolted together with the bolts (4) and compress the jointing material firmly against the surface of the pipe (7). The upper half clamp (2:9) has a threaded boss with a central hole (6: 12) which serves as a guide for the drill which makes a hole in the pipe wall. Any swarf from the hole is taken away by the flowing liquid or air, although when used with water the pressure is first cut off. The branch pipe can then be attached to the boss which can ve provided with either an internal or external thread.