#Pipeline toolbox hot tapping manuals
These manuals provide information on what to consider during welding, including burn-through prevention, flow in lines, metal thickness, fittings, post weld heat treatment, metal temperature, hot tap connection and welding design, and piping and equipment contents. Safety manuals and procedural outlines are available from the American Petroleum Institute (API), American Society of Mechanical Engineers (ASME), and other organizations for welding on in-service pipelines for all sizes, flow rates, and locations. Suitable valves include a ball or gate valve, but not a plug or butterfly valve. The valve on a hot tap connection can be either a block valve or a control valve for the new connection, and must allow the coupon (section of pipeline wall cut out by the drilling machine) to be removed after the cutting operation. The tee wraps completely around the pipeline, and when welded, provides mechanical reinforcement of the branch and carrier pipe. Connection to the existing pipe is made within a fitting, which can be a simple welded nipple for small (e.g., one inch) connection to a larger pipeline, or a full-encirclement split-sleeve tee for extra support when the branch is the same size as the parent pipeline. The cutting tool is used to bore a pilot hole into the pipeline wall in order to center a hole saw that cuts out the “coupon,” or curved section of pipeline wall. The drilling machine generally consists of a mechanically driven telescoping boring bar that controls a cutting tool. Hot tapping equipment is described below and shown in Exhibit 1. The primary equipment for a typical hot tap application includes a drilling machine, a branch fitting, and a valve. Hot tapping equipment is available for almost any pipeline size, pipe material, and pressure rating found in transmission and distribution systems. Hot taps permit new tie-ins to existing systems, the insertion of devices into the flow stream, permanent or temporary bypasses, and is the preparatory stage for line plugging with inflatable, temporary balloon plugs (stoppels). The process involves attaching branch connections and cutting holes into the operating pipeline without interruption of gas flow, and with no release or loss of product. Hot tapping is also referred to as line tapping, pressure tapping, pressure cutting, and side cutting. Hot tapping is an alternative technique that allows the connection to be made without shutting down the system and venting gas to the atmosphere.