Use of hot taps for gas pipelines can be expanded | Oil&Gas Journal

11/30/1998

John A. McElligott, Joe Delanty
TransCanada PipeLines Services Ltd.
Calgary
Burke Delanty
TransCanada PipeLines Ltd.
Calgary

---

TransCanada PipeLines Ltd., Calgary, has relied on hot tapping to complete more than 700 large diameter (12-30 in.), horizontal, high-pressure hot taps without incident since 1960.Its subsidiary, TransCanada Hot Taps (TCHT), has further refined the field procedures and completed forty-one 30 and 24-in. assemblies in 1998.

All taps were performed with no restrictions on flow or pressures (880, 1,000, and 1,440 psi maximum operating pressures), negligible emissions, and no deterioration in system integrity.

For TransCanada, the direct advantages of a hot tap over a cold connection resulted in the avoidance of gross revenue losses of $1 million (Canadian) or more per hot tap, no environmental emissions, seamless service, and no effects whatsoever on its shippers.

A hot tap is a method of joining a new tie-over pipe to an existing and loaded facility such as a pipeline or tank. The objective of the procedure is to cut an interconnection hole in the facility through a valved hot-tapping assembly without the need to evacuate the contents.

A successful hot tap will minimize operational effects and result in no spills or emissions. In this discussion, the generic term “hot tap” will include all of the technical operations necessary to prepare for and complete the interconnection of a new pipeline with an operating pipeline. The actual cutting of a hole in the pipeline will be referred to simply as “tapping” or “boring.”

The design, installation, and quality-control operations of a hot tap are described later.

• This 30-in. branch (left) was installed on a 48-in. (880-psi MOP) pipeline under full-flow conditions near Caronport, Sask. Note stiffener ring and centering device as well as the nondestructive examination (MPI) work. (Photograph courtesy TransCanada Hot Taps, Calgary) [38,590 bytes]
• Welders install a 30-in., round-body gate valve near Caronport, Sask. (Photograph courtesy TransCanada Hot Taps, Calgary) [32,689 bytes]
• Workers set up a TDW 936 hot-tap machine for a 24-in. tap on a 36-in. (1,000 psi MOP) pipeline under full-flow operating conditions in a residential subdivision in Barrie, Ont. (Photograph courtesy TransCanada Hot Taps, Calgary) [33,747 bytes]

Continue reading on ogj.com