Hot Tapping on High Pressure Nitrogen Pipeline

Location
Jurong Island

Project Timeline
February 2021

Technical Details
Pipe Material: Galvanized Steel SCH40
Pipe Medium: Nitrogen (N2) Gas
Pressure: 30 barg
Temperature: Ambient
Pipe Diameter: DN 250
Coring Diameter: DN 200
Height of work: 8 metres from ground

Technical Challenges
An industrial gas supplier engaged Alstern’s services to branch out a nitrogen pipeline without system shutdown. Main challenges for Alstern to expand the client’s pipeline were the high-pressure of pipeline and working at a height of 8 meters from ground.

Technical Solutions
Hot tapping is the go-to method for expansion of live pipelines. For hot tapping at this elevated site, scaffolding & personal protective equipment (PPE) were required. For preparation, a full encirclement saddle was welded onto the main pipe. Following this process, gate valve and hot tap machine were installed.

Hot tapping is a continuous process, the machine starts cutting through the pipe wall until the section of pipe (also known as coupon) is cut-off. After this, the cutter is retracted, and the gate valve is closed quickly to contain the high-pressure N2 pipeline. To conclude the work, the coupon is removed from the u-wires and the hot tap machine is disconnected from the gate valve.

The pipeline was successfully handed over to the client with the pipe branched out.

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