Faster installation and better protection from corrosion are just a couple of the advantages offered by Wellstream International Ltd. with its FlexSteel flexible steel pipe in onshore hydrocarbon gathering and injection applications.

According to the company, the pipe offers corrosion resistance and flow characteristics

FlexSteel pipe features inner and outer corrosion-proof sheaths sandwiching two tensile strips for strength. (Diagram courtesy of Wellstream International Ltd.)
superior to steel line pipe. In addition, the pipe arrives on location on spools, eliminating the standard welding operation necessary with lengths of standard pipe.

Since the flexible pipe went into commercial production in 2004, operators have specified more than 500 miles of the pipe in the United States and Canada.

The makeup of the pipe is straightforward. The inner layer is an extruded thermoplastic layer that maintains integrity and prevents carried fluids from leaking out of the pipe. Around that, the company contra-winds two carbon steel strip reinforcement bands spirally. Those strips provide the strength to resist internal pressure and tensile loads on the pipe. The final outermost layer is a thick, extruded external polymer shield that protects the inner layers from outside conditions, eliminating the need for cathodic protection and most coating repairs.

Installation costs typically run a third to a half of conventional rigid steel pipe installation, largely from savings storing long lengths of flexible pipe on a reel and minimizing the number of weld joints with the labor and inspection requirements that go with them.

In addition, high reliability and corrosion resistance lowers operating costs with the flexible pipe. Corrosion inhibitors are not required.

In most cases, the company said, an operator can install 3.1 to 6.2 miles (5 to 10 km) of flexible pipe a day with spools that hold approximately .6 miles (1 km) of pipe. In addition, no pipe-bending equipment is required.

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