Pipe-in-Pipe

Flow Assurance

Insulation Capabilities

Pipe-in-Pipe Overview

Pipe-in-Pipe Offshore Construction

1. Fixed

• suitable for majority of lay vessels
• field joint uses bulkheads or swaged connectors, no movement between flowline and carrier pipe
• permits vacuum in annulus
• heat loss from flowline to carrier pipe through metal connectors

2. Sliding

• S-lay & J-lay
• uses a butt weld on carrier pipe and allows the flowline to move freely
• flowline may or may not have alignment spacers
• thermal insulation may be on the outside if flow-through-annulus active heating is used

3. Restrained

• polymer bulkheads to hold insulation material in place
• these bulkheads transfer the load during installation and provide concentric alignment

Deepwater Pipe-in-Pipe

Active Heating Pipe-in-Pipe

Source : http://www.deepsea-eng.com/sites/deepsea-eng.com/files/media/DeepSea%20Pipe-in-Pipe%20technical%20presentation.pdf