Pipe-in-pipe field jointing system

Citation

(2001), "Pipe-in-pipe field jointing system", Anti-Corrosion Methods and Materials, Vol. 48 No. 6. https://doi.org/10.1108/acmm.2001.12848fad.010

Pipe-in-pipe field jointing system

Pipe-in-pipe field jointing system

Keywords: Hyperlast, Pipelines

Pipe-in-pipe field jointing has until now been a time-consuming and expensive commodity. Prior techniques required many man-hours to be used on each joint to accommodate welding, lifting, and waiting time for the pipe to be moved into place. These elements, together with the unusually long joints, meant that some pipelines required up to ten welds for each double joint, plus the use of many spacers to ensure correct centering of pipes.

ITP Interpipe reports that it has developed a system that self-centres the two pipes, requiring two welds as against the previous 10, and uses a smooth steel sleeve injected with "Hyperlast^®". The reward was a 25km contract from Elf, for the tieback of the Tchibeli Field, offshore Congo to the Nkossa production barge.

Hyperlast Limited, who base their products on extensive experience in materials technology and the offshore industry, worked with ITP to develop a suitable polymer jointing system. According to Hyperlast its "Hyperlast" 7983054 was developed to give excellent structural properties, low viscosity, fast curing time, and flexibility (Plate 4). These properties, together with the flexible characteristics of "Hyperlast", are believed to prevent a localised reduction in flexural rigidity, which could lead to unacceptable localised stress levels.

Plate 4 "Hyperlast" is injected into a smooth steel sleeve, in a new pipe-in-pipe field jointing system developed by ITP Interpipe

Major cost savings and throughput time were reportedly achieved on the Tchibeli project because of the low viscosity of "Hyperlast", which allows the polyurethane to flow quickly between the outer and inner pipes. In addition, the quick curing time claimed allows fast throughput, culminating in an average application cycle on the lay barge of only five minutes.

"Hyperlast" has been used in over 20,006 field joints both onshore and offshore. Complete design freedom is said to be achievable with the "Hyperlast" polyurethanes range, whose properties include fast curing time, controllable hardness, impact resistance, low temperature flexibility, and excellent adhesion; it can also be processed at relatively low temperatures.

All Hyperlast materials are stated to be quality assured (ISO 9001) and are backed by an outstanding technical backup team, and a research and development department.

Details available from: Hyperlast Limited, Tel: +44 (0)1663 746518; Fax: +44 (0)1663 746605; E-mail: help@hyperlast.co.uk; Web site: www.hyperlast.co.uk