Papers at the Evaluation and Rehabilitation Conference and Exhibition, held between 21 and 22 October 2009, described a wide variety of approaches and solutions. While replacement is sometimes the only option, and can provide an additional lifespan of 50+ years to a pipeline, rehabilitation is often the more cost effective solution. Many techniques have now been developed to assist pipeline owners with rehabilitation decision-making and implementation, and the rehabilitation industry is growing as a consequence.

The conference’s opening presentation focused on rehabilitating – and even, recycling – the pipes themselves after they have been lifted from the trench. Truboetal of Moscow and Incal Pipeline Rehabilitation of Houston described a plant that has been set up in Russia to refurbish 56 inch diameter pipes taken out of the ground by Gazprom. Upwards of 20,000 km of pipe per annum is currently being replaced in Russia by Gazprom and others, and the pipes can often be reused provided careful attention is taken to their refurbishment and subsequent inspection.

Bill Bruce of DNV Columbus gave a review of hot tap and sleeve welding. This process is fraught with issues that demand very careful attention to the details of the welding involved. The wrong temperature, or inattention, can lead to the perils of ‘burn-through’ and consequent leakage. Mr Bruce’s ‘rules of thumb’ to be considered for pipeline sleeving start with “Is the repair required at all?” – a question that surprisingly often can be answered in the negative.

Dr Chris Alexander from Stress Engineering of Houston gave a comprehensive overview of materials and techniques. Alan Morton of TD Williamson and Bart Davis of Neptune Research’s Syntho-Glass division spoke about various projects their companies had undertaken in which composite wraps had been used with great success. There is now a considerable range of composite-wrap alternatives, and care needs to be taken in specifying the one that is to be used for any particular job as their properties vary quite widely.

Two other ‘wrapping’ techniques were presented. Smart Pipe has developed what presenter Richard Huriaux described as a ‘mobile factory’ that allows a pipe to be made onsite using a process in which a high density polyethylene (HDPE) core pipe is wrapped with high-strength fibre tapes and windings, cased in an HDPE outer wrap and laid in the ground. Diameters up to 24 inches are currently feasible, and there are many advantages of this process over ‘traditional’ pipelaying. In addition, Pipestream of Houston, a company set up to develop new technology for Shell Global Solutions, is now able to wrap a host pipe with a steel reinforcing strip in such a way that the resulting wrapped pipe is considerably stronger than the original. The paper given by Ray Burke illustrated this by showing a series of burst tests where the host pipe burst well away from the location of the repair.

A major refurbishment job was then described by Sid Taylor of Incal. The project involved recoating 60 km of the Caspian Pipeline Consortium Oil Pipeline in Kazakhstan – a 1,510 km, 42 inch diameter line running from the Tengiz Oil Field to Novorossiisk on Russia’s Black Sea coast. The Russian contractor has developed an interesting and efficient coating removal, cleaning, and recoating system in the trench, which allows up to 150 m per day to be exposed, refurbished, and backfilled while in service.

Houston-based Dr John Smart of John Smart Consulting Engineers reviewed the problems associated with black powder in gas pipelines. Dr Smart pointed out that the problem is not only the physical aspects of the powder itself, but also its movement through a pipeline; it can be extremely damaging to both the internal pipe wall and rotating equipment, such as compressors, and management of the material demands considerable planning. One of the key research papers in this field was published in 1998 by Richard Baldwin of Southwest Research Institute in San Antonio on behalf of the Gas Research Council.

The final paper of the conference was from Doug Batzel of Galaxy Brushes in, Phoenix, Arizona, US. Mr Batzel gave an enthusiastic presentation on the importance of brush selection for cleaning pigs. Mr Batzel’s company has pioneered the development of so-called ‘pencil’ brushes, which are designed to deflect into pits and other internal pipeline features that stiffer wire brushes will pass over. This technology has already found favour with a number of pipeline operators in the Middle East who are reporting considerable success of their cleaning pig runs.