Economic Outlook Brightens For Pipeline Coating Developments

The economic crisis has affected pipeline construction as with many other industries, because of the lack of availability of finance for new projects, and because of the drop in oil and gas prices. However, oil prices are starting to rise again in 2010 and the outlook for pipe coating is very encouraging, according to Noru Tsalic, Consultant at Applied Market Information. He was speaking at the AMI conference on Pipeline Coating held February in Vienna, Austria.

Russia has the largest natural gas reserves and is in the top 10 for oil reserves. Transneft has 49,000 km of pipelines and Gazprom, the world’s largest gas company, has 169,000 km of gas transmission systems according to Tial. The most common onshore coating in the country is polyethylene. The average pipeline lifespan is 33 years and around 34% of oil trunklines are more than 30 years old, which shows the potential for market growth.

ExxonMobil is the largest global petroleum company and in 2007 was producing the equivalent of 4.2 million barrels of oil per day with seven new upstream projects. Michael Surkein of the Development division has reviewed pipe coatings. 

Fusion-bonded epoxy (FBE) is used up to 95C, with three-layer polyethylene up to 80C and three-layer polypropylene up to 110C (commonly used subsea). Polyurethane is sometimes added for insulation and compatibility with the polyolefin coating then becomes an issue. The company looks at aspects such as handling, cathodic disbondment and the ease of field joint coating. 

FBE is the main pipe coating in North America and ANZAC, whereas polyolefins predominate in Western Europe, North Africa, Russia and South America. Canusa-CPS is working on improved coating systems, for example, the PP preheat temperature in the new GTS-PP is down to 160C, with an improved operating temperature rating of 140C.

Salzgitter Mannesmann Forschung is a leading pipe coater. Chromium ions are used for pre- treatment for FBE coatings, but this process may be banned as it is very toxic. The company has recently studied alternative adhesion promoters including epoxysilane and aminosilane, Ti and phosphating. It is proving difficult to match the performance of chromating.

Wet sour gas is a corrosive hazard in the petroleum industry. Tuboscope/Vetco has an epoxy novolac coating with high hydrogen sulphide resistance and maximum service temperature of 204C, primarily for high pressure high temperature (HPHT), sour environments. It is said to be the only coating approved for Khuff Gas/Aramco and has also been tested by Vnigaz/Gazprom.

In Brazil, Petrobras has been studying the joints of FBE-coated pipes in the Ubarana pipeline. As the oilfields are aging, water injection is being used as the standard method to aid recovery, but this increases corrosion of pipes. This research has found a successful method of qualification for the water injection Ubarana 12-inch pipeline project with FBE on the girth welds.

Dow Coating Materials is producing new high glass transition temperature (Tg) resins for FBE coatings, developed by modelling the molecular structure of epoxy. These are for high service temperature operation and can raise the Tg by up to 50C. New curing agents enable the durability to be extended even further.