Various coating systems have been tried over the past 45 years and they have evolved with time and with innovation of new materials. Today, five main coating systems are commonly used for pipelines: three layer PE (3LPE), three layer PP (3LPP), fusion bonded epoxy (FBE or Dual FBE), coal tar enamel (CTE), asphalt enamel and polyurethane (PUR). The different systems are specified by pipeline owners and consultants based on various factors, including short-term cost, long-term cost, captive usage, regional availability of the coating material, control on handling, transportation and installation of pipelines, and technical reasons.

3LPE coating is dominant worldwide – with 50 per cent market share – for onshore pipelines, with the exception of North America. The trend is increasing with a greater number of projects coated with 3LPE in China, India and the Middle East. The increased acceptance of 3LPE is due to its broad operating temperature range (from -45°C to + 85°C) and ability to withstand very rough handling and installation practices without damage to the coating.

3LPE systems consist of an epoxy primer, a grafted copolymer medium density (MDPE) adhesive to bond the epoxy primer with a high density (HDPE) topcoat.

3LPP systems are recognised as excellent systems for offshore projects with elevated operating temperature (0°C to +140°C) and extreme mechanical stress on the pipes. Recent projects in the North Sea, Africa, Gulf of Mexico and Arabian regions have set new standards for 3LPP coatings, which provide access to deeper gas and oil fields.

3LPP system consists of an epoxy primer, a grafted copolymer PP adhesive to bond the epoxy primer with a PP topcoat.

FBE is dominant in North America, United Kingdom and a few other countries but the trend is declining in favour of 3LPE and PP Systems. Some pipeline owners have graduated from coal tar coating to Dual FBE as the cost has become quite competitive after increases in coal tar prices.

Coal tar and asphalt enamel are both still used in some countries. For many refineries, which have their own pipelines, coal tar is the cheapest coating option, being their own product. Both systems are declining and suffer from health and environmental concerns.

PUR systems are mostly used for pipeline rehabilitation projects or girth weld coating. PUR systems also suffer from health concerns.

In this context, PP systems with up to seven layers are increasingly gaining ground for technically challenging deep sea projects, with very high operating temperature, where several functional PP layers are used for thermal insulation foams. These foams, apart from insulation properties, should have high compressive strength so that they do not collapse under high external pressure in deep see environment.

HDPE and PP based systems offer excellent mechanical protection and long-term ageing performance.
Providers of innovative, value creating plastics solutions, Borealis and Borouge have over 40 years of combined experience in the polyolefins industry and a record of engaging with parties throughout the value chain. Borealis is pre-eminent in Europe with a strong leadership position in the industry whilst Borouge has a strong growing market presence in the Middle East, Asia-Pacific and Africa. Their long experience and expertise in the plastic pipe industry includes more than 20 years in steel pipe coating. In the 80s and 90s, the group supplied an extensive number of projects all over the world, initially with low density (LDPE) and MDPE compounds for pipe coating.

With continuous research and development, Borouge and Borealis’s first bimodal high density PE system with grafted MDPE adhesive was introduced in 1997 and it remains a leading 3LPE system. In 1990, Borealis introduced its first PP system.

Borouge and Borealis employ their unique Borstar™ technology to produce differentiated, high performance PE and PP polymer solutions for steel pipe coating. Borstar technology combines excellent processability and melt strength of the polymer with very high properties like notch resistance, abrasion resistance, improved impact at low and elevated temperatures, peel strength and indentation resistance. The HDPE and PP top coat are supplied in compounded form to withstand long term thermal ageing and light ageing.

A high level of investment in research and development in close co-operation with customers ensures the continual development of innovative new products and pipe system solutions. Several new products are under development including a PE top coat with very high resistance to slow crack growth, machine applied PE for field joint coatings, PP weight coating and PP injection moulded systems for field joint coating.
The result of this approach is a long pipeline service life with minimum maintenance cost for the pipeline owner, fast production and high output for the pipe coater, easy installation without repairs for the installers and peace of mind and reliability for the engineering consultant.