Duoline provides a specially formulated epoxy resin that provides excellent chemical resistant properties facilitating even such harsh procedures as acid washes.

The smooth surface finish leads to reductions in scale or paraffin build-up.
The Duoline system, a Glass Reinforced Epoxy (GRE), can be inserted in carbon steel tubing eliminating the need for special handling associated with chrome or alloy completions.
Duoline strings can be handled and run like any standard steel completion.
In addition, the Duoline system can be installed in new or even used tubing. The Duoline manufacturing specifications including high hoop strength, complete holiday free, strength and rigidity ensuring suitability for wireline or coiled tubing intervention. 
Kenneth Ross, a member of the Society for Petroleum Engineers, said at a recent oil and gas conference in Texas.
“Historically, the construction of a barrier between a corrosive fluid and a given material has been among the most effective means of protecting a valuable assets from unnecessary destruction. The evolution of the lining process for tubular goods has culminated in the prolific advance of composite materials as corrosion barriers, especially in the oilfield environment.”
Ross continued to outline the advantages of one particular method of protection, “costly corrosion damage has been largely mitigated by protecting the tubular goods with Glass Reinforced Epoxy GRE liners. This material has proven to be highly resistant to many forms of corrosive environments, durable to the extent of enabling wireline and coiled tubing operations, highly effective in gas service and well-suited to both downhole and surface environments in terms of material strength and performance.” The Duoline system utilises GRE technology.
The system is available in two grades, Duoline 20 and Duoline 35.  These cover the entire range of conditions found in the oilfield.
Duoline 20
The workhorse of the Duoline lining systems, Duoline 20 is targeted at the majority of downhole corrosive applications. The Duoline 20 system has a proven track record in a great number of demanding environments including water injection, CO2 injection, gas production, gas-lifted oil production and chemical disposal wells, onshore and offshore.
It has an outstanding performance history in environments containing produced fluids and gasses with CO2 and H2S and has successfully prevented corrosion in gas production wells with formation temperatures as high as 292°F (144°C), and is typically used in water injection and gas production service up to 250°F (121°C).
Duoline 35
The most recent Duoline system that has been developed is Duoline 35 made from the most advanced resin chemistry raising performance to a higher level within an operating temperature up to 350°F (177°C). Duoline 35 targets the most aggressive operating conditions that are found in oil and gas producing wells in the oil field today.
Tests have shown the Duoline 35 system to withstand temperatures exceeding 356°F (180°C) with concentrations of up to 15 per cent H2S and CO2. Duoline 35 targets those conditions that might otherwise require costly duplex stainless steels, with the potential to save operating companies over 50 per cent of their material costs.
Economic benefits
Duoline can provide significant financial savings on capital expenditure (capex) cost compared with expensive chrome or alloy completions. In addition Duoline allows for the complete removal of chemical inhibitors, providing both financial and operational savings.
Further operational (opex) savings can be realised from the trouble-free service that Duoline provides, eliminating the need for work-overs to be carried out on tubing due to corrosion, providing additional savings in rig time and cost, manpower time and costs, and savings from any associated loss of production.