Composite Piping Attracts Industry Attention

In 1995, the deep-water offshore oil industry was looking for strong, lightweight materials to replace the heavy alloy piping used on oil platforms in seawater. By reducing the weight of the piping materials on the service deck of a tension leg platform (TLP), the buoyancy of the TLP would increase. This would reduce the amount of structural steel needed below water, thereby significantly reducing the cost of a TLP.

Although carbon steel and copper nickel alloy pipe had traditionally been used on offshore platforms, advanced composites were known to be stronger, more resistant to corrosion, and lighter than steel. For example, composite pipe with a 6-inch diameter weighs 4 pounds per foot, whereas copper nickel pipe with the same diameter weighs 24 pounds per foot. Advanced composites also cost less initially than steel piping and have a longer life cycle. At the time that Specialty Plastics applied for the ATP award, the estimated life cycle of composite piping in seawater was 20 years, compared to 7 years for steel piping.

There were, however, obstacles to using composite piping that were related primarily to the lack of test data to support the materials' long-term durability. Engineers who were used to alloy pipe were uncomfortable with composites. Also, composite pipe fittings were expensive and labor-intensive to manufacture, and the methods used to join composite-to-composite piping and composite-to-alloy piping were unreliable. In addition, oil companies and regulatory agencies, such as the U.S. Coast Guard and the Mineral Management Service, thought that it was too risky to use the largely unproven composite materials for vital services, such as transporting water for extinguishing fires on an oil rig.

Innovative Design Concepts and Manufacturing Processes Proposed

Advanced composite piping had previously been partially developed in a U.S. Navy surface ship program. However, extensive work had not been performed on reliable joining methods and low-cost fittings. When Specialty Plastics decided to continue research and development, composite pipes were still considered an emerging technology. Therefore, this area of research, with a return on investment of six to eight years, was considered too risky for private industry. Thus, Specialty Plastics submitted a proposal to ATP for funding.

Advanced composites were known to be stronger, more resistant to corrosion, and lighter than steel.

An example of Speciality Plastics' joining and fitting of composite-to- composite and composite-to-alloy pipe segments.

Specialty Plastics' primary goals were to develop new technologies for joining and fitting composite-to- composite and composite-to-alloy pipe segments and to develop more efficient, less costly processes for manufacturing the fittings. The company proposed to improve joint technology by developing an integral flange technology and a heat-activated coupling technology. The integral flange is a joining method in which filaments are wound directly onto a pipe or fitting, thereby eliminating the joint. Joining composite components in this way, without the use of mechanical joints, protects the mechanical integrity of the pipe and is considered highly reliable.

A heat-activated coupling system is a simple, cost-effective means of joining composite-to-composite and composite-to-alloy pipe segments. It involves placing the prepreg laminate, made of fiberglass reinforcements impregnated with thermoset resins, over the pipe ends to be joined and applying heat around the laminate so that the thermoset resins cure and the laminate shrinks to seal the joints.

One issue with heat-activated coupling is that the resins do not cure completely and uniformly. Also, because metal is a better conductor and dissipates heat faster, the joining resins cure much more slowly on sections in contact with alloy pipe, resulting in leakage from these joints under normal loading conditions. To overcome these problems, Specialty Plastics planned to develop a computer-controlled heating device integrated with microsensors. The company also planned to design or identify joining resins that had desirable properties based on resin chemistry and curing behavior.

The company proposed to improve joint technology by developing an integral flange technology and a heat-activated coupling technology.

Specialty Plastics also sought to improve adhesive- bonded joints by enhancing the chemical bonding between the adhesive and the composites. Typically, adhesive and composite materials bond poorly due to the use of epoxy vinyl ester resins in fiberglass- reinforced structures and equipment. This has caused the failure of adhesive-bonded joints, generally at the interface between the adhesive and the composite surface. To overcome this problem, Specialty Plastics planned to chemically activate the joining surface so that the adhesive layer would be chemically bonded to it. The company also wanted to find a resin that had a chemical composition compatible with the joining surface.

Corrosion of metal piping costs approximately $20 billion each year.

Finally, the company explored the use of RTM technology. RTM is a molding process used to produce composite parts in which continuous fibers are placed inside a mold in the form of a two-dimensional woven fabric and injected with resin. Specialty Plastics planned to improve this technology by also using three-dimensional preforms, which could be mass-produced and were strong enough to maintain their shape when injected with the resin. The resin system would be the same as that used for composite pipe.

Specialty Plastics Anticipates Broad-Based Benefits

Specialty Plastics estimated that the market would grow to more than $10 million within 5 years of funding and to more than $40 million within 10 years. Oil companies investing in TLPs could realize potential savings of $20 million in capital investment, as well as additional benefits such as lower maintenance and life cycle costs. These cost savings would reduce the overall operating cost of a TLP and would increase the return on investment to the operator.

An increase in the use of TLPs would lead to an increase in domestic production of oil and gas. This would decrease the nation's need to import large amounts of foreign oil, a U.S. expense of more than $1 billion per week in 1995 and half of the national trade deficit. Increased domestic production would also result in more jobs in the United States ; for example, it has been estimated that a $30 million investment in oil and gas production can support 800 jobs in the oil and gas industry and even more in other areas of the economy.

Moreover, improved advanced composite piping systems would benefit industries where the corrosion of metal piping is a problem, such as the petrochemical industry, the commercial marine industry, and the pulp and paper industry. Corrosion of metal piping costs these industries approximately $20 billion each year.

Two New Processes Prove Successful

Specialty Plastics had to meet several requirements to achieve their goals of developing the integral flange, a heat-activated coupling system, enhanced chemical bonding between adhesives and composites, intelligent-filament winding, and RTM. These requirements and the company's related accomplishments are summarized below:

• Develop an optimal manufacturing procedure for integral flanges and computer programs to generate various winding patterns. Develop finite element modeling for integral flanges subjected to tension, bending, or both so that (1) material scraps are reduced, (2) the manual operation is eliminated, and (3) labor costs are reduced.
  Results: The company was able to reduce material scraps by 20 percent and labor costs by 20 percent as compared with the manual winding process used at the time.
• Develop a cost-effective process for manufacturing full-face flanges by using the integral flange technique. Results: The company reduced time and labor costs by 20 percent as compared with the currently used hand lay-up process.
• Complete the development andimplementation of an optical system to assist in the design of winding patterns.
  Results: A Specialty Plastics achieved a reduction in the cost and a 15-percent reduction in the time required to generate patterns.
• Develop a mold for a reducer joint and an elbow mold, set up RTM experiments, and produce a reducer.
  Results: The company compared the final properties of the reducer and the elbow, such as fiberglass content, and found that they increased more than 10 percent by weight. The ability to hold internal pressure on a hydro test was compared with that of conventional reducers and elbows and found to have increased more than 10 percent.

Specialty Plastics achieved the majority of its goals; however, it was unable to improve the surface adhesion of composite materials. The company had sought to increase the operating pressure of composite piping to 400 psi through improved adhesion, but was able to increase it to only 225 psi, which limits the applications of the piping to about 75 percent of the seawater cooling systems on offshore TLPs.

Also, the company's work on RTM was only partially successful, resulting in a modified RTM technology. However, based on the research it performed during the ATP project, today the company is using a modified, state-of-the-art form of RTM technology in which an additional application of resin is applied to the fibers in a wet-layer process outside the mold. This method is not as efficient as the technology originally proposed, but it produces a stronger flange.

Composites Piping Market Increases

In 1998, Specialty Plastics began to market resin transfer molded flanges, reducers, and elbows and started to earn revenue. Their chief customers, Shell Deepwater, Exxon, and Texaco, were all operating in the Gulf of Mexico . The company also adopted process improvements for the RTM of the fiberglass pipe fittings it was already selling. In May 1998, the U.S. Coast Guard approved the use of composite piping in fire systems, which, according to Richard Lea, former President of Specialty Plastics, was a major victory. "It proved that composite materials could endure fire levels with medium-scale fire testing." Since then, the industry in the Gulf of Mexico has used composite piping for fire and seawater systems.

By 1999, Specialty Plastics had completed 38 major projects, and approximately 40 percent of its offshore oil and gas industry revenue came from the sale of composite parts. The company had approximately 50 customers. By the end of 2002, the company had completed 25 additional projects. Overseas companies in Australia , West Africa, and Malaysia are also beginning to purchase the technology.

Specialty Plastics achieved the majority of its goals;
however, it was unable to improve the surface adhesion of composite materials.

Specialty Plastics' success attracted attention from prospective buyers, and the company was purchased in December 1998 for $4.5 million by EDO Fiber Science. Specialty Plastics is now a subsidiary of EDO Specialty Plastics and generates annual revenues of approximately $15 million.

From 1995 to 1998, Specialty Plastics published numerous journal papers and presented papers at various conferences in the area of composite materials. In addition, three company employees received awards, including the "1997 Tibbetts Award for SBIR Model of Excellence," sponsored by the U.S. Small Business Administration.

Conclusion

With ATP's assistance, Specialty Plastics developed several innovative composite joining and fitting technologies for composite piping systems. The company also developed a new manufacturing process for pipe fittings that has resulted in higher production rates, lower costs, and improved component properties. The company did not, however, improve the surface adhesion of composite materials, and its work on resin transfer molding (RTM) technology was only partially successful, resulting in a modified, state-of-the-art form of RTM technology.

The reliable joining methods that Specialty Plastics developed during this ATP-funded project have led to an increased use of composite piping systems on offshore tension leg platforms (TLPs) by the oil industry with significant cost savings. Since 1995, the U.S. market for composite piping has grown from less than $2 million a year to approximately $20 million a year, with growth of approximately 20 to 30 percent a year. Composite parts from the new technology have also been sold overseas in Australia, West Africa, and Malaysia.

Research and data for Status Report 95-11-0012 were collected during October - December 2002.

Return to Table of Contents or go to next section of Status Report No. 3.

Date created: April 4, 2006
Last updated: July 6, 2006

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