Dual Laminate Pipe and Equipment Made of Fiberglass Reinforced Plastics
CFI’s dual-laminates division has been particularly busy in recent years, thanks to the growing popularity of products in this market, including dual laminate pipe. Dual-laminate construction combines the primary corrosion barrier of a thermoplastic lining with the structural advantages that fiberglass reinforced plastics (FRPs) provide.
Products from such construction, including dual laminate pipe, are used when operational service requirements exceed the limits of straight FRP and steel. Low maintenance and design flexibility ensure that dual laminates are the preferred choice for harsh-environment applications, including those in which dual laminate pipe often resides.
Pipe is among many pieces of equipment used today because of double-laminate’s ability to handle various types of corrosive and high-purity liquids and gases, according to the Dual Laminate Fabrication Association (DLFA).
The DLFA is a nonprofit organization established in 1993 to create a forum for engineers to promote the use of dual laminate equipment, including double laminate pipe. DLFA members collaborate to bring design engineers the information and standards that make it easier to determine when dual laminate pipe and equipment should be used in a project.
In addition to dual laminate pipe, fabricated in such a manner are tanks, fittings, scrubbers and various other types of process equipment. The double-laminate process has been found to provide a cost-effective, long-term solution to corrosive liquids and gases when compared to other materials, such as high nickel alloys, the DLFA says.
Other advantages that double laminate products, including pipe, bring to a project include: lighter weight, longer service life, reduced downtime, increased productivity, both interior and exterior corrosion resistance, no geometric restrictions, no size restrictions and secondary corrosion protection.
How are dual laminate pipe and other products manufactured?
The thermoplastic linings that are used in dual laminate construction, including dual laminate pipe, are manufactured in roll or sheet form. Lining is formed and welded before it’s integrated with the FRP structure. (Types of welding used are hot-gas hand welding, flow-fusion machine welding and butt-fusion machine welding, according to the DLFA.) The thermoplastic lining is then is internally supported and the FRP is chemically or mechanically bonded to the lining.
A conductive carbon veil layer is integrated into the FRP corrosion barrier to make high-voltage spark testing of the lining easier. The conductive target , the DLFA says, should cover 100 percent of the lining.
Industries that use dual-laminate pipe and other double-laminate products include chemical processing, energy, mining, oil and gas, pharmaceutical, pollution control, power, pulp and paper, and semiconductors.
Custom Fiberglass Inc., as with similar companies, adheres to standards set forth by The American Society of Mechanical Engineers when it makes double laminate pipe and other equipment. Dual laminates are applicable to several ASME codes and standards that are related to both fiberglass reinforced plastics vessel design and FRP fabrication.
CFI has been manufacturing dual laminate products, including double laminate pipe, for more than 20 years. The types of thermoplastic linings that CFI uses in its products include: Kynar, poly vinyl chloride, Halar, polypropylene, high density polyethylene, teflon, chlorinated polyvinyl chloride and Teflon.