Uses of Fiberglass Pipe and Large Diameter Fiberglass Pipe
Applications and Key Benefits
Since the mid to late 1980’s underground large-diameter composite piping has continued to grow in applications and usage. Technological advancements in the filament winding process, corrosion resistance, education and outreach, and strong market forces have contributed to the popularity of fiberglass pipe. Definitions of what constitutes large-diameter pipes can vary, but generally speaking they range from 12” to 14’ in diameter.
Composite, or fiberglass pipe, has been utilized in a wide range of industries such as power generation, petrochemical and desalination. Fiberglass pipe is corrosion resistant, has a life cycle that often exceeds 30 years, and has become increasingly more desirable as an alternative to steel, other metal alloys, ductile iron, and concrete. According to an article published in 2008, titled “Large Diameter Pipe: Lasting Function in a World of Growth” more than 60,000 km (37,280 miles) of composite large diameter pipe are in operation around the world.
Although fiberglass was once viewed as specialty product, for its ability to withstand an attack from sulphuric acid, it has now become a standard material, if not the standard in major market segments for a variety of reasons. For example, fiberglass has been employed in drinking water projects, irrigation systems for agriculture, feed lines and penstock for hydroelectric power plants, power plant cooling water systems, gravity and pressure sanitary sewers systems, and pipeline rehabilitation “slip liners”. Over the past two decades fiberglass has begun to transcend it’s early stereotypes as a one-trick pony (e.g. corrosion resistance) and has demonstrated its value as a cost-effective material, offering a plethora of end-user benefits.
Chief among the reasons for fiberglass increased usage and popularity are key benefits such as high strength-to-weight ratio, dimensional stability, good mechanical properties, ease of installation, reduced installation costs, reduced maintenance cost, and overall durability in extreme conditions. Similarly, another advantage of fiberglass pipe is it has a smoother inner surface when compared to traditional construction materials. This attribute, smooth internal bore, resists scale-deposits and can create greater flow of service liquid over the life of the project.
When designing an underground large diameter pipe system many considerations need to be taken into account; local soil conditions, depth of water table, burial loads, live loads, deflection due to burial stress and operating temperatures—just to name a few. Similarly, an American Water Works Association manual, Fiberglass Pipe Manual, also known as M45, provides equations that take into account factors such as fluid velocity and fluid pressure, head loss due to turbulent flow, water hammer, buckling pressure, and surge pressure. Designing a proper underground piping system is a complex process that involves extensive calculations—product design should always be by qualified engineers.
Fiberglass Pipe: Past, Present And Future
From the early 1950s through the present, the use of machine-made piping has grown tremendously. Sullivan D. Curran, P.E. gives an overview of the last 45 years.
Today, Fiberglass Reinforced Thermosetting Plastic (FRP) is being used in many industrial product applications, including the storage and transfer of corrosive materials and the handling of other materials in corrosive environments. While FRP piping has a 30-year history, it is a modern day product material with many emerging applications that take advantage of its corrosion resistance, strength-to-weight ratio, low maintenance and life cycle cost. This article discusses the history of FRP piping, its current applications and the emerging technological advances for new applications of FRP piping in petroleum storage and handling facilities.
What exactly is FRP piping? Don’t confuse it with ordinary thermoplastic piping, such as PVC and polyethylene. Those thermoplastic systems typically employ non-reinforced, extruded pipe and injection-molded fittings and flanges. What strength they have comes from the sheer bulk of the material.
By contrast, FRP piping materials are manufactured by winding processes that employ epoxy resins, reinforced with continuous glass filaments. The resins used undergo irreversible chemical reactions as they cure, resulting in superior temperature capabilities, while the filament reinforcement makes the piping components mechanically far more capable than ordinary non- reinforced thermoplastics. This process is called thermosetting. The result is enhanced performance and lighter weight.
Also, don’t confuse hand lay-up with machine-made FRP products. Hand lay-up manufacturers number in the thousands, and include small shops that typically specialize in consumer products, such as bathroom vanities or pleasure boats. However, there are relatively few manufacturers of machine-made pipe. These are typically large companies that mass produce on-the-shelf and custom piping for petroleum, commercial, industrial or municipal applications for both domestic and overseas markets.
Machine-made FRP can have a higher glass loading content (i.e., a higher density glass fiber filament to resin ratios) than hand lay-up products. Also, machine made products are more reproducible since they are typically in a quality controlled environment. This article will focus on the advancements made in FRP machine-made pipe and fittings, as well as their applications in the petroleum industry.
Over a wooden barrel
In the early days, just after Colonel Drake’s discovery of oil near Titusville, Ohio in 1859, no pipe was used at all! The oil was pumped directly into wooden barrels for shipment. The first pipes were made from wood and later replaced with steel. However, the steel pipe was rapidly corroded by the combination of salt water and sour, high sulfur crude.
Although FRP technology was developed during World War II, it was more than a decade later when the first pipe was made from FRP by a hand lay-up method. This was done by applying a glass fiber cloth and resin by hand over a male mandrel (a rotating cylindrical mold that can be collapsible to remove the pipe). Although this hand lay-up method was suitable for some chemical industry applications, it did not have the combination of strength and cost-effectiveness needed to compete with steel in the petroleum industry.
In the 1950s, centrifugal casting was developed to produce pipe suitable for chemical and commercial applications and oil field gathering lines (piping between producing wells and storage tanks).
Also in the 1950s, a filament winding process was developed to manufacture pipe with tensioned glass fibers, which were oriented to bear the combination of hoop and axial forces. The process called for layers of glass fibers in a near axial orientation, and resulted in the development of down hole tubing able to withstand high pressure (up to 2,000 psi) for crude oil producing wells. Some of these earlier FRP tubing strings remain in service after more than 35 years of production. Tubing strings include threaded joints that connect the drill pipe together in “strings” as long as 1500 feet.
In the 1960s, a very efficient high-volume continuous-pipe-production process was developed for small diameter pipe that was rated for pressure up to 450 psi. The process was both efficient and capable of producing the high volume of pipe necessary to compete with steel. Large scale use of this pipe began in 1964; it was primarily installed in 2 inch crude oil gathering lines.
Developing the standards
In 1959, the American Society for Testing Materials (ASTM) published the first nationally recognized standards and test methods for FRP pipe: ASTM D1694, Standard Specification for Threads for Glass Fiber Reinforced Thermosetting Resin Line Pipe. This specification was developed by a group of representatives from fiberglass pipe manufacturers, oil companies and other industries.
In 1968, the American Petroleum Institute (API) published its first FRP pipe standard: API 15LR, Specification for Glass Fiber Reinforced Thermosetting Resin Line Pipe. Today ASTM and API publish numerous standards, specifications and test methods for FRP piping.
FRP machine-made piping today
The use of FRP machine-made piping has grown tremendously. From its original and major use in oil field gathering lines, FRP piping is now used in applications ranging from handling flammable and combustible liquids at retail consumer facilities to sewer and water mains in the municipal and industrial markets.
Here are some examples of current FRP piping applications in the oil and gas production industry:
(1) 4,000 psi 4 inch pipe in oil field service;
(2) 2 to 16 inch pipes for water filtration projects in climatic conditions as cold as Alaska and as hot as the Persian Gulf; and
(3) a salt water/crude oil 12 inch pipeline operating at 290 psi at temperatures up to 120 degrees Fahrenheit.
The handling of flammable and combustible liquids includes the underground piping of gasolines, gasoline-alcohol mixtures and alcohols at most of the nation’s retail and commercial vehicle fueling facilities. FRP piping was Listed by Underwriters Laboratories in the late 1960s. Since that time, more than 60 million feet of pipe has been successfully installed in gasoline refueling stations serving the nation’s motoring public.
While concrete sewer and drainage piping continues to dominate, there are many situations where FRP is the preferred choice. For example, concrete pipe deteriorates rapidly in decomposing sewage due to a hydrogen sulfide (H2S “rotten egg” gas) attack.
Hydrogen sulfide erodes the upper surface of the concrete pipe and will eventually cause a cave-in. However, FRP is not affected by either hydrogen sulfide or purging with caustic or hypochlorite to suppress sulfide odor. As a result, FRP pipe is frequently used as a liner in large diameter (48 to 60 inches) concrete pipe.
Future of FRP piping systems
• Computer software
Many architectural and engineering firms are now able to fully utilize the computer software program developed to enhance the design of FRP piping systems. The program makes it easy to step through complicated calculations and analysis when designing a new FRP piping system or when troubleshooting an existing FRP piping system. The software program typically includes: an analysis of liquid flow, free span (i.e., distance between pipe supports) and gas flow; thrust block design (i.e., lateral pressure capacity); chemical composition; and installation information.
• Bigger and better pipes
The oil and gas production industry will be requiring higher-pressure rated and larger-diameter piping to control corrosion problems in produced fluid lines (i.e., water contaminated with salt, sulphur and other corrosive elements). It is not uncommon to “produce” and treat seven barrels of water for each one barrel of crude oil brought out of the ground.
In addition to solving corrosion problems, FRP piping can be designed with a flame-retardant additive. This additive reduces the spread of flames in non-critical areas or in critical areas. Coated with an intumescent paint or insulated with an intumescent material, the paint and coating expand to form an incombustible foam insulation. This latter system will maintain the serviceability of the piping for a minimum of three hours under flow conditions (i.e., the piping remains in active service, such as a fire main.).
FRP firewater protection piping is solving weight problems when used in offshore oil production platforms. Weight savings in the design of a platform can save the owner from $2.00 to $4.00 per pound in construction costs by reducing the weight of the support structure (e.g., savings up to 750 tons). (See the next issue of PE&T for more information on FRP and fire protection.)
• Trench-less piping
This is a rapidly growing technology in which micro- tunneling for new piping and slip lining for the rehabilitation of existing piping do not disturb roadbeds or other aboveground structures.
Micro-tunneling: While tunnel boring has been used on large tunnel projects, micro-tunneling is a new application for trench-less piping. In micro-tunneling the FRP pipe is hydraulically jacked, and pushes a machine-operated cutter head through the substrata.
It takes hundreds of tons of jacking pressure to push large diameter piping hundreds of feet. For example, 18 inch diameter FRP pipe can be jacked at pressures up to 90 tons, and 9 foot diameter FRP pipe at pressures up to 1,750 tons to push lengths of pipe and their coupling joints hundreds of feet.
In the past, stainless steel sleeves have been used as a reinforcement around concrete pipe joints to withstand hydraulic jacking pressures. However, FRP sleeve joints are proving to be a cost-effective replacement for the stainless steel used in concrete pipe jacking.
FRP pipe and joint systems are proving to be more cost effective than their concrete counterpart. This is because FRP’s smoother outside surface and lighter weight significantly reduce the jacking pressure required, and permit jacking of longer piping runs than concrete, thus reducing installation costs and time.
Slip-lining: This is a trench-less method of rehabilitating an existing pipe with a minimum of excavation. New and rehabilitated sewer and drainage pipes are no longer limited to relatively small diameter FRP slip-lining methods.
Centrifugal-cast FRP pipe may be used since it is machine-made on a female mandrel rather than a male mandrel as is filament-wound FRP pipe. Centrifugal-cast FRP pipe technology has advanced and yields a machine-made pipe with close outside diameter tolerances in diameters up to 96 inches. The light weight and smooth outer surface permits jacking the pipe inside an existing pipe, thus rehabilitating leaking concrete sewer pipe up to 102 inches (i.e., nine feet in diameter).
This system of rehabilitation minimizes the jacking pressures required to push the FRP pipe through existing concrete pipe, and it is done even as sewage flow continues. For example, a trench-less project is underway to rehabilitate 6,000 feet of a 102-inch sewer in Los Angeles with a minimum excavation by using 9 foot diameter FRP pipe.
• New chemical processes This typically involves piping exposure to such chemicals as acetone, methylene chloride, hydrochloric acid, ethylene dichloride, phenol, toluene, xylene, ethyl acetate, and methyl acetate. Specialty metals such as titanium are typically used for resistance to such chemicals, but they are prohibitively expensive. However, resin selection such as furan based materials are extremely solvent-resistant and a cost effective alternative to titanium.
Petroleum marketing facilities
Traditionally petroleum marketing facilities used steel piping. It was low in cost and met the 2 hour 2,000 degree Fahrenheit code requirement for the handling of flammable and combustible materials. While retail facilities have adapted to new material advances (e.g., FRP underground tanks, piping and flexible connectors), distribution terminal designers and contractors have been slow to apply non-steel technologies. Following are several areas where the terminal facility designer should consider FRP piping applications:
Underground piping:
Underwriters Laboratories has UL 971 Listed FRP piping for flammable and combustible service in diameters of 2, 3, 4 and 6 inches. The 1996 edition of NFPA 30 references UL 971, and permits using these FRP pipe diameters in distribution terminals.
While the terminal designers prefer to locate piping aboveground for ease of environmental testing (i.e., visual inspection rather than periodic pressure testing), the Uniform Fire Code (UFC) revised its rule in 1995. UFC now requires the installation of piping underground. This will require cathodic protection systems and the ever-present requirement for periodic testing. Therefore, a cost effective alternative to both underground steel piping and cathodic protection is FRP pipe consistent with UL Listed diameters.
Sewer and drainage:
Pollution prevention-related projects include containment, recycling, discharge reduction and sewage treatment. Concrete piping is not suitable for the handling of petroleum-related effluent for two reasons: (1) because of the high leakage rate in the pipe joining methods available; and (2) steel piping will corrode in an underground environment.
Large diameter FRP piping is available up to 9 feet in diameter, and designed with leak free joints. As described above, trench-less new or slip-lining rehabilitation piping methods are cost effective and provide a minimum of disruption in operations.
Corrosive chemicals:
Today, it is becoming more common to blend motor fuel additives at the terminal. Many of these additives (e.g., gasoline detergent additives) are corrosive to traditional carbon steel. With blending systems located at the truck loading rack, underground piping is commonly installed under the driveway areas and lends itself to FRP piping.
Firewater protection:
Scale from internal corrosion of steel piping in a firewater protection system is known to plug nozzles and sprinkler heads. To combat the effects of corrosion and internal scaling, metallic firewater systems using untreated water require continuous maintenance. In untreated or “non-neutral” (i.e. controlled pH) firewater systems, it is questionable how much of a metallic system is in an effective operating condition at a given moment.
FRP fire-resistant material systems are being developed and should prove to be cost effective in certain fire protection applications where firewater is corrosive to steel, such as marine vessels and off-shore drilling platforms.
Discuss
OPUS: Pair: Process Piping : Fiberglass-Reinforced Plastic (FRP) Pipe
Process Piping:
Fiberglass-Reinforced Plastic (FRP) Pipe
Process piping involves non-hydronic piping systems, generally used to convey chemicals. When...
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Fiberglass-reinforced plastic (FRP) pipe is a composite material using a polymer matrix...
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Benefit of Material to Systems Application
Glass reinforced resin pipe is one of the strongest piping materials by weight in use today. Most of these piping products are made by using filament winding or centrifugal casting techniques. Varying conditions of service has resulted in the use of three major FRP piping resins: epoxy, polyester, and vinyl ester.
Like most plastic piping systems, FRP is durable, safe and easy to install. In addition, it is very cost competitive when compared to many metal-alloy piping systems. Most FRP piping has both internal and external chemical resistant barriers.
Although FRP piping is normally heavier than other plastic piping systems, it weighs less than most other metal piping systems resulting in freight and labor savings. One of the distinguishing factors that separate FRP piping from thermoplastic piping systems is the ability to maintain working pressure at increases in temperature. Most thermoplastic piping working pressure capability decreases with an increase in temperature.
FRP piping systems has made significant inroads into markets previously served by alloy-steel piping.
System Application and Material Usage
FRP piping is commonly available in size ranges from 1” to 24” diameter and can be fabricated in much larger diameters with the limiting factor being the ability to safely and economically transport these unwieldy loads. Most FRP systems are available in various pressure ratings depending on the application.
The two most commonly used joining methods for FRP are adhesive bonding for bell and spigot ends (mostly used on pipe diameters 12” and below) and butt-strap adhesive, used mainly for larger diameter or specially formulated piping systems. The bell and spigot joining method provides installation savings compared to other piping systems. The butt-strap joining method is more labor intensive but still very cost competitive when compared to welded piping systems.
FRP is not only used for piping and fittings, it is a common material for valves, tanks, scrubbers, duct, and other fluid handling products. FRP normally handles higher temperatures and pressures better than thermoplastic piping however, when temperatures exceed 250 F and working pressures are greater than 200psi, metal piping systems are usually the better choice.
