High-Temp Textiles

Lewis Dill

December 1, 2003

The development of high-temperature textiles has come a long way in the past 30 to 40 years. Prior to this, asbestos was the primary fiber material specified to make textiles for high-temperature fireproofing and insulation applications throughout the world. Asbestos is a naturally occurring fiber that has been mined and processed since 4000 B.C., when it was used as wicks for lamps. In 1724, Benjamin Franklin purchased a fireproof purse made from asbestos that is now at the Natural History Museum in Washington D.C. In "The Wizard of Oz," the Wicked Witch of the West appeared on a broom made of asbestos. Asbestos has most of the desirable properties needed to make great high-temperature textiles. Government and industry engineers specified asbestos in most of the high-temperature fireproofing, insulation and gasket applications. Into the late 1990s, the solid fuel boosters of the space shuttle were still insulated with asbestos.

Today, many countries continue to use refined asbestos as their "primary" fiber for fireproofing and making high-temperature textiles. However, during the early 1970s, in Western countries, general health concerns and problems about asbestos, Asbestosis and asbestos-related liabilities have all but eliminated its use in the United States, Western Europe and a few other countries.

Now, there are many other choices of man-made base fibers to choose from that are much safer to use than asbestos. These include fiberglass, high purity silica, quartz, ceramic, basalt, carbon, aramid, stainless steel and blends or composites of two or more of these materials. These are then made into yarn, thread, fabric, rope, tubing and felts with various coatings and colors in different weights, thicknesses, densities and yields. Using these textile combinations, talented fabricators apply these textiles to make a whole host of flexible insulation products for almost any high-temperature application.

Indispensable Applications

Applications for high-temperature insulation textiles have become indispensable in most industries around the world. What follows are just a few examples.

Flexible removable/reusable insulation blankets have been around since before World War II, primarily used on Navy, Coast Guard and commercial marine vessels to insulate hot piping, engine compartments and exhaust systems. The industrial sector in the United States geared up their use of removable/reusable insulation in the late 1970s, when the Organization of the Petroleum Exporting Countries (OPEC) decided to embargo oil to the United States, and the cost of energy went from $0.50/mmBTU to $5/mmBTU. Until that time, most industrial facilities didn’t insulate high-maintenance pipes, valves, fittings and equipment unless it was critical to process control or quality. Today, non-insulated high-maintenance equipment that operates at 300 degrees Fahrenheit (F) will yield a payback on investment of about a year if insulated. At 500 degrees F and above, this payback becomes a few months or if insulated with flexible removable/reusable insulation. New materials and fabrication techniques allow flexible removable/reusable insulation blankets to be reused many times in applications as high as 1,400 degrees F and having vibration that would shake any other form of insulation apart.

Today we have high-temperature textiles that will handle very high levels acidity and alkalinity in insulation applications. New and better high-temperature textile materials are also available for making soundproofing or noise abatement blankets. Flexible removable/reusable insulation blankets are just one of the important applications of high-temperature textiles.

High-temperature knitted or braided tubing made from aramids, fiberglass, amorphous silica, carbon and other exotic materials are used to insulate electrical wire or hydraulic and pneumatic hoses from hot sources. Insulated wire, piping and hoses are normally part of all process equipment and are critical to the successful operation of the systems. These are the products that link most of the equipment controls used by all industries. If the system needs to be fireproofed or shielded from elevated temperatures, high temperature insulation textiles are normally used.

Personnel Protection

Manufacturing and construction companies use high-temperature textiles as curtains and blankets to protect or insulate people and equipment from welding, grinding or cutting touch sparks, spatter and slag. During maintenance shut downs or turnarounds, industrial plants will section off areas as "Hot" with high-temperature textiles used as barricades, curtains and blankets to help ensure worker safety. Most commercial kitchens have a fire blanket hanging on the wall or nearby in the case of a grease fire. Many movie and stage theaters use high-temperature textiles as curtains in case of fire. As the awareness for safety becomes a larger influence in our lives, high temperature, non-flammable textiles for curtains and blankets will find more applications.

High-temperature textile clothing protects our firefighters, racecar drivers, astronauts, plant and mill workers in some of the hottest, toughest environments on earth. Specialty man-made fibers such as Nomex®* or other aramids and fiberglass blends now dominate the construction and plant worker market. Space suits are made of high temperature quartz and carbon materials. Currently, companies are diligently working to find high-temperature textile solutions for saving firefighters and property from the many wildfires found in the western parts of the United States. Leather, fiberglass, silica, carbon and aramids fabrics and felts are used together and separately to make gloves, aprons, shirts, pants, chaps and other protective clothing for workers in high temperature environments. Safety and comfort are the benefits driving this market.

The automotive industry uses high temperature textiles for insulating engine compartments and exhaust systems in most of the automobiles that we all drive. In higher power output motors, the turbo chargers and exhaust systems can exceed 1,400 degrees F. Thus, it becomes increasingly necessary to insulate the engine compartments and exhaust systems of commercial vehicles such as 18-wheelers and large horsepower tractors, combines and heavy construction equipment. One landfill company needed to insulate its exhaust systems on its large combines because of fires being started at the landfill from its hot exhaust systems. Racecars of all types use high temperature insulation textiles as a lightweight, durable insulation to keep the drivers as comfortable as possible while on the track.

The aerospace industry uses high-temperature insulation textiles all over most space, commercial and private aircraft. Space shuttles use special high-temperature insulation blankets in the cargo bay to protect valuable loads during liftoff and re-entry. Strong, high-temperature carbon fiber fabric is used to make the composite materials for the shuttles. Most pressurized aircraft use hot bleed air from the engines to air condition, heat and drive many of the aircraft systems. Lightweight, high-temperature textiles play a large role in insulating the bleed air systems, along with baffling and insulating ducting, hoses, wiring, engine compartments and exhaust systems on aircraft.

Metal industries use high-temperature insulation textiles for a considerable number of applications. High-temperature textiles are made into curtains and blankets to shield workers and heat sensitive equipment from the radiant heat and splashing of molten metals. High-temperature textiles are also used to help maintain slow, controlled cooling in the heat treating and annealing process.

Steam Applications

Power plants use high-temperature textiles throughout most of their facilities. Most of the steam and condensate system will use removable/reusable insulation blankets on the high-maintenance pipes, valves, fittings and equipment. The steam turbines get special high-temperature blankets to keep condensate from forming in the turbine section. Natural-gas-fired turbines will get blankets on the turbines and exhaust systems.

The food processing industry uses high temperature textiles to insulate their ovens and steam system. High-temperature PTFE/Teflon coated or laminated fiberglass fabrics are applied to make most of the conveyor belts used when making your favorite processed foods. Special PTFE/Teflon impregnated, high temperature textiles are used as chemical splash shield in the food processing industry to protect people and food.

The pulp and paper industry uses high-temperature textiles through out their processes. PTFE impregnated fiberglass fabrics are used in the pulp digesting areas as chemical splash shields and in flue duct expansion joints because of their high temperature and hostile chemical resistant properties. Large boiler houses generate vast amounts of steam, which is used throughout the paper making process to dry the paper, help digest wood chips in pulp and to generate electrical power for utilities. Where there is steam, there should be many applications for removable/reusable insulation and gaskets made from high temperature textiles.

High-temperature insulation textiles have worked to insulate some of the toughest and most diverse applications that man has made for himself. The challenge for the future is to keep developing new and better high temperature, chemical resistant materials from which we can make better high temperature textile fiber, yarns, fabrics, ropes, tubing, felts, films and coatings.