National Insulation Association’s Insulation Science Glossary

February 2024 Version

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Abatement

To reduce or make void any substance such as the removal of noise, asbestos or lead. See asbestos abatement definition as one form of removal.

 

Abrasion Resistance

The ability of a material to withstand abrasion without appreciative erosion.

 

Absolute Humidity

The ratio of the mass of water vapor to total volume of an air sample. The I-P units are pounds of moisture per pound of cubic foot of air and the SI units are grams or kilograms of moisture per cubic meter of air.

 

Absorptance

The ratio of the radiant flux absorbed by a body to that incident upon it.

 

Absorption

Transformation of radiant energy to a different form of energy by interaction with matter.

 

Adsorption

Adsorption is the physical adherence or bonding of ions and molecules onto the surface of another molecule.

 

Acoustical Treatment

Application of absorbing insulation for sound control.

 

Adhesive

A substance used to bond materials by surface attachment.

 

Aerogel

A homogeneous, low-density solid state material derived from a gel, in which the liquid component of the gel has been replaced with a gas. The resulting material has a porous structure with an average pore size below the mean free path of air molecules at standard atmospheric pressure and temperature.

 

Air Conditioning

See conditioned air.

 

Air-Quality Contamination

Reduction in air quality due to introduction of any of a wide variety of pollutants. Specific to insulation system components, potential pollutants could be VOCs, formaldehyde, particulate matter, or from mold or mildew growth on or in the insulation system.

 

Alkalinity

The quality of a material to be basic or alkaline when exposed to moisture or water producing a blue reaction to litmus paper. A pH measure greater than 7.0.

 

Ambient

Surrounding-encompassing (Generally applied to temperature, humidity and atmospheric conditions).

 

Ambient Temperature

The average temperature of the medium, usually air, surrounding the object under consideration.

 

Annular Space (Annulus)

The distance between a penetrating item and the surrounding opening.

 

Anti-Abrasive Coating

Cushioning material applied where insulation contacts the pipe, duct, vessel or adjacent insulation to prevent eroding of either or both.

 

Anti-Sweat

Any application that prevents condensation.

 

Apparent Thermal Conductivity

A thermal conductivity assigned to a material that exhibits thermal transmission by several modes of heat transfer resulting in property variation with specimen thickness, or surface emittance. (See conductivity, thermal).

 

Apparent Thermal Resistivity

A thermal resistivity assigned to a material that exhibits thermal transmission by several modes of heat transfer resulting in property variation with specimen thickness, or surface emittance. (See resistivity, thermal, R-value).

 

Appearance Covering

Materials used to improve the aesthetics of the finished insulation.

 

Application Temperature Limits

Minimum and maximum temperatures between which it is usually safe to service finishes, adhesives and sealants without endangering the integrity of the material.

 

Area Weight

Weight per unit area for a specified sample, in units of lbs/ft² (kg/m²).

 

Asbestos Abatement

A procedure for the removal, enclosure or encapsulation of asbestos containing materials from buildings or areas.

 

ASJ:  All Service Jacket; (Traditional Paper type )

A white, flexible reinforced lamination with Paper as exposed layer which is used as a vapor retarder and finish for pipe, tank and equipment insulation.

 

ASJ:  All Service Jacket; (Polymeric film type)

A white, flexible reinforced lamination with Polymeric film as exposed layer which is used as a vapor retarder and finish for pipe, tank and equipment insulation.

 

Asphalt Cut-Back

Petroleum asphalt coating with mineral solvents. (This is a vapor-retarder mastic).

 

Asphalt Emulsion

A colloidal dispersion of petroleum asphalt coating with water. (This is a breather mastic).

 

ASTM International

ASTM International provides a global forum for the development and publication of international voluntary consensus standards for materials, products, systems, and services.

 

Attenuation

The limiting of sound propagation from one area to another.

B

Bands

Strapping used to fasten insulation and/or jacketing in place.

 

Batt

Blanket insulation manufactured to dimensions as required by a specific application.

 

Beading

Process of curling the edge of metal jacketing to accommodate sealing.

 

Bedding Compound

A plastic material (mastic) used to imbed insulation. Acts as a cushion, anti-abrasive and adhesive.

 

Bends (Tube Turns)

Pipe, factory or field formed, to pre-determined radii.

 

Binder

Substance contained in insulation material that stabilizes the fibers (sometimes called a thermal setting resin).

 

Blackbody

The ideal, perfect emitter and absorber of thermal radiation. It emits radiant energy at each wavelength at the maximum rate possible as a consequence of its temperature, and absorbs all incident radiance.

 

Blanket Insulation

A relatively flat and flexible insulation in coherent sheet form furnished in units of substantial area.

 

Blanket Insulation, Metal Mesh

Blanket insulation covered by flexible metal-mesh facings attached on one or both sides.

 

Bleeding

The diffusion of coloring through a coating from its base or substrate (such as bleeding of asphalt mastic through a paint top coat).

 

Blister

Rounded elevation of the surface of a mastic resembling a blister on the human skin, usually the entrapment of air or vapor.

 

Block Insulation

Rigid insulation preformed into rectangular units.

 

Board Insulation

Semi-rigid insulation preformed into rectangular units having a degree of suppleness, particularly related to their geometrical dimensions.

 

BOCA

Building Officials and Code Administrators.

 

Body

The viscosity or consistency of a mastic or coating.

 

Bond Strength

The force in tension, compression, cleavage or shear required to break an adhesive assembly.

 

Bonding Time

The time required for an adhesive to reach its optimum bonding strength.

 

Box Rib

Aluminum sheet formed to have alternating parallel grooves and ridges with a cross section approximating a square wave.

 

Box Trench

Built-up enclosure either in a shallow trench or buried underground.

 

Branch

Distribution piping or ductwork, same as a main duct except, smaller and from or returning to the main, serving two or more runouts.

 

Breather Coating

A weather barrier coating designed to prevent water (rain, snow, sleet, spillage, wash water, etc.) from entering the insulation system, while still allowing the escape of small quantities of water vapor resulting from heat applied to the moisture entrapped in the insulation.

 

British Thermal Unit (Btu)

The amount of heat required to raise one pound of water one degree Fahrenheit at 59 F., specifically 778.26 ft. lbs.

 

Building Envelope Insulation

Insulation materials or systems used to encapsulate the building space or portions of the building that are normally conditioned with heating or cooling. The envelope includes floors, walls, and roofs. Building envelope insulation may also be applied around unconditioned spaces to prevent unwanted heat flow.

 

Built-Up Roof

A composition roof composed of layers of roofing felt mopped with hot asphalt and usually topped with gravel.

 

Butt Joints

The end joints of pipe insulation.

 

Butt Strip

Strips of similar jacket material applied around pipe insulation butt joints to either seal joints or for aesthetics.

C

C-Value (Thermal Conductance)

See Conductance, thermal.

 

Calcium Silicate

Insulation composed principally of hydrous calcium silicate, and which usually contains reinforcing fibers.

 

Calibration Foils

Standardized thickness foils or shims used for adjusting the calibration of coating thickness gauges to ensure accuracy.

 

Calipers

An instrument with adjustable leg(s) used to measure the thickness of objects or the distance between surfaces.

 

Canvas

A plain-weave cotton fabric used for jacketing or covering.

 

Capillarity

The ability of a cellular, fibrous or granular material to diffuse water into its structure.

 

Caulk

To seal and make water and/or airtight.

 

Cellular Elastomeric

Insulation composed principally of natural or synthetic elastomers, or both, processed to form a flexible, semi-rigid or rigid foam that has a closed-cell structure.

 

Cellular Glass

Insulation composed of glass processed to form a rigid foam having a predominately closed-cell structure.

 

Cellular Insulation

Insulation composed of small, individual cells separated from each other. The cellular material may be glass or plastic such as polystyrene, polyurethane, polyisocyanurate or elastomeric.

 

Cellular Plastic Expanded

Beads of plastic expanded by chemical or thermal means and bonded together chemically or thermally.

 

Cellular Plastic Extruded

Extruded plastic with cells formed by thermal or chemical means.

 

Cellular Polyimide

Insulation composed of the reaction product in which the bonds formed between monomers during polymerization are essentially imide units forming a cellular structure.

 

Cellular Polystyrene

Insulation composed principally of polymerized styrene resin processed to form a rigid foam having a predominately closed-cell structure.

 

Cellular Polyurethane

Insulation composed principally of the catalyzed reaction product of polyisocyanate and polyol compounds, processed usually with fluorocarbon or hydrocarbon gas to form a rigid foam having a predominately closed-cell structure.

 

Cellular Spray Foam

Open- or closed-cell cellular insulation composed principally of the catalyzed reaction product of 2 or more materials, typically polyisocyanurate and poly-hydroxy compounds, that react when mixed and expand up to 30–60 times their liquid volume after being sprayed in place. This expansion conforms to the shape of the substrate being insulated.

 

Cellulosic Fiber

Insulation composed principally of cellulose fibers usually derived from paper, paperboard stock or wood, with or without binders.

 

Cement, Finishing

A mixture of dry fibrous or powdery materials, or both, that when mixed with water develops a plastic consistency, and when dried in place forms a relatively hard, smooth protective surface.

 

Cement, Insulating

A mixture of dry granular, fibrous or powdery (or both) materials that when mixed with water develops a plastic consistency, and when dried in place forms a coherent covering that affords substantial resistance to heat transmission.

 

Ceramic Fibers

Pure silica heated and expanded to produce fibers from which high-temperature insulation can be made. Sometimes called Refractory Ceramic Fibers.

 

Certificates of Conformance

A document certified by a competent authority that the supplied good or service meets the stated specifications. The manufacturer is often the source for a certificate of conformance for a product.

 

Chalking

A soft white or gray appearance on the surface of a weathered finish.

 

Checking

Openings of a coated surface characterized by the appearance of fine cracks in all directions.

 

Chemical Resistance

Capability of a material to withstand exposure to acids, alkalis, salts and their solutions.

 

Chicken Wire

Hexagonal wire netting (poultry mesh) used as reinforcement or as a metal-mesh facing.

Cladding (as related to insulation jacketing)—synonymous with jacketing

Discussion—The three terms “jacketing”, “lagging”, and “cladding” are considered synonymous in most metal jacket related applications and geographies. However, in some cases in the power industry in North America the term “lagging” has a different meaning than “jacketing” or “cladding” and refers specifically to a heavier gauge of jacketing.

 

Clearance

Adequate space allowed for installation of insulation materials.

 

Closed Cell Foam

A material comprised predominantly of individual non-interconnecting cellular voids.

 

Coating

A liquid or semi-liquid that dries or cures to form a protective finish, suitable for application to thermal insulation or other surfaces in a dry thickness of 30 mils or less per coat.

 

Code (Building)

A set of construction and materials standards, usually statutory. Model building codes are adopted by each municipality from the major code organizations. The major code authorities are BOCA, (Building Officials and Code Administrators, primarily Midwest), ICBO (International Council of Building Code Officials, West and Indiana), and SBCCI (Southern Building Code Congress, International, South). The local municipality or state can choose which major building code is adopted.

 

Coefficient of Linear Expansion/Contraction

The change in a unit length of a material corresponding to a unit change in the temperature of the material.

 

Combustible

Provides enough fuel to make insulation capable of burning.

Comfort Insulation

Thermal or acoustical insulation applied to control the ambient environmental conditions for workers’ safety.

 

Compaction Resistance

The property of a fibrous or loose-fill material that resists compaction under load or vibratory conditions.

 

Compatible Materials

Two or more substances that can be mixed or used together without separating, reacting, or adversely affecting the materials.

 

Compressive Strength

The property of an insulation material that resists any change in dimensions when acted upon by a compaction force.

 

Concealed Spaces

Spaces not generally visible after the project is completed such as furred spaces, pipe spaces, pipe and duct shafts, spaces above ceilings, unfinished spaces, crawl spaces, attics and tunnels.

 

Condensate Drain

Piping carrying condensed water from air conditioning or refrigeration drip pans to a point of discharge.

 

Condensate Return

The liquid formed by condensation of vapor. In steam heating it is water condensed from steam. In air conditioning it is the water extracted from the air by cooling.

 

Condensation

The act of water vapor turning into liquid upon contact with a cold surface.

 

Conditioned Space

Building area supplied with conditioned air that is heated or cooled to a certain temperature and may be mechanical controlled to provide a certain humidity level.

 

Conductance, Air Film,

The time rate of heat flow from a unit area of a surface to its surroundings, induced by a unit temperature difference between the surface and the environment.

 

Conductance, Thermal, C-value

The time rate of steady state heat flow through a unit area of a material or construction induced by a unit temperature difference between the body surfaces.

 

Conduction

The transfer of heat energy within a body or between two bodies in physical contact.

 

Conductivity, Thermal (k-value)

The measure of heat that pass through a unit area of a homogeneous substance, through a unit thickness, in a unit of time, for each unit temperature difference. The lower the k-value, the higher the insulating value.

Note: I-P units are Btu – in / hr – ft² – °F and typical SI units are Watts / m – °C.

Textbook definition: The time rate of steady heat flow through a unit area of a homogeneous material induced by a unit temperature gradient in a direction perpendicular to that unit area.

 

Conformance Requirements

The criteria to be fulfilled in an implementation of a specification or fulfillment of a contract. Requirements include drawings, procedures, specifications, workmanship details, plus fitness of the product for the intended use.

 

Contact Adhesive

An adhesive that when tacky to the touch will adhere to itself instantaneously on contact.

 

Convection

The transfer of heat by movement of fluids.

 

Corrosion

Deterioration by chemical action such as rust on steel.

 

Corrosion Retarder (as Related to Insulation Jacketing)

See Moisture Barrier (as related to insulation jacketing)

 

Couplings

Screwed, soldered, welded or mechanical/grooved connections between links of pipe.

 

Cover

To place insulation and/or finish materials on, over or around a surface so as to insulate, protect or seal.

 

Coverage

The area to be covered per unit volume of coating to obtain specified dry thickness and desired performance.

 

Covering Capacity, Dry

The area covered to a dry thickness of 1 inch (25 mm) by 100 lb. (45.4 kg) of dry cement when mixed with the recommended amount of water, molded and dried to constant weight.

 

Covering Capacity, Wet

The area covered to a wet thickness of 1 inch (25 mm) by 100 lb. (45.4 kg) of dry cement when mixed with the recommended amount of water and molded.

 

Crevice Corrosion

Localized corrosion of metal jacketing surface at, or immediately adjacent to, an area that is shielded from full exposure to the environment because of close proximity between the metal and the surface of another material.

 

Crimping

Corrugating of the metal edge to reduce diameter or facilitate bending. Used on fitting gores to mate with beaded edge of adjacent segment or on end caps for tanks and vessels.

 

Cross Crimped

Synonymous with ³/₁₆  in. corrugated.

 

Cryogenic Insulation

Insulation for extremely low-temperature processes surfaces from –100 F to –459 F (absolute zero).

 

Cupped Head Pin

Capacitor discharge welded insulation fastener pin with a fixed washer.

 

Cure

To change the properties of a plastic or resin by chemical reaction, usually accomplished by the action of either heat or a catalyst.

 

Curved Radius Block

See curved segments.

 

Curved Segments

Rigid insulation material consisting of a multitude of identical or similar pieces that have been molded or fabricated to fit tightly on a specific outside diameter of a pipe, vessel, or tank. Examples of curved segments are curved radius block and curved sidewall segments.

D

Damming

The use of a substance to support firestopping materials until cured.

 

Decibel (Db)

A logarithmic measure of the ratio of like power quantities as used in describing levels of sound pressure or sound power.

 

Decomposition

The separating or breaking down of a substance into its component compounds or basic elements.

 

Deep Corrugated

Aluminum sheet formed to have alternating parallel grooves and ridges with a cross section approximating a sine wave.

 

Delamination

The separation of the layers of material in a laminate.

 

Density, Apparent (of Applied Insulation)

The mass per unit volume of in-place mass thermal insulation.

 

Dew Point

Saturation temperature where water vapor and liquid occur simultaneously.

 

Dewpoint Temperature

The temperature at which condensation of water vapor in a space begins for a given state of humidity and pressure as the vapor temperature is reduced; the temperature corresponding to saturation (100% relative humidity) for a given absolute humidity at constant pressure.

 

Diatomaceous Silica

Insulation composed principally of diatomaceous earth with or without binders, and which usually contains reinforcing fibers.

 

Diffusivity, Thermal

The ratio of thermal conductivity of a substance to the product of its density and specific heat.

 

Dimensional Stability

That property of a material that enables it to maintain its original size, shape and dimensions.

 

Dry

To change the physical state of a substance by the loss of solvent constituents by evaporation, absorption, oxidation or a combination of these factors.

 

Dry Film Thickness Measurement Tool

A device used to measure the thickness of a dry paint or coating. Equipment to accomplish this measurement includes mechanical gauges and ultrasonic thickness gauges.

 

Dual Temperature

Systems of equipment that operate as cold condition and hot application.

 

Duct

A passageway made of sheet metal or other suitable material used for conveying air or other gas.

 

Duct Board

A rigid, specially produced board insulation intended for use in ducts and other HVAC components.

 

Duct Board (Fabricated)

Duct wall material, produced from duct board, that has been grooved or cut at various shapes and angles and fastened together to create straight duct sections, elbows, offsets, or other standard air distribution system components to contain, direct, and maintain the integrity of the air flow in HVAC duct systems.

 

Duct Flange (Stiffener)

A structural or fabricated angle iron shape, attached to the exterior surfaces of a duct at specified intervals for the purpose of reinforcing the metal and assembly of the ducts.

E

Efflorescence

A white powdery substance occurring on the surface of coated insulation products caused by the migration of soluble salts from the insulation, followed by precipitation and carbonation.

 

Elastomeric

A closed-cell foam insulation containing elastomers that provide the property of high elasticity.

 

Emissivity

Emissivity is for pure materials that are perfectly smooth. The ratio of the radiant flux given off (emitted) by a surface to that given off (emitted) by a blackbody at the same temperature and under the same conditions.

 

Emittance

Emittance is for rough and contaminated surfaces (practical surfaces). The ratio of the radiant flux given off (emitted) by a surface to that given off (emitted) by a blackbody at the same temperature and under the same conditions.

 

Emittance, Directional

The ratio of the radiance from a surface in a particular direction to the radiance from a blackbody at the same temperature under the same conditions.

 

Emittance, Hemispherical

The average directional emittance over a hemispherical envelope covering a surface.

 

Emittance, Spectral

An emittance based on the radiant energy emitted per unit wavelength interval (monochromatic radiant energy).

 

Emittance, Total

An emittance that is an integrated average over all wavelengths of radiant energy emitted.

 

Emulsion

Insoluble fine solids or liquids dispersed in another liquid, usually water.

 

Energy Conservation

Reduction of heat transfer from systems by the use of insulation. Note that reducing heat transfer conserves natural resources, reduces energy usage, lowers energy costs, and is environmentally beneficial as it also reduces undesirable emissions associated with energy production.

 

Engineered Head Segment

Rigid insulation pieces with all surfaces molded, machined, or fabricated to fit with minimal gaps on complex curved vessel ends (also called heads).

 

Epoxy Resins

A two-part compound of an epoxy and catalyst that cures at ambient temperatures to form finishes which are highly resistant to solvents and chemicals. A high bond adhesive.

 

Exhaust Duct

A duct carrying air from a conditioned space to an outlet outside the building.

 

Expanded Metal Lath

See lath—expanded metal.

 

Exposed Spaces

Those spaces not referred to as concealed or as defined by the specifier.

F

FDA Approval

Compliance with the Food and Drug Administration’s regulations for food handling operations.

 

Facing

A flexible sheet product used to cover insulation and provide (1) physical protection, (2) finished surface, and (3) moisture vapor function when needed.  Facings may be of various combinations of materials or a monolayer film.

 

Fan

A mechanical air-moving device.

 

Fiber Glass

See fibrous glass.

 

Fiber-Reinforced Plastic (FRP)

A composite material consisting of a polymer matrix reinforced with fibers. The fibers usually consist of glass, carbon, aramid, or basalt.

 

Fibrous Glass

A synthetic vitreous fiber insulation made by melting predominantly silica sand and other inorganic materials, and then physically forming the melt into fibers. To form an insulation product, there are often other materials applied to the mineral wool such as binders, oils, etc. Commonly referred to as either fiber glass or fiberglass.

 

Fibrous Insulation

Insulation composed of small diameter fibers that finely divide the air space. Fibers used are silica, rock wool, slag wool, or alumina silica.

 

Film (Wet)

The applied layer of mastic or coating before curing or drying.

 

Finish

(As related to insulation metal jacketing)

The texture of the metal surface.

 

Finishes

Jackets, mastics or strong films used for aesthetics or to protect insulation from at least one or more of the following: weather, mechanical, and/or personnel abuse.

 

Finishing Cement

A mixture of various insulating fibers, fillers and binders with water, with or without hydraulic cement, to form a smooth trowelable paste insulation for smooth application over insulating cement or unfinished block insulation.

 

Fire Resistance

The property of a material or assembly to withstand fire or give protection. It is characterized by the ability to confine a fire and to continue to perform a given structural function.

 

Fire Retardance (FR)

The property of a material that retards the spread of fire.

 

Fire Safety

Fire Safety is the set of measures taken to protect property, assets, or persons from fire and smoke.

 

Firestopping

Furnishing and installing a material or a combination of materials to form an effective barrier against the spread of flame, smoke, gases and moisture. It is to maintain the integrity of the fire-rated construction.

 

Fish-Mouth

A gap between layers of sheet materials caused by warping or bunching of one or both layers.

 

Fitting Cover

The insulation for a pipe fitting composed of the specified thickness of insulation material, which may be preformed. Also, a preformed jacketing.

 

Fittings

Items used to change size, direction of flow, level or assembly of piping, except for unions, grooved couplings, flanges, valves or strainers.

 

Fixture Connection

Final piping connections to plumbing fixtures (usually exposed and chrome-plated).

 

Flake Insulation

A granular type of insulation where the particles are in the form of small flakes that insulate by finely dividing the air space. These flakes may or may not be bonded together.

 

Flame Retardant

The quality of a material to limit the flame spread across its surface.

 

Flame Spread

The index rate expressed in distance and time at which a material will propagate flame on its surface.

 

Flange

A projecting collar attached to a pipe for the purpose of connecting to another pipe, valve or fitting.

 

Flange Cover

The insulation for a pipe flange composed of the specified thickness of insulation material, may be preformed. Also, a preformed jacketing.

 

Flash Point

The temperature at which combustion is initiated.

 

Flashing

The arrangement of metal or other weather barrier

 

Flexibility

That property of a material that allows it to be bent (flexed) without loss of strength or integrity.

 

Flexible cellular material

A cellular material that will not rupture within a specified time when bent around a mandrel at a specified uniform temperature and rate.

DISCUSSION—Test Methods D3574 “Standard Test Methods for Flexible Cellular Materials – Slab, Bonded and Molded Urethane Foams” provides a standard procedure for assessing whether an insulation material is a flexible cellular material.

 

Flexible Granular

Flexible Granular insulation can be bent (flexed) without loss of strength or integrity.  It can be supplied flat or in rolls, with or without facings. Aerogel and microporous are produced in flexible types. Flexible granular usually includes a carrier or a facing to contain or support the granular material during use.

Flexible HVAC Duct

Ducting that is factory manufactured with a combination of wire helix, inner core film, flexible insulation, and an outer jacket that imparts flexibility for ease of installation in residential and commercial HVAC air distribution system applications.

 

Foamed Plastic

Plastic expanded to a cellular form by thermal or chemical means.

 

F-Rating

A rating usually expressed in hours indicating a specific length of time that a fire-resistive barrier can withstand fire before being consumed or permits the passage of flame through an opening in the assembly, as determined by ASTM E814 (UL 1479).

 

Freeze/Thaw Stability

The property of a product that allows it to be subjected to temperatures below freezing and still be useable when returned to room temperature.

 

Freeze Protection

The use of insulation materials or systems on the outer surface of a pipe or tank and is sometimes coupled with heat tracing to slow the loss of heat into the ambient environment to prevent freezing of the contents of pipe, tank, or equipment.

 

Fresh Air

Air taken from outdoors.

 

Fresh Air Duct (Make-Up Air)

A duct used to convey outdoor air to a point within the building, terminating at the mixing plenum, air handling unit or discharge grill.

 

FSK

Foil scrim Kraft.  This is a laminate composed of a thin layer of aluminum foil, glass fiber reinforcing scrim, and Kraft paper.

 

Fuel Contribution

Combustible by-products from a substance generated or emitted in a burning environment.

G

Galvanic Corrosion (Electrolysis)

Effect of two dissimilar metals in the presence of an electrolyte to produce a weak voltaic cell causing depleting or pitting of the more soluble metal.

 

Glass Cloth

Closed-weave glass fiber used as a finish jacket.

 

Glass Fabric

Open-weave glass fiber used as a reinforcing membrane.

 

Glass Fiber

An inorganic fiber manufactured as continuous filament from molten glass or silica, normally used for reinforcement, tissue or textiles.

 

Glass-Reinforced Plastic (GRP)/Glass Fiber Reinforced Plastic (GFRP)

Composite material consisting of a polymer matrix reinforced with glass fibers. GRP material can be used for insulation jacketing. GRP materials fall underneath the broader category of Fiber-Reinforced Plastic (FRP).

 

Glass Scrim

See glass fabric.

 

Gore

Jacketing for elbows, fittings, or other non-straight portions of the piping system made from a multitude of similar overlapping pieces.

 

Granular Insulation

Granular insulations are composed of small nodules that contain voids or hollow spaces. These materials are sometimes considered open-cell materials because gases can be transferred between the individual spaces. Aerogel, calcium silicate, microporous, and expanded perlite insulations are considered granular insulation. It has two subcategories: Flexible and Rigid, defined below.

Granular, Flexible insulation can be bent (flexed) without loss of strength or integrity.  It can be supplied flat or in rolls, with or without facings. Aerogel and microporous are produced in flexible types. Flexible granular usually includes a carrier or a facing to contain or support the granular material during use.

Granular, Rigid insulation opposes any tendency to bend (flex) under load and may lose strength or integrity when bent.  It can be supplied as blocks or in a preformed pipe configuration.  Calcium silicate, microporous, and expanded perlite are produced in rigid types.

 

Graybody

A body having the same spectral emittance at all wavelengths.

H

Half-Shell Segments

Rigid insulation material that has been molded or fabricated into two identical pieces that will fit tightly around a specific outside diameter of pipe.

 

Handicapped Fixtures

Exposed fixture connections located in facilities for the handicapped. Waste and hot piping exposed connections in these areas are usually insulated for personnel protection.

 

Hanger (Pipe)

Devices used to support piping.

 

Hazcom Article

An “article” means a manufactured item: (1) which is formed to a specific shape or design during manufacture; (2) which has end use function(s) dependent in whole or in part upon its shape or design during end use; and (3) which does not release, or otherwise result in exposure to, a hazardous chemical under normal conditions of use. Products that meet the definition of “article” do not require a safety data sheet (SDS).

 

Heat Flow, Heat Flow Rate

The quantity of heat transferred to or from a system in unit time.

 

Heat Flux

The heat flow rate through a surface of unit area perpendicular to the direction of heat flow.

 

Heat Flux Transducer (HFT)

A device containing a thermopile (or equivalent) that produces an output that is a function of the heat flux.

 

Heated Space

Building area supplied directly with heat.

 

Heel

The outside of an elbow.

 

Hertz (Hz)

A measurement of sound frequency measured in cycles per second.

 

High Pressure Condensate

That condensate directly received from high-pressure steam lines.

 

High Pressure Steam

Steam at or above 75 pounds per square inch gauge pressure.

 

High Rib Lath

A metal lath with a built-in rib used to provide air space under insulation applications.

 

High Velocity Duct

A duct designed with air flow at more than 2,000 feet per minute velocity with a static pressure exceeding 6 inches.

 

Homogeneous Material

A material in which relevant properties are not a function of the position within the material.

 

Horizontal Piping

Any piping up to and including 45° from the horizontal plane.

 

Housings (Built-Up)

Assembled or fabricated at the construction site.

 

Housings (Casings)

Enclosures of sheet metal or other material to house fans, coils, filters or other components of air handling equipment.

 

Hubs

Caulking or cement connections between pipe joints.

 

Humidity

A measure of the amount of water vapor in the ambient air.

 

Humidity, Absolute

The ratio of the mass off water vapor to total volume of an air sample. The I-P units are pounds of moisture per pound of cubic foot of air and the SI units are grams or kilograms of moisture per cubic meter of air.

 

Humidity, Ratio

The ratio of the mass of water vapor to the mass of dry air in an air sample. The I-P units are either pounds of moisture per pound of dry air or grains of moisture per pound of dry air; the SI units are grams of moisture per gram of dry air.

 

Humidity, Relative

One of the following ratios (a) the mole fraction of water vapor in a given moist air sample to the mole fraction in the air sample saturated at the same temperature and pressure; (b) the vapor pressure in a given moist air sample to the vapor pressure in the air sample saturated at the same temperature and pressure and (c) the humidity ratio in a given moist air sample to the humidity ratio in the air sample saturated at the same temperature and pressure. There are no units.

 

Hybrid or Composite Insulation System

Two or more insulation materials combined into one system that is often, but not always, intended to utilize some performance advantages of each of the individual materials to achieve specific system performance goals.

 

Hydraulic Cement

Cement that sets and hardens by chemical reaction with water (hydration) and is capable of doing so underwater.

 

Hygienic Coverings

Materials used over insulation to provide a smooth, cleanable surface, which are commonly used in food and beverage processing or pharmaceutical facilities.

 

Hygrometer

An instrument used to measure the amount of humidity and water vapor in the atmosphere, in soil, or in confined spaces.

H

IARC

International Agency for Research on Cancer

 

ICBO

International Council of Building Code Officials.

 

ICC

International Code Council.

 

Impact Resistance

Capability of an insulation material and/or finish to withstand mechanical or physical abuse.

 

Impale

To pierce or fix by piercing on a sharp point or pin.

 

Infrared Imaging (or Thermography)

The use of cameras capable of imaging infrared (IR) radiation to determine the temperature of an object or multiple portions of an object. In the insulation industry this is used to find portions of an insulation system that are hotter or colder than other portions and, thereby, identify portions of an insulation system that are not performing as intended.

 

Infrared Thermometer

An instrument that determines the temperature of a small area of a surface without physically contacting that surface. This temperature measurement is based on the thermal radiation emitted by the area being tested. The accuracy of this instrument also depends on knowing the emissivity of the surface being tested.

 

Insulate

To cover with a material of low thermal conductivity in order to reduce the passage or leakage of heat.

 

Insulating Cement

A mixture of various insulating fibers and binders with water to form a moldable paste insulation for application to fittings, irregular surfaces or voids.

 

Insulation

Those materials or combination of materials that retard the flow of heat.

 

Insulation System (Energy) Efficiency

A measure or characterization of how well an installed insulation system works to prevent thermal losses or gains; and/or how well desired temperatures are maintained and energy consumption is minimized. (See 3E Plus)

 

Insulation Hanger

A device such as a welded pin, stud, or adhesive-secured fastener that carries the weight of insulation.

 

Interface Temperature

The boundary temperature between two surfaces, usually insulation layers, in contact with each other.

 

Intumescent

A characteristic of certain firestop products that when exposed to heat, expand to seal and fill any void in the penetration. When exposed to fire, intumescent products will form a hard char.

J

Jacket (as Related to Insulation Jacketing)

A protective covering installed over thermal insulation.

 

Joint

The place where two adjacent pieces of material or jacketing meet. They may be overlapped, sealed, filled (pointed) or finished by the application of tape, cement, mastic, coatings, additional layer of insulation materials or other compounds.

K

k-Value (Thermal Conductivity)

See Conductivity, thermal.

L

Lacing

A method of joining or securing insulation materials, reinforcements, or finishes for insulation materials using eyelets, hooks, wire, cord, etc.

 

Lag

(v.) To apply lagging. (n.) A single piece of covering material.

 

Lagging (as related to insulation jacketing) synonymous with jacketing

Discussion—The three terms “jacketing”, “lagging”, and “cladding” are considered synonymous in most metal jacket related applications and geographies. However, in some cases in the power industry in North America the term “lagging” has a different meaning than “jacketing” or “cladding” and refers specifically to a heavier gauge of jacketing.

 

Lagging Adhesive

Water-based resin emulsion products that are used to adhere lagging cloth to the insulation and to itself at the lap joints. They also seal and size the fabric and shrink it tightly to the surface. They can be brushed or sprayed.

 

Lagging—Insulation

Definition 1: A block material for insulating tanks and boilers, usually curved or tapered and can be made from any of several insulation materials.

Definition 2: Insulation used on pipe, tanks, ducts, vessels, or other mechanical equipment

Discussion: Lagging-insulation is usually applied in the form of cut, pieced together or mitered parts.

 

Lagging—Jacketing

Jacketing installed over insulation.  Also, see “Jacket.”

 

Laminate

A product made by bonding together two or more layers of material or materials.

 

Laminates

Materials made by bonding (through the use of heat, pressure, adhesives, or any combination thereof) two or more layers of materials. The layers can be comprised of similar or dissimilar materials.

 

Laminate jacket

A thin, flexible sheet material intended for use as a jacket over thermal insulation on pipe, duct, or equipment, and consisting of multiple layers of polymer film and aluminum foil bonded together.

DISCUSSION—A laminate jacket is available with or without a factory-applied pressure-sensitive adhesive.

DISCUSSION—Laminate jacket is commercially available in different widths, it typically is provided in approximate widths of pipe insulation sections.

 

Laminate tape

A thin, flexible sheet material intended for use as a tape to seal and secure a laminate jacket over thermal insulation on pipe, duct, or equipment.

DISCUSSION—Laminate tape always has a factory-applied, pressure-sensitive adhesive which first requires removal of a release liner.

DISCUSSION—Laminate tape is commercially available in several different widths.
DISCUSSION—A laminate tape can also include a polymer coating as a top surface.

 

Lap Adhesive

The adhesive used to seal the butt joints and laps of insulation jackets.

 

Lath—Expanded Metal

A lattice type of material of various gauges and sizes, used to provide reinforcement for insulation materials. Also used as a facing for metal-mesh insulation.

 

Lath—High Rib

A metal lath with a built-in rib used to provide air space under insulation applications.

 

Log Mean (Radius)

The equivalent value of insulation thickness for pipe (curved surfaces) to produce the same resistance to heat flow as per flat areas.

 

Loose-Fill Insulation

Insulation in granular, nodular, fibrous, powdery or similar form designed to be installed by pouring, blowing or hand placement.

 

Loose or Fill Insulation

Insulation consisting of loose granules, fibers, beads, flakes, etc., which must be contained and are usually placed in cavities.

 

Low-Pressure Condensate

Condensate is directly received from low-pressure steam.

 

Low-Pressure Steam

Steam at or below 15 pounds per square inch gauge.

 

Low-Velocity Duct

A duct designed with air flow at not more than 2,000 feet per minute velocity with static pressure not above 2 inches.

M

Main

Piping or ductwork from a source to the last branch connection or from the last branch connection returning to the source or to a termination point.

 

Marine Insulation

Insulation used on sea-going vessels, including Naval and Coast Guard, water-going product carriers, cruise ships, pleasure boats, and offshore oil platforms. Applications can include insulation for envelope (hull), bulkhead (interior vertical panels), HVAC, exhaust, fuel, refrigeration, and process insulation systems. Some approvals may be required for application.

 

Mastic

A protective coating applied by spray or trowel to weatherproof or otherwise prevent deterioration of the insulation to which it is applied.

 

Mat

A piece of insulation of the semi-flexible type, composed of fibers of one or more kinds in which the fibers are in random arrangement, used to support another material.

 

Mean Specific Heat

The quantity of heat required to change the temperature of a unit mass of a substance one degree, measured as the average quantity over the temperature range specified. (It is distinguished from true specific heat by being an average rather than a point value).

 

Mean Temperature

Sum of the cold surface temperature and the hot surface temperature divided by two. (Thermal conductivity charts are calculated to use mean temperatures).

 

Mechanical Couplings

Bolting devices used in assembly of piping.

 

Mechanical Insulation

Insulation used for or on cold or hot pipes, ducts, tanks, vessels, and equipment to achieve thermal, acoustical, and personnel safety requirements in residential, industrial, and commercial applications, including process systems.

 

Mechanical Insulation Accessories

Components used in conjunction with the insulation that is applied in a mechanical insulation system.

 

Medium Pressure Condensate

Condensate directly received from medium-pressure steam.

 

Medium Pressure Steam

Steam under 75 pounds per square inch gauge, but above 15 pounds psig.

 

Medium Velocity Duct

A duct designed with airflow over 2000 feet per minute velocity with a static pressure below 6 inches.

 

Melamine Insulation

A typically open cell foam material consisting of formaldehyde-melamine-sodium bisulfite copolymer supplied as sheets for use as thermal or acoustical insulation.

 

Membrane Reinforcement

Woven or non-woven fabrics used for saturation and embedment in mastic and coating applications to provide strength, continuity, and impact resistance. See glass fabric.

 

Metal Lagging

See jacket.

 

Metal Sheets

Thin-gauge metal pieces composed of various alloys of stainless steel, steel or aluminum for use as protective covering materials on pipe, tank, equipment, and vessel insulation. Each individual sheet is sized to conveniently fit around or over the insulation system.

 

Metal Rolls

Thin-gauge metal in the form of a long sheet that is rolled up and composed of various alloys of stainless steel or aluminum for use as protective covering materials on pipe, tank, equipment, and vessel insulation. Individual pieces or sheets must be cut from the roll prior to use.

 

Micrometer

A device that accurately measures small distances or thicknesses between its 2 faces.

 

Microporous Insulation

Material in the form of compacted powder with an average interconnecting pore size comparable to or below the mean free path of air molecules at standard atmospheric temperature and pressure. Microporous insulation may contain fibers to add integral strength and opacifiers to reduce the amount of radiant heat transmitted.

 

Mineral Fiber

Synthetic mineral fibers are fibrous inorganic substances made primarily from rock, slag, or glass. These fibers are classified into two general groups: fiberglass (glass wool) and mineral wool (rock wool and slag wool). Note that many mechanical fiberglass products are typically lighter with maximum use temperatures of up to 1000°F while mineral wool mechanical products are generally heavier with a maximum use temperature of 1200°F. There are exceptions and manufacturers’ data must be consulted to ensure the maximum use temperature of the product is appropriate for its intended application.

 

Mineral Wool

A synthetic vitreous fiber insulation made by melting predominantly igneous rock, and or furnace slag, and other inorganic materials, and then physically forming the melt into fibers. To form an insulation product, there are often other materials applied to the mineral wool such as binders, oils, etc.

 

Mixed Air Duct (Plenum)

A duct or plenum located at a point where air returned from a space inside the building, and fresh air are mixed or metered by dampers for redistribution through the air handling unit.

 

Moisture Barrier (as related to Insulation Jacketing)

A polymeric film or coating applied to the inner surface of metal jacketing for the primary purpose of reducing electrolytic, pitting, or crevice corrosion of the jacketing

Discussion – moisture barriers are not water vapor barriers or water vapor retarders

 

Moisture Barrier (Other)

A substance that is impervious to liquids and is used to stop moisture intrusion.

 

Moisture Retarder (as related to Insulation Jacketing)

A layer of plastic film or other material applied to the inner side of metal jacketing to inhibit jacket corrosion by interfering with the formation of a galvanic cell between the dissimilar metals of the pipe and jacket or by preventing crevice corrosion

Discussion—A moisture retarder is not an insulation system water vapor retarder and does not perform the same function.

 

Mold and Mildew Resistance

The property of a material that enables it to resist the formation of fungus growth.

N

Needled Glass

Glass fibers that are held together, typically in blanket form, by use of pin-punching repeatedly to entwine the fibers. Needled blankets do not employ the use of organic binders to hold together the insulation blanket.

 

NFPA

National Fire Protection Association.

 

Noise Reduction Coefficient (NRC)

A single number rating that is the arithmetic average of the individual sound absorption coefficients at 250, 500, 1000, and 2000 Hz to the nearest 0.05.

 

Nominal Pipe Size (NPS) Piping

The name of the sizing system for pipes used with IP units. The NPS system is employed to indicate the name of the pipe size, not its actual dimensions, wall thickness, or outer diameter. These actual dimensions can only be determined by consulting the appropriate table of actual sizes associated with each NPS size and wall thickness.

 

Noncombustible

A material that will not contribute fuel or heat to support a fire to which it is exposed.

 

Nonflammable

A material that will release very little heat when exposed to fire or flame.

 

Nuclear Encapsulated or Reflective Metallic Insulation (RMI) Cassettes

An insulation system made of heavy gauge stainless steel sheets on the outside and light gauge stainless steel foils separated by ¼-inch to ½-inch gaps on the inside. The thermal performance depends primarily on maintaining the low emittance of the concentric foil layers. The 1/4-inch to 1/2-inch wide air spaces between the foils provide some thermal energy control.

O

Octave Band

A frequency band with an upper-frequency limit equal to twice the lower limit.

 

Offset

A change in location or direction of a main, branch or runout. It may be located in a riser or horizontal run of piping or duct.

 

One-coat Cement

A mixture of various insulation fibers, fillers, and binders with hydraulic-setting cement. The material can be applied directly to fittings to match adjacent insulation thickness in one application and smoothed to provide a hard finish.

 

Open Cell Foam

A material comprised predominantly of interconnecting cellular voids.

P

Panel

A prefabricated unit of insulation and lagging.

 

Patching

Repair or restoration of damaged existing insulation. See Reinsulate.

 

Perlite

Insulation composed of natural perlite ore expanded to form a cellular structure.

 

Perm

The unit measure of vapor transmission consisting of one grain of water through one square foot of a membrane in an hour at 1-inch mercury vapor pressure difference.

 

Permeance

See water vapor permeance.

 

Permeability

See water vapor permeability.

 

Personnel Protection System (as related to insulation)

A system installed or mechanical device used for avoiding physical harm from thermal and acoustical hazards.

 

pH

A measure of the acidity or alkalinity of a solution, numerically equal to 7 for neutral solutions, increasing with increasing alkalinity and decreasing with increasing acidity (potential of hydrogen).

 

Phenolic Foam

A foamed insulation made from resins of phenols condensed with aldehydes.

 

Pin Weld

Attachment of insulation anchor pins to ductwork or equipment usually by capacitor discharge welding.

 

Pinhole

A very small hole through a mastic or coating.

 

Pipe

A circular conduit for the conveyance of liquids or semisolids.

 

Pipe Insulation

Insulation in a form suitable for application to cylindrical surfaces.

 

Pipe & Tank Wrap

A flexible mechanical insulation formed either by continuous mat or segmented pieces of fibrous insulation adhered to various facing materials for the purpose of wrapping large diameter pipes, ducts, or vessels.

 

Piping Isometrics

Drawings provided by a technical designer intended to illustrate piping lengths, sizes, locations, and elevations for a mechanical system. Isometrics may contain additional information about treatment of pipes for a specific purpose or service intended.

 

Plenums

A compartment or chamber to which one or more ducts are connected, that forms a part of the air distribution system, and that is not used for occupancy or storage.  A plenum is often formed in part or in total by portions of the building.

 

Pointing

Applying or shaping cements or mastic with a small pointed trowel.

 

Poly Scrim Kraft (PSK)

Laminate facing or covering consisting of metalized or non-metalized polymeric film with a reinforcing scrim and a kraft paper backing

 

Polyfilm

A multilayer film used as a moisture retarder on metal jacketing consisting of at least one layer of ethylene/methacrylic acid copolymer and one or more layers of other polymers, usually polyethylene.

 

Polyethylene

A closed-cell, thermoplastic material used for insulation.

 

Polymeric (Plastic/Rubber) Rolls (as related to insulation protective jacketing)

Thin-gauge polymer in the form of a long sheet rolled up for use as a protective covering material on pipe, duct, tank, equipment, and vessel insulation. Individual pieces or sheets must be cut from the roll prior to use.

 

Polymeric (Plastic/Rubber) Sheets (as related to insulation protective jacketing)

Thin-gauge polymeric pieces composed of various materials, usually a plastic or rubber, for use as protective covering materials on pipe, tank, equipment, and vessel insulation. Each individual sheet is sized to conveniently fit around or over the insulation system. Polymeric sheets and some fitting covers are available at various thicknesses. Typical polymeric jacketing materials are Polyvinyl Chloride (PVC), Polyvinylidene Chloride (PVDC), Polyethylene Terephthalate (PET), Polyvinyl Fluoride (PVF), Elastomeric, and Glass Reinforced Plastic.

 

Polyimide

See cellular polyimide.

 

Polyisocyanate

A closed-cell, thermoset, plastic foam formed by combining isocyanurate, polyol, surfactants, catalysts and blowing agents.

 

polykraft

A multilayer composite film used as a moisture retarder on metal jacketing consisting of at least one layer of minimum 40 lb kraft paper and one or more layers of plastic film, usually polyethylene at a minimum thickness of 1.5 mils.

 

Polymer

A long chain molecule resulting from the chemical attachment of short molecules (monomers) of the same product. For example, when ethylene (a gas) is polymerized, the synthetic resin polyethylene is produced.

 

Polyolefin

A closed-cell thermoplastic material used for insulation, typically polyethylene.

 

Polyvinyl Chloride (PVC)

A polymerized vinyl compound using chloride.

 

Polyvinyl Fluoride (PVF)

A polymerized vinyl compound using fluoride.

 

Pre-insulated Panel Systems

Factory-fabricated panel systems that incorporate an insulation layer, an outer layer of rigid or semi-rigid material serving as a structural support and protective jacketing material, and various methods of holding these laminated panels together and in place.  Varying configurations of metals or plastics are the most common support/jacket material used in pre-insulated panels.

 

Pre-insulated Piping Systems

Pre-assembled piping systems that incorporate piping, insulation, and a vapor retarder if needed, and an external covering/protective jacket in an assembly. This assembly is installed in a single operation. Joints between assemblies of pre-insulated pipe are connected and insulated on site.

 

Pressure Sensitive Tape

A tape with adhesive pre-applied.

 

Poly/Scrim/Kraft/Poly (PSKP)

Laminate facing or covering consisting of two layer of metalized or non-metalized polymeric film with a reinforcing scrim and kraft core between.

 

Poly/Scrim/Poly (PSP)

Laminate facing or covering consisting of two layers of metalized or non-metalized polymeric film with a reinforcing scrim between.

 

Psychrometer

A hygrometer consisting of a wet-bulb and a dry-bulb thermometer used to determine atmospheric humidity.

 

Pumped Condensate (Discharge)

Condensate in liquid state from condensate receivers to feed water heaters, deaerators, or boilers.

 

Puncture Resistance

That property of a material that enables it to resist punctures or perforations under blows or pressure from sharp objects.

 

Punking

Partial or full thermal decomposition of binding agents, within an insulation material, caused by exposure to a temperature higher than the decomposition temperature of the binding agent. This slow, flameless decomposition may result in exothermic heat build-up that accelerates the decomposition. The inorganic portions of the insulation material typically remain unaffected if the temperature does not exceed the stated service temperature of the insulation material. This decomposition of the binder can result in thermal and structural degradation of the insulation.

Q

Quads or Pipe Section Quarters (PSQ)

Rigid insulation that has been molded or fabricated into 4 sections of equal dimension and thickness to provide a complete single-layer of insulation around a given size of larger-diameter pipe. Pipe section quarters are typically used for pipe insulation on piping diameters greater than 24-inch NPS up to 36-inch NPS. The term “quads” can also refer to 4-piece pressed metal elbow-fitting jackets.

R

R-Value (Resistance)

See Resistance, thermal.

 

Radiance

The rate of radiant emission per unit solid angle and per unit projected area of a source in a stated angular direction from the surface (usually the normal).

 

Radiant Flux Density

The rate of radiant energy emitted from unit area of a surface in all radial directions of the overspreading hemisphere.

 

Radiation

The passage of heat from one object to another without warming the space between.

 

Radiography (industrial)

An imaging technique using X-rays, gamma rays, or similar high-energy electromagnetic radiation to penetrate and view the internal structure (e.g. flaws) of an object, such as metal pipe.

 

Reflectance

The fraction of the incident radiation upon a surface that is reflected from the surface.

 

Reflective Insulation

Insulation depending for its performance upon reduction of radiant heat transfer across air spaces by use of one or more surfaces of high reflectance and low emittance.

 

Refractory Insulation

Insulation for extremely high-temperature applications, typically above 1,200°F.

 

Refractory Materials

Materials, usually fibers, that do not significantly deform or change chemically at very high temperatures. Manufactured in blanket, block, brick, or cement form.

 

Reinforcing Cloth or Fabric

A woven cloth or fabric of glass or resilient fibers used as reinforcement to a mastic.

 

Reinsulate

To repair insulation to its former condition. (If insulation is to be removed and replaced, it should be so stated.)

 

Relative Humidity

One of the following ratios (a) the mole fraction of water vapor in a given moist air sample to the mole fraction in the air sample saturated at the same temperature and pressure; (b) the vapor pressure in a given moist air sample to the vapor pressure in the air sample saturated at the same temperature and pressure and (c) the humidity ratio in a given moist air sample to the humidity ratio in the air sample saturated at the same temperature and pressure. There are no units.

 

Removable and Reusable Covers

Insulation materials or pads, enclosed in a fabric or metal (mesh, or sheet), designed to be readily removed and reinstalled.

 

Resiliency

The property of a material that enables it to recover its original shape and thickness after compression.

 

Resistance to Acids, Caustics, and Solvents

The ability of a material to resist decomposition by various acids, caustics and solvents to which it may be subjected.

 

Resistance to Air Erosion

The ability of an insulation material to resist erosion by air currents over its surface.

 

Resistance, Abrasion

The ability to withstand scuffing, scratching, rubbing or wind-scouring.

 

Resistance, Freeze-Thaw

Resistance to cycles of freezing and thawing that could affect application, appearance or performance.

 

Resistance, Impact (Toughness)

Ability to withstand mechanical blows or shock without damage seriously affecting the effectiveness of the material or system.

 

Resistance, Thermal, (R-value)

A measure of the ability to retard heat flow rather than the ability to transmit heat. R-value is the numerical reciprocal of “U” or “C,” thus R = 1/U or 1/C. Thermal resistance R-value is used in combination with numerals to designate thermal resistance values: R-11 equals 11 resistance units. The higher the “R,” the higher the insulating value. The I-P units are °F – ft² – hr / Btu; the SI units are °C – m² / W.

 

Resistivity, Thermal, r

The quantity determined by the temperature difference, at steady state, between two defined parallel surfaces of a homogeneous material of unit thickness, that induces a unit heat flow rate through a unit area. (r in SI units: m K/W.) (r in inch-pound units: h ft F/Btu or, h ft ² F/Btu in.)

 

Retrofit

The application of additional insulation over existing insulation, new insulation after old insulation has been removed, or new insulation over existing, previously uninsulated surfaces.

 

Return Air

Air returned from conditioned spaces to an air-handling unit.

 

Return Air Duct

A duct carrying air from a conditioned space to the mixing air duct or plenum unit.

 

Rigid Granular

Rigid Granular insulation opposes any tendency to bend (flex) under load and may lose strength or integrity when bent.  It can be supplied as blocks or in a preformed pipe configuration.  Calcium silicate, microporous, and expanded perlite are produced in rigid types.

 

Rigid Removable and Reusable Covers

Insulation covers that include an insulation material that is enclosed in a rigid cover designed to be readily removed and reinstalled.

 

Rigid Wrap-around Insulation

Segments of insulation material that have been adhered to a facing giving rigid insulation materials flexibility of application.

 

Rigidity

The property of a material that opposes any tendency for it to bend (flex) under load.

 

Riser

The vertical portion of a main, branch or runout.

 

Rock Wool (Mineral Wool)

A synthetic vitreous fiber insulation made by melting predominantly igneous rock and other inorganic materials, and then physically forming the melt into fibers. Also,see Mineral Wool.

 

Run-Out

Piping or duct work from or to a branch or main serving one: a) plumbing unit or fixture connection. b) heating and/or cooling unit, coil, convector, unit heater, fin tube, equipment connection, etc. c) HVAC diffuser or register or d) process equipment connection.

S

Saddle

Rigid support for piping or equipment with allowance for insulation.

 

Sample

A group of items, observations, test results, or portions of material, taken from a large collection of items, observations, test results, or quantities of material, which serves to provide information that may be used as a basis for making a decision concerning the larger collection.

 

Safety Data Sheet (SDS)

A document that manufacturers and importers of chemicals use to identify and classify chemical hazards so that downstream users can be informed about and better understand these hazards.   The Hazard Communication Standard (HCS) (29 CFR 1910.1200(g)) requires that the chemical manufacturer or importer provide Safety Data Sheets, (formerly known as Material Safety Data Sheets or MSDS’s), for each hazardous chemical.

 

Safety Edge

An edge of metal jacketing that has been de-burred or rounded by a rolling operation

 

Safety Hem

A rounded edge of metal jacketing created by folding the edge of sheet jacketing completely back upon itself using a roll former or a brake

Discussion– The fold is made toward the underside of the jacketing so that the original edge is hidden and the external appearance of the jacketing is preserved

 

SBCCI

Southern Building Code Congress, International.

 

S-Clip

A device (in the shape of an “S”) for supporting insulation, bands or jacketing.

 

Score

To cut grooves in rigid insulation so that it may be cracked and fitted to round or irregular surfaces.

 

Scored Insulation

Flat insulation material that has grooves cut in the insulation so that it can be wrapped around a round or irregular surface. The groove in scored insulation extends most of the way through the insulation and the thin remaining intact insulation layer is typically broken at the outer insulation surface during installation, requiring the use of banding, wire, or tape as holding/fastening devices. (See also V-Grooved Insulation)

 

Scrim

A woven, nonwoven, or knitted fabric composted of continuous strands of material used for reinforcing or strengthening materials like ASJ or FSK insulation facers.

 

Seal

To make water-tight or airtight.

 

Sealant

Sealants in insulation function primarily as water and vapor seals. They may also be used as adhesives, and for expansion joints for metal, masonry, cellular glass, etc. They must exhibit low shrinkage, excellent adhesion and permanent flexibility.

 

Sealer

A liquid coating used to prevent excessive absorption of finish coats into porous surfaces.

 

Securements

Any device, wire, strap or adhesive used to fasten insulation into its service position and hold it there.

 

Self-Extinguishing

The property of a material that enables it to stop its own ignition after external ignition sources are removed.

 

Service Temperature Limits

The temperature to which the jacket or coating may be subjected when applied over insulation. It does not refer to the operating temperature of the equipment, vessel, or pipe.

 

Shear Strength

The ability of a material to resist cleavage.

 

Shelf Life

The period of time during which a material, especially packaged adhesive, coating or sealant,  can be stored under specified temperature conditions and remain suitable for use.

 

Shield

Metal protector to prevent crushing of insulation at pipe hangars.

 

Shrinkage

That property of a material that indicates its proportionate loss in dimensions or volume due to temperature changes or aging.

 

Slag Wool

A mineral wool made usually from molten blast-furnace slag by the action of jets of steam under high pressure.

 

Smoke Density

The amount of smoke given off by the burning material compared to the amount of smoke given off by the burning of a standard material.

 

Soaking Heat

A test condition in which the specimen is completely immersed in an atmosphere maintained at a controlled temperature.

 

Solar Resistance

The property of a material to resist decomposition by the ultraviolet rays from the sun or the passage of radiant heat from the sun.

 

Solids Content

The percentage of the non-volatile matter in adhesives, coatings or sealants. It may be based on weight or volume.

 

Solvent

Any substance, usually a liquid, that dissolves another substance.

 

Sorption

Sorption refers to the process in which one substance takes up or holds another (by either absorption or adsorption)

 

Sound Absorption Coefficient (SAC)

The percentage of sound energy incident on the surface of a material that is absorbed by the material.

 

Sound Meter (Sound Level Meter, Noise Meter, or Decibel Meter)

Device used for the measurement of acoustic energy. It is commonly a hand-held instrument with a microphone and readings are typically expressed in decibels.

 

Sound Transmission Class (STC)

A single number rating based on sound transmission loss measurements of a partition between adjacent closed rooms.

 

Sound Transmission Loss (STL)

The reduction in level measured in decibels as sound energy passes through a material or composite construction.

 

Specific Heat

The ratio of the amount of heat required to raise a unit mass of a material 1 degree, to that required to raise a unit mass of water 1 degree at some specified temperature.

 

splice roll

Metal jacketing sold in roll form where the package contains two separate pieces of metal jacketing rolled approximately end to end.

Discussion—A splice roll occurs when the metal coil being used to form the roll jacketing reaches its end before the required roll length is obtained.

 

split roll

Synonymous with splice roll.

 

Sprayed-on Insulation

Insulation of the fibrous or foam type that is applied to a surface by means of power spray devices.

 

SSL

Self-sealing lap, as in the overlap on pipe insulation jacket.

 

Standards

Published documents that establish specifications and procedures designed to ensure the performance and reliability of materials, products, methods, and/or services.

 

Standard Test Method

An established method for conducting a test in science or engineering, such as a physical or chemical test. It is a definitive procedure that produces a reliable result, either quantitative or subjective.  A test can be considered a technical operation or procedure that consists of the determination of one or more characteristics of a given product, process, or service according to a specified protocol.

 

Standing Seam

Folded configuration of jacketing to achieve watershed for the top flat surfaces of ductwork, vessels, or tanks. Also used to provide rigidity.

 

Steady State (Thermal)

A condition for which all relevant parameters in a region do not vary over two consecutive steady-state time periods by more than the steady-state tolerance, and no long-term monotonic drifts are present. Where, the steady-state time period is the time constant of the apparatus-specimen system with additional time necessary if physical phenomena are present, such as moisture transport, which could cause a long-term monotonic drift.

 

Stiffener (Duct Flange)

A structural or fabricated angle iron shape, attached to the exterior surfaces of a duct or bulkhead at specified intervals for the purpose of reinforcing the metal and to prevent vibration.

 

Stone Wool

See Rock Wool.

 

Strainer

A filter or sieve used in fluid piping to trap scale and other entrained particles.

 

Strength, Transverse (or Flexural)

The breaking load applied normal to the neutral axis of a beam.

 

Stud

Used to hold heavy insulation and/or panels in place. Applied with arc welder, studs differ from pins in that they are generally ¼-inch or greater in diameter.

 

Stud Weld

Attachment of insulation anchors to tanks or vessels by means of drawn arc welding.

 

Supercool

The action of cooling a substance below its freezing temperature without the material becoming a solid.

 

Supply Air Duct

A duct that carries conditioned air from air supply units to room diffusers or grilles.

 

Support (Insulation)

A mechanical device that carries the weight of insulation.

 

Surface Coefficient

The ratio of the steady-state heat exchange rate (time rate of heat flow per unit area of a particular surface by the combined effects of radiation, conduction, and convection) between a surface and its external surrounding (air or other fluid and other visible surfaces) to the temperature difference between the surface and its surroundings.

(See conductance, film).

 

Surface Temperature (TA)

The surface temperature of finished insulation.

T

Tack

The property of an adhesive that enables it to form a measurable bond immediately after adhesive and adherent are brought into contact under low pressure.

 

Tear Strength

The property of a material that enables it to resist being pulled apart by opposing forces.

 

Temperature Cycling

The situation where the temperatures involved in a system change through 2 or more temperature extremes and may involve multiple repetitions of this change.  The temperature that is changing can be inside a pipe or vessel or it can be the ambient temperature.

 

Temperature Limits

The upper and lower temperatures at which a material will experience no change in its physical properties.

 

Test Specimen

The portion of a test unit needed to obtain a single test determination.

 

Thermal Conductivity (k-Value)

See Conductivity, thermal (k-value)

 

Thermal Capacity

The quantity of heat required to change the temperature of the body one degree. For a homogeneous body, it is the product of mass and specific heat. For a nonhomogeneous body, it is the sum of the products of mass and specific heat of the individual constituents. (May also be seen as heat capacity.)

 

Thermal Insulation

Definition One: Insulation applicable within the general temperature range of –300 F to 1800 F.

Definition Two: A material or assembly of materials used to provide resistance to heat flow.

 

Thermal Insulation System

Applied or installed thermal insulation complete with any accessories, vapor retarder, and facing required.

 

Thermal Properties of Insulation

Usually expressed as C-value, K-value, R-value and U-value.

Thermoplastic Rubber (TPR)

A material with melting and molding properties of plastic while still maintaining some of the flexible properties of rubber. TPR can be as soft as a gel-like material or almost as hard as molded plastic.

 

Throat

Inside radius of an elbow.

 

Through-Penetration Firestops

A type of sealing system space between an opening in a wall or floor and an object passing through this opening designed and used to prevent some combination of the spread of flame, smoke and gasses, or water through the opening. These systems also limit the temperature rise on the non-fire side of the wall or assembly.

 

Traced

The supplying of auxiliary heat to a pipe or piece of equipment by means of a companion line containing a hot fluid or electric resistance. It can be thermally or mechanically bonded to the pipe or equipment.

 

Transference, Thermal

The steady-state heat flow from (or to) a body through applied thermal insulation and to (or from) the external surroundings by conduction, convection, and radiation. It is expressed as the time rate of heat flow per unit area of the body surface per unit temperature difference between the body surface and the external surroundings.

 

Transmission, Heat

The quantity of heat flowing through unit area due to all modes of heat transfer induced by the prevailing conditions.

 

Transmittance, Thermal (U-value)

The combined thermal value of all the materials in a insulation system, air spaces, and surface air films. The heat transmission in unit time through unit area of a material or construction and boundary air films, induced by unit temperature difference between the environments on each side. The I-P units are Btu / (hr – sq ft – deg F temperature difference) and the SI units are W / (sq m – deg C temperature difference). Note: This heat transmission rate has been called the overall coefficient of heat transfer.

 

T-Rating

A rating usually expressed in hours indicating the length of time that the temperature on the non-fire side of a fire-rated assembly exceeds 325°F above its ambient temperature as determined by ASTM E-814 (UL-1479).

 

Tube Turn (Bend)

Pipe, factory, or field formed, to pre-determined radii.

U

UL

Underwriters Laboratories. An independent materials testing company. UL provides testing, evaluation, and listing services for products having specific safety-related features. UL test standards generally are similar to ASTM International standards when both exist.

 

Underground

Insulation applied on piping and equipment located below grade and in direct contact with the surrounding soil.

 

Union

A coupling device for connecting pipes.

 

Urethane

Plastic foam of rigid polyurethane closed-cell insulation in board, pipe insulation or foamed-in-place form.

 

U-Value (Transmittance)

See Transmittance, Thermal (U-value)

V

Valve

Any of various devices that regulate liquid or gas flow by opening, closing or obstructing its passage.

 

Vapor Drive (in reference to water vapor)

The driving force for water vapor to diffuse from a location with a higher partial pressure of water vapor to a location with a lower partial pressure.  The partial pressure of water vapor at any location is a factor of the total pressure (usually one atmosphere), the concentration of water vapor in the air, and the temperature of the air.

 

Vapor Stop

Constructions in a pipe insulation system made up of materials that greatly impede the flow of liquid and gaseous water. Vapor stops are perpendicular to the pipe, adhere to the pipe, and adhere to the vapor retarder on the outer surface of the insulation.  As a result of their performance and location, they are used to greatly limit the passage of liquid or gaseous water from one section of a pipe insulation system to another. If water or water vapor does enter one portion of a pipe insulation system, the presence of vapor stops on either side of this portion will limit the extent of damage that the water can cause.  They are also used at insulation termination points to prevent the intrusion of water (liquid) or water vapor into the insulation system.

 

Ventilating Air

Air supplied to or removed from any space by natural or mechanical means.

 

Ventilating Duct

Duct supplying or removing air by natural or mechanical means.

 

Vermiculite

Insulation composed of natural vermiculite ore expanded to form an exfoliated structure.

 

Vertical Piping

Any piping that is less than 45° from the vertical plane.

 

V-Grooved Insulation

Rigid or flexible insulation board that may be laminated to a fabric or other flexible facing material and then shaped by cutting a series of Vs into the insulation in such a way that the resulting system can be wrapped around a pipe, tank, or duct. (See also Scored Insulation.)

 

Vibration Resistance

The property of a material that indicates its ability to resist mechanical vibration without wearing away, setting or dusting.

 

Vinyl

The name of a class of resins or sheeting.

W

Warpage

The change in the flatness of a material caused by differences in the temperature and/or humidities applied to opposite surfaces of the material.

 

Washer (Insulation Clip)

Self-locking flat metal device applied to anchor pins to secure the insulation in place.

 

Water Absorption

The increase in weight of a material expressed as a percentage of its dry weight or volume after immersion in water for a specified time.

 

Water Resistant

Capable of withstanding limited exposure to water.

 

Water Vapor Diffusion

The process by which water vapor spreads or moves through permeable materials caused by a difference in water vapor pressure.

 

Water Vapor Permeability

The time rate of water vapor transmission through unit area of flat material of unit thickness induced by unit vapor pressure difference between two specific surfaces, under specified temperature and humidity. Water vapor permeability is measured in the IP system in perm inches.

 

Water Vapor Permeance

The time rate of water vapor transmission through unit area of flat material or construction induced by unit vapor pressure difference between two specific surfaces, under specified temperature and humidity conditions. Water vapor permeance is measured in IP system in units of perm.

 

Water Vapor Pressure

The pressure of water vapor at a given temperature; also the component of atmospheric pressure contributed by the presence of water vapor.

 

Water Vapor Resistance

The steady state vapor pressure difference that induces unit time rate of vapor flow through unit area of a flat material (or construction that acts like a homogeneous body) for specific conditions of temperature and relative humidity at each surface.

 

Water Vapor Resistivity

The steady state vapor pressure difference that induces unit time rate of vapor flow through unit area and unit thickness of a flat material (or construction that acts like a homogeneous body), for specific conditions of temperature and relative humidity at each surface.

 

Water Vapor Retarder (Barrier)

A material or system that significantly impedes the transmission of water vapor under specified conditions.

 

Water Vapor Retarder Jacket

Any material or composite meeting the requirements of a water vapor retarder and used for the jacketing of insulation material. It may be factory furnished or field applied and may or may not be adhered to the insulation material.

 

Water Vapor Transmission Rate (WVTR)

The steady state water vapor flow in unit time through unit area of a body, normal to specific parallel surfaces, under specific conditions of temperature and humidity at each surface. The I-P units are lbs / hr – ft2; the SI units are grams / hr – m2.

 

Waterproof

Impervious to prolonged exposure to water or water entry.

 

Weather/Vapor-Retarder (barrier)

A vapor retarder that also protects from atmospheric conditions.

 

Weather Barrier

A breather jacket or coating which allows passage of water vapor yet protects from atmospheric conditions.

 

Weld Pin

Made of carbon steel, stainless steel or aluminum in various lengths for attaching insulation to metal surfaces. Applied by welding, usually with a weld gun.

 

Wet Film Thickness (WFT)

The thickness of a wet applied film that is measured before any drying, loss of solvent, or curing has occurred. Wet film thickness is at its maximum immediately after the application.

 

Wet Film Thickness Gauge

A device used to measure the thickness of a wet film.  (See Wet film Thickness)

 

Wetting and Adhesion, Surface

The mutual affinity of and bonding between finish and the surface to which it is applied.

 

Wicking

Action of absorbing by capillary action.

 

Wood Fiber

Insulation composed of wood/cellulosic fibers, with or without binders.

 

REVISION AND CORRECTIONS DATED:  March 28, 2024

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