Glossary – Allied Packing & Rubber, INC

ABRASION – Progressive wearing away of material.

ABRASION RESISTANCE – The ability of a material to resist mechanical wear.

ADAPTER – 1) Fittings of various sizes and materials used to change an end fitting from one type to another type or one size to another. (i.e., a male JIC to male pipe adapter is often attached to a female JIC to create a male end union fitting); 2) the grooved portion of a cam & groove coupling.

ADHESION – The clinging, binding or sticking of two material surfaces to one another, such as rubber to rubber, rubber to metal or rubber to cloth.  It also refers to the bond strength between two surfaces.

ALUMINIUM – A pliable, lightweight metal that has good electrical and thermal conductivity, high reflectivity, and resistance to oxidation.

AMBIENT TEMPERATURE – The temperature of the surrounding environment.

ANSI – Abbreviation for “American National Standard Institute”.

ARAMID – A family of polymers used in a fibrous form as packing materials. 

ASME – Abbreviation for American Society of Mechanical Engineers.

ASSEMBLY – A general term referring to any hose coupled with end fittings of any style attached to one or both ends.

ASTM – Abbreviation for American Society for Testing and Materials.

ATTACHMENT – The method of securing an end fitting to a hose (e.g., banding, crimping, swaging, or screw-together-2 piece or 3 piece-style-reusable fittings).

BAND – (1) A metal ring that is welded, shrunk, or cast on the outer surface of a hose nipple or fitting; (2) a thin strip of metal used as a non-bolted.

BARBED AND FERRULE FITTING – A two-piece hose fitting comprised of a barbed insert (nipple), normally with peripheral ridges or backward-slanted barbs, for inserting into a hose and a ferrule, usually crimped or swaged.

BEARINGS – A machined or molded plastic ring used as a guide ring or wear ring in a hydraulic cylinder.

BEATER ADD (BEATER SATURATED) – A manufacturing process for making non-metallic sheet that employs a papermaking process using Fourdrinier or cylinder-type paper machines. Bellows- That portion of an expansion joint which accommodates the movement of the joint convoluted or flat.

BELT TYPE EXPANSION JOINT – An expansion joint in which the flexible bellow portion of the joint is made flat and bolted or clamped to metal adapter flanges or frames.

BELTS – A v-belt, flat belt or drive belt made from plastic or rubber.

BEVEL CUT – An angled cut at the seam (or joint) of a packing ring.

BLOCKING AGENT – A coating applied to braided packing to fill the area between the fibers, blocking the passage of media through the body of the braid, and improving its sealing characteristics.  This may be a grease, an oil, or a PTFE dispersion.

BOLT HOLE CIRCLE – A circle on the flange face around which the center of the bolt holes are distributed.

BOLT HOLE PATTERN/DRILL PATTERN – The systematic location of bolt holes in the flanges and expansion joint flanges where joint is to be bolted.

BOLT IN BAFFLE/FLOW LINERS – A baffle that is designed to be bolted to the breach flange.  NOTE: Bolt in baffles/flow liners require the use of a seal gasket.

BOLT TORQUE – The amount of twisting or turning effort required to turn the nuts on a gland follower.  The load that the gland follower exerts on a valve packing set can be expressed in terms of a specific bolt torque.

BOND – The union of materials by use of adhesives, usually used in related parts vulcanized after attaching.

BONDED SEALS – A flat steel washer with a rubber sealing ring molded into the center to fit over a bolt to provide a seal.

BONDING AGENTS – Substances or mixtures of substances that are used for attaching rubber to metal, fabrics or other substrates. Generally the rubber compound is vulcanized by heat in the process. Cyclized rubber or rubber isomers, halogenated rubber, rubber hydrochloride, reaction product of natural rubber and acrylonitrile, polymers containing diisocyanates, are all used.

BOOT/BELT – The flexible element of an expansion joint usually consisting of rubber and rubber coated fabric.

BORE DIAMETER – The outside of dimension of the annular space that packing is inserted into. 

BRAID OVER BRAID – A type of braiding construction in which a series of round braided layers are braided on top of one another.

BRAID OVER CORE – A type of braiding construction in which yarns are round braided over a core.  Cores may be composed of an elastomer extrusion, a plastic compound extrusion, another braid, or other materials.

BRAID – Yarns or filaments woven together to form a hollow or solid structure.  A braid may have a round(braid over braid), square(simple crossing pattern), or Lattice(interlocking) weave pattern.  Braids may have round, square, or rectangular cross-sectioned shape.  The woven portion of a hose used as reinforcement to increase pressure rating and add hoop strength. Various materials such as polyester, cotton or metal wire are used. A hose may have one or more braids, outside or between layers of hose material.

BREAK IN LUBRICANT – A lubricant added to the surface of braided packing. Break-in Lubricants are used to protect the packing from charring during the initial start-up of rotating equipment, such as pumps and mixers.

BUNA –  (aka NBR, Nitrile) is the standard in hydraulic and pneumatic sealing elastomers. Its oil resistant nature makes it the top choice of materials being used with petroleum based hydraulic fluids. Buna has a good abrasion resistance, high tensile strength and resistance to compression set.

BUNA N – A general term for the copolymers of butadiene and acrylonitrile. Typical commercial polymers are Hycar and Paracril.

BUSHING – A metallic or carbon ring used to take up excess space in a stuffing box.

BUTT CUT – A straight cut at the seam (or joint) of a packing ring.

BUTT JOINT – Joining two ends of material whereby the junction is perpendicular to the ID of an O-ring.

BUTT WELD – Process in which the edges or ends of metal sections are butted together and joined by welding.

C OF C CERTIFICATE OF CONFORMANCE OR CERTIFICATE OF COMPLIANCE – A document, usually signed and dated pertaining to a particular lot or purchase ( )f item(s), which describes any standards, specifications, tests, materials and/or performance attributes to which the referenced item(s) have met or will meet.

C.I. – The abbreviation for cloth- inserted, indicating a sheet of rubber containing one or more plies of fabric covered with rubber.

CALENDER – 1) A step in the production of braided packing where a braided material is fed through rollers to squeeze it to its finished size. 2) A machine which is used to calendar a braid. Capped end: a hose end covered to protect its internal elements.

CARBON STEEL (C.S.) – Carbon steel is steel in which the main alloy is carbon. Carbon steel is used to manufacture spiral wound gaskets (S.W.G).

CENTERING RING (GUIDE RING) – A solid piece of metal used on the OD of a gasket winding in order to center the gasket properly on the sealing surface by locating the ring against the studs in the connection.  The ring also acts as a compression limiter to prevent over compression of the winding.

CENTRIFUGAL PUMP – A type of pump which relies on the rotation of an impeller to generate pressure and cause flow.

CHEVRON PACKING – Also known as Vee Packing and Stack Packing, an automatic Hydraulic and Pneumatic seal designed for sealing rods, rams, pistons, and plungers. Consisting of a male and female adapter and at least (3) Chevron “vee” rings which utilize a distinct hinge area to allow automatic reaction to pressure. Chevron-type packing are lip-type seals and are gland sensitive.

CHEVRON PACKINGS – Also called V-Packing, Vee packing, Chevron Packing, Parachute packing or v-set packing. A complete vee packing set contains multiple “V” shaped sealing rings stacked and nested together with a male adapter on one end and a female adapter on the other end.

CLOSED CELL – A cell totally enclosed by its walls and hence not interconnecting with other cells.

CLOTH BOTH SIDES (CBS) – Rubber sheet consisting of a ply of fabric or cloth on each surface.  CDS: Cloth on just one side.

CLOTH INSERTED (CI) – Rubber sheet containing one or more plies of fabric or cloth, in which the fabric is completely covered with rubber.

COLD FLOW – Permanent and continual deformation of a material that occurs as a result of prolonged compression or extension at or near room temperature.

COMPOSITE HOSE – Non-vulcanized hose that consists of the following: An internal wire helix; A multi-ply wall of thermoplastic films and reinforcing fabrics in proportions that give the required physical properties and provide a complete seal. (Note: The film content may be built of tubular films.) A cover consisting of fabric with an abrasion resistant polymeric coating; An external helix wire.

COMPOUND – The mixture of rubber or plastic and other materials, which are combined to give the desired properties when. Used in the manufacture of a product.

COMPRESSED HEIGHT – The height of a packing ring or packing set after it has been compressed in the stuffing box.

COMPRESSED SHEET – A hasketing material primarily containing fibers, rubber and fillers, manufactured on a special calendar (known as a “sheeter”) in such a manner that the compound is caused to build up under high load as an oriented sheet on one roll of the sheeter.

COMPRESSIBILITY – The quality or state of being compresible.  In the case of gasketing, it is the percent loss of thickness when subject to a given load.

COMPRESSION PACKING – A deformable material used to control the passage of a pressurized fluid between surfaces that move in relation to each other.

COMPRESSIVE STRESS – Force per unit area compressing (squeezing) the seal.

CONTINUOS OPERATING TEMPERATURE (COT) – Actual operating temperature of service.

COPPER SEAL RINGS – Rings made from thin copper formed over fibrous filler to seal in high temperature.

CORE – The inner portion of a hose, usually referring to the material in contact with the medium.

CORK –  Gasket material manufactured from the cork tree. Cork material is typically combined with rubbers to give it greater resistance to chemicals and solvents. Cork is a low compression jointing.

CORNERS – Molded, formed, or radius belt corners of rectangular/square expansion joint.

CORROSION– Gradual chemical or electrochemical attack on a metal by atmospheric moisture or other agents.

CORROSION INHIBITOR – An ingredient added to packing, whcih decreasesor eliminates the possiblity of galvanic corrosion in the stuffing box. Corrosion inhibitors may be classified as either passive or active.  See “Active Inhibitor”, “Passive Inhibitor”, and “Galvanic Corrosion”.

CORRUGATED – Formed into alternating peaks and valleys; typically limited to sheet metal 0.024″ and thinner.

CORRUGATED HOSE – Hose with a carcass fluted, radially or helically, to enhance flexibility or reduce its weight.

COUPLER – The female portion of the cam & groove connection with the cam arms.

COUPLING – A frequently used alternative term for fitting.

CREEP RELAXATION – A transient stress-strain condition in which strain increases concurrently with the decay of stress.  More simply put, it is the loss of tightness in a gasket, measurable by torque loss.

CRIMP/CRIMPING – A fitting attachment method utilizing a number of fingers or dies mounted in a radial configuration. The dies close perpendicular to the hose and fitting axis, compressing the collar, ferrule, or sleeve around the hose.

CROSS SECTION – An O-ring as viewed if cut at right angles to the axis showing internal structure. 1) the view of a part as if it were cut to show its internal structure. 2) the distance between the shaft or stem surface and the bore of a stuffing box.  See also “Packing Space”. 3) the shape of a packing ring at a cut.  A packing ring could have a square, rectangular, or round cross-section.

CRYOGENIC – Of or relating to a very low temperature.

CUP AND CONE -The shape of certain types of die-formed ring sets. In a “cup and cone” set the rings have conical surfaces that nest into one another.

CUP PACKING – A specific type of hydraulic or pneumatic sealing element which seals primarily on its outside diameter.

CURE – the act of vulcanization.

CUT-RING SET – A braided material cut into individual rings for a specific stem/stuffing box size and packaged as a set.

CYCLE AND ADJUST PROCEDURE – A procedure used to consolidate a packing set after it has been installed in a stuffing box. This procedure helps to reduce the amount of gland load relaxation that occurs after the valve has been put into service.

CYLINDER – A device which converts fluid power into linear mechanical force and motion. It usually consists of a moveable element such as a piston and piston rod, plunger rod, plunger, or ram, operating within a cylindrical bore.

CYLINDER BORE – The internal diameter of the cylinder.

DEFORMATION – A stress induced change of form or shape.

DENSITY – The ratio of the mass of a body to its volume, expressed as Lb/Ft3 or gm/cc. It is common for die-formed graphite foil rings to be produced to a specific density.

DIAPHRAGM SHEET – PTFE or sheet rubber (generally fabric-reinforced) from which flat diaphragms are cut.

DIE CUT – Shaped articles cut with a die from a sheet of material.

DIE FORMING – A manufacturing process in which braid or graphite foil is compressed in a mold to form a ring.

DIN – Abbreviation for Deutsches Institut für Normung. English translation is German Industry Standard – it is the European equivalent to ASTM.

DRILL PATTERN – The systematic location of bolt holes on the mating and expansion joint flange through which the expansion joint will be attached.

DRUM CURE – A method of vulcanizing rubber in which the product is wrapped around a drum and cured in hot air or steam, usually with a separator or wrapping jacket.

DUROMETER – An instrument for measuring the hardness of rubber and plastic compounds. The most common Durometer is Type A or A-2 is an instrument for determining the hardness or rubber by measuring its resistance to the penetration (without puncturing) of a blunt indentor point impressed on the rubber surface against the action of a spring; a hand and special scale indicate the resistance to penetration 01. “Hardness”. The scale reads from zero (0) to 100, zero (0) being very soft and 100 being very hard. The Type D durometer has a sharp indentor point and is used to measure varying degrees of hard rubber up to ebonite.

DUROMETER HARDNESS – An arbitrary numerical value measuring the resistance to indentation (without puncturing) of the indentor into the surface or rubber. Or a numerical value, which indicates the resistance to indentation of the blunt indentor of the durometer.

DYNAMIC SEAL – A seal required to prevent leakage past parts which are in relative motion. The opposite of static seal.

E-COATING – A coating process where an electric charge is used to bond the paint to the metal outer ring for Garlock spiral wound gaskets. The result is a smooth, drip-free finish with superior chip resistance. The process is also environmentally friendly, as no ozone-depleting propellants are used in the process.

ELASTIC LIMIT – The limiting extent to which a body may be deformed and yet return to its initial shape after removal of the deforming force.

ELASTOMER – An elastic rubber-like material which, in the vulcanized state and at room temperature, can be stretched repeatedly to at least twice its original length. Upon release of the stress, this material will immediately return to approximately its original length.

ELONGATION – The increase in length expressed numerically as a fraction or percentage of the initial length.

END RING – A ring used at the top or bottom of a packing set, usually functioning as a wiper ring and/or an anti-extrusion ring. See also “Anti-extrusion Ring”, “Junk Ring”, and “Wiper Ring”. EPDM – EPDM is a synthetic rubber used to manufacture gaskets. EPDM gaskets are suitable for use with water; a grade for use with drinking water is also available. EPDM is suitable for use up to 120 degrees centigrade (°C).

EPDM – Ethylene Propylene Diene Monomer; an elastomer.

EPR – (aka EPDM, Ethylene Propylene) is used in applications that deal with acids, weak alkalis, and automotive break fluid. EPR is also an acceptable FDA material.

EXPANSION – The increase in any linear dimension or volume.

EXTERNAL PRESSURE – Pressure (Lbs./Sq. Inch) exerted on the OD of a seal.

EXTRUDE/EXTRUDED/EXTRUSION – Forced through the shaping die of an extruder; extrusion may have a solid or hollow cross section.

EXTRUSION – 1) Distortion, under pressure, of portion of seal into clearance between mating metal parts. 2) Material, under pressure, which is forced through the opening of a die in order to obtain a desired cross sectional shape.

EXTRUSION – The distortion, under pressure, of a portion of a seal into the clearances between mating metal parts.

FABRIC FINISH – See “Fabric Impression.” The term “Cloth Finish” is used interchangeably.

FABRIC IMPRESSION – A pattern in the rubber surface formed by contact with fabric during vulcanization (usually during Drum Curing). Fabric is a composite material made by binding a cotton duck material with an elastomer such as Buna or Fluoroelastomer. The result is a stiff material with a high tensile strength. Fabric is used widely in hydraulic applications.

FATIGUE – The weakening or deterioration of a material occurring when a repetition or continuous application of stress causes strain.

FDA – United States Food and Drug Administration.

FERRULE – A metal cylinder placed over a hose end to affix the fitting to the hose. See braid sleeve, interlocking ferrule, and sleeve.

FILLER – Any compounding material, usually in powder form, added to gasketing materials either to improve quality or reduce cost.

FITTING/COUPLING – A device attached to the end of the hose to facilitate connection.

FLANGE JOINT– A joint formed by two abutting flanges.

FLANGE – Rim or edge projecting at right angles to provide strength, or a means of attachment to another part.

FLANGES – That part of an expansion joint used for fastening the joint into the system. Can be either metal or same materials as the bellows.

FLOW DIRECTION – Direction of media (fluid, gas, air, etc.) movement through the system.

FLOW METER – A device used to measure the flow rate of a fluid through a pipe. In packing applications a flow meter may be used to measure the amount of flushing fluid that is entering and/or leaving the stuffing box.

FLUID SIDE – The side of the seal which in normal use faces toward the fluid being sealed.

FLUROMYTE – A material that exhibits high tear strength and abrasion resistance and is preferred over Polymyte in high friction applications. Fluromyte has an excellent resistance to ozone, oxygen, petroleum and phosphate ester based fluids.

FOAM – Foam, or sponge, is rubber that has been formed into an air-filled matrix structure. It is typically used to manufacture environmental, and dust, seals for equipment. Foil – Another name for thin gauge aluminum (see Aluminum).

FORCE POUNDS – The total load required to deflect an expansion joint a distance equal to the maximum rated movement of the product.

FPM – Abbreviation for “Feet per Minute”, a measure of the surface speed of a rotating shaft.

FRAME – The complete angle iron or plate frame to which belt of bellows portion of the expansion joint is attached.

FRICTION COATING – A rubber covering applied to the weave of a fabric simultaneously with impregnation.

FRICTION FACTOR – An empirically determined factor used to estimate the frictional force generated by the packing on a valve stem. It is important to note that this is not the same as “Coefficient of Friction”.

FRICTION – Resistance to motion due to the contact of surfaces which normally generates heat.

Full Faced (F.F.) – A full faced gasket is a gasket that covers the full face of the flange. A full faced gasket will have bolt holes, as the bolts will run through the flange and the gasket. FULL-FACE GASKET- A gasket covering the entire flange surface and including bolt holes.

FUNCTIONAL LIP DIAMETER – The apparent inner diameter of the seal when the seal case is concentric with the outer diameter of the sizing mandrel in an air gage, light box, or similar inspection equipment.

GASKET – A flat, non-moving, compressible rubber-like device squeezed between two flat surfaces forming a static seal. Gaskets can be made from homogeneous rubber, fabric reinforced rubber, fibrous materials with rubber binders, flexible graphite, PTFE and many other materials. Some gaskets are made from a combination of metal and fibrous materials and some are all metal. An o-ring, while not flat is also referred to as a gasket at times. A deformable material, which, when clamped between essentially stationary faces, prevents the passage of matter through an opening or joint. Gasket- a generic term for a part the fits between two pieces of metal, typically for sealing purposes. Gaskets are commonly, although not always, made of flexible and compressible material.

GASKET SPACER – A gasket material cut to fit in a stuffing box between braided packing rings. Gasket spacers may be used to provide protection against abrasive particles, to increase the pressure resistance of some packing sets, or to reduce the flow of fluid through the body of the braid.

GASKETING – Material in bulk from from which gaskets may be cut.

GLAND FOLLOWER – A part which protrudes into a stuffing box to compress a packing set or packing ring.

GLAND LOAD – The amount of load applied to a packing set.  This may be expressed in terms of force (lbs, N) or in terms of pressure (psi, kPa).

GLAND PRESSURE – The amount of pressure applied to a compression packing set by the gland follower, usually expressed in psi or kPa.

GLAND STUD – A threaded rod or eye bolt, extending from a valve or pump body, that is used to compress a packing set.

GRAPHITE – Graphite is a gasket material commonly used with steam.

GREASE SEALS – Also called oil seals, rotary seals or shaft seals. Made of rubber to seal grease in a housing with a rotating shaft.

GROOVE – The area in which a hydraulic seal is contained for the purpose of sealing against a rod, or cylinder wall or an annular seal cavity.

GUIDE RINGS – See also wear rings, guide rings or bearing rings. Usually made from a form of PTFE or PTFE.

HARDNESS (A) – The relative resistance of rubber to the penetration (without puncturing) of a blunt point impressed on its surface.

HARDNESS (B) – Resistance of metal to penetration of the surface.

HEAT EXCHANGER – A piece of equipment designed to transfer thermal energy from one media to another. The unit is typically a long cylindrical body with multiple tubes passing within the body. Media of one temperature flows within the body but external to the tubes, while media of another temperature flows within the tubes, thus allowing thermal energy to exchange without cross-contamination of the products.

HIGH PRESSURE SEALS – Seals to be used in high pressure hydraulic applications made from PTFE, urethane or fabric reinforced material.

HOSE BAND CLAMP – Use with low or medium pressure and suction service. Pre-formed flat stainless steel, high carbon steel. Attached with special locking band tool.

HOSE CLAMP – A device used to hold a hose onto a fitting.

HOSE DOUBLE BOLT CLAMP – Use with low or medium pressure and suction service with large sizes of combination nipples or couplings. Cast malleable iron, plated, and brass. Applied over hose and bolted into position.

HOSE SINGLE BOLT CLAMP – Use with low pressure and suction service on shank couplings, combination nipples, and pipe nipples. Cast malleable iron, plated. Attached by bolting tightly on hose.

ID – Abbreviation for “Inside Diameter”. Used when denoting the inside dimension of a packing set, usually equal to the stem or shaft diameter.

INNER BOLT CIRCLE (I.B.C) – I.B.C. gaskets, or joints, fix within the diameter of the bolt circle. Otherwise known as raised face joints (R.F.), they are contrasted with full faced gaskets (F.F.) which cover the face of the flange and have bolt holes.

INNER DIAMETER (I.D.) – The inner diameter specifies the inner dimension, or bore size, of the gasket.

INNER RING– A solid ring used on the ID of a spiral wound gasket in higher pressure applications. This ring also acts as a compression limiter and provides protection from the media stream. Innercore: the innermost layer of a hose; the hose material in contact with the medium.

INSIDE FACE – That surface of the inner case which faces, and is usually in contact with, the fluid being sealed.

INTERLOCKED HOSE – Formed from profiled strip and wound into flexible metal tubing with no subsequent welding, brazing, or soldering; may be made pressure-tight by winding in strands of packing. Interlocking clamp: a clamp which engages the fitting in a manner which prevents the clamp from sliding off the fitting, typically a bolt or U-bolt style with interlocking fingers which engage an interlock ring on the fitting. Interlocking ferrule: a ferrule, which physically attaches to the fitting preventing the ferrule from sliding off the fitting. INTERNAL PRESSURE – Pressure (Lbs/Sq. Inch) exerted on the ID of a seal.

IPT – Iron pipe threads; a reference to NPT or NPTF.

ISO – Abbreviation for International Standards Organization.

JACKET – Seamless tubular braided or woven ply generally on the outside of hose.

JACKETED GASKET – Type of gasket with a metallic cover either partially or completely surrounding a filler material to improve temperature, pressure, chemical and crush resistance.

JUNK RING – A ring added to the bottom of a packing set as either an anti-extrusion ring or as a bushing. See also “Anti-extrusion Ring”, and “Wiper Ring”.

LANTERN RING – A ring added to a packing set to assist in the introduction of a flush fluid to the stuffing box. This ring is usually made of plastic or metal.

LATTICE BRAID® – A Garlock trade name for a type of braided construction. In this method, the yarn is braided in an interlocking weave, making it very difficult to unravel. This construction yields a dense, tightly woven packing material having a square cross-section. Other packing manufacturers have different names for this braiding method.

LIP DIAMETER – The inner diameter of the seal lip, measured with the spring installed.

LIP HEIGHT – The axial distance from the outside seal face to the toe face.

Lip Packing & Rings – Could be the description of a u-cup or of an oil seals. A seal with a lip design to provide sealing.

LIP SEAL – Lip seals have a pronounced lip-type design and rely on this lip surface to provide a seal under pressure. Also known as pressure activated.

LUBRICATION – The use of a liquid or fluid to reduce the friction, heat or wear between two surfaces where movement is taking place.

MANUFACTURED FLANGE TO FLANGE DIMENSION – The manufactured width of the joint measured from the joint flange face to flange face.

MATTE FINISH – A more uniform surface finish imparted to the sheet surface by temper rolling with shot-blasted rolls.

MECHANICAL FITTING/REUSABLE FITTING – A fitting attached to a hose, which can be disassembled and used again.

MECHANICAL PROPERTIES – The properties of a material that reveal its elastic and inelastic behavior when force is applied, thereby indicating its suitability for mechanical applications.

MEDIA – The fluid which is being sealed.

MENDER – A fitting or device used to join two sections of hose.

MISALIGNMENT – The out-of-line condition that exists between the adjacent face of the equipment/system flanges.

MODULUS – In the physical testing of rubber, the pressure in pounds per square inch or Newtons per square meter of initial square cross-sectional area necessary to produce a stated percentage of elongation, compression or shear. Directly related to the stiffness of the material.

MOLDED TYPE EXPANSION JOINT – An expansion joint in which the entire wall of the joint is molded into a ÒUÓ or convoluted configuration. The joint is manufactured by a molding process. MOVEMENTS – The dimensional changes which the expansion joint is required to absorb, such as those resulting from thermal expansion or contraction.

NEOPRENE – Synthetic rubber made by polymerizing 2-chlor-1, 3-butadiene. Neoprene compounds are rioted for their resistance to oil, sunlight and ozone. There are various types, most of which are vulcanizable without the use or sulfur. Neoprene is resistant to ammonia, freon, oxygen, ozone and many other fluids. An excellent material for use in pump and refrigeration applications. Neoprene is a synthetic rubber used to manufacture gaskets. Neoprene gaskets are commonly used for exposed environment applications, such as those involving sea water. Nipple – The internal member or portion of a hose fitting.

NITRILE – Nitrile is a synthetic rubber used to manufacture gaskets. Nitrile gaskets are commonly used for applications involving oils and fuels.

NITRILE RUBBER – A generic term comprising the various copolymers of butadiene and acrylonitrile. The copolymers vary essentially in butadiene-acrylonitrile ratios, Mooney values and staining properties. They are resistant to solvents, oils, and greases and to bent and abrasion. Some trade names are Chemigum, Krynac, Nipol, Hycar, and Paracril. The Germans first produced the nitrile rubbers and called them Buna N and Perbunan.

NON-ASBESTOS – Non-asbestos materials replace asbestos gasket materials. These materials typically have a kevlar, glass, or carbon base, and are otherwise known as compressed fibre gasket materials.

NON-METALLIC EXPANSION JOINT– Expansion joint which utilizes flexible non-metallic material to accommodate joint movements.

NOZZLE END – An end of hose in which both the inside and outside diameters are reduced.

NPT/NPTF – abbreviation for national pipe threads. See fitting/coupling -Pipe Thread Fittings.

O.D. – Outside diameter measured at tangency between bottom radius (R1) and side.

OAL – Overall length.

OD – An abbreviation for “Outside Diameter”, used to denote the outside dimension of a packing set (usually equal to the stuffing box bore).

OE/OEM – Original equipment manufacturer.

OEM – Abbreviation for “Original Equipment Manufacturer”.

OIL SEAL – A seal designed primarily for the retention of oil.

OIL SEALS – Also called grease seals, rotary seals or shaft seals. Made of rubber to seal grease in housing with a rotating shaft.

OIL SWELL – The change in volume of a gasketing product resulting from contact with oil.

OMNI-DIRECTIONAL STRENGTH – Strength in all directions.

OPEN CELL – A cell not totally enclosed by its walls and hence interconnecting with other cells.

OPERATING CONDITIONS – The pressure, temperature, motion, and environment to which a hose assembly is subjected.

O-RING – An elastomeric seal of homogeneous composition molded in one piece to the configuration of a torus with circular cross section; more simply, a round ring with a round cross section. O-rings – O-ring seals are circular rings of various cross-sectional configurations installed in a gland to close off a passageway and prevent escape or loss of a fluid or gas. An oring is specified by three of its features: its dimensions, material, and hardness. Material and hardness specify the elastomeric compound and Shore A (durometer) hardness of the compound that is used to manufacture the o-ring. An O-ring’s dimensions are described by stating its inside diameter (I.D.) and its cross-section. Designing for o-rings depends on three major and interrelated variables: the operating conditions or environment the seal will experience, the gland geometry into which the seal will be installed and the three variables account for the fact that there are so many different types of seals and applications.

OS& D HOSE – The abbreviation for oil suction and discharge hose.

OVERALL LENGTH (OAL) – The total length of a hose assembly, which consists of the free hose length plus the length of the coupling(s).

OZONE CRACKING – Surface cracking or cracks caused by exposure to an atmosphere containing ozone.

P X T VALUE – A numerical value resulting from the multiplication of the internal pressure and the temperature of the fluid involved. In English system, usually psi x °F = PTValue.

PACKAGING – A unit that provides protection and containment of items plus ease of handling by manual or mechanical means.

PACKING – An adjustable sealing device on a ram, valve stem or pump shaft — old technology and leakage is required for lubrication. If packing leaks, it is simply tightened slightly to ‘control’ the leakage. For pumps and valves, packings can be rope-like, braided into continuous lengths and then cut to size to fit a shaft. For hydraulic applications, v-shaped fabric reinforced rubber rings are used. Early hydraulic packings were made from leather. For a rubber o-ring, that particular item can be found called a seal, a gasket and a packing ring – even in U.S. government technical specifications dating back 50 years.

PACKING GLAND – The space into which a compression packing is inserted. Also known as a Stuffing Box.

PACKING GROOVE – A groove machined into a flange or joint to accommodate a packing ring.

PACKING HOOK – A tool, similar to a corkscrew, for removing packing from a stuffing box.

PACKING SPACE – The distance between the shaft or stem surface and the bore of a stuffing box. Packing space (x) can be calculated by the following equation: x = (OD-ID)/2. Pads – A rubber part used as an anti-vibration device.

PAPER FINISH – Finish resulting from vulcanizing in contact with paper.

PAPER – Gasket paper, otherwise known as cellulose paper or oil paper jointing, is a paper impregnated with chemicals to make it resistant to oils, fuels, and solvents.

PERMEANT FITTING  – The type of fitting which, once installed, may not be removed for reuse.

PERMANENT SET– The degree to which an elastic material fails to return to its initial form after deformation.

PERMEABILITY – To permit passage of gas through the molecular structure of a given material.  The quality or condition of allowing passage of fluid/gases/air through a material such as rubber.

PH – The measure of the strength of an acid or base. On the pH scale, a neutral solution (neither acidic or basic) has a pH of 7. Solutions with a pH below 7 are acidic; the smaller the pH value, the more acidic the solution. Solutions with a pH above 7 are basic.

PLASTICIZER – A compounding ingredient which can change the hardness, flexibility or plasticity of an elastomer.

PLATE FINISH – A commercially smooth surface, resulting from vulcanization between press plates (platens).

PNEUMATIC SEAL – An extruded or molded elastomeric seal designed to expand and retract to provide a secure, reliable seal that can hold, position, or handle objects in a wide range of applications.

PNEUMATIC SEALS – Any seal or packing ring, usually flexible rubber, used to seal against compressed air instead of hydraulic fluid or other liquid.

POLYMYTE – An elastoplastic material with exceptionally high tear strength. Its high durometer makes it suitable for applications where extrusion is a problem. Polymyte can be used with petroleum based fluids, water based fluids, phosphate ester fluids, some chlorinated fluids and many solvents.

POLYURETHANE – (Aka Hythane, Garthane) makes an excellent choice for hydraulic systems due to its good temperature range and high abrasion resistance. Urethanes are highly resistant to petroleum oils, hydrocarbon fuels, oxygen, ozone, and weathering.  A synthetic elastomeric material made by chemically reacting a polyol and a diisocyanate in such a manner that a high molecular weight polymer is formed.

PRE-COMPRESSION – Compression of the expansion joint during installation (shortening the F/F) so that in the cold position the joint has a given amount of compression in addition to the rated amount of compression. The purpose of pre-compression is to allow for unexpected or additional axial extension.

PRESS CURE – A method of vulcanizing rubber by the use of heated platens, which can be brought together and separated by hydraulic pressure or mechanical action, to cure rubber sheet under pressure.

PRESSURE ABSOLUTE – The pressure above zero absolute. (i.e the sum of atmospheric and gage pressure).

PRESSURE – Force per unit area, usually expressed in pounds per square inch (PSI) or kilograms per square centimeter.

PRESSURE RATING – The pressure the material can seal against.

PRESSURE, GAUGE (PSIG) – Pressure differential above or below atmospheric pressure, expressed as lbs./ or psig.

PRIMARY LIP – The normally flexible elastomeric component of a lip seal assembly, which rides against the rotating surface and affects the seal.

PSI – Abbreviation for “Pounds per Square Inch”, a unit of pressure. PSI: pounds per square inch.

PTFE – Abbreviation for Polytetrafluoroethylene, a polymer having excellent chemical resistance. PTFE dispersion is used as a coating for many styles of packing. Some packing styles are constructed of PTFE fibers. Teflon® is DuPont’s trade name for their PTFE materials. PTFE is a plastic used for making gaskets. PTFE is extremely chemically inert, and as such is resistant to chemicals and corrosives. PTFE also has a low co-efficient friction. A high molecular weight fiuoroplastic polymer with carbon atoms shielded by fluorine atoms having very strong inter atomic bonds, giving it chemical inertness.

PVC – Polyvinyl chloride. A low cost thermoplastic material typically used in the manufacture of industrial hoses. The operating temperature range is -500°F to +1750°F (-295.5°C to +954.4°C).

RADIAL LIP SEAL– A type of seal which features a flexible sealing member referred to as a lip. The lip is usually of an elastomeric material. It exerts radial sealing pressure on a mating shaft in order to retain fluids and/or exclude foreign matter.

RADIAL LOAD – The total force (load) acting on the seal lip which tends to maintain contact of the lip on the shaft. It is the sum of the forces developed from seal interference and the garter spring.

RADIUS CORNERS  – Rounded corners. Measurement from the center of a diameter to its circumference.

RAISED FACE JOINT – A raised face joint, otherwise known as an I.B.C. (inner bolt circle) gasket, is a ring that sits within the diameter of the bolts holding the flanges together. It is contrasted with a full faced (F.F.) gasket which covers the face of the flange and has bolt holes.

RECOVERY (GASKETING) – The increase in thickness of a gasket after a load is removed.

RECOVERY – The degree to which a product returns to its normal dimensions or shape after being distorted.

REGULAR BRAID – A type of braided construction which yields a soft, flexible packing material having a square cross-section. Also referred to as “Square Braid”.

REINFORCEMENT – The strengthening members, consisting of either fabric, cord, and/or metal, of a hose.

RESILIENCE – The ratio of energy given up by the elastomer upon releasing it from a definite deformation to the energy required to produce the deformation. Unless the deforming is momentary, the result obtained will be complicated by the partially plastic nature of the elastomer.

RESILIENT – Able to recover rapidly, i.e. elastic.

RETAINING RINGS – Segmented metal rings installed directly against the back of the expansion joint flange and bolted through to the metal flange of the pipe.

RIMSEAL – A sealing device used on the rim of round plate or rim of a wheel.

RING JOINT/RING TYPE JOINT (R.T.J) – Is a metal ring of oval or octagonal section, usually made of soft iron or stainless steel.

ROD SEALS – Any seal used on the rod of a hydraulic or pneumatic cylinder made from rubber or plastic.

ROLL– Sheet rubber and gasketing material of a uniform width rolled up on itself from which gaskets and other products of various shapes may be cut.

ROTATION (FLANGE) – The warping, bowing or bending of a flange that can occur from too much bolt load.

ROUND BRAID – A braiding method that yields a hollow tube of yarn. See also “Braid Over Braid” and “Braid Over Core”.

RPM – An abbreviation for “Revolutions Per Minute”, a measurement of the rotary speed of a rotating shaft.

RUBBER – A material that is capable of recovering from large deformations quickly and forcibly, and can be, or already is, modified to a state in which it is essentially insoluble (but can swell) in boiling solvent, such as benzene, methyl ethyl ketone, and ethanol-toluene azeotrope. A rubber in its modified state, free of diluents, retracts within 1 minute to less than 1.5 times its original length after being stretched at room temperature (18 to 29oC) twice its length and held for 1 minute before release.

SEAL – An elastomeric ring-shaped component used in a constantly moving, dynamic application – either reciprocating or rotating shaft – providing a near positive no leak mode in a hydraulic cylinder, ram, mixer or gear box – as examples. (Note: no sealing device is absolutely 100% positive). Seal rings can be u-shaped, v-shaped, o-shaped, metal inserted, radial lipped, multiple lipped or a simple flat ring. Any device designed to prevent or control the movement of fluid from one chamber to another to exclude contaminants.

SEAL ASSEMBLY – A group of parts, which includes sealing surfaces, provisions for initial loading, and a secondary sealing mechanism which accommodates the radial movement necessary for installation and operation.

SEAL GASKET– A gasket that is placed between two adjacent metal parts to make a gas tight connection.

SEAL KITS – Any group of seals, o-rings, wiper rings and back-up rings used to repair a specific hydraulic cylinder.

SEAL OUTER DIAMETER – The external diameter of a lip-seal assembly, which normally corresponds to the outer diameter of the outer seal case.

SEAL SOLUTION – Any gasket or seal, which, when properly installed, prevents the escape of matter.

SEALABILITY – The measure of fluid leakage both through and across both faces of a gasket. Measured either by using ASTM F-37 or DIN 3535 equipment and procedures.

SEATING LOAD – The load required to properly compress a seal. This will vary depending on the size and shape of the seal. (This does not include operating hydro end forces.)

SELF-ENERGIZING O-RING – O-ring with a hole drilled on the pressure side, allowing pressure to equalize inside the O-ring; prevents collapse of the ring.

SHANK – That portion of a fitting, which is inserted into the bore of a hose.

SHEET MATERIALS – Rubber or fibrous material used to make gaskets.

SHEETER – The special calendar used to make compressed sheet.

SHELF LIFE – The length of time a product can be stored, under specific conditions, before the product expires. Each product varies depending on the material, adhesive, and printing process (check with Production for specifics).

SHELF/STORAGE LIFE – The period of time prior to use during which a product retains its intended performance capability.

SHIMS – Flat, thin metal gasket-like parts used as spacers to position machinery or align equipment.

SILICONE ADHESIVE – Adhesives made from silicone polymers that have excellent high temperature resistance. Silicone compounds are generally not recommended for dynamic sealing applications due to poor tensile strength and abrasion resistance. Silicone does exhibit excellent resistance to extreme temperature and is an acceptable FDA material. Typical use for silicone is in dry heat applications and food processing applications.

SILICONE – Silicone is a synthetic rubber used to manufacture gaskets. Silicone can withstand 200°C, and is chemically inert, which gives it application in the food processing industry. SINGLE-END COATING- The process of applying a coating to the individual yarns (or “ends”) of a packing before they are braided. This process results in a very thorough, uniform coating throughout the braid.

SIZE, ACTUAL– Actual dimensions of the part, including tolerance limits.

SIZE, NOMINAL– Approximate size of part in fractional dimensions.

SKIM COAT– A layer of rubber laid on a fabric but not forced into the weave. Normally laid on frictioned fabric.

SKIVE – The process of slicing or veneering off a sheet of PTFE from a billet.

SLEEVE – A metal cylinder that is placed over a pump shaft in the sealing area. In pumping applications, certain media and packing materials can cause abrasive wear on the rotating surface. A sleeve is a relatively inexpensive, replaceable component which protects the pump shaft from wear. Sleeve: a metal cylinder, which is not physically attached to the fitting, for the purpose of forcing the hose into the serrations of the fitting.

SLURRY – A fluid mixed with solid particles. In packing applications handling slurries, abrasion is a major concern. Steps must be taken to minimize abrasive wear of the packing materials. Spacers – A ring with flat sides to provide specific dimensional spacing between two components.

SPECIFIC CONTACT PRESSURE – Seating load divided by seal contact area.

SPECIFICATIONS (SPECS) – The details of a part: dimensions, material call outs, type style, size information, etc.

SPIRAL WOUND GASKETS (S.W.G) – Spiral wound gaskets are made of a metal coil, or winding, with a material filler. Spiral wounds allow for a higher bolt loading of the pipe flanges. Spiral wounds can withstand very high pressures.

SPIRAL – A method of applying reinforcement in which there is not interlacing between individual strands of the reinforcement.

SPLICE – A joint or junction made by lapping or butting edges, straight or on a bias, and held together through vulcanization or mechanical means. A fitting or device used to join two sections of hose.

SPLICES – Procedure for making endless boot or bellows from open-ended material. Splicing may be accomplished by one or more of the following: cementing, bonding, heat sealing, stitching, vulcanizing, or mechanical fasteners.

SPONGE RUBBER – Cellular structure produced by adding gasifying substance to rubber compound, expanding and curing in heated mold. Cells may be open (interconnecting) or closed.

SPOOL PACKING – Packing material that is braided and sold on a spool, as opposed to cut-ring sets or die-formed ring sets.

SQUARE BRAID – A type of braiding construction that yields a soft, flexible packing material having a square cross-section. Also referred to as “Regular Braid”.

SQUEEZE SEAL – Also known as “Installation Activated”, a squeeze seal relies on the squeeze or compression it achieves at installation to create a seal. This squeeze or compression is due to its high degree of interference. This type of seal generally seals well at low pressure; however, in dynamic applications, it is characterized by a high wear rate and friction.

STACK HEIGHT – 1) The combined height of all the rings of a packing set. 2) The combined height of all the components in a stack of Belleville washers used to live-load a packing set.

STAINLESS STEEL (S.S.) – Stainless steel is a steel alloy resistant to corrosion.

STATE OF CURE – The cure condition of vulcanization relative to that at which optimum physical properties are obtained.

STATIC SEAL – A seal whose sealing surface sees no motion-the opposite of dynamic seal.

STEM PACKING – A type of homogeneous or multi-braided packing used on the stem of a valve to stop leakage.

STRONG OXIDIZER – In packing applications, strong oxidizers cause the degradation of organic packing materials such as carbon, graphite and cellulosic fibers. PTFE packing materials are usually used in these applications due to their oxidation resistance.

STUFFING BOX – The space into which compression packing is inserted. Also known as a “Packing Gland”.

SW – A Garlock Metallic Gasket style consisting of a winding alone, without a centering ring.

SWI – A Garlock Metallic Gasket style consisting of a winding and an inner ring.

SYMMETRICAL SEALS – A seal that has the same shape on either side of its center line.

TEFLON – (aka PTFE, TFE) can be used in applications with extreme temperatures, extreme pressures and extreme chemicals. Since Teflon has a tendency to cold flow and has no memory, it is often filled with other materials (glass, bronze, and nickel) before it is used to make piston seals, rod seals and wipers.

TENSILE STRENGTH – The amount of tensile stress that causes a specimen to rupture; measured in psi.

TEXTURIZATION – The process of embossing a texture on the surface of graphite foil to achieve better adhesion between layers of graphite foil, and prevent delamination of a die-formed graphite ring.

TFE – Polytetrafluoroethylene. See PTFE.

THERMAL BARRIER – A layer of insulating material designed to reduce the surface temperature at the gas sealing layer to a level compatible with its heat resistance capability.

THERMAL CONDUCTIVITY – A measure of the rate at which thermal energy is transferred through a substance. High thermal conductivity is an advantage in pump packing applications where it is important to transfer frictional heat away from the shaft/ packing interface so that the packing does not burn.

THERMAL EXPANSION – The increase in volume or length of a material that occurs as a result of a temperature increase.

TINSEL– Fine slit widths of metallic foil. Die-formed rings are made from tinsel and used as junk rings, bushings, and in some cases even as bearings. Garlock manufactures rings made from copper tinsels.

TOLERANCE – The upper and lower limits between which a dimension must be held.

TORQUE – Informal Definition: A measure of “twisting force”. In packing applications, one might be concerned with the torque applied to the gland stud nut, or the torque required to overcome friction between the packing and the valve stem.

TUBING – A non-reinforced, homogeneous conduit, generally of circular cross-section.

U-CUP – A type of seal used in a hydraulic or pneumatic cylinder. It’s cross section is U-shaped to allow oil to energize the seal body to properly block oils and seal correctly.

U-CUPS – A “U” shape cup sealing ring designed to seal in one direction along a shaft or rod in a hydraulic or pneumatic cylinder.

ULTIMATE ELONGATION – The maximum elongation prior to rupture.

UNCOMPRESSED HEIGHT– The height of a packing set or packing ring before being compressed in the stuffing box.

U-PACKINGS – A “U” shape cup sealing ring designed to seal in one direction along a shaft or rod in a hydraulic or pneumatic cylinder.

U-SEALS – A packing in which the element has a “U”-shaped cross-section.

VACUUM – Negative pressure, when a gasket or seal is used to prevent the passage of external media or air into the system.

VALVE PACKING – Braided packing used in the stuffing box of a valve stem to make a positive seal.

VALVE STEM PACKING – Braided packing used in the stuffing box of a valve stem to make a positive seal.

VEE PACKING – Also called V-Packing, Vee packing, Chevron Packing, Parachute packing or v-set packing. A complete vee packing set contains multiple “V” shaped sealing rings stacked and nested together with a male adapter on one end and a female adapter on the other end.

VITON – Viton is a synthetic rubber used to manufacture gaskets. Viton can withstand temperatures up to 250°C, and is a very inert but expensive rubber. Viton gaskets are typically used in extreme environments, in the presence of acids and corrosives.

V-PACKING – Also known as Vee Packing, Vee Sets, Chevron Packing, and Parachute Packing. A multiple ring set of packings whose center rings or sealing rings are V-shaped to form sealing lips. The V-rings stack on top of each other and have a male and female adaptor on each end to make the set flat. This packing type is adjustable.

V-RINGS – Also called V-Packing, Vee packing, Chevron Packing, Parachute packing or v-set packing. A complete vee packing set contains multiple “V” shaped sealing rings stacked and nested together with a male adapter on one end and a female adapter on the other end.

VULCANIZING AGENT – Any material which can produce in rubber the change in physical properties known as vulcanization, such as sulfur, polysulfides, organic polynitro derivatives, peroxides arid quinone dioximes.

VULCANIZATION – An irreversible process during which a rubber compound through a change in its chemical structure (for example, cross-linking) becomes less plastic and more resistant to swelling by organic liquids and elastic properties are conferred, improved, or extended over a greater range of temperature.

VULCANIZED SPLICE – A splice that is bonded with heat and pressure.

WASHERS – Round, flat rings used as spacers, gaskets or slip devices under the head of a bolt.

WEAR RINGS – Wear rings, guide rings, guiding rings, bearing rings for hydraulic cylinder rods.

WEAR SLEEVE – A replaceable metal ring generally used in assemblies to eliminate expensive shaft replacement caused by grooving that may occur at the seal-shaft interface.

WEAR SLEEVES – Wear rings, guide rings, guiding rings, bearing rings for hydraulic cylinder rods.

WEAR STRIPS – Strips of abrasion resistant plastic, PTFE or PTFE material – Wear rings, guide rings, guiding rings, bearing rings for hydraulic cylinder rods.

WEATHERING – The surface deterioration of a rubber article during outdoor exposure, such as cracking, crazing, or chalking.

WEEPAGE – A minute amount of liquid leakage by a seal.

WELDING BLANKET – A fire resistant blanket that is placed over the expansion joint to protect it from weld splatter during field welding operation.

WICKING – Leakage through a gasket, not around it.

WIPER RING – A ring of braided packing, used in conjunction with graphite foil rings to wipe a reciprocating valve stem clean of graphite particles and keep the graphite contained in the stuffing box.

Wiper Rings – A ring which rides tight against a rod, with a sharp lip to scrape or wipe off excess oil, dirt or dust in a hydraulic or pneumatic cylinder.

WIRE REINFORCED – A hose containing wires to give added strength, increased dimensional stability; crush resistance.

WORK PRESSURE – The maximum operating pressure encountered during normal service.

YARN – Generic term for continuous strands of textile fibers or filaments in a form suitable for weaving or otherwise intertwining to form a textile fabric.

YIELD STRENGTH – The amount of stress which causes a material to permanently lose its elasticity.

YIELD – The length of a packing material of a specified weight (Ft/ Lb). The inverse of this value (Lb/Ft) is also sometimes referred to as yield.