Glossary of Terms
Every industry has its own technical terminology. Browse our comprehensive guide to common FRP, composite, and nonmetallic engineering terms.
Anisotropic
Having different physical properties in different directions. FRP laminates are anisotropic materials because their strength properties vary depending on the orientation of the glass fibers.
Acoustic Emission (AE) Testing
A non-destructive testing (NDT) method that detects high-frequency sound waves emitted by micro-cracking or fiber breakage in composite structures under stress.
ASME RTP-1
American Society of Mechanical Engineers standard for Reinforced Thermoset Plastic Corrosion-Resistant Equipment, governing vessel design, fabrication, inspection, and testing.
ASME Section X
ASME Boiler and Pressure Vessel Code rules governing Fiber-Reinforced Plastic Pressure Vessels.
Barcol Hardness
A measure of surface hardness obtained with a Barcol Impresser (typically Model 934-1), used to evaluate resin cure and polymer cross-linking density.
Biaxial Winding
A filament winding process where continuous glass strands are wound at opposing angle pairs (e.g. ±55°) to optimize hoop and axial tensile strength.
Bonding / Secondary Joint
The structural connection of prefabricated FRP pipe or vessel sections using manual resin-impregnated glass tape overlays.
Chemical Barrier (Corrosion Barrier)
The inner layer of an FRP laminate (typically 100 to 110 mils thick) designed to withstand corrosive process media, usually composed of a synthetic veil and high-resin layers.
Chopped Strand Mat (CSM)
A non-woven reinforcement fabric consisting of randomly oriented cut glass fibers held together by a binder, used for corrosion barriers and structural laminates.
Composite Material
A material formed by combining two or more distinct constituents—such as glass reinforcement and polymer matrix—to achieve superior mechanical and chemical properties.
Cure
The chemical reaction (polymerization) during which a thermosetting resin transitions from a liquid state into a solid, cross-linked matrix.
Delamination
The separation of adjacent layers or plies in a composite laminate, often caused by resin starvation, impact, or interlaminar shear stress.
Dual Laminate
A composite structure consisting of a thermoplastic liner (e.g. PVC, CPVC, PP, PVDF, E-CTFE, PFA) mechanically or chemically bonded to an FRP structural outer shell.
E-CR Glass
An Electrical/Corrosion Resistance glass fiber formulation engineered without boron or fluorine to provide enhanced acid corrosion resistance.
Epoxy Resin
A thermosetting polymer resin characterized by high mechanical strength, excellent adhesion, and low shrinkage, widely used in high-performance piping.
Exotherm
The heat generated during the chemical cross-linking reaction of thermosetting resins during curing.
Filament Winding
An automated fabrication process where continuous resin-impregnated fiber strands are wound around a rotating mandrel under controlled tension.
Finite Element Analysis (FEA)
A computational engineering technique used to model complex stress distributions, thermal expansion, and mechanical deformation in FRP vessels and piping.
Fitness-For-Service (FFS)
A quantitative engineering assessment to determine whether in-service damaged or aged nonmetallic equipment can continue operating safely.
FRP (Fiberglass Reinforced Plastic)
A composite material consisting of a thermosetting polymer resin matrix reinforced with glass fibers.
Glass Content
The percentage of glass reinforcement by weight or volume in a finished composite laminate, determined via burn-off testing (ASTM D2584).
Hand Lay-Up
A manual fabrication method where layers of glass reinforcement are placed on a mold and impregnated with liquid resin using hand rollers.
HDT (Heat Deflection Temperature)
The temperature at which a polymer sample deforms under a specified flexural load, indicating thermal stability bounds.
Hydrostatic Testing
A pressure test performed using water or liquid media to verify the structural integrity and leak-tightness of piping and pressure equipment.
Interlaminar Shear Strength
The resistance of a composite laminate to internal sliding forces parallel to the fiber plies.
Isophthalic Polyester
A thermoset polyester resin offering good general corrosion resistance and mechanical toughness for industrial FRP applications.
NACE / AMPP
Association for Materials Protection and Performance (formerly NACE International), developing global corrosion control standards.
NDT (Non-Destructive Testing)
Inspection techniques—such as acoustic emission, ultrasonic thickness measurement, and Barcol testing—that evaluate material integrity without causing damage.
PE (Polyethylene / HDPE)
A tough, lightweight thermoplastic polymer commonly used for chemical distribution and water piping systems.
PP (Polypropylene)
A versatile thermoplastic polymer with high chemical resistance and elevated temperature performance up to 180°F (82°C).
PVDF (Polyvinylidene Fluoride)
A high-purity fluoropolymer liner material providing exceptional resistance to strong acids, halogens, and aggressive organic solvents.
Resin Starvation
A laminate defect where insufficient resin is present to fully saturate and encapsulate glass fibers, leading to void formation and dry spots.
Roving
A collection of continuous glass fiber strands gathered without twisting, supplied on spools for filament winding or pultrusion.
Structural Laminate
The outer structural portion of an FRP pipe or tank wall engineered specifically to resist internal pressure, vacuum, wind, and seismic loads.
Thermoplastic
A polymer material that becomes pliable and moldable above a specific temperature and solidifies upon cooling, capable of heat welding.
Thermoset
A polymer resin that permanently cures through irreversible chemical cross-linking, providing high thermal and dimensional stability.
Veil (Surface Veil)
A thin, resin-rich non-woven fabric (synthetic or glass) placed on the outermost wetted surface of an FRP corrosion barrier to prevent fiber exposure.
Vinyl Ester Resin
A high-performance thermoset resin combining the chemical resistance of epoxy with the rapid cure and ease of processing of polyester resins.
Viscosity
A fluid's resistance to flow, critical during resin formulation to ensure proper glass fiber wet-out without sagging.
Void
Air or gas bubbles entrapped within an FRP laminate during fabrication that weaken mechanical properties and compromise corrosion resistance.