NCCER Insulator flashcards
NCCER Insulator · Build recall with a focused review session.
33 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Thermal conductivity (k)
- A material property describing heat flow through a unit thickness per unit area per degree of temperature difference, expressed in Btu·in/(h·ft²·°F); lower values indicate better insulation.
- Thermal resistance (R)
- The resistance of a material to heat flow, calculated as thickness divided by thermal conductivity; higher R means better insulating performance for a given thickness.
- Cylindrical heat loss formula
- For a pipe, heat loss is Q = 2πkL(T_hot − T_cold) ÷ ln(r2/r1); this accounts for the increasing surface area as radius grows outward.
- Mineral wool service limit
- Mineral wool insulation is commonly rated to about 1200°F, with some high-temperature grades rated to 1900°F; exceeding the rated limit degrades the binder and reduces performance.
- Cellular glass service limit
- Cellular glass is a closed-cell rigid insulation commonly rated to about 800°F; it resists moisture but is brittle and must not be compressed or struck during installation.
- Calcium silicate insulation
- A rigid, high-temperature insulation commonly rated to about 1200°F, used on steam and process piping; it is cut with a handsaw and installed without compression.
- Polyisocyanurate limit
- A closed-cell foam insulation commonly rated to about 300°F; above that temperature the cell structure and facer degrade, so it is used on chilled and low-temperature service.
- Elastomeric foam limit
- A flexible closed-cell insulation commonly rated to about 250°F, used on chilled water and refrigerant lines; it is installed with adhesive-sealed seams to form a vapor retarder.
- Vapor retarder placement
- The vapor retarder is placed on the warm side of the insulation in above-ambient service and on the outer jacket in below-ambient service, with sealed laps to block moisture migration.
- Insulation cutting tools
- Mineral wool and fiberglass are cut with a serrated insulation knife or saw; rigid products such as calcium silicate and cellular glass are cut with a handsaw and are not compressed.
- Banding spacing
- Insulation is secured with banding or wire commonly spaced 9 to 12 inches on horizontal runs, with closer spacing near fittings and terminations to prevent sagging.
- Weatherproof jacketing
- Aluminum, stainless, or coated steel jacketing protects insulation from weather and mechanical damage; laps shed water downward, and expansion allowance is left at each end.
- Insulation PPE
- Safety glasses, cut-resistant gloves, long sleeves, and respiratory protection when cutting mineral wool or removing old insulation reduce eye, skin, and inhalation hazards.
- Closed-cell vs open-cell
- Closed-cell insulation traps gas in sealed cells, blocking convection and moisture; open-cell insulation allows air and water vapor to move through, so it needs a separate vapor retarder.
- Mean temperature effect on k
- Thermal conductivity rises with temperature for most insulation, so thickness is selected using the mean temperature of the insulation, not the pipe or ambient temperature alone.
- Insulation thickness selection
- Thickness is chosen so that surface temperature, heat loss, or condensation control meets the specification at design conditions; it is not chosen by a single fixed rule.
- Heat loss calculation Q
- For a pipe, Q = 2πkL(T_hot − T_cold) ÷ ln(r2/r1); this is the basis for checking whether installed thickness meets a specified heat-loss limit.
- Surface temperature verification
- Surface temperature is checked with a calibrated contact or infrared thermometer; infrared readings need emissivity correction, and a low-emissivity jacket can read colder than the true surface.
- Dew point check
- Condensation control is verified by confirming the jacket surface stays above the dew point of surrounding air at design temperature and humidity; a reading below dew point indicates insufficient thickness.
- Economic thickness
- The thickness at which installed insulation cost plus the present value of energy loss is minimized; beyond this point, added thickness costs more than the energy it saves.
- ASTM C680
- A standard practice for estimating heat loss or gain from insulated pipe and equipment surfaces; field measurements are compared against values calculated by this method.
- ASTM C335
- A standard test method for steady-state heat transfer properties of horizontal pipe insulation; results are used to compare products and to support heat-loss calculations.
- Thermal imaging survey
- An infrared survey reveals missing insulation, gaps at fittings, and wet insulation; wet sections appear as hot or cold anomalies because water sharply raises conductivity.
- Wet insulation handling
- Wet insulation must be removed and replaced, not dried in place, because moisture raises conductivity, promotes corrosion under insulation, and can freeze in below-ambient service.
- Acceptance criteria
- Performance is accepted when measured or calculated values meet the specification's maximum heat loss per linear foot, maximum surface temperature, or minimum R-value.
- Corrosion under insulation
- Moisture trapped against carbon steel by a breached vapor retarder causes corrosion under insulation; inspection includes checking for jacket breaches and moisture in the insulation.
- Emissivity correction
- Infrared thermometers assume a surface emissivity; shiny metal jacketing has low emissivity, so uncorrected readings can be significantly lower than the true surface temperature.
- Jacket breach inspection
- Visual inspection looks for open seams, dents, and failed sealant in the jacket; any breach in below-ambient service allows moisture entry and must be repaired.
- Heat loss per linear foot
- A specification limit stating the maximum allowable heat loss for each foot of insulated pipe at design conditions; calculated or measured loss is compared against this limit.
- Insulation effectiveness check
- Effectiveness compares actual heat loss with the bare-pipe heat loss; a well-insulated line shows a large reduction, and a small reduction signals missing or wet insulation.
- Design conditions
- The specified operating temperature, ambient temperature, humidity, and wind speed used for thickness selection and performance verification; field results are compared against these values.
- Jacketing expansion allowance
- Metal jacketing is installed with allowance for thermal expansion at each end so it does not buckle or crush the insulation as the pipe heats and cools.
- Fitting insulation verification
- Fittings, valves, and flanges are common heat-loss and condensation points; inspection confirms that removable covers or fitted insulation are in place and properly sealed.