Insulation True and False Flashcards
The ultimate cost of insulation should be the only design consideration factor.`
false
A good-quality vapor barrier is guaranteed to exclude water vapor entirely.
false
Most thermal insulating materials have a higher thermal expansion coefficient than metals.
false
The provision of air spaces for thermal insulation purposes is recommended.
false
When fluids are static in pipes or vessels and the ambient temperate is below the freezing point of the contained fluid, there is no way to prevent freezing.
false
If a cold surface is at a temperature lower than the freezing point, moisture will freeze and tend to rupture and break away the insulation.
true
An increase in the amount of insulation applied will raise the rate of heat loss through the insulation and raise the total cost during the life of the product.
false
The required life of the insulation system shall be considered because this affects the annual cost and hence the economic thickness.
true
Aerogels pose no chemical threat to the environment.
true
Dense brick has a relatively low conductivity.
false
The manufacturer’s declared value of thermal conductivity is only appropriate to the temperature of use.
false
If conservation of heat or power is the deciding factor, the cost savings per year is the most important factor, compared to installed cost.
true
The ability of air to hold water in the vapor phase is reduced as the temperature decreases.
true
The main advantage of molded insulation is the ease of application and replacement when undertaking repairs for damaged lagging.
true
Loosefill material and unbonded mattresses are liable to compact under the influence of vibration and thermal cycling.
true
Goals in thermal science are to minimize capital and operation costs as well as heat loss.
true
For any given heat loss, a material of low thermal conductivity will be thicker than an alternative material of high conductivity.
false
Low bulk density is normally associated with low thermal conductivity in the low and medium temperature ranges.
true
Thinner layers of insulation increase the surface area emitting heat and also increase the outer surface that will require protection.
false
Difficult or unusual site conditions will influence the selection or application of insulating materials.
true
Internal condensation and ice formation will appreciably increase the effectiveness of the thermal insulating material.
false
The main purpose of insulation is to limit the transfer of energy between the inside and outside of a system.
true
Aerogels have the highest thermal conductivity of any material used for cryogenic service.
false
Thinness creates more space in and around pipe racks and equipment.
true
Due to the difference in expansion coefficients of metals and insulating materials, it is necessary to make allowance for the differential movements between the hot surface, the insulant, and the finish.
true
Before any stripping work is carried out, it is necessary to determine what type of insulating material is involved.
true
Insulation materials can be classified into organic and inorganic types.
true
An air space is much more effective for thermal insulation purposes than a space of similar dimensions filled with one of the convectional insulating materials.
false
Epoxy and polyester resins give good resistance against mechanical damage, together with protection against the weather and against chemical spillage.
true
Care needs to be taken to ensure that vapor barrier does not add seriously to the fire hazard of a complete system.
true
Low-temperature insulators are used in low-temperature heating and steam equipment, steam lines, flue ducts, etc.
false
Aerogel insulation systems will not break during shipment.
true
Normally, the theoretical heat loss will be based on the manufacturer’s declared value of thermal conductivity and, unless otherwise stated, it will refer to conditions of ambient still air at 20° C (68° F).
true
Thermal conductivity is always specified at real-time temperature of the insulation material.
false
There are two basic types of monolithic lining: castable refractory and plastic refractory.
true
For materials to be used at elevated temperatures, it will be necessary to consider the many factors that may result in deterioration under conditions of service.
true
Dense refractory brick is required in most furnaces to withstand the high internal temperature.
true
A thermal insulator is a poor conductor of heat and has a high thermal conductivity.
false
The difference between mouldable (moldable) and rammable material is that the latter is a stiffer mix, making it more self-supporting.
true
Thermal insulation may be applied for protection of personnel from injury through contact with equipment.
true
Aerogels are lighter than other insulation materials.
true
The required thickness of insulation for any specific application depends on the characteristics of insulating material as well as the purpose of the equipment.
true
The thermal conductivity of most insulating materials varies only with temperature.
false
As a general rule, a vapor barrier will be required over the insulation on all plant working at temperatures below the relevant “ dew point” of the ambient air.
true
Technical requirements should take precedence over economic considerations when the insulating material is required to avoid danger to personnel.
true
The thermal conductivity of materials decreases with temperature.
false
Asbestos or any product containing asbestos materials shall be applied by means of a spray process.
false
Thermocol is mainly used as cold insulation for piping and cold storage construction.
true
It is acceptable for insulation to interfere with the operation of expansion joints.
false
Before vapor barrier is applied, the insulant shall be smooth and regular with all joints tightly butted together so that there are no gaps.
true
The effectiveness of vapor barrier is expressed in terms of the rate at which water vapor is transmitted through it under defined conditions.
true
When the technical requirements of the application have been met, the total cost (distinct from the initial cost) during the life of the installation is the prime consideration.
true
When a plaster-type finish is applied, an expansion joint shall be provided by cutting at a circumferential joint in a single layer or in the outer layer of a double-layer system.
true
A high thermal conductivity is desirable to achieve a maximum resistance to heat transfer.
false
Requirements for the preparation of surfaces need to be clearly stated.
true
On tanks and vessels, preformed slabs or mattresses may be used on hot service, but on cold duties, slabs are normally used.
true
For very low temperatures, the use of multiple vapor barriers may be justified.
true
At the junction between preformed insulating materials and fixed steel work, the joint area shall be packed with mineral fiber to accommodate differential thermal movement.
true
Expansion joints need to be provided in furnace refractories at regular intervals to avoid overstressing the bricks at elevated temperature.
true
Insulation prevents condensation on cold surfaces and the resulting corrosion.
true
The thermal expansion coefficients of plastic pipe are generally much lower than those of metals.
false
All thermal insulating materials in common use are nonflammable.
false
Aerogels offer poor resistance to flame spread and smoke emission.
false
Aerogels are extremely hydrophobic and therefore have outstanding resistance to moisture.
true
Pipes of small diameter have relatively high surface temperatures and low rates of heat loss.
false
Insulation can be classified into three groups according to the temperature ranges for which they are used: low-temperature insulation (up to 90° C; 194° F); medium-temperature insulation (90-325° C; 195-620° F); high-temperature insulation (325° C [620° F] and above).
true
Inorganic insulations are based on hydrocarbon polymers, which can be expanded to obtain high void structures.
false
All refractory must be heated quickly from cold owing to the need to minimize the stresses created by differential thermal expansion.
false
Insulation is recommended for steam, condensate, heating, and hotwater supply mains, in order to conserve heat and avoid high ambient temperatures.
true
Air flow over an outer surface will tend to reduce the surface temperature and increase the rate of heat loss.
true
