Industrial Process
Insulation plays a vital role in the design consideration of Industrial Process equipment to provide thermal, acoustic, fire protection and safety benefits.
Overview
Industrial Process facilities such as power stations, petrochemical plants, refineries and food and drink factories will have a significant investment in process equipment to ensure consistent results. This equipment must therefore be designed to ensure controllable, efficient and safe operation.
Insulation will play a vital role in the design consideration of this equipment to provide thermal, acoustic, fire protection and safety benefits.
Effective insulation of pipe work, for example, when used to control temperatures, can result in considerable savings in operating costs and the reduction of carbon emissions. Furthermore, insulation increases safety by protecting employees from coming into contact with extremely hot and cold equipment.
The sound absorption properties of insulation should also be taken into consideration to prevent noisy machinery adversely affecting the working environment and creating noise pollution for surrounding properties.
Specifically, insulation should be used by the industrial and mechanical engineer to effectively control:
- Operating temperatures for reduced energy costs and consistent production results
- Surface temperatures for the creation of a safe working environment
- Sound transmission for the prevention of excessive noise breakout.
Advantages
The Knauf Insulation range of products has been specifically engineered to provide high levels of thermal, acoustic and fire protection insulation for pipes, equipment and vessels forming part of industrial process plant.
Each product within the Knauf Insulation range offers unique benefits, not only for the client, but for the designer, specifier, stockist, contractor and installer.
Description and function of the layers
The pipeline can be manufactured of steel, aluminium alloy or other alloying elements so that it can conform with application-specific priority requirements. Generally, the pipe can be shaped differently in cross section, for example with circular and noncircular cross section (curved or angular). The basic function of the pipeline is the water transportation, as well as the steam and air-conditioning supply with respect to the different properties of a transported medium (the temperature dependence) within the required time period.
The thermoinsulating layer consists of the mineral fibre material approaching an ideal thermal contact resistance behavior. The thermoinsulating layer fulfils the function of optimal thermal resistance of the pipeline in order to eliminate or minimize the heat losses providing the required reliability of the thermal conditions on the surface of any insulation.
The spike (clip anchor) can be welded or sticked to the bearing base and in this manner we can compensate the mass loading of installed insulation into the pipeline. In general, the number of spikes (clip anchors) per 1 m2 useful area depends on the type of pipeline or the technological device and load factors. The two basic materials, steel and aluminium are used in their production.
Cladding i.e. sheathing is predominantly made of aluminium. The pipeline should be covered by a sheathing protected against mechanical damages and atmospheric exposure. Sheathing enables the movement of pipeline with regard to the thermal expansivity of aluminium (the thermal expansion of aluminium is twice that of steel). Changes in surface temperature of sheathing are caused by the direct sunlight (increased temperature) or by the cool and rainy weather (decreased temperature). For this reason, the large thermal dilatation occurs between the pipeline and covering. The thermal dilatation can be prevented by adjustable joints.
Design principles
Insulation can be fixed to the pipeline by strips of rustless metal or combined method with the fixation spikes (clips). The best way is to apply insulation in two or more layers according to required thickness. This method is useful for insulation of devices having a temperature higher than 500 °C , wherein said layers should have a different bulk density. The insulation material with higher bulk density should be installed at high temperature direct on a surface because high density bulk insulation materials have superior insulation and bulk properties. Thermal insulation at low temperatures can be made using a low bulk density material. At the same time, the joints between layers should be moved i.e. adjustable so as to provide the uniformity of insulation. Any insulation should be applied only in dry conditions and finally protected against the harmful effects of atmospheric exposure.
It is very important to prepare the surface of pipelines or devices (especially in case of existing supply network and devices) according to manufacturer's instructions. First, any unfinished steel surface covered by dirt and rust must be cleaned (to scrape off rust blisters and to wash away any foulness). However, for removal of grease or fat we recommend you to use the products based on organic solvents and detergents. All anticorrosive steel surfaces should be cleaned only by using brushes made of anticorrosive steel. It is prohibited to use chlorinated solvents, detergents or cleaning products containing chloride.
The significant aspect of the sheathing (cladding) process is to avoid potential galvanic corrosion which occurs when metals having different composition come into contact with each other. Thereat self-tapping screws or rivets made of identical material should be used for best results. Aluminum as a the sheathing cannot be used for high operating temperature, because the melting point of aluminum is about 600° C.
The main principles of heat cladding:
- to choose the right type and thickness of the thermal insulation
- insulated surface must be clean and dry
- to determine the sufficient space between insulated pipes and tubes available for maintenance activities
- to install all valves easy to service, because the insulated pipe may not be trampled under foot during repair works
- to install valve spindle accurately (not nose-up) so as to avoid leakage of the moisture or the water into the insulation material
- to install the thermal isulation continuous without thermal bridges
- to prevent possible damage of insulation and sheathing
The most frequent errors made by users during realisation
- First of all, inadequate thickness of thermal insulation - the insulation layer can be sometimes undersized which may cause the energy loss.
- Most frequently problems are often connected to the fact, that customers use insulation materials in unsuitable temperature (unrelated to the behaviour of mineral wool). The mineral wool backed products should be applied per the manufacturers instruction with respect to the correct application at the recommended temperature.
- Insulation should be installed tightly, without the thermal bridges. Whenever, the installed insulation must remain stable and precisely anchored so as to prevent any eventually damage caused by loose and fallen insulation.
- Exterior sheathing provides enhanced surface atmospheric water resistance in order to protect the construction especially against climatic effects. Protection against the mechanical damages is only the secondary aspect.
- The galvanic corrosion does not occur under normal conditions, only between different constituents of the same metal as well as between different metals, that can lead to detachment of the sheathing.
