POLYBOND Polybond Limited, Unit 6 William Street, Northam, Southampton, Hants. S014 5QH Tel: 023 80 223266 Fax: 08700 527587 |
Furnascote is a collective name for a series of refractory coatings having a high zirconia content, they are designed to protect the refractory bricks in furnaces and boilers etc., easily applied by trowelling, brushing or spraying by unskilled labour.
Each of our brand of Furnascotes is designed to fulfil a particular function and therefore be effective within a definite temperature range, the various types are shown below :
Furnascote HiGlazeGlazed types give a brilliant glaze to even the roughest refractory surface - used as a finishing coat on ships and industrial furnaces. | Temperature °C850 to 1260 |
Furnascote NONVITUniversal (non-vitrous type) gives a smooth matt white surface to refractory linings - used in industrial furnaces and oil refineries for protection against thermal shock, bonding, patching and plugging. As a basic coat for ships furnaces. | Temperature °C10 to 1910 |
The change from coal to fuel oil has created difficult conditions for refractories which older materials based on silica and alumina cannot withstand. The use of Furnascote reduces the frequency of repairs.
Furnascote reduces slag adhesion, reduces spalling, eliminates cracking and above all, produces gas-tight surfaces.
Furnascote refractory coatings are all normally supplied in the form of a powder packed in plastic tubs containing 25 kilos. Designed to withstand arctic, tropical and monsoon climates which enables stocks to be kept indefinitely in store without deterioration.
For best results - generally, in ships, oil refineries and industrial furnaces the following system should be used :
The refractory surfaces must be thoroughly cleaned with a scraper or wire brush, removing all loose pieces. Where cracks due to spalling have occurred in the refractory, the edges of the cracks must be cleaned and any gaps filled in with Furnascote NONVIT so as to level the rrefractory surface as effectively as possible.
After filling gaps, spalls and cracks with Furnascote Non Vit, mix more Non Vit with water to form a very thick paste on the following bases :
As soon as the NONVIT priming coat is leveled off, even though it is still damp, the Furnascote Hi Glaze finishing coat can be applied and is made up on the following basis :
We will be pleased to give advice on special applications on knotty problems.
After the Furnascote is brushed on to the refractory surface and left to dry, the furnace is fired. Make certain that the coating is dry. Thin coats dry quickly, approx 2 hours but thicker coatings require 24 to 72 hours drying time. Firing when begun should be regular so that the temperature increases steadily up to the required point.
For special conditions where low temperatures are required in furnaces for example 100 to 538°C. Furnascote Non Vit may be used as it sets as a monolithic coating from room temperature upwards and sets hard in several hours. The higher the rise in temperature, the more rapidly it hardens. Best results are obtained if a 3mm coating is applied on old or new fire bricks.
Non Vit also resists high temperature conditions up to 1910°C and is widely used in oil refinery H.T. furnaces because of its resistance to corrosive chemicals.
Non Vit is particularly resistant to Vanadium by-products.
Non Vit has potential uses in the layers of vaults of Fast Reactors of Nuclear Power Plants because of its High Zircon content.
Non Vit has tremendous resistance against Thermal Shock.
Depending on the degree of roughness and porosity of the surface, the coverage of the material when properly mixed will be of the order of 0.8 to 1.4 m² per litre (0.6 to 1.2m² per kilo of the material in its dry form) in a single coating. This is calculated on brushed coatings of one millimeter.
A vivid illustration showing the effect of NONVIT as a barrier coat can be seen our Furnascote full literature booklet "Aluminium Smelting".
The same process as used in ships furnaces - a priming coat of Furnascote Non Vit followed by a finishing coat of Hi Glaze can be used in all types of industrial furnaces to give resistance against ravages of fuel oil.
The system also withstands damage by solid fuels such as coal, peat, wood and industrial wastes.
Where dense quality fire bricks and catables display gloss surfaces and past experience has shown that flaking does occur after firing, we advise as follows :
Apply a revolving abrasive wheel of the Norton Crystalon type to the face of the bricks or castables for a few seconds to scratch the skin and 'de-scale' the surface. Wet the 'de-scaled' bricks with fresh water to reduce dust from rising. The apply brush coatings of Furnascote in the normal way, allow to dry before firing. This treatment will increase the adhesion of Furnascote to give superb results on glassy, dense fire bricks.
The level of grassing in molten metals can be reduced by the use of Furnascote NONVIT which, by sealing the firebricks or catables, prevents the leaching of reactive materials contained in the firebrick or castable.
Apart from helping to anneal metals, NONVIT, even as a 'wash coat' will assist in annealing firebricks, castables, monolithics and thus reduce the tendancy to 'thermal shock'.
Furnascote Non Vit is recommended for use in the following applications wherever fuel oil and solid fuels are employed in furnaces (NONVIT is particularly recommended in applications against Thermal Shock).
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| For bonding expensive firebricks use NONVIT | Stop spouts and channels slagging with Hi Glaze | Inside walls and lips of receivers will last longer with NONVIT | Castables, brick walls, jet burner areas are protected by using NONVIT | Broken firebricks can be re-inforced with NONVIT |
Polybond LtdUnit 6, William Street, Northam, Southampton, Hampshire, SO14 5QH
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