Refractory Anchor Systems Part 2 of 2

Refractory Anchor Systems Part 2 of 2

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Metal anchors are most commonly utilised, some typical maximum operating temperatures are shown in the table below:

TYPICAL MAXIMUM TEMPERATURE.                         GRADE OF STEEL.

               450°C                                                              Carbon Steel

               900°C                                                              304 Stainless Steel

              °C                                                             310 & 310S Stainless Steel

              °C                                                             Incalloy 601

Other materials are available on request and would be imported as required.

Anchor lengths should be a minimum of 25mm below the hot face lining and tests have shown that the anchor tip may be 150°C to 350°C below the hot face refractory temperature, however in general it is accepted to use the higher grade anchor material to that of the hot face temperature.

Another consideration is the coefficient of thermal expansion of the anchor material, which will be higher that the refractory material, thus the stresses produced can result in lining cracking and eventual failure of the refractory material and also the anchor. It is suggested that all anchors be coated with a material (bitumen) that will burn out at low temperature and allow very small movement between the anchor and castable lining to accommodate the differential expansion. Plastic caps only cover the anchor tips and are not adequate, the whole anchor should be coated. It is also said that the plastic caps help with the longitudinal expansion were most of the damage is done to the refractory material, full anchor coating helps with the radial expansion. It is good manufacturing practice to not produce anchors with the legs being the same length, this cause a shear plain across the anchor tips and results in the hot face of the refractory lining breaking off exposing the anchor tips to the hot face and shortening the life of the refractory lining.

Anchor Spacing tables should be used as a guide only as each application should be considered according to the type of unit being lined, the temperature, the high stress areas, the formation of cracking, side wall or roof application. On large side walls support plates (wall seats) should be used to take the load off the anchors, this must also be used to separate monolithic and brickwork applications, it also makes it easier for future repairs.

Typical Anchor Spacing Table:

              LINING THICKNESS       &#