Polyimide-amide Failure in Korea
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Polyimide-amide Failure in Korea

Yellow “polyimide” fibres are not necessarily P84^® fibres.

Following story happened in a Korean cement plant:

After a series of upset conditions during start up of the rotary kiln in a Korean cement plant, several P84^® bags had to be replaced. The OEM had specified polyimide felt for the bags which were installed as replacement but showed a dramatic failure within 2 weeks of operation. When the samples were checked in the Inspec Fibres laboratory it turned out that the fibre material being used for the polyimide felt was obviously a polyamide-imide or polyimide-amide. This fact can easily be determined by the cross section of the fibres as it can be seen in pictures 1 and 2.

Picture 1:
Microscopic picture of the cross section of the needle felt obtained from the Korean cement plant.
As can be seen the cross section of the fibres is round to oval. These are typical cross sections of polyamide-imide/polyimide-amide fibres.

Picture 2:
This is a microscopic picture of the cross section of P84^® fibres, a pure polyimide fibre.

Compared to round or other “dog bone “ shaped dry spun fibres P84^® comprises a typical blend of irregular shaped cross sections resulting in a strongly increased specific fibre surface.

Compared with the initially installed P 84^® bags the polyamide-imide material in this case was totally blinded and chemically degraded (see pictures 3 and 4) .

Picture 3:
Cross section of the polyamide-imide needle felt obtained from the filter bag of the above mentioned Korean cement installation.

The cement dust has completely penetrated the needle felt.

Picture 4 is showing the
cross section of a P84^® needle felt taken from a filter bag of the same installation.
It can be clearly seen that the cement dust cake is concentrated at the surface of the needle felt. The dust has not penetrated into the depth of the needle felt.

Laboratory tests show polyimide- amide in the application of hot gas filtration being susceptible to moisture in the flue gas (see picture 5). The failure in the Korean cement plant confirms similar findings in various installations where the polyimide-amide material was damaged within weeks.

P84^® polyimide needle felt can help to prevent problems as shown above in your bag house.