From your photos it does not look like asbestos. However until this is proven you should treat the seal as if it was. Asbestos has straight, needle like fibres. These can break up into smaller straight needle like fibres and this can continue on until they become microscopic.
As the seal is already exposed and flaking a way to seal the material needs to be found while a course of action is determined.
There is still a lot of asbestos about 'safely' encased by a variety of means. Most people with an OH&S, engineering or mechanical trade would be experienced in identifying asbestos, I would strongly advise it being checked out before attacking it to replace it.
There are other materials that were used to replace asbestos, some of these are also hazardous so even though the material may not be asbestos taking suitable precautions is still needed.