Tmoose
Mechanical
- Apr 12, 2003
- 5,633
Attached is an image of a "pad" seal we use on Ball tube Mill.
We want to improve the service life a lot.
The sealing element ( pad ) is shown as a red strip.
The OD is about 65 inches. The pad radial thickness is about 4 inches.
Historicaly We have required the seal to be "one piece" with an overlapping joint. It has to be cut so it can be installed with the machine assembled.
The surface speed is about 240 fpm.
On one side is relatively clean ambient "seal air" at 5 psi or less.
On the other side is ambient power plant air.
The pad seal is initially flat and preloaded about 1/8 inch.
It is backed up by spring steel fingers shown in green.
The rotating component is cast iron, or sometime steel that starts out finished to about 16 µin Ra maximum.
Currently we use a few different gasket materials for the pad. Typically I believe they are fiberglass type materials impregnated with coatings as would be used for pipe flanges.
We lubricate them at installation with some fancy thread lubricant for oil industry drill collars and drill pipe. Re-lubrication while assembled is impossible with the current design.
I'm wondering if some other sheet material would be more durable when continuously sliding than "gasket" material, but don't know if that would be a urethane or filled teflon or something else altogether.
I am more interested in starting with the experiences of the motley crew here on ENG-Tips than a "sales engineer" that answers the phone at a plastics supplier.
We want to improve the service life a lot.
The sealing element ( pad ) is shown as a red strip.
The OD is about 65 inches. The pad radial thickness is about 4 inches.
Historicaly We have required the seal to be "one piece" with an overlapping joint. It has to be cut so it can be installed with the machine assembled.
The surface speed is about 240 fpm.
On one side is relatively clean ambient "seal air" at 5 psi or less.
On the other side is ambient power plant air.
The pad seal is initially flat and preloaded about 1/8 inch.
It is backed up by spring steel fingers shown in green.
The rotating component is cast iron, or sometime steel that starts out finished to about 16 µin Ra maximum.
Currently we use a few different gasket materials for the pad. Typically I believe they are fiberglass type materials impregnated with coatings as would be used for pipe flanges.
We lubricate them at installation with some fancy thread lubricant for oil industry drill collars and drill pipe. Re-lubrication while assembled is impossible with the current design.
I'm wondering if some other sheet material would be more durable when continuously sliding than "gasket" material, but don't know if that would be a urethane or filled teflon or something else altogether.
I am more interested in starting with the experiences of the motley crew here on ENG-Tips than a "sales engineer" that answers the phone at a plastics supplier.
