Type A - Sealing using synthetic rubber NBR (Perbunan)
Type B - Sealing using synthetic rubber FPM (Viton)
GN749 Hexagon Socket Threaded Pipe Plug, Steel
The dimensions of the threaded plugs GN 749 comply with DIN908, but deviating from the latter is the elastic seal.
This seal is retained in a radial undercut in the mating face which prevents it from dropping out and in particular it does not extrude when the plug is tightened. For this reason the seal can be of a softer material which will give better sealing.
Steel ST, Tensile strength class 5.8 (500 N/mm²), ultrasonically and tensile tested, zinc plated, nano-passivated (silver / yellowish)
Type A - temperature resistant up to 100 °C
Sealing ring - rubber NBR (Perbunan)
Type B - temperature resistant up to 180 °C
Sealing ring - rubber FPM (Viton®), identification by off black finish of the seal.