NGP 6300J Flexible Graphite Seal Rings NGP 6300J die formed rings provide the primary seal within the packing set. NGP 6300J is corrosion inhibited and manufactured to 90lbs. per cubic foot density. Nuclear Graphite Products (NGP) Main Page NGP 524 Graphitic Yarn Page NGP 6300J Flexible Graphite Seal Rings Page NGP Belleville Spring Washers Page NGP 193 B-7 Gland Studs Page NGP Style 6350 Graphite Lubrication Page NGP 6000 Composite End Rings Page NGP 5005 Graphite Spacer Bushings Page