Style 690 is a braided expanded low sulfur, low contaminant flexible graphite yarn. It also contains a sacrificial corrosion inhibitor. Style 690 is a nuclear grade packing.

Style 690 is available in the following cross-section range:
1/8" to 1 1/2" (3.0 mm to 38.1 mm)
 

Applications
Style 690 is suitable for steam, water, oil, solvents, alkalis, acids, and most chemicals. Exceptions are oleum, fuming nitric acid, aqua regia, and fluorine.
Style 690 is recommended for valve applications. It is also excellent for (nuclear) valves and other static applications where low sulfur, contamination specifications are required.