Semi-Metallic gaskets are designed to feature soft, pliable sealing materials – which enhance the tightness of the assembly with lower overall load requirements when compared to full metallic gaskets. They are most popular due to this configuration, and are available in a wide variety of styles and sizes. They can typically be fabricated of any metal which is available in thin strip or sheet, and which can be welded. Therefore, they can be used against virtually any corrosive medium dependent upon the choice of the metal and filler/facing material. Additionally, they can be used over the complete temperature range from cryogenic to approximately 2000ºF. Semi-metallic gaskets can generally be used in pressures ranging from vacuum to those seen in ASME B16.5 standard 2500 pressure class flange ratings. They are resilient and, as a consequence, can compensate somewhat for flange movement that may occur due to temperature gradients, variations of pressure and vibration.
Lamons offers the following filler / facing materials for semi-metallic gaskets:
| Temperature Range | |
| PTFE | -325° F to 450° F |
| O2i-Oxidation Inhibited Graphite | -325° F to 850° F |
| Oxidation Resistant Grade APX2-FG | -325° F to 975° F |
| HTG (High Temperature Gasket) | -325° F to 1500° F |
| Mica | -325° F to 1832° F |
| Ceramic | -325° F to 2000° F |
