Answer ... Flange has various shapes and sizes, and the type of flange used in actual working conditions has a significant impact on the recommendation of gasket material. Standard ANSI raised flanges are perfect for use with our pressed fibers and GYLON® gaskets. Elastomer (rubber) gaskets can be crushed in such flanges.
Non-metallic flat flanges work best with elastomeric (rubber) gaskets, such as various STRESS SAVER® gaskets. The GYLON® 3545 is also suitable for some applications. Compression fibers and standard GYLON® are frequently used in all-plane carbon steel flanges, but the compressive stress on these flanges is well below our recommended minimum compressive stress. Therefore, the amount of compression of the gasket is small; if there is unevenness on the flange surface, the gasket may not achieve the sealing effect. Because the leakage rate of the gasket depends on the compressive stress used, the tightness of the connection may not be as expected by the customer.
Glass lined flanges are used in many chemical applications. Because these flanges often have "corrugations" when firing, it is recommended to choose the softer GYLON® series, such as 3545, 3565, and 3504. Before ordering the gaskets, the gap between the flanges placed apart must be measured. Gasket thickness should be four to five times the maximum gap measured.
Stainless steel (SS) flanges are common in many factory chemical applications, and low-strength stainless steel bolts are often used. Considering the chemical nature and the low pressure stress of the bolts, 3545, 3565 and 3504 are generally recommended. Nevertheless, we still recommend the use of high strength, strain hardened stainless steel bolts. Due to the very small amount of chloride that can be filtered out, the 3000, 98206 and Stress Saver XP models are preferred for stainless steel flanges. See Stress Saver XP in the Engineering Gasket Catalog. When considering other models, consult Garlock Engineering.