These are constructed winding a tape of ferrous material that is pre-formed (generally V) together with a filler. The winding of the two elements continues until the desired diameter is reached. Generally the shape is circular but it can also be oval with or without crosses according to the specific needs of the customer.  These gaskets are quite versatile, with a strong adaptation to the different working conditions of the sealing system. In fact, they have optimal elastic return compared to metallic gaskets. The spiral wound gaskets therefore pose as a bridge between the smooth plastic gaskets and the metallic gaskets. These represent a strong innovation in that they allow in many cases for substitution of the metallic gaskets, with the advantage of having reduced tightening loads.

The type of spiral depends on the field of application in relation to the temperature, the pressure and the type of flange. To satisfy all of these conditions, different types have been developed which allow you to optimize and make the best of their function.

Type S11
The internal and external diameters are reinforced by metal-only circles without fillers to give greater stability and better compression. Mainly suitable for couplings, LTG/STG and for SMF/LMF masculine-feminine couplings.

Type S13
In this case the gasket is provided with the outer ring. Even in this case the ring has different functions but mainly that of acting as a centering ring on the flange, thus facilitating its assembly and preventing the lateral expansion of the seal (blow out). General application for flanges on a smooth surface.

Type S14
In this version the gasket is provided only with the inner ring. The ring has different functions, among which that of anti-turbulence and erosion reduction in that the internal diameter is usually equal to the internal diameter of the flange, avoidance of material deposits in the gap of the flanges, and normally it is the same material of the seal that protects it from corrosion. Used also for SMF/LMF masculine-feminine joints.
Type S15
The gasket is provided with both rings. The internal ring is used in cases of high pressure and operating temperature or where corrosive or toxic fluids are present, in all of the applications with PTFE filters. It is advised with graphite fillers for dimensions 24" and larger for the 900 class, 12” for the 1500 class and 4” for the 2500 class.

Type TLS S13/ S15
The spiral wound LOW STRESS gasket is provided with an external ring (S13LS) or external and internal (S15LS). The particularity of these spirals is given by ensuring the compression and the seal applying minor bolt tension or a flange overload for classes 130 and 300 in replacement of gaskets by sheet metal.

Tipo ovale
The gasket is made depending on the needs of the customer with or without rings. Used particularly for manholes and valves with oval passage section.

Tipo S18 con traverso
Gaskets made according to the customer’s design, used mainly on heat exchangers and water tanks. Any metal-plastic cross will have a greater thickness than that of the internal reinforcement ring.

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