| Tecnoservice Italia manufactures spiral wound gaskets in a big range and dimensions: circulars, ovals, with inner and outer ring according to customer’s requests and international standards specificartion : ASME B16.20a (ex API STD 601), ANSI B16.21, DIN, BS, AFNOR, etc.. |
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Our technology in this production is what most up-to-date exists on the market. The plant, projected by us, is based on a 40 years experience and has allowed us to produce gaskets with diameters from 1 / 2” up to over 4 meters. |
During the years we have realized different projects and plants situated in all over the world, cooperating with the main engineering international companies. |
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| 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. |
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Types of Spirals |
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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. |
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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. |
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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. |
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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. |
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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. |
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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. |
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Type oval 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. |
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Type S18 with sideways 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. |
| Spiral wound gaskets are essentially made of two elements: a metal part generally consisting of steel or derived alloys that have the function of absorbing the loads and generating the tensional state, and a filler that allows sealing between various metal coils. The steels used as fillers are different in order to follow the diverse temperature and pressure needs of the sealing system. |
The fillers used in spiral wound gaskets are diverse and are chosen depending on two fundamental parameters: Download file "scope of seals" GraphiteGraphite is nothing more than carbon in elementary form, obtained by cracking reactions to hydrocarbons. The crystalline structure is lamellar and due to the effect of carbon hybridization which sees that the arrangement of atoms is carried out on an equal level. The different plants are kept together by secondary bonds of lower intensity. The application of small loads determines the slip of the different layers giving the material a low consistency and a high spathic nature. These structural features give graphite a self-lubricating property, of good compressibility which combined with high chemical inertia make it suitable in many applications. Graphite has a very high thermal conductivity and therefore it is ideal in applications of heat exchange. It is used mainly for piping, valves, pumps etc. The only limit is the operating temperature, which cannot exceed 400° C for the occurrence of the oxidation phenomenon, even if special process conditions permit exceeding the temperature.PTFEPolytetrafluoroethylene is a polymer with high specific weight characterized by the bond Fluoro Carbon. Chlorite MineralsThese are chlorite minerals additized with graphite (mica-graphite). These materials are applied to standard-service applications. Ceramic Fibres
Formed by aluminium silicate fibres. These materials have a low sealant effect compared to other fillers, and therefore have an excellent temperature stability up to 2300° F (1250° C). They are resistant to attack by many corrosive agents (hydrofluoric acid and phosphoric acid), including alkali. They are recommended when you can not use graphite filler or PTFE. |
The metallic materials used in spiral wound gaskets are different for the diverse needs of elasticity, corrosion resistance and chemical resistance required in the various fields of application.
Carbon steels are the most economic and versatile in industry, have an excellent ductility and optimal mechanical properties that can be improved through appropriate heat treatment. One of the limitations of their use is low resistance to corrosion. To this end, and to improve some mechanical properties, steels are additized with other metals (Ni, Cr, Si, Mo, Ti, etc.). Depending on the quantity and type, steels can be divided into:
• Low bonded steels
• Stainless steels
• Medium bonded steels
• Highly bonded steels
• Bonded steels
Belonging to this category are steels with percentages of additives on the percentage point.
We can affirm that:
Nickel: Increases the hardness and mechanical properties at low temperature, and in particular corrosion resistance.
Chromium/Si: Improves the hardness, abrasion resistance, corrosion resistance and oxidation resistance.
Molybdenum: High Temperature Load:
The addition of a few percentages of these elements determines the formation of a layer of oxide adhering to the surface that protects them from further oxidation. The corrosion resistance, from the liquid viewpoint, is instead the same as carbon steel.
There are more than 70 steels with the general composition of 12%-30% of Cr, or 22% of Ni
To these steels, alloys are added which have a strong resistance to corrosion.
We can divide them into three groups:
• Martensitic
• Ferritic
• Austenitic
Contain from 12 to 30% of Chromium plus controlled C + additives. Typical steel in this category is AISI 410. Corrosion resistance is less than the other three groups.
Contain from 15 to 30% Chromium with low carbon content, less than 0.1%. AISI 430 is a typical example. The corrosion resistance is good, even if ferritic steels don’t resist acids such as HC1 very well. They can be used to neutralize corrosive solutions, for example AISI 430 is used for air-nitric acid plants.
The most corrosion resistant steels compared to the other two groups. They have an average composition of 15-26% Cr, 6022% nickel, while the percentages of carbon are kept low (0.08%) to minimize the percentages of carbide. These steels can be stabilized with the addition of titanium, tantalum and we will have the type AISI 321, AISI 348. Other types of steel instead have a level of carbon below 0.03% like AISI 304 and 316L. Finally, the addition of Molybdenum improves its corrosion resistance.
This is a group restricted to alloys with a corrosion resistance that is higher than the stainless steels. A very common one is Alloy 20 with its various commercial names. Durimet 20 with a composition of 0.07 C 29% Ni, 20% Cr, Mo 2%, 3% Cu.
We have other alloys such as:
Incoloy 825 : 40% Ni, 21% Cr, 3% Mo, 2,25% Cu
Hastelloy G-3: 44% Ni, 22% Cr, 6.5% Mo, 0.05% C
This group contains high percentages of Nickel.
Hastelloy B-2 61% Ni, 28% Mo, excellent resistance to acids such as hydrochloric, phosphoric and sulphuric.
Tecnoservice Italia S.r.l.
Via Miola, 18
25036 Palazzolo sull'Oglio (BS)
Tecnoservice Italia is a company certified UNI EN ISO 9001:2015 and is always focused in maintaining of highest quality levels...
+39 035 910452
