The materials commonly used in the field of industrial sealing (for example, rubber or non-asbestos with aramid fibre and elastomeric filler) usually do not fit all of the necessary standards of strength, width, and chemical and mechanical resistance that certain applications could require.
FF.GI srl is a pioneer in the envelope gasket industry and we have reached the highest quality standards, using innovative materials, advanced technologies and a qualified work force. Every type of gasket is studied and designed to fulfil the most stringent requirements of a constantly evolving market.
The PTFE external envelope
Commonly called an “envelope”, it has the purpose of protecting the internal part of the gasket from the substances which they are in contact with.
These envelopes are mostly made of:
All of the listed materials comply with US laws:
- FDA, Food and Drug Administration, department of Health and Human Services, Code of Federal Regulations 21 CFR Ch.1;
- USA regulations sections 177.1550 (a) (1) and (b) Perfluorocarbon Resins;
There are different types of envelopes based on their application and the customers’ requirements. In the case of larger diameters and smaller quantities the cost could be too high so the envelopes can be welded at one point to reduce costs.
The welding process is done “end to end” (a butt weld) without overlapping the two PTFE parts; the perfect execution of the welding is ensured by using the correct parameters of temperature, pressure and time on the part to be welded. Destructive and non-destructive tests are frequently carried out to ratify the welding process.
GRA-FLEX
5200
5200
Expanded graphite reinforced with A1200 aluminium double foil that gives high mechanical resistance to the graphite, but at the same time makes it flexible and perfect to be the internal part of a PTFE envelope gasket.
FLON-CHEM-1011-PINK PTFE
Modified PTFE reinforced with silica. It maintains the thermal and chemical resistance of PTFE but has a better elasticity necessary for the sealing process; this gasket is completely FDA and can be used at temperatures of up to 260°C.
BLUFLEX®
3000
3000
Universal non-asbestos joint with a base in aramid fibre and nitrile rubber filler
Bio-soluble ecological ceramic fabric ECOSILC
Material made from carded bio-ceramic wire: good temperature stability, excellent resistance to thermal shocks, good chemical resistance.
Thanks to its softness and flexibility it is recommended for glazed flanges, glass flanges and irregular surfaces.
Corrugated Wave Ring
The corrugated wave ring gives the envelope gasket the necessary elasticity for a perfect seal, and at the same time an effective adaptability to any irregularities in the flange. It is usually furnished in stainless steel AISI 316 (1.4401) or AISI 316 Ti (1.4571).
Single-hole clip
The single-hole clip is the most common and it’s used to link the gasket to the grounding with cables, screws and fixing bolts. Particularly for the oval gaskets or big round gaskets, these clips could be used to fix the gasket to the flange where it is installed.
Doubl-hole clip
The double-hole clip is the evolution of the single-hole clip for envelope gaskets that have to be installed between flanges. In fact, with a double hole clip you can completely eliminate all other solutions for fixing the gasket to the machine (cables, screws, bolts) making the gasket cheaper and easier to remove. In addition, the yellow and green colouring allows the gasket to be seen easily inside the machine; these gaskets are available up to DN200 in one piece without welding.
