SPIRAL WOUND GASKETS

A requirement of any gasket is the ability to recover under variable loads. The effects of pressure and temperature fluctuations, the temperature difference across the flange face, together with flange rotation, bolt stress relaxation and creep, demand a gasket with adequate flexibility and recovery to maintain a seal under variable and uneven loading. The spiral wound gasket, invented by Flelitallic, meets these requirements.

A spiral wound gasket is manufactured by spirally winding a preformed metal strip and a filler on the outer periphery of metal winding mandrels. The winding mandrel outside diameter forms the inner diameter of the gasket and the laminations are continually wound until the required outer diameter is attained.

Normal practice is to reinforce the inner and outer diameters with several plies of metal with no soft fillers being introduced. Our method of manufacture includes custom designed devices which provide control of gasket density that permit compression to the operating thickness under a specified load. This engineered product is thus "tailor made" to be compatible with the flanged closure in which it is to be used.

For example, a closure designed for vacuum service may require a gasket of exactly the same dimensions as a closure designed for 1500 PSI service. The closure designed for the vacuum service would have relatively light bolting indicating the necessity for a soft gasket, while the 1500 PSI application would have heavy bolting indicating a relatively dense gasket. It is usually within our capability to satisfy both requirements.

Style CG

Utilizes an external ring which accurately centers gasket on flange face; provides additional radial strength to prevent gasket blowout and acts as a compression stop. A general purpose gasket suitable for use with flat face and raised face flanges. Class 900 and above an internal ring is recommended.

Style CGI

A style CG gasket fitted with internal ring which gives an additional compression limiting stop and provides heat and corrosion barrier protecting gasket windings and preventing flange erosion. Suitable for use with flat face and raised face flanges and specified for high pressure/temperature service - class 900 and above or where corrosive or toxic media are present.

Style R

Basic construction type, inner and outer diameters are reinforced with several plies of metal without filler to give greater stability and better compression characteristics. Suitable for tongue and groove or male and female or grooved to flat face flange assemblies.

Style RIR

Solid inner metal ring acts as a compression stop and fills the annular space between flange bore and the inside diameter. Designed to prevent accumulation of solids, reduce turbulent flow of process fluids and minimize erosion of flange faces. Suitable for male and female pipe flanges.

Style HX-RIR

The style HX-RIR is a variation of the style "RIR" spiral wound gasket, developed for use on heat exchanger TEMA type flange arrangements. In conjunction with an inner ring, the standard spiral wound construction also supports an outer wound steel nose, designed for the purpose of accurate gasket location. Available with or without pass partition bars.

Carrier Ring

The carrier ring gasket consists of two spiral wound gasket seals recessed into each face of a metallic core. The major benefits of the carrier ring are the high recovery characteristics of the double spiral arrangement and its increased strength and handlability over a standard configuration. Carrier rings can be used on flat face, raised face and tongue in groove type flanges, or any non standard assembly, where high operating pressure/temperature conditions dictate the selection of the absolute spiral wound seal.

Style HE

Style HE gaskets are for heat exchangers where pass bars (ribs) are required. The outer portion is of standard spiral wound construction, whereas the rib portion is normally of single or double jacketed style, securely fastened to the ID of the spiral wound portion.

Style HE-CG

This style is identical to the Style HE, except that it is fitted with an outer ring on the OD. This outer ring can act as a centering guide and provides additional radial strength to prevent gasket blowout. It also acts as a compression stop.

Style LS

ANOTHER NEW DEVELOPMENT FROM FLEXITALLIC. The style LS spiral wound gasket has been engineered by Flexitallic to provide an alternative to sheet gaskets in Class 150 and Class 300 service. Style LS gaskets have the inherent strength, resiliency and blowout resistance of spiral wound gaskets, yet require low bolt load for seating.

They are manufactured with high purity Flexicarb flexible graphite filler or PTFE filler for optimum sealability, and are available for the full range of standard Class 150 and Class 300 flanges, as well as other non standard low pressure flanges. Style LS gaskets are a safe, economical alternative to tanged graphite gaskets.

Style CG-RJ

This style designates a Special CG gasket sized to be used on standard ring joint flanges. The outer ring is dimensioned to cover the ring joint grooves and to prevent the spiral wound portion from entering the groove. This type of gasket should be used only as a maintenance repair item. If Flexitallic gaskets are to be used in new construction, it is advisable to use standard raised face flanges and our Style CG gaskets.

Style 625

Style 625 spiral wound gaskets are similar to style R gaskets, except original thickness is 0.0625". These gaskets are widely used wherever space restrictions indicate the need for a wafer thin gasket design capable of sealing high pressures.

Flexite Super

Thoroughly researched and developed by Flexitallic to meet industry's demand for an alternative to asbestos filled spiral sound gaskets, and available only from Flexitallic. FLEXITE SUPER has temperature and chemical resistance similar to asbestos, while exhibiting superior sealability over asbestos filled spiral sound gaskets. It is available in all sizes, styles and pressure ratings, with compressibility and recovery characteristics equivalent to asbestos filled spiral wound gaskets. Flexite Super has been field tested and proven, and can be used from cryogenics to temperatures in excess of 842ºF in steam, hydrocarbons, heat transfer fluids, alkaline solutions, solvents, aqueous and salt solutions, fuel oil, hydraulic oil, halogens, and general service in mild acids. Flexite Super is tested for leachable chlorides and meets the 200 parts per million requirements for total soluble chlorides.

Flexicarb

FLEXICARB is high purity flexible graphite with no binders or fillers. It exhibits superior sealability, and excellent resistance to a wide range of chemicals. FLEXICARB can be used at temperatures from cryogenics to 900ºF in an oxidizing atmosphere, and up to 6000ºF in a reducing or neutral atmosphere. Its unique combination of low permeability, inherent lubricity, and compressibility make Flexicarb suitable for critical gas and vacuum service. Leachable chloride content of Flexicarb is 100 ppm maximum. Available in standard, nuclear or corrosion inhibitor grades.

Polytetrafluoroethylene (PTFE)

PTFE is used as a filler material in Flexitallic gaskets where extreme chemical inertness is required for temperatures ranging from cryogenic to 482ºF. PTFE is unaffected by any known chemicals except molten alkali metals and fluorine precursors. Because of its low permeability, PTFE is also frequently used as a filler material on Flexitallic gaskets in vacuum applications. Gaskets wound with PTFE should be fully confined either by fitting in a groove or providing both an external and internal ring.

Ceramic Fiber Paper

Consists of aluminum silicate fiber with an organic binder. This material has excellent high temperature stability to 2300ºF. It resists attack from most corrosive agents (except hydrofluoric and phosphoric acids) as well as concentrated alkalies.