Garlock GYLON EPIX Style 3504 EPX Hex-Profile PTFE Gasket Sheet

Hex-profile PTFE sheet that replaces two thicknesses with one

GYLON EPIX Style 3504 EPX is the patented hex-profile version of the blue 3504 PTFE sheet. Garlock states that one thickness does the job of two: seal performance and load retention equal to 1/16 in material, with the compressibility and conformability of 1/8 in material, and that the material is the same as traditional GYLON.

The patented hexagon pattern creates what Garlock calls superb sealing and the ability to conform to imperfect flange surfaces. Media listed are moderate acids, some caustics, hydrocarbons, solvents, hydrogen peroxide, refrigerants and cryogenics. Garlock’s interchange list names Chesterton ESC-B and Flexitallic SIGMA 500.

Technical specifications

Values are the typical properties printed in the Garlock spec sheet (Rev. Aug 2023). Garlock marks them as a general guide.

EN 13555 values and engineering data for Style 3504 EPX

The datasheet for this style carries EN 13555 characteristics, which Garlock says can be used for calculations to EN 1591-1 and for ASME PCC-1 Appendix I or O. Maximum tolerated assembly stress Qsmax is 29,000 psi (200 MPa) at 68 °F (20 °C), falling to 8,700 psi (60 MPa) at 482 °F (250 °C). The minimum stress for sealability class 0.01 mg/(m-sec) is 725 psi (5 MPa) at 580 psig (40 bar) and 1,450 psi (10 MPa) at 1,160 psig (80 bar).

Load retention after 16 hours at 500 °F with 7,250 psi (50 MPa) gasket stress is 50 %, and hot blowout testing with thermal cycles gives a rating of 432 °F (222 °C) at 435 psig. Garlock asks to be contacted if the gasket cross-section is narrower than 0.5 in (12.7 mm).

Related Garlock gasket sheets

The sheets below cover related PTFE gasket duties from Garlock.

Documents, ordering details and quotation

Tell us the flange class and facing so thickness and cut size can be matched. To price the job we need the medium, pressure, temperature, flange details, available bolt load, thickness and quantity, and whether sheet or finished gaskets are wanted. The datasheet figures are typical test values, so have the final selection reviewed against the real operating conditions, and ask Garlock for a chemical compatibility opinion where the medium is unusual. Related products are in gaskets, seals and pipe fittings.

How the Garlock Style 3504 EPX works

The sheet sits between two flanges. The bolts compress it, and it fills the surface marks on each flange face. The hexagon pattern gives each cell a small sealing area under a high local stress, while the sheet stays flexible enough to follow the flange. The PTFE body resists chemical attack.

Where the Style 3504 EPX is used

• Chemical process flanges
• Acid and caustic lines
• Solvent and hydrocarbon lines
• Refrigerant and cryogenic lines
• Glass-lined and uneven flanges

Selection checklist for the Style 3504 EPX

• Fluid and concentration
• Operating temperature
• Operating pressure
• Flange material and finish
• Bolt load available
• Sheet size
• Thickness
• Cut gasket or full sheet

Installation, commissioning and maintenance notes for the Style 3504 EPX

Clean both flange faces and check them for deep scores. Cut the gasket to size with sharp tools. Centre it on the flange and tighten the bolts in a cross pattern in several steps. Check the bolt load after the first heat cycle. Do not reuse a gasket after it has been compressed.

Requesting a quotation for the Garlock Style 3504 EPX

Please send the fluid, the temperature, the pressure and the sheet size. Seven Star LLC serves industrial customers in Oman and the GCC and replies with a quotation based on the information provided.

Style 3504 EPX composition

The sheet is PTFE with aluminosilicate microspheres in a hex profile.

Style 3504 EPX colour

The sheet is blue.

Style 3504 EPX thickness advantage

One thickness gives the load retention of 1/16 in and the conformability of 1/8 in.

Style 3504 EPX temperature limits

The maximum temperature is 500 degrees F, and the ideal limit is 400 degrees F.

Style 3504 EPX minimum temperature

The minimum temperature is minus 450 degrees F.

Style 3504 EPX pressure limits

The ideal limit is 750 psig and the maximum is 1200 psig.

Style 3504 EPX tensile strength

The tensile strength across the grain is 2000 psi.

Style 3504 EPX design factors

The design factors are m of 2.5 and y of 2000 psi.

Style 3504 EPX leak rate

The nitrogen leak rate by ASTM F37B is 0.15 ml/hr.

Style 3504 EPX sheet example

A sheet example is 0.094 in thick and 60 x 60 in.

Gasket records for the Style 3504 EPX

Record the flange, the bolt torque and the date of each gasket change.

Choosing the right Style 3504 EPX thickness

Choose the thickness that suits the flange gap and the bolt load available.