Gaskets are ubiquitous components in a processing plant. Every flange, equipment joint and connection point will have some form of gasket to prevent fluids from compromising (i.e., leaking from) a process system. However, effective sealing can pose challenges. A new form of polytetrafluoroethylene (PTFE) gasket, Gylon Epix, already has successfully addressed a number of persistent problems at plants.
The gasket, which is available in 3⁄32-in.-thick, 60-in. × 60-in. sheets, features a raised hexagonal pattern (Figure 1). It exhibits enhanced compressibility over both 1⁄16-in. and 1⁄8-in. traditional gaskets, seals easily when compressed by flanges and maintains assembled bolt torque better than comparable 1⁄8-in. PTFE gasket materials.
Trials at three early adopters of the new material underscore its value.
Fatty acid production. A German manufacturer of oleo-based chemicals, including fatty acids, glycerin, fatty alcohols and fatty esters used in consumer and personal health products, was experiencing problems sealing a 29.3-in. (745-mm) outside-diameter spiral heat exchanger. A gasket located atop the heat exchanger was exposed to polysaturated fatty acid and coolant at a continuous temperature of 428°F (220°C) and pressure of 87 psig (6 bar). J-type clamp bolts fasten the lid to the heat exchanger. Spiral heat exchangers present challenges because the gasket must seal across the entire face of the lid, requiring a gasket that will efficiently transmit the force from the bolts across its entire surface.
The traditional PTFE sheet gasket was allowing leakage across the exchanger’s spiral passes, decreasing efficiency. The gasket exhibited cuts from the spiral separation bars and required frequent changes that disrupted manufacturing and decreased plant productivity.
We installed Gylon Epix 3501-E in December 2017 and, after six months of testing, concluded it sealed well. Upon disassembly in July 2018, we found it to be in good condition, with no traces of cuts, discoloration, brittleness or sticking to the lid (Figure 2). We installed a new gasket in July 2018, which now has completed a successful one-year trial; the gasket continues to perform well.
Phosphate processing. New or refurbished equipment generally seals bolted connections well. As the equipment ages, gaskets and flange surfaces help seal gaps caused by corroded, worn, misaligned or repositioned equipment flanges. At a Mexican acid processor, Class 150, 8-in. raised-face flanges of the inlets and discharges of phosphoric and sulfuric acid transfer pumps had become worn and corroded. Temperatures were 104°F (40°C) and pressures 57 psig (4 bar). The 1⁄8-in.-thick glass-filled PTFE gaskets didn’t consistently provide a tight seal. So, the plant applied mastic filler to treat damaged flange surfaces as a stop-gap measure.
We installed Gylon Epix 3504 in December of 2017; it performed successfully without the need for flange treatments or special installation handling. Its enhanced compressibility fills the gap of imperfect flanges. It performed well until its removal in September of 2018 when the pump mechanically failed for a reason not related to the gasket. The acid processor is adding Gylon Epix to its approved materials list because it worked without the need for mastic, was flexible and easy to handle, and performed with zero leaks.
Terephthalic acid manufacturing. A southeastern U.S. producer of terphthalic acid (TPA) was experiencing leaks with traditional glass-filled PTFE sheet gaskets on a pressure vessel operating at 230°F and 60 psig that has a 60-in. × 10-in. rectangular gasket joint opening. Large rectangular joints can have uneven surfaces due to warpage of the cover. In July of 2018, Gylon Epix 3504 was installed and is still in service as of September 2019 and performing well. The company has accepted the product into its system and is re-ordering.
JIM DRAGO, PE, is principal applications engineer for Garlock Sealing Technologies, Palmyra, N.Y. Email him at firstname.lastname@example.org.