Galvanic corrosion is an electrochemical process that occurs between two dissimilar metals, or between a metal and a conductive non-metallic material, when both are exposed to an electrically conductive media. In the case of a packing gland, it occurs between a metal component and the carbon or graphite packing. Under these conditions, the material that is closest to the anodic end of the galvanic scale will be corroded in preference to the one that is closest to the cathodic end of the scale. (See Table 1.) As the distance between materials on the galvanic scale increases, a corresponding rise occurs in the rate and the extent of the corrosion.
In a valve or a pump using packing made of either graphite or carbon, a galvanic reaction may be initiated as soon as any electrically conductive fluid, such as water, is introduced. Since graphite is more cathodic than the metals that make up valves and pumps, it is the metal that may
There are many aged and aging process plants in operation today. In fact, many of the processing plants for power, chemicals, oil, etc., have been in service for more than 50 years. And while the piping itself may remain intact, their bolted flange gasket joints and connections are becoming misaligned, corroded and damaged due to repeated handling, chemical exposure and thermal cycling. This can lead to costly ruptures that may result in millions of dollars in damages, downtime, noncompliance penalties, irreparable environmental impact and litigation.
There is a solution that can extend the life of aging piping systems, preserving their functionality: raising the surface profile on polytetrafluoroethylene (PTFE) gaskets. This design modification can prevent leaks, spills and other releases in chemical processing plants by reducing and managing
When you're specifying a gasket for even the simplest application, it is important that the gasket supplier know all the operating parameters.
There are five major pieces of information needed to select the appropriate gasket, known by the acronym S.T.A.M.P.:
While gaskets are most often used in standard ANSI flange connections
Abrasive media comes in many forms—from mining slurries to wood pulp and even substances as seemingly mild as liquid chocolate. This diversity rules out a one-size-fits-all solution for abrasive pumping applications. However, today’s broad range of materials, from carbon fiber packing to graphite-filled polytetrafluoroethylene (PTFE) bushings, includes products capable of meeting an equally broad range of abrasive wear requirements.
Few materials offer the abrasive resistance and heat dissipation of carbon fiber yarns. Braided compression packing made from this material excels under extreme conditions, including exposure to a variety of chemicals, temperatures approaching 850 F (454 C) in oxygen-rich atmospheres (up to 1,200 F/649 C in steam) and shaft speeds in excess of 4,000 feet per minute (fpm).
Flange gasket storage is often an after-thought for many of our customers. While incorrect gasket installation procedures is the #1 culprit when it comes to gasket failure, gasket storage can play a large role in the quality of the gasket being installed.
Flange gaskets are highly engineered products, and their performance depends on many factors. Certainly design, manufacture, installation, and process conditions are all critical, but so is storage before use. Gasket materials often remain in storage for a long time before they are placed into service. Unfortunately, storage practices for gasket materials are generally not optimal or controlled well enough. This article provides guidance for the storage of different gasket materials to preserve their integrity.
Garlock launched of ABRA-SHIELD™ in 2018, an expansion joint material designed for abrasion resistance and sustainability in demanding high temperature operating conditions.
As the newest addition to Garlock’s family of abrasion resistant expansion joint materials, ABRA-SHIELD™ joined ABRA-LINE® and Natural Rubber to provide a variety of liners that cater to increased abrasion protection. ABRA-SHIELD™ will be an option for use with a number of expansion joint products that Garlock offers – including styles 204, 206, 7250, 8400 and 9394. These expansion joints also provide high levels of protection from stress, misalignment, vibration, noise, shock and corrosion.
Garlock has expanded their Ultra Low Emissions family of products to include a spiral wound gasket. The FLEXSEAL® ULE is designed for use where leakage control is critical and the aggressive application requires a spiral wound design. It’s manufactured using high performance graphite, and offers maximum protection against oxidation. The standard design includes an inner ring and outer ring, as well as preformed metal wire to enhance compressibility and sealability. The FLEXSEAL® ULE spiral wound is another product born from Garlock’s customer driven innovation.
GYLON EPIX™ is a newly developed family of PTFE gaskets. It is manufactured using a patented, profiled surface based on Garlock's proven Fawn, Off-White, and Blue GYLON® to create highly conformable materials for optimum sealing performance.
GYLON EPIX™ provides superior functional performance by combining the traditional attributes of GYLON® with an innovative surface design. It offers a broader range of applications than traditional PTFE gaskets that are used in worn and pitted flanges. In addition, this evolutionary material
In industries such as chemical processing, hydrocarbon refining, and power generation, leakage from extreme temperature process streams can result in loss of efficiency and production as well as adverse environmental impacts and compromised employee safety. One of the most commonly used sealing products in systems subject to high pressures and temperatures is a spiral-wound gasket. These gaskets typically consist of filler and winding materials selected on the basis of application requirements and end-user preference. Proper selection of these materials is critical to achieving the desired performance in all applications.
The two most common filler materials in spiral-wound gaskets are graphite (can withstand temperatures up to 850 ºF) and polytetrafluoroethylene (PTFE; tolerance up to 500 ºF). Other filler materials are used mainly for their thermal insulating properties, not for sealability; these include mica, exfoliated mica, and ceramics. While graphite and PTFE perform satisfactorily in terms of temperature and chemical resistance, they have limitations. Graphite is not compatible with heavily oxidizing media at any temperature, nor can it withstand continuous operating temperatures above 850 ºF. Beyond 850 ºF, volume loss through oxidation becomes excessive and sealing effectiveness is compromised.
Many high-temperature systems, such as exhaust manifolds and flanged piping connections in exhaust systems, are oxidizing. Other services are oxidizing because of the operating temperature and media involved.
THERMa-PUR™ is a proprietary gasketing material created by Garlock and designed for use in high temperature sealing applications. It is produced using an environmentally friendly, solvent-free process and combines a unique formulation with a patent-pending fiber core. THERMa-PUR is yet another innovative Garlock Sealing Technologies sealing solution that provides more than just temperature resistance.
In addition to our existing line of THERMa-PUR offerings, Garlock is now adding a high temperature THERMa-PUR Spiral Wound. The THERMa-PUR Spiral Wound gasket is designed for use in extreme temperature and aggressive chemical applications. THERMa-PUR Spiral Wounds are yet another innovative family of Garlock products born from customer driven innovation.