Tag Archives: Fluid Sealing Association

ASTM International Committee Releases Latest Room Temperature Tightness Test

The American Society for Testing and Materials (ASTM) International Committee F03 on Gaskets recently released the latest standard practice to derive gasket design constants for the proper design of bolted flanged joints (BFJs): ASTM F2836-18. End users of gaskets can then use these gasket constants for proper BFJ design using calculation methods that are currently being developed by a special working group of American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC) Section VIII at the time of this publication. In this article, the current test procedure, the mathematical models of the test evaluation and the calculation of the characteristics are described and discussed.

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Updates to FSA’s KnowledgeBase

The online FSA KnowledgeBase was officially launched in May 2017 as part of the FSA’s mission to be “. . . the primary source of technical information” for the fluid sealing industry’s products and their applications. This marked the transition from a print-based handbook focus to an online focus for training and education resources. At launch, the KnowledgeBase contained approximately 35 pieces of content and videos across seven categories of mechanical seal subject matter. Since that time, the FSA has expanded and improved the site content, which now has more than 230 files on mechanical seals, expansion joints, and an archive of “Sealing Sense” articles spanning the full range of FSA topics. There are more than 750 registered users, and the site has tracked nearly 5,000 online sessions from that user base.

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How Not to Use a Rubber Expansion Joint

Rubber expansion joints are likely the least understood and most abused component in a piping system. They are flexible, stretchy and easily forced into lots of places despite what the installation instructions say. Most of the time, rubber joints are merely an afterthought in multi-million dollar piping systems – until things go awry.

The rubber joint is unmatched for vibration isolation. If properly installed, a rubber joint can greatly reduce equipment nozzle loads. Its resilience allows it to be installed in many different systems under a range of temperatures, pressure, and media. What could possibly go wrong?

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The Danger of Complacency in Equipment Selection & Installation

When working with valves, flanges and pumps, operators should never be complacent. The wrong gasket or packing in a deadly application could result in loss of life. Ensuring the correct materials are suitable for the application requires special attention because safety is critical. As Gordon DeLeys, compliance assistance specialist at the United States Occupational Safety and Health Administration (OSHA), said, “Safety should not be a company priority since priorities in an organization can and usually change. Safety and health need to be a core value of an organization. Safety is really a case of values versus priorities.”

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How to Prevent Galvanic Corrosion of Valve Stems

Valve packing is a necessity for plants trying to contain product and meet the latest emission requirements However, finding a sealing product that works and has longevity can be a challenge. Graphite-based packing can be a good choice for stem sealing when elevated temperature requirements are necessary. This is due to graphite’s ability to maintain its sealing properties at temperatures that cause polytetrafluoroethylene (PTFE) to break down and allow leaks to occur. However, graphite is not an electrical insulator like PTFE; graphite will act as a metal and undergo galvanic corrosion if the environment is right.

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The Bolt as a Machine & the Importance of Liberal Lubrication

The bolt as a screw is one of the six simple machines. A simple machine magnifies or changes the direction of an input force. By means of mechanical advantage, a bolt can dramatically increase its input force. Take for example an 8-bolt flange with 3/4-inch diameter bolts. By manual effort alone, a person can easily develop a total bolt load of over 110 tons. This article explains the mechanics by which the mechanical advantage is possible and then draws attention to how friction can deteriorate the end effect of a bolt’s mechanical advantage.

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What to Understand About Chemistry to Make the Best Materials Choices

In chemistry, a strong oxidizer is a substance (like chromic acid) that can cause other substances (like seals and gaskets) to lose electrons. So, an oxidizer is a chemical species that undergoes a reaction that removes one or more electrons from another atom. This causes a change in mass. Metals will turn into their respective heavier oxides, and the carbon in graphite will oxidize into carbon dioxide – which, although molecularly heavier, is a gas at room temperature. This happens in pumps, valves, pipelines or any other equipment that have seals and gaskets carrying a strong oxidizer. It will cause pitting or rust and, depending on your choice of seal material, may require shorter service intervals.

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Custom Rubber Expansion Joints

Keeping aging facilities and equipment maintained is an everchanging task that can jeopardize the goal of maximizing uptime. Years of thermal cycling, vibration or foundation settling can disorient piping or pumps. Piping engineers will use rubber expansion joints to account for these types of challenges in a rigid piping system. Permanent misalignment can set
in after years of operation. The original size expansion joint could no longer be the best fit when it comes time to replace.

Replacing a permanently misaligned expansion joint connection with the original part could lead to reduced service life and/or missed expectations of the new expansion joint. Determining the best way to accommodate this when it comes time to replace the existing expansion joint can have long-term effects on reliability.

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Sealing High-Speed Shafts in Turbomachinery

Rotating liquid pump shafts that are originally sealed with soft packings mostly use contacting face seals, also known as mechanical seals. Typical rotational speeds are roughly between 1,000 and 3,600 revolutions per minute (rpm). In turbomachinery — such as compressors and expanders—the rotational speeds are higher and mechanical seals would not
immediately appear to be an option, due to greater rubbing speeds along with a lack of liquid cooling and lubrication.
Nevertheless, from the late 1970s when they were first marketed, noncontacting mechanical seals, known as dry gas seals in cartridge form, have been used in most gas turbomachinery.

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API 622: Valve Packing for Fugitive Emissions

The American Petroleum Institute (API) has developed two commonly used standards designed specifically for the petroleum industry. They include API 622 “Type Testing of Process Valve Packing for Fugitive Emissions,” and API 624 “Type Testing
of Rising Stem Valves Equipped with Graphite Packing for Fugitive Emissions.” API 622 and API 624 may be specified by an end-user. Valve OEMs must use API 622-approved packing for any valve on test for API 624.

Since the introduction of the U.S. Clean Air Act in 1963, the U.S. Environmental Protection Agency (EPA), as well as individual states, have set increasingly stringent restrictions regulating fugitive emissions from industrial facilities.

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