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Technical

Improving Valve Sealing Performance and Reliability

From time to time, we are re-posting well-received or particularly valuable articles that have previously run on VALVEMagazine.com so that those who might have missed them will be able to catch up on the best of the best. This article, “Improving Valve Sealing Performance and Reliability” initially ran on November 17, 2014.


Approximately 300,000 tons of fugitive emissions are released each year in the United States, according to the Fluid Sealing Association, and regulations put in place to lower that number are being added every year.

Combine that regulatory pressure and the stresses of today’s economic environment, and it is obvious that original equipment manufacturers (OEMs) and end users are increasingly seeking solutions that not only reduce emissions but also result in a permanent and noticeable increase in the service life of their products and equipment. Performance, value, reliability, repeatability and safety are all factors that are taken into account when developing and purchasing products to perform in this environment.


The Science Behind Steam Assisted Flares

Flares are a common site in petrochemical plants. They are used to safely incinerate products that need to be disposed. Ideally, the load on a flare would be very light. However, there are times where there is a large amount of product that cannot be stored and incineration is the most practical solution. High loads on flares will normally occur during an upset condition such as a safety valve opening or a unit being out of service that would normally process the product being sent to the flare.

When incinerating these products, combustion efficiency is of paramount importance as well as the avoidance of “smoking” or releasing carbon that can be seen. To accomplish both of these goals, flares often use steam or air for the flaring process.

Great-Tasting Brews Show Value of New Water Purification System

Consumers don’t often think about the fact that their electric power, clothes and even the semiconductors that go into the chips for computers and cell phones are manufactured using massive amounts of water. In fact, in 2013, private industry was responsible for 65% of freshwater withdrawals. While increased concern about climate change has successfully led to declines in electricity use in the U.S., industry continues to be as inefficient with its water use today as it was 20 years ago.

“What little public awareness there’s been on water conservation has focused on steps families take in their homes: shorter showers, shrinking their lawns, flushing the toilet less frequently. Industry basically has been mirroring those steps: tightening valves and reducing the use of high pressure hoses in cleaning applications. These are certainly important, but are simply a first step in how we can minimize water waste,” says Nadav Efraty, CEO of Desalitech.

Valves in a Cement Slurry Line

Basically everywhere you look in modern society, you see something made of concrete. Often we see trucks traveling down the road, drums spinning to keep the cargo mixing on their way to a job site in a subdivision or business park. It’s so common, in fact, that most people barely give it a second thought, but the process that turns limestone into towers of concrete and steel is one that creates its own challenges for valves in a cement plant, especially those in the slurry line.

One of the largest cement companies in the world is Lafarge, which produces cement for residential and commercial construction and for oil wells. Ed Kunkel worked for Lafarge at its plant in southwestern Ontario for more than 30 years, and he provided much of the process line and valve specification information for this article. We also spoke Ed Holtgraver of QTRCO, Inc., Tomball, TX, who provided us with additional information about valves and actuation.

Digital Valve Control Leads to Increased Plant Availability

Surge is characterized by fast flow reversals through a compressor and is caused by a large-scale breakdown of flow patterns within the compressor. Surge happens at low flow rates, often when the downstream demand decreases. When flow decreases below a certain minimum point, flow patterns in the compressor become unstable and fluid can move back through the compressor from the high-pressure side to the low-pressure side.

Because surge is a fast, high energy phenomenon, it can introduce excessive dynamic loads on internal components, such as thrust bearings, seals and blades as well as introduce unwanted pipeline vibrations. The cost of replacing compressor seals alone is on the order of $20K to $50K. Over time, surge can introduce fatigue failures that can damage the entire compressor.

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