07282017Fri
Last updateThu, 27 Jul 2017 5pm

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How to Choose the Best Rapid Prototyping Method

How to Choose the Best Rapid Prototyping Method

As new products are designed, including ...

Monitoring Valve Health via the Internet

Monitoring Valve Health via the Internet

Most valve end users are already using s...

Valves in Oxygen Service

Valves in Oxygen Service

In his presentation at VMA’s 2017 ...

Thermal Spray Coating

Thermal Spray Coating

Q: What are the pros and cons of us...

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The Actuation Selection Process

The Actuation Selection Process

Tuesday, 25 July 2017  |  Carlos Gamero

A common misconception in our industry is that actuating a valve is as simple as putting the most cost-efficient actuator on top of your valve of choi...

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Industry Headlines

Wolseley Industrial Group Names Daniel Hogge District Manager

8 HOURS AGO

Daniel Hogge has been appointed district manager of Wolseley Industrial Group’s Mid-Atlantic region, which includes Georgia, South Carolina and North Carolina and most of Florida and Virginia. Effective Aug. 1, Hogge will be responsible for managing the financial results of Wolseley Industrial G...

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TAQA Awards Schlumberger EPCIC Contract for Otter Field

1 DAY AGO

OneSubsea, a Schlumberger company, has been awarded an engineering, procurement, construction, installation and commissioning (EPCIC) contract for a subsea multiphase boosting system by TAQA for the Otter field in the UK North Sea. OneSubsea leverages Cameron flow control, process technologies and m...

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U.S. Crude Oil Production to Reach Record High in 2018

10 HOURS AGO

In EIA’s latest Short-Term Energy Outlook (STEO), total U.S. crude oil production is forecast to average 9.3 million barrels per day (b/d) in 2017, up 0.5 million b/d from 2016. In 2018, EIA expects crude oil production to reach an average of 9.9 million b/d, which would surpass the previous rec...

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Shale Sector to Be Cash Flow Positive by 2020

1 DAY AGO

The tight oil sector has struggled to generate positive cash flow since 2010. Last year, only one company in the sector posted positive cash flow. But there is light at the end of the tunnel. Wood Mackenzie’s new report " When will tight oil make money? " calculates that the five largest tight oil...

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U.S. Consumer Confidence Rebounds in July

1 DAY AGO

The Conference Board Consumer Confidence Index, which had declined marginally in June (a downward revision), improved in July . The Index now stands at 121.1, up from 117.3 in June. The Present Situation Index increased from 143.9 to 147.8, while the Expectations Index rose from 99.6 last month to 103...

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IHS Market PMI Index Reached Four-Month High in July

2 DAYS AGO

July data revealed a further acceleration in business activity growth across the U.S. private sector. At 54.2, up from 53.9 in June, the seasonally adjusted IHS Markit Flash U.S. Composite PMI Output Index signaled the strongest rate of expansion since January.

The pickup in business activity growth ...

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Extreme Valve Testing

VM-smr11-cryogenic_testTwo commonly used low temperature tests today measure the degrees for liquid nitrogen and liquid natural gas.

Valves today face more challenging conditions from a wider range of applications. As a result, users are asking for more and better testing.

Filling a valve up with water, adding pressure and looking for leaks might work for some valve specifications, but many of today’s demanding valve requirements call for much more stringent testing and evaluation. Special service applications such as hazardous fluids, nuclear power plants, high-pressure pipelines and more dictate a much broader testing and inspection regimen than traditional simple tests.

Many users are requesting valve manufacturers prove their products will operate satisfactorily at the higher and lower temperatures and more extreme pressures that their valves are advertised to reach. These may be the lowest cryogenic temperatures or elevated temperatures close to 1000° F (538° C). Such tests call for specialized equipment and test procedures.

VM-smr11-cryogenic_test_2Cryogenic testing is generally performed at temperatures ranging between -50° F (-46° C) and -320° F (-196° C).The most common of these more extreme tests is cryogenic testing. Such testing is generally performed at temperatures ranging between -50° F (-46° C) and -320° F (-196° C)—most often at -320° F (-196° C), which is the temperature of liquid nitrogen (LN). Standard practice is for the valve to be immersed in the LN up to the packing gland area, if the valve is equipped that way. The packing must be kept out of the LN or it could freeze the packing, seizing the stem and causing the valve to lock up and fail to operate. Because polymer seals do not function well at cryogenic temperatures, valve end connections must be the type that makes a solid mechanical connection. These include threaded, flanged or caps welded onto buttweld-end ends. Socketweld-end and buttweld-end valves without welded-on caps are very difficult to test at the lowest cryogenic temperatures.

One of the most popular low temperature services today is liquid natural gas (LNG). Valves for LNG are sometimes tested at -320° F (-196° C), but a more accurate test is performed at the actual LNG temperature of -260° F (-162° C).

Cryogenic testing is costly and hazardous and should only be performed by experienced, trained personnel. The test procedures for cryogenics are available from several standards-making-organizations, as well as end users. The most significant differences in testing procedure documents are allowable leakage rates.


VM-smr11-cryogenic-table1

PIPELINE VALVES

Pipeline safety has come to the forefront lately because of catastrophic pipeline failures. These failures have occurred primarily on older pipelines because quality requirements for new pipeline construction are very stringent. Valves for pipeline service are also scrutinized very closely. While all pipeline valves are hydrostatically tested at the factory, usually in accordance with API 6D, additional tests are almost always performed. The most common extreme test for pipeline valves is a long duration shell test, which is carefully monitored by a recording device tracking the pressure and the temperature of the valve as it is tested.

During these enhanced duration shell integrity tests, the pressure on the valve must be maintained, or the pressure drop must coincide with a proportional drop in temperature to avoid valve failure. It is not uncommon for test durations to run several hours long.


FUGITIVE EMISSIONS TESTING

VM-smr11-preparing_for_fugitive_emissions_testA valve is prepared to undergo fugitive emissions tests.The desire to keep our nation’s air clean is manifested in the valve industry through the Clean Air Act and various state and local regulations. For manufacturers to meet today’s low emissions requirements, valves must be tested to determine their ability to contain these fugitive emissions (FE). FE testing is now a requirement by most refiners and chemical companies that must contain hazardous fluids as part of their everyday processes.

FE testing requires the valve be pressured up with an easily measurable gas such as methane or helium, and then checking the body and seals, particularly the packing, for leakage. An alternative method is to create a vacuum drawn on the valve through a closed piping system and introducing a tracer gas into the areas of the valve exterior susceptible to FE leakage.

Two distinct schools of thought exist on what gas should be used to FE test a valve—schools separated by the Atlantic Ocean. In Europe, it is deemed unsafe to test with methane, so all testing must be performed with helium; in the U.S., the preferred test media is methane, which more closely resembles the molecular structure of the volatile organic compounds (VOCs) that both industry and government are working hard to control.

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