12182017Mon
Last updateMon, 18 Dec 2017 3pm

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Process Instrumentation in Oil and Gas

Process Instrumentation in Oil and Gas

Process instrumentation is an integral p...

Check Valves in LNG Cryogenic Service

Check Valves in LNG Cryogenic Service

Because natural gas is currently conside...

Will Smart Machines Obsolete Human Resources?

Will Smart Machines Obsolete Human Resources?

Is artificial intelligence (AI) going to...

Is Valve Live Loading an Option?

Is Valve Live Loading an Option?

Valves leak. There’s no getting ar...

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Construction and Mining: Is 2018 The Year for Growth?

Construction and Mining: Is 2018 The Year for Growth?

Tuesday, 12 December 2017  |  Kate Kunkel

While there is a degree of optimism in the mining industry that hasn’t been seen for some years, much uncertainty still exists in this sector. A...

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Industry Headlines

United Valve Names Jim Nelson Engineering and Production Manager

2 DAYS AGO

United Valve LP has promoted Jim Nelson to production and engineering manager. Nelson will be responsible for overseeing all production and engineering activities at United Valve.

“Jim Nelson has demonstrated consummate professionalism and shown his strong leadership skills, earning the respect ...

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Setpoint I.S. Honored by Baton Rouge Business Report

3 DAYS AGO

Setpoint Integrated Solutions (Setpoint I.S.) was honored this fall at the Baton Rouge Business Report’s Top 100 Private Companies Luncheon. Celebrating its 35th Anniversary this year, the Baton Rouge Business Report hosts many events in the community.

At the most recent event , the Top 100 Private C...

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EIA Forecasts Record U.S. Oil Output in 2018

3 DAYS AGO

The U.S. Energy Information Administration (EIA) estimates that U.S. crude oil production averaged 9.7 million barrels per day (b/d) in November, up 360,000 b/d from the October level. Most of the increase was in the Gulf of Mexico, where production was 290,000 b/d higher than in October. Higher pro...

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Chemical Industry Growth Rate Surpasses 20-Year Average

4 DAYS AGO

The U.S. chemical industry is riding a global wave of growth as the world’s major economies experience an upswing for the first time in a decade. Increased output and accelerating growth rates that surpass the previous twenty-year average will help cement the business of American chemistry as ...

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Empire State Manufacturing Grew at Slower Pace in December

-1 DAYS AGO

Business activity continued to grow at a solid clip in New York State, according to firms responding to the December 2017 Empire State Manufacturing Survey . The headline general business conditions index, at 18.0, remained close to last month’s level. The new orders index and the shipments inde...

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U.S. Industrial Production Up 0.2% in November

-1 DAYS AGO

Industrial production moved up 0.2% in November after posting an upwardly revised increase of 1.2% in October. Manufacturing production also rose 0.2% in November, its third consecutive monthly gain, and was 2.4% above its year-earlier level.

The increase in November reflected a gain of 0.4% for durabl...

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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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