05272017Sat
Last updateFri, 26 May 2017 2pm

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The Future of Coal: Efficiency Over Politics?

The Future of Coal: Efficiency Over Politics?

Many changes in the power industry have ...

Valve World Americas Event Set for June 20-21

Valve World Americas Event Set for June 20-21

End users, distributors, EPC/AEC personn...

Water Hammer

Water Hammer

Water hammer is a shock wave transmitted...

Turning the Tables on Valve Corrosion

Turning the Tables on Valve Corrosion

Multiple valve manufacturers and users w...

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Industry Headlines

Emerson Acquires MYNAH Technologies

3 DAYS AGO

Emerson has completed the purchase of MYNAH Technologies, a long-time Emerson alliance partner. The addition of MYNAH will help support Emerson Automation Solutions and its Operational Certainty program. Terms of  the acquisition were not disclosed.

MYNAH software is currently in use at more than ...

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Roger Fix Named Chairman of Flowserve

4 DAYS AGO

In its most recent annual meeting, Flowserve announced that Bill Rusnack and Lynn Elsenhans have retired as members of the board of directors. Flowserve also announced that board member Roger Fix has been elected to replace Rusnack as chairman.

"Bill and Lynn provided years of distinguished service to ...

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Oil-Fired Plants Provide Small Amount of U.S. Electric Capacity, Generation

2 DAYS AGO

According to the U.S. Energy Information Administration , roughly 70% of petroleum-fired electric generating capacity that still exists today was constructed prior to 1980. Utility-scale generators that reported petroleum as their primary fuel comprised only 3% of total electric generating capacity at...

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ExxonMobil, SABIC Agree on Proposed Petrochemical Project

4 DAYS AGO

Affiliates of Exxon Mobil and SABIC (Saudi Basic Industries Corporation) signed an agreement to conduct a detailed study of the proposed Gulf Coast Growth Ventures project in Texas and begin planning for front-end engineering and design work. The agreement was signed during the Saudi-US CEO Forum in R...

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Kansas City Fed Manufacturing Survey Shows Expansion in May

1 DAY AGO

Tenth District manufacturing activity continued to expand at a moderate pace in May, and expectations for future activity increased strongly. Price indexes were mixed, but recorded little change overall. The month-over-month composite index was 8 in May, up from 7 in April but down from 20 in March.

Ac...

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Business Borrowing for Capital Investment Up 8% in April

2 DAYS AGO

The Equipment Leasing and Finance Association’s (ELFA) Monthly Leasing and Finance Index, which reports economic activity from 25 companies representing a cross section of the $1 trillion equipment finance sector, showed their overall new business volume for April was $7.9 billion, up 8% year-ov...

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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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