06252017Sun
Last updateFri, 23 Jun 2017 4pm

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Why Air Valves are Needed in Water Applications

Why Air Valves are Needed in Water Applications

Air valves are hydromechanical devices d...

Achieving Profitability Through Maintenance Management

Achieving Profitability Through Maintenance Management

One of the distinctions between maintena...

Control Valve Positioner Performance Diagnostics

Control Valve Positioner Performance Diagnostics

There has been discussion for some years...

Are Your Safety Instrumented Systems Proof Tests Effective?

Are Your Safety Instrumented Systems Proof Tests Effective?

Many people assume that a proof test of ...

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Industry Headlines

ITT Announces President of Industrial Process Business

2 DAYS AGO

ITT Inc. has appointed David J. Malinas as president of its Industrial Process business, reporting to Luca Savi, ITT's COO. In this role, Malinas will be responsible for delivering the strategic and operating plans of ITT's Industrial Process business, which employs about 2,500 people globally and h...

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Chesterton Expands Environmental Consulting Expertise

4 DAYS AGO

A.W. Chesterton Company  is expanding its global environmental solutions expertise with the addition of two highly experienced industrial emissions specialists, Bronson Pate and Beau Stander. Both will be joining FluidEfficiency, a Chesterton business group. Pate and Stander will serve in the ro...

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Smart Technology Transforming Oil & Gas Industry

3 DAYS AGO

“A new cadre of services companies, trying to sell the energy industry on the promise of a more efficient digital age, is fighting to get smart technology onto pipes, tanks, platforms and drills, in some cases deeply discounting prices to gain market share,” the Houston Chronicle reports .

C...

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U.S. Refineries Running at Peak Levels

4 DAYS AGO

Gross inputs to U.S. petroleum refineries, also referred to as refinery runs, averaged a record high 17.7 million barrels per day (b/d) for the week ending May 26, before dropping slightly to 17.5 million b/d for the week ending June 2 and 17.6 million b/d for the week ending June 9. According to th...

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Economic Indicators Index Rises for Fifth Straight Month

1 DAY AGO

The Conference Board Leading Economic Index (LEI) for the U.S. increased 0.3% in May to 127.0, following a 0.2% increase in April, and a 0.4% increase in March.

“The U.S. LEI continued on its upward trend in May, suggesting the economy is likely to remain on, or perhaps even moderately above, its...

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U.S. Manufacturing Technology Orders Continue Strong Recovery

2 DAYS AGO

Manufacturing technology orders made year-over-year gains in April according to the latest U.S. Manufacturing Technology Orders report from The Association For Manufacturing Technology (AMT). It was also the first month that orders showed gains year to date for 2017.

Monthly orders were up 12.3% compar...

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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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