05052016Thu
Last updateWed, 04 May 2016 7pm

i

Food and Beverage Processing

Food and Beverage Processing

When wandering the grocery store aisles,...

Variable Frequency Drives in Electric Actuators

Variable Frequency Drives in Electric Actuators

Electric actuators are vital for operati...

Subscribe

SUBSCRIBE

•  Digital magazine

•  Print magazine

•  VALVE eNews

Read the latest issue of VALVE Magazine

BUYERS GUIDE 300x220

New Products

  • ja-news-2
  • ja-news-3

Industry Headlines

G7 Countries Vow to Support Energy Investments

10 HOURS AGO  |  Chris Guy

Leaders from Canada, France, Germany, Italy, Japan the UK and the U.S. have pledged to “promote investing in energy projects through the oil pri...

Readmore

Loading...
Advertisement
i

Industry Headlines

Spirax Sarco Supporting the Enbridge Ride to Conquer Cancer

13 HOURS AGO

Spirax Sarco USA is teaming up with Spirax Sarco Canada for the Enbridge Ride to Conquer Cancer. From June 11-12, 2016, participants will cycle 200 km with thousands of other men and women throughout the countryside of Ontario, Canada. All net proceeds will benefit Princess Margaret Cancer Centre.

Th...

Readmore

Garlock Acquires Rubber Fab Technologies

1 DAY AGO

Garlock has acquired the business and assets of Rubber Fab Gasket & Molding Inc. through its parent company EnPro Industries.

Rubber Fab, headquartered in Sparta, NJ, is a recognized supplier of high performance sanitary gaskets, hoses and fittings for hygienic process industries such as pharmace...

Readmore

G7 Countries Vow to Support Energy Investments

10 HOURS AGO

Leaders from Canada, France, Germany, Italy, Japan the UK and the U.S. have pledged to “promote investing in energy projects through the oil price crash to ensure a steady stream of supply” and “encourage financial institutions to invest in energy projects and infrastructure,&rdquo...

Readmore

New Study Shows Demand for Natural Gas Will Grow

13 HOURS AGO

The National Association of Manufacturers (NAM) Center for Manufacturing Research and IHS Economics released a new comprehensive study that reveals how natural gas has strengthened manufacturing and encouraged U.S. manufacturing growth and employment and highlights the positive impact to communities a...

Readmore

U.S. Economy Grew 0.5% in First Quarter

1 DAY AGO

U.S. GDP increased at an annual rate of 0.5% in the first quarter of 2016, according to the advance estimate released by the Bureau of Economic Analysis. In the fourth quarter, real GDP increased 1.4%.

The increase in real GDP in the first quarter reflected positive contributions from personal consumpt...

Readmore

ISM: Manufacturing Activity Increased in April

2 DAYS AGO

Manufacturing expanded in April as the PMI registered 50.8%, a decrease of 1% from the March reading of 51.8%, indicating growth in manufacturing for the second consecutive month, following five consecutive months of contraction in manufacturing.

The Institute of Supply Management (ISM) reports that 15...

Readmore

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.

Advertisement

  • Latest Post

  • Popular

  • Links

  • Events