05242016Tue
Last updateTue, 24 May 2016 3pm

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Industry and Regulatory Changes in Offshore Operations

Industry and Regulatory Changes in Offshore Operations

On May 13, 2016, the offshore oil and ga...

Strategies for Successful SIS Valve Diagnostic Implementation

Strategies for Successful SIS Valve Diagnostic Implementation

End users and contractors alike strive t...

Stop Check Valves

Stop Check Valves

Stop check valves are vital to several i...

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Industry Headlines

MRC Global Expands Service to Chemours in the U.S. Gulf Coast

17 HOURS AGO

MRC Global Inc. announced that its subsidiary, MRC Global (US) Inc., has been awarded an agreement to be the primary provider of pipe, valve, fitting (PVF) products and services to all U.S. locations of The Chemours Company. The five-year agreement added the Gulf Coast region and also includes valve a...

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Sunbelt Supply Opens Shanghai Valve and Automation Center

3 DAYS AGO

Sunbelt Supply celebrated the grand opening of its new Valve and Automation Center with an open house on May 12, 2016 in Shanghai, China. The open house welcomed 80 customers and manufacturers. Attendees toured the newly stocked warehouse and automation center .

Sunbelt Supply Shanghai is a joint ventu...

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Gulf Coast Petrochemical Boom Contributing to Global Plastics Glut

-1 DAYS AGO

A surge in new plastics chemical capacity coming from low-cost producers in North America (specifically the U.S. Gulf Coast), the Middle East and China is driving the global market for key plastics polyethylene (PE) and polypropylene (PP) to oversupply, which will pressure margins for producers and ...

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U.S. Chemical Production Stalled in April

20 HOURS AGO

According to the American Chemistry Council (ACC), the U.S. Chemical Production Regional Index (U.S. CPRI) was flat in April , following a 0.4% gain in March, and a 0.1% decline in February, as measured on a three-month moving average (3MMA). In April, the Gulf Coast was the only region to post a smal...

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Markit PMI Shows U.S. Manufacturers Stagnating in May

-1 DAYS AGO

The U.S. manufacturing sector crept closer to stagnation in May, with the seasonally adjusted Markit Flash U.S. Manufacturing Purchasing Managers’ Index (PMI) registering only slightly above the neutral 50.0 mark at 50.5. This was down from 50.8 in April and signaled only a marginal improvement...

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Why Innovation is the Key to U.S. Manufacturing Growth

22 HOURS AGO

Manufacturing may be facing some headwinds, but it’s undeniably in the midst of a technological renaissance that is transforming the look, systems and processes of the modern factory. Despite the risks — and despite recent history — industrial manufacturing companies cannot afford ...

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Actuation in Nuclear Power Plants

vmfall11_nuclear_h

The thousands of actuators used in a nuclear plant face some pretty tough conditions as well as rigorous testing.

Currently, 104 nuclear power-plant reactors are working in the United States, and all of them have operating environments that are extremely challenging. Of those 104 plants, 35 are classified as boiling and 69 as pressurized water reactors.

While the design details vary from plant to plant, each nuclear facility has thousands of valve actuators used in various processes and applications. The newest-generation nuclear plant has more than 13,000 valves.

It’s clear, then, that valve actuators play vital roles in maintaining process safety, efficiency and productivity in a wide range of situations.

This article contains a brief description of some of the special circumstances encountered in challenging nuclear environments and the different styles of actuators used to meet demanding operational and safety requirements.

STRICT GUIDELINES AND REQUIREMENTS

vmfall11_nuclear_electric_actuatorWith O-ring sealed covers in place on this electric actuator, the motor, limit and torque switches, as well as other electrical components, are housed within a pressure-tight enclosure. This keeps out dirt and moisture and prevents breathing from expansion and contraction of the internal air caused by temperature changes.All equipment used in nuclear plants built in the United States is certified under stringent guidelines mandated by the Nuclear Regulatory Commission (NRC). Verification of reactors or equipment to standards from other countries is not acceptable for the 104 working reactors in the U.S.

To understand basic requirements the nuclear power industry faces in this nation, a review of the similarities and differences between nuclear power and fossil power is helpful.

In a fossil power plant, coal might be crushed and mixed with air to boil water, which produces steam to drive a turbine. With nuclear reactions, the process is different, but the operational objective is essentially the same—to heat water to produce steam to drive a turbine. With a coal steam generator, the activity of burning the pulverized coal and producing steam is contained within what is termed the “boiler island.” Because of the strong similarity to what happens in the coal plant, many engineers and technicians in a nuclear plant refer to the area where steam generation occurs as the “nuclear island.”

vmfall11_nuclear_cutawayThis cutaway illustration shows the internal components of a typical electric actuator.Within the nuclear reactor, equipment must meet rigorous standards. Since radiation is very high, the standards require all equipment materials used in this phase of the process to withstand high levels of radiation for the life of the plant. Therefore, materials such as iron or steel are required rather than aluminum. Also, temperatures in this portion of the plant are elevated, which will affect seal materials. The combination of severe environmental conditions determines the various coatings and paints allowed for use in this area, which is known as “inside containment.”

To be suitable for service in a nuclear reactor, an actuator must go through specific testing by outside testing agencies. The test reports produced must then be reviewed not only by the actuator suppliers, but by consulting engineers and the utilities themselves. Many documents also are reviewed by the NRC.

The tests for actuators used “inside containment” apply to all styles. The plants use electric motor operators as well as pneumatic cylinder actuators and hydraulic cylinder actuators. All of these actuators must be tested to ensure they can withstand the environment for their expected lives. Also, in addition to environmental concerns, the actuators must be able to operate during extreme accident conditions such as an earthquake.

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