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Last updateThu, 29 Sep 2016 6pm

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Caution: Horizontal Stem Installation Ahead

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Industry Headlines

Siemens Industry Partners for Self-Funded Efficiency Project

Thursday, 29 September 2016  |  Chris Guy

Montgomery County, TN has partnered with Siemens Industry Inc. to begin a nearly $5 million, self-funded efficiency project. The project will begin in l...

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Industry Headlines

Siemens Industry Partners for Self-Funded Efficiency Project

-1 DAYS AGO

Montgomery County, TN has partnered with Siemens Industry Inc. to begin a nearly $5 million, self-funded efficiency project. The project will begin in late October and will be completed by fall of 2017.

Siemens has guaranteed the savings – including 2,473,263 kWh of electricity per year; 34,154 c...

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Wolseley Reports 2016 Full Year Results

1 DAY AGO

Wolseley plc delivered an improvement in overall results for the fiscal year ending July 31, 2016, up 8.5% from last year. Revenue of $18.7 billion was 4.2% ahead at constant exchange rates and 2.4% ahead on a like-for-like basis. Price deflation, particularly in the U.S., reduced revenue by 1.5%. Imp...

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Construction Chemicals Market to Reach $40,154M by 2022

20 HOURS AGO

According to a new report published by Allied Market Research, the construction chemicals market is poised to reach $40,154 million by 2022, from $27,162 million in 2015, growing with a CAGR of 5.6% from 2016 to 2022. The concrete admixtures segment leads the construction chemicals market with more th...

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Goldman Sachs: U.S. Shale Firms to Pump More Oil by 2017

21 HOURS AGO

“Though the collapse in prices caused a wave of bankruptcies, total U.S. oil production has only fallen by about 535,000 barrels a day so far this year compared with 2015, when it averaged 9.4 million barrels, according to the latest federal data,” The Wall Street Journal reports .

“As...

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Durable Goods Orders Unchanged in August

18 HOURS AGO

New orders for manufactured durable goods in August were little changed at $226.9 billion, the U.S. Department of Commerce announced, following a 3.6% July increase. Economists were predicting a 1.5% decrease in August. Excluding transportation, new orders decreased 0.4%. Excluding defense, new orders...

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U.S. Consumer Confidence Surges to Nine-Year High

1 DAY AGO

The Conference Board Consumer Confidence Index, which had increased in August, improved further in September. The Index now stands at 104.1, up from 101.8 in August. The 104.1 figure is the highest since August 2007.

“Consumer confidence increased in September for a second consecutive month and i...

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The Human Factor in Valve Operation

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Worker safety, efficiency and the cost of operations, and most recently, new methods of control, are key focal points in operating valves. One factor that affects all areas is the role and level of human involvement in the processes.

THE CHOICES

Opening or closing valves can be completed either by manual input or automated devices driven by various energy sources. Manual operators are simple, inexpensive and require little peripheral planning beyond the installation and orientation of operators in the process line. Automated devices, on the other hand, require input energy systems, control systems, additional installation space and infrastructure for support, operation and maintenance.

Two concerns considered during selection of manual operators are the effort required to operate the valve and the number of turns some valves require. A lot of effort and a high number of turns can result in personnel fatigue, safety concerns, excessive time for operation and the need for multiple personnel. Also under consideration in selecting manual operators are the valve’s expected frequency of operation and the physical location of the operation, such as whether it might be high in a superstructure or situated in an inhospitable environment. Both also present challenges to humans.

Designers have to weigh all of these factors in their decision matrix to receive the most productive yet acceptable selection of how a valve should be operated. Two aspects that primarily define operator selection are human factors and economic factors. Human factors can be defined as the human capability to cycle the valve in a safe, timely and economically sound manner. These factors require considerations such as the work needed to be done (turns and rim pull) to operate the valve, the environment in which the valve is located, the time required to complete the task, and the health and safety of the personnel involved. Economic factors include the cost of the actuator as well as the cost of infrastructure, which could include wiring, controls system, power required and ongoing maintenance to support automated solutions.

THE SPECS INVOLVED

Specifications for the highest values personnel should exert on levers or handwheels to operate a valve are defined in the industry, with current API specifications limiting pull to 360 newtons (80 pounds-force). Mechanical advantage can be used to decrease the pull required to open or close the valve by increasing the length of the lever or diameter of the handwheel mounted on the valve. How­ever, the maximum lever length or handwheel diameter is also limited by industry specifications.

As valve torque increases, maximum limits imposed by industry standards result in levers transitioning to gear units to increase mechanical advantage. However, this increase in mechanical advantage comes with the disadvantage of increasing the number of turns to move the valve across the full stroke distance.

The higher number of turns results in longer time required to cycle the valve at a constant number of revolutions per minute. With significant gear reduction, the number of turns required for full cycle can number in the hundreds. This increased number of turns leads to a greater opportunity for accidents or injury to personnel due to repetitive motion and fatigue. Companies will limit the rim pull and number of turns to reduce the risk. Once established limits are exceeded for turns, the valve is generally required to be automated.

Communicating what human factor limits might be imposed on valves can provide suppliers the opportunity to recommend the best value of operator for manual valves. Until recently, the valve industry was limited to levers, bevel gears and traditional worm gears for manual cycling. Once these devices exceeded worker safety limits, a valve purchaser’s only choice was to select an automated solution. However, new devices available in the marketplace extend the range of manual operators. These devices can reduce initial capital costs, reduce site design complexity and minimize operating expenditures. The devices include high-efficiency gear operators and portable drivers coupled with well-designed arrestors.


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