Nonstandard Valve Model for Pipe Stress Analysis: Angular, 3-way, 4-way, with Actuator

In the process or the power piping industry, many a time several non-standard valves are used for some specific requirements. A few examples of those are Angular Valves, Three-Way valves, Four-way valves, valves with heavy Actuators, etc. This need to be modeled properly to get the actual effect is stress analysis. this article will briefly discuss the modeling of such valves.

Angular Valve With Equal Legs

If the angular valve has equal legs, then it can be modeled using an ordinary valve element. Just put it into a node between two pipes. Pipes can have a different diameter. One half of valve length will be placed through the first pipe direction and one half through another.

Modeling Angular Valve with Equal Legs
Modeling Angular Valve with Equal Legs

Angular Valve With Unequal Legs

If the valve has unequal leg lengths, then it can be modeled using rigid elements. The total weight of rigid elements should be equal to the valve weight. To model temperature expansion the temperature and material should be specified in a rigid element. Also, flanges can be added into end nodes of the valve to check leakage.

 Modeling Angular Valve With Unequal Legs
Modeling Angular Valve With Unequal Legs

Three-Way Valve

The three-way valve can be modeled just using 3 rigid elements. The total weight of rigid elements should be equal to the valve weight.

Modeling Three Way Valve in Start-Prof
Modeling Three Way Valve in Start-Prof

Four-Way Valve

In START-PROF four-way valve can be modeled using 4 rigid elements. The total weight of rigid elements should be equal to the valve weight.

Modeling 4-way Valve in Start-Prof
Modeling 4-way Valve in Start-Prof

Valve with Heavy Wheel, Actuator or Actuator Modeling

In START-PROF the heavy wheel or actuator can be modeled as node weight load at the actuator center of gravity. This mass should be connected to the valve using rigid elements with zero weight to consider eccentricity. Proper modeling of actuator eccentricity is especially important for seismic analysis of piping systems because the eccentric mass will produce a great additional torsion and bending moments on the piping system.

Modeling Valve with Actuator
Modeling Valve with Actuator

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Alex Matveev

Alex Matveev is one of the authors of pipe stress analysis codes GOST 32388-2013 Process Piping, and GOST 55596-2013 District Heating Networks. He is also one of the developers of PASS/Start-Prof software, which is developed since 1965 and used in 95% of process, power, district heating, gas and oil transportation design companies in Russia and CIS countries; it is industry standard in that region. He is the head of the PASS/START-PROF pipe stress analysis software development team. Also, He offers technical support and training for users of their software that number already 3000+, developing since 1965, industry standard in several countries for 50+ years, translated into English in 2017, come out from their domestic market, and started sales for the international market since 2018.

2 thoughts on “Nonstandard Valve Model for Pipe Stress Analysis: Angular, 3-way, 4-way, with Actuator

    1. Flanges can be added to valve length. Just increase the length of rigid elements
      Or add flange element https://www.passuite.com/kbase/doc/start/WebHelp_en/index.htm#t=flange.htm

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