Smart Operation Mode Editor

Operation Mode Editor allow you to analyze several operation modes of piping in one project file. Smart Operation Mode Editor is high-level tool. It automatically generates the special template load cases for operation mode and additional force-based loads combination, specified by user. Manual creation of load cases is not needed. User can concentrate on piping design, not on creation of proper load case combinations. Smart operation mode editor will take care on this itself without errors due to human factor and lack of knowledge.

You can add Operation Modes or Force Loads.

Operation Mode - piping operation mode with certain pressure, temperature, fluid weight, support displacements, etc. (1, 2, 3, etc.). Main operation modes is used to model different displacement-based loads on piping. For example main modes could be general operation mode, emergency operation mode, test mode, steaming mode, hog and sag modeling for ship piping etc. Main operation mode has several piping states: hot state, cold state.

Force Loads - additional forces applied to the one of operating modes (4.1, 6.1, etc.). Force loads are used to model additional sustained and occasional forces like safety valve thrust forces, slug flow loads, water hammer loads, blast loads, wind loads, snow loads, ice loads, etc. Concentrated forces are applied in nodes and uniform forces are applied in pipes. The number of force loads is unlimited.

Here are the example of operation modes (below). Piping has five operation modes: Main, steaming, filling, discharging, test. Operation mode 2 has two additional force loads (relief valve 1, relief valve 2).

To see online description of automatically generated load case templates just click help buttons "?":

When all operation modes are added, this window can be closed. You can select the current operation mode on the toolbar. All data will be displayed and entered only for current operation mode. If you open the pipe properties, you will see pressure and temperature only for current operating mode. If you want to see the properties of another operation mode, then you should change the current operation mode and open the pipe properties again.

Properties, that can be changed in different main operating modes:

• Pressure

• Temperature

• Fluid density

• Insulation weight

• Additional uniform loads in the pipe

• Additional loads in the node

• Support movements

• Ambient temperature in Project settings

All other properties can't be changed.

If several operating modes are specified in operation mode editor, then first sustained operating mode is used for La and Lb calculation and these values are used for all operating modes.

If more than one operation mode is specified, then "L" buttons appear near the fields that can be changed in different operation modes. If you click this button you will see all property values in different operation modes.

Default Operating Modes

In new project should be added at least one operating mode. If test mode analysis is checked in project settings, then test mode should be added too. Below you can see the example of minimum set of operating modes for new project. If test mode is not required then first row can be deleted

Real Load Cases

Real loads cases are generated based on the information specified in operation mode editor. After you run analysis, START-PROF automatically generate template load cases according to operation modes.

A differential friction model is used for START-PROF piping analysis. Sequential transition from one state to another is considered as a chain:"installation mode" - "operating mode" - "cold mode". At each state, an analysis of the deformed state is done. For example, when analyzing in cold mode, the piping in the current stressed-deformed state corresponding to the operating mode is considered and weight plus negative temperature difference (cooling) is added. Friction force is each support is first change direction, while leaving the support in its place, then start to move to their position in installation mode. But supports do not return to their initial (installation) position.

Theoretically, several cycles of "operation state" - "cold mode" occurring during piping use can be considered. But experiments show that the first heating-cooling cycle gives the greatest stress amplitude, so the first cycle is sufficient for determining fatigue failure margins.

Elastic deformation transitions into plastic (residual) deformation in high-pressure pipelines with creep. This leads to gradual decrease of stress in operating mode and negative stress in cold mode. RD 10-249-98 section 5.2 and GOST 32388-2013 use averaging factor χ and relaxation factor δ in safety analysis for pipelines with creep, which decrease the real temperature difference in operating mode and increase it in cold mode. This allows an approximate safety analysis with a margin, but does not give an accurate value of  node displacement, which determines the piping deformed shape, and visible displacement and support loads. Separate analyses are done in START-PROF to overcome this shortcoming:

• stress relaxation in operating mode is not taken into account for calculating loads on equipment supports (i.e., analyses are done for the first heating without considering χ and δ factors)

• piping state after stress relaxation is used for safety analysis and equipment load analysis in cold state (i.e., taking into account averaging factor  χ and relaxation factor δ)

Table Legend

L - load case

T - design temperature

Tambient - Ambient temperature, input in Project Settings

Tt - test temperature, input in Project Settings

P - design pressure

Pt - test pressure

Sh - allowable stress at hot temperature

Sc - allowable stress at cold temperature

Sy - yield stress at test temperature

St - allowable stress at test temperature

fat - fatigue curve

SUS - sustained

OPE - operational

OCC - occasional

HGR - hanger selection

CLD - cold

EXP - expansion

F - additional non-weight loads. Considered in all operating modes. Not used for seismic load value calculation

Fw - additional weight loads. Considered in all operating modes. Used for seismic load value calculation (Fw+W)

H - variable or constant spring hanger force

CS - cold spring

W - pipe weight+Insulation weight+fluid weight or pipe weight+Insulation weight+fluid weight depending on code requirement. Also insulation weight can be zero in installation state. FOR GOST 32388, GOST 55596 and some other codes the following value is used: pipe weight*1.1+Insulation weight*1.2+fluid weight*1.0 or pipe weight+Insulation weight+fluid weight depending on code requirement.

Ww - pipe weight+Insulation weight+(water or zero weight at test state)

D - support displacement at operation state

Dt - support displacement at test state

Dd - Support settlement

E, alfa - elastic modulus and thermal expansion factor

χ - creep stress averaging factor

δ - creep stress relaxation factor

Load Cases for low-temperature piping (RD 10-249-98, GOST R 55596-2013, GOST 32388-2013, CJJ/T 81-2013)

For piping without creep, template loads cases are shown in table below

• Load cases L1 - L2 are performed for operation modes in which the "Spring Selection" option is activated

• Load cases L3 - L5, L4* are performed for each main operation mode with mode type = SUS (sustained)

• Load cases L6 - L8 are performed for operation modes in which the "Cold State" option is activated

• L9 check is performed between cold and hot mode and between different operation modes

• Load case L10 is performed for test mode

• Load cases L11 - L12 are performed for each main operation mode with mode type = OCC (occasional)

• Load cases L13 - L15 are performed for each additional force-based loading

• If options "Seismic", "Wind", "Snow" are selected then automatically performed several additional load case analysis for seismic, wind and snow loads

Note * - pressure is assumed to be 0 in RD 10-249-98.

Load Cases for high-temperature piping (RD 10-249-98, GOST 32388-2013)

Load cases for high-temperature piping the same as for low-temperature piping, but have two differences:

• Load cases L3 - L6 for main operation mode is different. In L5 the creep piping behavior is considered

• Added load case L6* that take into account the self cold-springing effect that happen in high-temperature piping due to creep

• If options "Seismic", "Wind", "Snow" are selected then automatically performed several additional load case analysis for seismic, wind and snow loads

Note * - pressure is assumed to be 0 in RD 10-249-98.

Load Cases for SNIP 2.05.06-85 and SP 36.13330.2012

Load cases:

• Load cases L1 - L2, L5 are performed for operation modes in which the "Spring Selection" option is activated

• Load cases L3, L3*, L3** are performed for each main operation mode

• Load case L4 is performed for test mode

• Load case L6 is performed for each additional force-based loading

• If options "Seismic", "Wind", "Snow" are selected then automatically performed several additional load case analysis for seismic, wind and snow loads

Note * - analysis uses standard load values without considered load safety factors

Load Cases for ASME B31, EN, GB and DL/T Codes

Template loads cases are shown in table below:

• Load cases LH1 - LH2 are performed for operation modes in which the "Spring Selection" option is activated

• Load cases L1 - L6 are performed for each main operation mode

• Load case L7 is performed for operation modes in which the "Cold State" option is activated

• L9 check is performed between cold and hot mode and between different operation modes

• Load case L10 is performed for test mode

• Load cases L11 - L13 are performed for each additional force-based loading

• Load cases L4 and L8 are performed for main operation mode in which the "Creep" option is activated

• If options "Seismic", "Wind", "Snow" are selected then automatically performed several additional load case analysis for seismic, wind and snow loads

Option 1. Consider hot modulus for support loads (in Project Settings)

Option 2. Stress range from operation to cold (in Project Settings and Stress Table)

Note: SIF and k-facrtors are calculates using maximum pressure from all load cases except occasional and test, and used for all load cases except occasional.

See also piping operating modes for more information.

* - additional non-code load cases to consider the creep effect (detailed creep analysis requirements are missing in B31.1 and B31.3 codes)

On the screenshot below the explanation where are the each load case is used.

Stresses:

Loads, Displacements, Expansion Joint Deformation

Internal Forces

Menu Access

File > Operation Mode Editor