Smart Operation Mode Editor

The Operation Mode Editor enables analysis of multiple piping operating conditions within a single project file. This high-level tool automatically generates specialized load case templates for operating modes and user-specified force-based load combinations. Manual load case creation is eliminated, allowing engineers to focus on piping design rather than load case configuration. The editor ensures proper load case combinations without human error or knowledge gaps.

You can add either Operation Modes or Force Loads.

Operation Mode - Defines a specific piping operating condition with pressure, temperature, fluid weight, support displacements, and other parameters (labeled 1, 2, 3, etc.). Main operation modes model displacement-based loads such as normal operation, emergency scenarios, testing, steaming, or ship piping hog/sag conditions. Each main operation mode includes hot and cold states.

Force Loads - Additional forces applied to specific operating modes (labeled 4.1, 6.1, etc.). These model sustained and occasional loads including safety valve thrust, slug flow, water hammer, blast, wind, snow, and ice loads. Apply concentrated forces at nodes and uniform forces along pipes. The number of force loads is unlimited.

The example below shows five operation modes: Main, steaming, filling, discharging, and test. Operation mode 2 includes two additional force loads (relief valve 1 and 2).

Click the "?" help buttons to view online descriptions of automatically generated load case templates:

Close this window after adding all operation modes. Use the toolbar to select the current operation mode. All data display and entry applies only to the current operation mode. Pipe properties show pressure and temperature for the current operating mode only. To view another mode's properties, change the current operation mode and reopen pipe properties.

Properties that vary by main operating mode:

• Pressure

• Temperature

• Fluid density

• Insulation weight

• Additional uniform pipe loads

• Additional nodal loads

• Support movements

• Ambient temperature in Project settings

All other properties remain constant across operating modes.

When multiple operating modes are specified, the first sustained operating mode determines La and Lb calculations for all modes.

Multiple operation modes trigger "L" buttons next to mode-specific fields. Click these buttons to view property values across different operation modes.

Default Operating Modes

New projects require at least one operating mode. If test mode analysis is enabled in project settings, include test mode as well. The example below shows the minimum operating mode set for a new project. Remove the first row if test mode is not required.

Real Load Cases

START-PROF automatically generates template load cases based on operation mode editor specifications after analysis execution.

START-PROF piping analysis uses a differential friction model. Sequential state transitions follow the chain: "installation mode" - "operating mode" - "cold mode". Each state analyzes the deformed condition. Cold mode analysis starts from the operating mode stressed-deformed state, then applies weight plus negative temperature difference (cooling). Friction forces at each support first reverse direction while the support remains stationary, then begin moving toward installation positions. Supports do not return to original installation positions.

Theoretically, multiple "operation state" - "cold mode" cycles could be analyzed. Experimental data shows the first heating-cooling cycle produces the highest stress amplitude, making it sufficient for fatigue failure margin determination.

High-pressure pipelines with creep experience elastic deformation transitioning to plastic (residual) deformation. This gradually reduces operating mode stress and creates negative cold mode stress. RD 10-249-98 section 5.2 and GOST 32388-2013 use averaging factor χ and relaxation factor δ for creep pipeline safety analysis, decreasing real temperature difference in operating mode and increasing it in cold mode. This approximate safety analysis provides margin but doesn't accurately calculate node displacement (determining piping deformed shape, visible displacement, and support loads). START-PROF performs separate analyses to address this limitation:

• Operating mode stress relaxation ignored for equipment support load calculations (first heating analysis without χ and δ factors).

• Post-relaxation piping state used for safety analysis and equipment load analysis in cold state (including 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. Excluded from seismic load calculations.

Fw - Additional weight loads. Considered in all operating modes. Included in seismic load calculations (Fw+W).

H - Variable or constant spring hanger force

CS - Cold spring

W - Pipe weight + Insulation weight + Fluid weight (composition varies by code). Insulation weight may be zero in installation state. GOST 32388, GOST 55596 and similar codes use: pipe weight*1.1 + Insulation weight*1.2 + fluid weight*1.0 or alternative combinations per code requirements.

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)

Non-creep piping uses the template load cases below:

• L1 - L2: Operation modes with activated "Spring Selection"

• L3 - L5, L4*: Each main operation mode with mode type = SUS (sustained)

• L6 - L8: Operation modes with activated "Cold State"

• L9: Check between cold/hot modes and different operation modes

• L10: Test mode

• L11 - L12: Each main operation mode with mode type = OCC (occasional)

• L13 - L15: Each additional force-based loading

• "Seismic", "Wind", "Snow" options generate additional load cases for seismic, wind, and snow loads

Load Cases for High-Temperature Piping (RD 10-249-98, GOST R 55596-2013, GOST 32388-2013)

High-temperature piping (creep) uses the template load cases below:

• L1 - L2: Operation modes with activated "Spring Selection"

• L3 - L5, L4*: Each main operation mode with mode type = SUS (sustained)

• L6 - L8: Operation modes with activated "Cold State"

• L9: Check between cold/hot modes and different operation modes

• L10: Test mode

• L11 - L12: Each main operation mode with mode type = OCC (occasional)

• L13 - L15: Each additional force-based loading

• "Seismic", "Wind", "Snow" options generate additional load cases for seismic, wind, and snow loads