Restraint Loads

This table displays support and restraint reaction forces. Loads are shown as projections on coordinate axes. Forces aligned with coordinate axes are positive. Counter-clockwise moments (viewed from axis end) are positive. Lifted-off supports and restraints are highlighted in blue.

See also How to Reduce Nozzle Loads in PASS/START-PROF

Table content and display depend on four configurable properties:

Property

Description

Operating Mode

Select operating mode for result display

Maximum - displays maximum absolute values from all operating modes

View analysis results from additional force loadings, seismic, wind, and ice loading cases

Submode

For each operating mode, PASS/START-PROF calculates multiple piping states

  • Maximum - displays maximum absolute load values for each axis across all states (Operating, Cold, Test, Cold after relaxation)

  • Maximum and minimum - displays maximum and minimum load values across all states. Includes non-stressed state with zero forces. Data displays in two lines: upper line shows minimum value, lower line shows maximum value. Note: The six calculated loads for a support (forces PX, PY, PZ and moments MX, MY, MZ) may act in different states and not simultaneously. If supports, equipment, or structures fail safety checks with min/max values, analyze separate load combinations individually.

  • Maximum + Seismic - includes seismic load cases

  • Maximum and minimum + Seismic

  • Operating state

  • Cold state

  • Test state

  • Cold state after relaxation

Occasional Loads

  • Maximum + Seismic - maximum static plus seismic loads

  • Maximum and minimum + Seismic

Coordinate System

Loads and moments displayed as projections on coordinate axes:

  • Global axes (X, Y, Z) - Px, Py, Pz, Mx, My, Mz (Fig. 1a)

  • Support local axes (Xmm, Ymm, Zmm) - ΔXmm, ΔYmm, ΔZmm, φXmm, φYmm, φZmm (Fig. 2). Restraint axes remain in horizontal and vertical planes regardless of piping slope. Typically used for support load determination. Not displayed for nodes with pipe direction changes >0.5° or multiple pipe elements, or pipe slopes >45°.

  • Pipe local axes (Xm, Ym, Zm) - Pxm, Pym, Pzm, Mxm, Mym, Mzm, aligned with elements adjoining the support (Fig. 1b). Typically used for nozzle load determination.

Fig. 1. Support loads in global and local coordinate systems

Fig. 2. Loads in local restraint axes

Support Type

Displays loads only for selected support types

Diameter

Pipe diameter connected to support. Helps assess load magnitude relative to pipe size.

Resultant

Square root of sum of squares of loads along X,Y,Z axes. Required by some equipment manufacturers.

Load Factor

Available only when local restraint axes coordinate system is selected. Support load factor k must be specified (typically 1.0 or 0.8 per SNIP 2.05.06-85 section 8.44).

When load factor k ≠ 1.0:

  • Applied only to fixed anchors and moment-free anchors

  • Loads from pipes on both sides (N1 and N2) in same direction are combined as N1+N2

  • Loads N1 and N2 in opposite directions: smaller value multiplied by k then combined as N1+N2×k (|N2|<|N1|)

  • Factor k not used for end node supports

Factor k accounts for friction force uncertainties and uneven piping heating. Applied only to horizontal plane loads (forces along Xmm and Ymm axes, moment around Zmm axis). Not applied to vertical forces (Zmm axis) or moments around Xmm and Ymm axes.

For more information: How to Avoid Zero Anchor Loads?

Menu Access

After analysis: Output > Restraint Loads