Learn about PASS/START-PROF pipe stress analysis software

Compressor API 617

The Compressor element models centrifugal and axial compressors with nozzle load verification per API 617 standards. Each compressor object connects to 2-4 nodes. Allowable loads are checked for individual nozzles and the complete assembly. Results appear in the Nozzle and Equipment Loads Table. See also Nozzle Load Reduction in PASS/START-PROF .

Two compressor modeling approaches are available:

1. Connect compressor nozzles to pipe end nodes. Nozzles automatically model as fixed anchors with thermal expansion simulated as anchor displacement.

2. Connect compressor nozzles to intermediate nodes. Model the compressor body using rigid elements, cylindrical shells, and other components. Thermal expansion derives from element temperature changes.

Properties

 

Property

Description

Name

Element identifier. When checked, displays in 3D view.

Auto nozzle thermal movement calculation

Calculates nozzle movements as DX×α×(T-Ta), DY×α×(T-Ta), DZ×α×(T-Ta), where α is the thermal expansion coefficient (from material properties), T is equipment temperature, Ta is ambient temperature, and DX, DY, DZ are distances from compressor center. Disable to specify movements manually.

Material

Material selection from materials database.

Manufacturing technology

ASME B31.1, ASME B31.3, and DL/T 5366-2014 standards use Wl=1.0 for seamless pipe. Electric-welded pipe Wl values come from database. Details...

For GOST 32388-2013, pipe properties vary by type (seamless or welded).

Temperature

Compressor operating temperature. Details...

This property varies by operating mode. Click to view values across all modes.

Allowable loads factor

Default: 1.0. Range: 0.5-20.0. Adjust per manufacturer specifications. Multiplies allowable loads De and Dc.

Shaft direction

Shaft X-axis orientation per standard diagrams:

Compressor center offsets

Reference node and XYZ offsets to compressor center (point 3 in diagrams).

Release restraints for hanger selection

Releases specified restraints during weight case for spring hanger selection. Restraints remain active during main analysis. This technique isolates weight loading from nozzles, allowing springs to carry exact loads for zero displacement under weight. Options:

  • Release vertical restraint – Vertical direction only

  • Release custom restraints – Manual restraint selection

  • Release all restraints – All directional restraints

Suction nozzle

Discharge nozzle

Additional nozzle 1

Additional nozzle 2

Node connection for each nozzle. For disconnected piping, select "Set Custom Loads" to define loads manually.

API 617 Allowable Load Verification

Per API 617, individual nozzle loads must not exceed:

Total compressor loads must not exceed:

Menu and Toolbar Access

To insert a compressor, select target nodes and use: Insert > Equipment > Compressor API 617/619