How to Setup a Constant Spring Support

Constant spring supports allow vertical movements of the pipe due to thermal expansion or contraction and have a fixed load output throughout their travel range. They are used when vertical movement is high (from 50-75 mm upwards) and when stress at the pipe nozzles and equipment has to be very limited.

Basic Setup

Before proceeding, check Understanding Support Datasheet topic for a better knowledge on information architecture.

Step 1: Enter basic data

First of all, select ‘Constant‘ on ‘Type of Support’ combo box.
Define ‘Single/Double Type’ configuration (if double, select how you will enter loads on ‘Load Calculations’ field, by support or spring).
Enter ‘Operational Load (Hot Load)’ value.
Enter ‘Vertical Movement (+/-)’ value. Positive or negative values are allowed.

Advanced Setup

Total travel is not the movement you entered

A constant support’s travel is sized with a margin above and below the required movement, then raised to the minimum travel its size and product line require, then rounded up. The result is normally larger than the movement you entered — often substantially so on small movements.

This is by design. A constant support positioned with no margin has nowhere to absorb the difference between calculated and actual movement.

See Travel and travel reserves.

Travel reserves change the sizing

Unlike variable springs, where reserves only trigger a warning, on a constant support they enter the sizing directly. Defining them replaces the default margin and changes the total travel — and therefore potentially the selected size.

Constant models

C51 and C52 vertically arranged constant effort units have some minimum total travel limitations by size, in order to avoid clashes between the rod and the spring casing when the hanger shows angulation, so the same load and movement can select a different size compared with C50, C53, C54 and C55 models.

Therefore, when choosing a hanger type constant support, if you don’t have any configuration preference, it is usually more optimal to choose a C50 or C53 horizontal model.

Positioning

The software centres the required movement within the total travel: the operating and installed positions sit symmetrically about the mid-point, adjusted if you have defined asymmetric reserves.

Variability

Zero, by definition of the type. The load is constant throughout the travel. This is the reason to use a constant support, and the field is not applicable.