How to Setup a Snubber (Shock Arrestor)

Hydraulic snubbers are special elements designed to absorb large impacts in the piping due to seismic phenomena or other circumstances like water hammers.

During the normal operation and movement of piping, they do not restrict movements, offering minimal resistance. However, when a sudden impact occurs, they lock themselves becoming highly rigid supports, protecting the system against that event. They can be installed in any position with relation to the pipe by the use of special beam attachments (“rear brackets”), highly rigid clamps and special enlargement pipes.

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 ‘Snubber‘ 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

Combined extension is what drives the selection

A snubber is selected on four inputs: operating load, movement, installation length and clamp option. The movement used is not the vertical movement on its own — it is the combined extension, which accounts for the vertical and axial movements together over the installation length.

The practical consequence is counter-intuitive but geometrically correct: pure axial movement on a long snubber produces a small extension, because the displacement is almost perpendicular to the axis. A short snubber with the same axial movement extends much more.

Installation length

Derived from the structure and pipe elevations. The combined extension must fall within the admissible travel of the selected part, so installation length and movement together determine what is available.

If the installation length is too short for any valid part, the software reports a reference capacity based on a relaxed length constraint. That value tells you what size would be needed — it is not a part you can install in the space available.

Clamp options

The same three dynamic clamp options as struts. Any excess over the catalogue dimension, however small, produces a calculated dimension.

Extension tubes

Where the geometry requires it, the snubber carries an extension tube whose weight is added to the assembly. The type of extension depends on how long it needs to be.

Deviation angle

Not applicable. The software sets it to zero.