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# RE: Fire Sprinkler Thrust Loads

• To: "'seaint(--nospam--at)seaint.org'" <seaint(--nospam--at)seaint.org>
• Subject: RE: Fire Sprinkler Thrust Loads
• From: "Bill Cain, S.E." <bcain(--nospam--at)ebmud.com>
• Date: Mon, 19 Oct 1998 12:51:06 -0700

```For a fire sprinkler pipe with grooved joints (e.g., Victaulic), there is
some longitudinal growth of the pipe due to cumulative movement at each of
the joints.  If more than one brace per run is used to resist seismic loads
in the longitudinal direction (along the pipe), some thrust will be induced
on these supports.

Similarly, if the lateral braces (normal to the pipe) are close to a change
in direction loads may also be imposed on the braces due to the same growth
mechanism.  It would be a function of the stiffness of the pipe vs. the
stiffness of the support.

A lesser amount of growth due to elastic action of the pipe under pressure
loading can occur (because the pipe is placed in longitudinal tension to

Bill Cain, S.E.
Oakland, CA

-----Original Message-----
From:	Horning, Dick/CVO [SMTP:dhorning(--nospam--at)CH2M.com]
Sent:	Monday, October 19, 1998 12:34 PM
To:	'seaint(--nospam--at)seaint.org'
Subject:	RE: Fire Sprinkler Thrust Loads

As a free-body diagram will show, the thrust would be taken through the
pipe
wall in longitudinal tension, as long as there are no unrestrained joints
in
the pipe.

-----Original Message-----
From:	Joshua Matthews [SMTP:base.engr(--nospam--at)internetMCI.com]
Sent:	Saturday, October 17, 1998 11:05 AM
To:	seaint(--nospam--at)seaint.org
Subject:	Re: Fire Sprinkler Thrust Loads

I recently spoke with a friend who is a contractor who was being
requested to
verify that a new metal building that they had constructed be
checked for
"thrust" loads in the plumbing of the fire sprinkler system.  The
plumbing is
braced back (and checked) to the structure for seismic loads but
Factory
Mutual has requested that it be checked for "thrust" of the water
moving
through the system (particularly at bends in the plumbing). It would
seem that
most of the forces in the plumbing would be resolved within the
plumbing
itself and not be exerted on the structure (two opposing bends might
create
tension in the pipe)

I have not heard of this before, has anyone else had this question
come up or
have any experience with this situation?