Suggest consideration of HDPE for your downstream underground, which is 
specifically(ideally) suited to UG pipe movement in seismic areas (See PPI’s 
MAB-9 – Design of HDPE Watermains for the Lateral Spread Seismic Hazard).  In 
addition, the strain relief between pump discharge and the underground piping 
using an UL/FM approved expansion fitting, as has been shared, or an unlisted 
option such as a Proco Expansion Joint, which is approved by the AHJ, which can 
accommodate the necessary offset potential as well as withstand ambient 
exterior conditions, at the topside stub through the wall aboveground prior to 
going underground outside the footprint of the fire pump/tank slab.

Ryan L. Hinson, PE*, SET**  \  Burns & McDonnell
Fire Protection Engineering Group
O 612-900-3755 \  M 763-688-4045
[email protected]<mailto:[email protected]>
*Registered in Fire Protection in: AK, LA, MD, MN, PA, TX, & UT
**NICET IV - Water-Based Systems Layout

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From: Prahl, Craig <[email protected]>
Sent: Tuesday, March 10, 2026 9:14 AM
To: Discussion list on issues relating to automatic fire sprinklers 
<[email protected]>; Mike Watts <[email protected]>
Subject: [Sprinklerforum] Re: Flexible assembly on pump discharge in seismic 
category D area

Thanks Steve.  This condition is way outside the normal scope of seismic issues 
we typically deal with inside buildings.

The seismic movement condition the ME is worried about was between the pump 
building and the underground fire main.  So, traditional seismic assemblies 
won’t work since this needs to be able to be buried in the dirt.

Craig Prahl | Jacobs | Fire Protection SME – EV, AM, DC, Special Hazards
[email protected]<mailto:[email protected]> | 
www.jacobs.com<https://urldefense.com/v3/__http:/www.jacobs.com/__;!!KZTdOCjhgt4hgw!-_khxU8gU0_6jc895I7kRbnU8JghRDsWgqOblZ4jr7Qp2IVbR30VYw_hWvNFtphnl0uWpB9KIvbYi1pvZz4$>
1041 East Butler Road   Greenville, South Carolina  29606
CONTACT BY: Phone 1-864-676-5252, Email or MS TEAMS

From: Welsh, Steve <[email protected]<mailto:[email protected]>>
Sent: Tuesday, March 10, 2026 9:31 AM
To: Mike Watts <[email protected]<mailto:[email protected]>>; Discussion 
list on issues relating to automatic fire sprinklers 
<[email protected]<mailto:[email protected]>>
Subject: [EXTERNAL] [Sprinklerforum] Re: Flexible assembly on pump discharge in 
seismic cat D area

Craig, Not sure if this was your question too. “An approved seismic separation 
assembly shall be installed where sprinkler piping, regardless of size, crosses 
building seismic separation joints at ground level and above. ” Normally,

Craig,

Not sure if this was your question too. “An approved seismic separation 
assembly shall be installed where sprinkler piping, regardless of size, crosses 
building seismic separation joints at ground level and above.” Normally, you do 
not need a separation at the building foundation slab as the slab moves with 
the ground. However as you are going through a building exterior wall, the wall 
could move differently than the ground. Thus, the extra separation is required.

Notes: There are clearance requirements at the foundation slab. There will also 
be clearance requirements at the exterior wall. You will some type of flexible 
weather seal.

Steve Welsh, PE  \  Burns & McDonnell
Senior Fire Protection Engineer
M 410-978-3836

From: Mike Watts <[email protected]<mailto:[email protected]>>
Sent: Monday, March 9, 2026 5:52 PM
To: Discussion list on issues relating to automatic fire sprinklers 
<[email protected]<mailto:[email protected]>>
Subject: [Sprinklerforum] Re: Flexible assembly on pump discharge in seismic 
cat D area

https://www.metraflex.com/products/fire-protection-division/?matchtype=e&network=g&device=c&keyword=metraflex%2520fireloop&campaign=1880371110&adgroup=72795587649&matchtype=&network=g&device=m&keyword=&campaign=1879994101&adgroup=67581073182&gad_source=1&gad_campaignid=1879994101&gclid=Cj0KCQjw37nNBhDkARIsAEBGI8NDEzU6QG8GfbpPNfSPMWigac-U8CJvEPSnVW2RWo1KlqAmv4AklogaAifAEALw_wcB<https://urldefense.com/v3/__https:/www.metraflex.com/products/fire-protection-division/?matchtype=e&network=g&device=c&keyword=metraflex*2520fireloop&campaign=1880371110&adgroup=72795587649&matchtype=&network=g&device=m&keyword=&campaign=1879994101&adgroup=67581073182&gad_source=1&gad_campaignid=1879994101&gclid=Cj0KCQjw37nNBhDkARIsAEBGI8NDEzU6QG8GfbpPNfSPMWigac-U8CJvEPSnVW2RWo1KlqAmv4AklogaAifAEALw_wcB__;JQ!!B5cixuoO7ltTeg!ES1I0tkpdwyMxl6bJ1RYWw6_hcvK0_bF8NByooGVV96uEO-CXq3VJ5nXZBtDcC5trHoa3ucAYFSJ2i-KZXyZ$>


Mike Watts  RME-G-3218231

Sprinkler Service Manager

[Image removed by sender. image]

Firetrol Protection Systems, Inc.

4616 W. Howard Lane, Building 7, Suite 700

Austin, Texas 78728

[email protected]<mailto:[email protected]>

Office 512-687-0115<tel:+15126870115>

Cell 512-660-4411<tel:+15126604411>

________________________________
From: Prahl, Craig <[email protected]<mailto:[email protected]>>
Sent: Tuesday, February 10, 2026 9:28:47 AM
To: Sprinklerforum 
<[email protected]<mailto:[email protected]>>
Subject: [Sprinklerforum] Flexible assembly on pump discharge in seismic cat D 
area

I have a packaged fire pumphouse, discharge exists horizontally through the 
wall and then turns down to connect to the underground outside of the bldg. The 
seismic design category SDC) is “D”. I am being told by the project ME that we 
should

I have a packaged fire pumphouse, discharge exists horizontally through the 
wall and then turns down to connect to the underground outside of the bldg.



The seismic design category SDC) is “D”.



I am being told by the project ME that we should have a flexible connection on 
the discharge side outside the bldg. to accommodate the potential of 8-inches 
of movement between the pumphouse and underground piping system.



I’ve looked around to try and find such an assembly for 8” pipe suitable for an 
outdoor installation and so far haven’t found such a device.



So, my question for those out there in seismically active areas, is this 
standard practice and who makes such an assembly?



Craig Prahl | Jacobs | Fire Protection SME – EV, AM, DC, Special Hazards

[email protected]<mailto:[email protected]> | 
www.jacobs.com<https://urldefense.com/v3/__http:/www.jacobs.com/__;!!KZTdOCjhgt4hgw!-_khxU8gU0_6jc895I7kRbnU8JghRDsWgqOblZ4jr7Qp2IVbR30VYw_hWvNFtphnl0uWpB9KIvbYi1pvZz4$>

1041 East Butler Road   Greenville, South Carolina  29606

CONTACT BY: Phone 1-864-676-5252, Email or MS TEAMS



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