Internal Inspections &
Obstruction Investigations
5-Year Internal Inspection
o Perform a 5- Year internal inspection on every other wet pipe sprinkler
system and every dry pipe sprinkler system.
o Perform a 5-Year internal inspection on every check valve.
o During the check valve inspection, we take apart the check valve, check
for debris and corrosion, clean out the valve and advise of any issues.
o During the pipe inspection, we will drain the system and check the pipe
for the presence of foreign organic or inorganic material (debris, sediment,
build-up).
To protect people, property, and production from fire, an internal inspection of piping to monitor corrosion
is needed every five years (according to NFPA 25) or more if necessary. If a pipe is corroded or
obstructed when a fire ignites, it could cause the fire suppression to fail when needed most. Learn more
about what is involved in an internal investigation and the triggers for an obstruction investigation.
o The sprinkler system is checked at the following points:
o Flushing connection at the end of one main.
o A sprinkler head toward the end of (1) branch line.
o If the presence of sufficient foreign organic or inorganic material is found to obstruct pipe or sprinkler
heads, the obstruction investigation shall be conducted on all wet sprinkler system and all dry sprinkler
systems.
o During the obstruction investigation, we further investigate the following areas:
o System Valves
o Riser
o Cross Main
o Branch Line
o The obstruction investigation may include a flushing of the sprinkler systems, to attempt to clean out any debris
from the pipe.
o Please find a list of the triggers for an obstruction investigation on the back of this flyer. Additional information
can also be found in NFPA 25 2014 Edition, 14.3 Obstruction Investigation and Prevention.
Obstruction Investigation
An obstruction investigation shall be conducted for system or yard main piping
wherever any of the following conditions exist.
1) Defective intakes for the fire pumps taking suction from open
bodies of water.
2) The discharge of obstruction material during routine water tests.
3) Foreign material in fire pumps, in dry pipe valves, or in check
valves.
4) Foreign material in water during drain tests or plugging of
inspector's test connections.
5) Unknown materials are heard in the system piping during draining,
refilling, or otherwise flowing water through the system
6) Plugged sprinklers
7) The presence of sufficient foreign organic or inorganic material is found in the pipe.
8) Failure to flush yard piping or surrounding public mains following new installations or repairs.
9) A record of broken public mains in the vicinity.
10) Abnormally frequent false tripping of a dry pipe valve.
11) A system has been supplied with raw water via the fire department connection.
12) There is reason to believe that the sprinkler system contains sodium silicite or highly corrosive fluxes in
copper systems.
13) Pinhole leaks
14) 50% increase in the time it takes water to travel to the inspector's test connection from the time the
valve trips during a full flow trip test of a dry pipe sprinkler system when compared to the original system
acceptance test.
All of the above information can be found in NFPA 25 2014 Edition 14.3 Obstruction Investigation
Prevention. If you have any additional questions or concerns please do not hesitate to contact us. The method of contractor selection has not been determined at this time.
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