Thursday, May 5, 2016

Corrosion

All corrosion, all the time.



The following photos are from a New England mill.  The mill facility is now used to store paper goods [not shown] for a major retailer.





An improper corrosion related leak repair is noted below:



Possible dissimilar metal corrosion.  Copper drain from RPZ backflow preventer in physical contact with black iron fire sprinkler main.  Leakage from RPZ RV impinging upon fire sprinkler main.





Below are photographs that show complete failure of a riser-to-FDC feed due to extensive corrosion, photo credit goes to my colleague D.H.




There's more to the story.  The 4" feed extending from the riser (to the right in the above photos) goes to a FDC.  Unfortunately, due to a darken riser room and an inexperienced fire sprinkler inspector the corrosion failure was not detected during regularly scheduled routine NFPA 25 inspection.  The failure was found, to the inspector's embarrassment, by the local fire department.  An investigation in the matter showed the inspector did not use a flashlight and was not knowledgeable.



The following shows an electrical vane type water flow switch that has corroded.  This switch, photographed as found, likely leaked and failed.  One or more technicians incorrectly cut the wires and re-programmed the fire alarm panel such that it would indicate a normal condition.  This was found overseas (2012).

System below is located in Southeastern US.  Pipe is showing exterior surface corrosion.  NFPA 13 does not define what a corrosive environment. Designer did not consider this exposure to be an issue, pipe is not painted or protected from corrosive weather conditions.


Nipples too.




On foam concentrate level indicator:


On another system, look up:


And on a pump sensing line:






A dry-system in a parking garage in a western state is shown below.  Note the "missing" condensation drum drip (freeze fracture failure).  Of note, the paint or pipe exterior coating is starting to fail.  NFPA 13 does not define corrosive environments.  AHJ allowed standard pipe to be used.



Valve trim issues:


Below, a dry pipe system with thin wall pipe.  Pipe is constantly failing.



Below, a 13D standalone pump and tank system:





There is a lot "not right" with the following photo:










The following is NOT subject to ordinary NFPA 25 inspection as it is above a ceiling.  We have to wait for this to leak below the ceiling.  See NFPA 25's scope section:


Following photo shows some surface corrosion, possibly a function of water chemistry. 



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