NFPA Journal - September/October 2013 - (Page 18)

>>perspectives learned—that microbiologically influenced corrosion is a byproduct of this specific corrosion process but not the driver, in most cases. The driver in dry-pipe systems seems to be trapped water. There were also issues of incompatible pipe in the sprinkler system installation at the museum and collection storage facility— lection and storage facility, so we didn’t get dripping. What we found in the mechanical room of the facility, where the humidity increased, was that the crystals would go back into liquid form and drip. We had a nice fluorescent-blue puddle on the floor. I won’t put chemicals in the system again. Chemical additives aside, are wet-pipe systems the answer to the corrosion problem? in my opinion, where an option exists, wet-pipe systems are the best choice for cultural resource properties. In wet-pipe systems, you do see corrosion, but you don’t see the same level of corrosion. The oldest sprinkler system that we have was installed in 1977 in our data center. It’s a wetpipe system and it has never leaked. There are applications where these systems are not appropriate, such as unheated spaces in cold climates. However, in my opinion, where an option exists, wet-pipe systems are the best choice for cultural resource properties. How have the 2010 and 2013 editions of NFPA 909 addressed the corrosion concerns? sections of galvanized pipe had been put in that shouldn’t have been there. In general, though, I feel the cause has something to do with the metallurgy of the pipe, though I can’t say what on earth it is. You used chemical corrosion additives in the system. Did they help? When we installed a new, standard wet-pipe system in our collection and storage facility, we put in a corrosion protection system that includes these chemicals. About 18 months later, we started seeing some crystals growing on the outside joints of the piping. I think the chemical was leaching and forming those crystals. We have controlled humidity in the col- 18 NFPA JOURNAL SEPTEMBER/OCTOBER 2013 We added language to the body of the code that includes protocols for dealing with corrosion if your water supply or your environmental conditions indicate that you’ll have an abnormal corrosion problem in a dry- or wet-pipe system. As a requirement, if you’re going to put in a wet-pipe or preaction system, you have to assume you have those conditions and you need a plan to address them. NFPA 25 has protocols for inspecting and testing the system. NFPA 909 has taken this a step further to require an internal corrosion inspection every five years. There’s a significant amount of annex material telling you how to do that inspection. We also added another section to the body of the code requiring that, where chlorinated polyvinyl chloride (CPVC) sprinkler pipe is used, it must be installed in accordance with the manufacturer’s instructions. We also require a plan to ensure that only materials that are compatible with CPVC are used on the system over time. If you’re going to use CPVC in a cultural resource facility, you have to have a plan in place to keep the incompatible materials away from the system so it doesn’t fail. There’s also a significant amount of annex material on that issue. Photograph: The Colonial Williamsburg Foundation

Table of Contents for the Digital Edition of NFPA Journal - September/October 2013

NFPA Journal - September/October 2013
Contents
First Word
In a Flash
Perspectives
Firewatch
Heads Up
Research
Structural Ops
In Compliance
Buzzwords
Outreach
Electrical Safety
Wildfire Watch
Cover Story: Furniture Flamability
Special Report
NFPA Reports
NFPA Reports
Fire Analysis + Research
Section Spotlight
What’s Hot
Looking Back

NFPA Journal - September/October 2013