Thanks Joe -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Joe Hankins Sent: Tuesday, May 22, 2007 9:49 AM To: [email protected] Subject: Re: Galvanized sprinkler pipe at 130F
As the old saying goes, when you hear the sound of hooves, think horse, not zebra. The recommendation against using galvanized pipe above 130 degrees is because it doesn't work, not because it isn't needed. Galvanzing protects steel pipe because corrosion attacks zinc in preference to steel. The zinc is sacrifced to protect the steel. But, at temperatures above 130 degrees, the zinc corrodes so fat that it doesn't provide protection for very long. FM recommends galvanized pipe in dry systems because of the scale that forms in unprotected pipe. Over the years, this scale has plugged sprinklers in a number of fires. Un-galvanized dry systems will require flushing more often than galvanized. One problem that has shown up with galvanized pipe in dry systems is pin-hole leaks that show up only a couple of years after the system is installed. A combination of two problems cause this. First, if pipe is not properly sloped and drained regularly, puddles form. Oxygen disolves in this water, making it a powerful corrosion agent. The second problem is poor galvanizing where "holidays" (small gaps in the coating) occur. These can have the effect of "focusing" the corrossion onto the small bare spot, thereby drilling a hole through the pipe. With schedule 10 pipe, this doesn't take long. The most reliable way to avoid this is to avoid "dipping" pipe after it's rolled by using a pipe where the galvanizing layer is applied to the sheet steel before it is rolled. IDOD is an example of this. I was, indeed, working on my Tiger. I had to replace a standard 3-position Lucas switch (off, flicker, and short). Speaking of Lucas, did you know they made Vacuum cleaners at one time? They really, really sucked! Joe > > > _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
