Relating to CRR sounds reasonable. Is there anything threadable that has a CRR of 1 or greater that is not sched 40? Wheatland GL is 0.61 to 0.25 for 1"-2" for example. XL has virtually the same ID but no CRR listed but it must be the same as GL.
Now Dyna Thread is interesting. CRR stated of 1 but 3.6% larger ID than sched 40. Not sure I follow that though. If the wall is less than sched 40 how can it have a CRR of 1? If it's 3.6% less seems based on the formula CRR = (X/X40)^3 should be a CRR of about 0.9. OK that's much better than 0.61 BUT it's NOT 1. Chris Cahill, P.E. Fire Protection Engineer Sentry Fire Protection, Inc. 763-658-4483 763-658-4921 fax Email: [email protected] Mail: P.O. Box 69 Waverly, MN 55390 Location: 4439 Hwy 12 SW Waverly, MN 55390 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Ed Kramer Sent: Wednesday, June 16, 2010 4:52 PM To: [email protected] Subject: threaded thinwall hanger spacing Max hanger spacing is covered in section 9.22 and Table 9.2.2.1(a) (NFPA 13 2010). Threaded thinwall pipe has a max hanger spacing less than other steel pipe in sizes 1 1/2" to 3". Maybe I'm just not seeing it, but is there a clear definition of "thinwall"? I've always assumed it meant any pipe with a wall thickness less than sched 40/sched 30. Today I read the commentary in the handbook that follows 9.2.2.1 - it says hangers on threaded thinwall need to be spaced closer together "because of the reduced remaining pipe wall thickness between the inside diameter and the thread root diameter". That sounds very similar to Corrosion Resistance Ratio (CRR). So if my threaded "thinwall" has a CRR of 1.0 or greater, is it "thinwall" in the context of 9.2.2.1? In other words, does the reduced hanger spacing apply? Ed Kramer Littleton, CO _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
