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Re: Pipe sizes

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One of the mechanical engineers in our office gave me a reference that indicates that Schedule No. = 1000 x P / SE, where P is the operating pressure in psi, S is the allowable bursting stress at operating temperature in psi and E is the quality factor based on the casting method.

Our office is has been  using the HSS designations for structural and architectural applications. Does anyone know whether for pipe designations, we should be using nominal or actual dimensions? example: HSS 1.900 x .145

Jim Kestner, P.E.
Green Bay, Wi

Robert Rollo wrote:


I have had a curiosity question for quite some time.  Sure, I know of the existance of "schedule #'s" for pipe sizing (SCH 10, 20 , 40 , 80, 120), but what does that really mean?  What is the history of these numbers?  Whose "schedule" is it?

Despite repeated reminders, I can not seem to get my architects to quit indicating 1 1/2 " SCH40 handrails, whick exceed maximum allowable OD.  Does anyone out there specify round tube per A500B like 1 1/2 x 1/8 for handrails?  I often see 1 1/2" SCH10 for rails, which are compliant.

Thanks in advance for help with this, its driven me crazy for years.

robert d. rollo, PE
Corporate Associate
(806) 747-0161vox
(806) 747-7146 fax