pipe schedule 2

[rahulbarve]

hi
just out of curiosity.....
does anyone know what is the meaning of the numbers 40, 80, 100, etc when we refer to Schedule 40 ,Schedule 80, Schedule100 Pipes respectively...
cheers
Rahul

 

[SaskGear]

It refers to the pipe wall thickness.

 

[handleman]

http://en.wikipedia.org/wiki/Schedule_40

-handleman, CSWP (The new, easy test)

 

[CorBlimeyLimey]

I'm still looking for the meaning of number 42.

 

[rahulbarve]

thx handleman...
so its for preessure rating ....but looks like it doesnt fit to tht anymore.. so conclusion... the numbers are just arbritary...
thx
rahul

p.s...corb limey--- for tht meaning u would have to be close to the question --> earth ending soon... so rather happy "looking" for answer.

 

[migueldiazch]

This is something that I found in the PIPING HANDBOOK, Mohinder L. Nayyar, P.E.
"Schedule is expressed in numbers (5, 5S, 10, 10S, 20,20S, 30, 40, 40S, 60, 80, 80S,100, 120, 140, 160). A schedule number indicates the approximate value of the expression 1000 P/S, where P is the service pressure and S is the allowable stress, both expressed in pounds per square inch (psi). The schedule numbers followed by the letter S are per ASME B36.19M, and they are primarily intended for use with stainless steel pipe. The pipe wall thickness specified by a schedule number followed by the letter S may or may not be the same as that specified by a schedule number without the letter S. Refer to ASME B36.19M and ASME B36.10M."

 

[CorBlimeyLimey]

See also thread177-148207

 

[racookpe1978]

But, more importantly, from that that 2006 thread that Corblimey found comes the following additional caution:

JLSeagull (Electrical)
2 Mar 06 18:29
ASME B36.10M-2004, WELDED AND SEAMLESS WROUGHT STEEL PIPE

"The original intent of the Committee was to establish a system of Schedule Numbers for pipe size/wall thickness combinations which would have an approximately uniform relationship equal to 1000 times the P/S expression contained in the modified Barlow formula for pipe wall thickness as defined in the Appendix to this standard. The resulting Numbers departed so far from existing wall thicknesses in common use that the original intent could not be accomplished. The Schedule Numbers were then adopted strictly as a convenient designation system for...”

Thus - for today's designs, you cannot use the "schedule number" to calculate anything. Use the exact rated values of pressure for each different material. DON'T CALCULATE using this formula.

Equally true, the "original" fitting designations "150 pound" or "300 pound" were correct for saturated steam in the early 50's. If you had other fluids (cold water or chemicals or air or non-flammable gasses) then the allowed pressure in that same "300 lb" valve or flange or tee would be different.

 

[MJCronin]

CorBlimey....

http://en.wikipedia.org/wiki/Phrases_from_The_Hitchhiker's_Guide_to_the_Galaxy

-MJC