Schedule Numbers for Piping

Pipe schedule pertains to the wall thickness of the pipe, by convention or definition. There are schedules 5, 10, 20, 40, 80, and 160 (and maybe some less used ones in between). I understand there is a historical basis for these as to how much pressure they can contain, but I have never seen them calculated. Instead, you get this information from engineering books and pipe mfrs' literature, which typically give nominal pipe size, actual O.D., schedule number, and wall thickness. In the smaller sizes at least, Sch 40 is called standard; Sch 80 is XS (extra strong); Sch 160 is XXH (double extra strong). S40 and Sch 40 mean the same thing. I don't recall ever seeing 40S Sch; that seems like a redundant misprint.

I have heard of schedule 40s this is simply schedule 40 in stainless stee,l standard.

schedule 40 would be for carbon steel. this is based on american standard B36.10

Also dimensional standard is (IPS) which stands for "Iron Pipe Size"

for example 3 inch IPS pipe O.D. is approx. 3.5 inches. with a .216 nom. wall.

there is also a schedule 30 which I like to use on fire protection mains which are normally schedule 10. with the MIC corrosion problems I stay away from the thin wall pipe.

I have over 45 years in the piping design field and have found Grinnell a good source for info over the years. If you know a good pipe fitter ( steam fitter) that person may have an extra pipe fitters hand book that will be most helpfull in piping sizes, pressure ratings etc.

Schedule Number is thickness of pipe.

Schedule is written as "SCH"

For stainless steel pipe suffix "S" used after schedule number to differentiate it for carbon steel pipe.

ASME 36.10 M (for carbon steel pipe)

In carbon steel pipe schedule number are as follow-

SCH10,SCH20,SCH30,SCH40,SCH60,SCH80,SCH100,SCH120,SCH140,SCH160.(Total 10 Nos)

ASME 36.19 M (for stainless steel pipe)

In stainless steel pipe schedule number are as follow-

SCH5S,SCH10S,SCH40S,,SCH80S,(Total 4 nos.)

SCH40 and SCH40S has same thickness except for 12" pipe.

SCH80 and SCH80S has same thickness except for 10" and 12" pipe.

Just a history lesson. Many many 'Engineers' do not understand that a 1" BSP or R25 in foreign, has an OD to match the OD of schedule pipe. BS4 (really old) defined gas piping (household gas) by bore and gave rise to the BSP thread (British Standard Pipe Thread) which became the world standard. Later the wall thicknesses were developed for higher pressures by the American National Standards Institute (ANSI) specifically for the Oil Process Industry and including sufficient corrosion allowances to give outdoor service life of many years. Inspection and Paint treatments followed on. The more modern, and lighter, European standard PN16 for example, were targetted at less material, and shorter outdoor life, to give an economic piping system for industrial process piping where good maintenance and modern painting/galvanising etc systems can give equivalent service life. PN is not compatible with ANSI or the much older BS10 flange systems that each have their own bolt pitch circle and number of bolts arrangement. The only common factor is that they all work with nominal inch pipe sizes even though PN prefer to give their flanges a metric 'name' (100:PN16 = 4":PN16). NPT is the American version of BSP pipe threads which are very similar but not compatible. Even the modern ThinWall (trademark?) systems have not been able to standardise though 'truebore' seems to be gaining popularity with the id being 100 and the wall thickness wrapped around that true bore. These are usually Stainless Steel and can be cost effective against schedule pipes, particularly ANSI's heavier system. Apologies for the history lesson, based on failing memory, but I hope this helps to put things in context. With International Instrumentation Suppliers trying to standardise between these standards the piping scheduler, and draughtsmen will continue to have to cope with this multitude of standards.

Dear Amoiz,

40 SCH - The word Schedule refers to the wall thickness of the pipe.

As the schedule no increases the wall thickness and the weight of the pipe increases.

40 S SCH- S- refers to the Stainless pipes

Rest the no without suffix for ex 10, 40 ,80 refers to the welded and seamless wrought steel pipe.

Regards

Earnest.

Hi, Schedule Numbers for piping is used for expressing the thicknesses of pipes as the same NPS has a different thicknesses and about the difference between the schs 40 and 40s, S means Seamless for any certifications don't hesitate to ask Best Regards Mostafa M. Farid

S not stands for Stainless Steel but stands for Seamless i'm sure of that

Good Answer Lahane82, with my GA.

And Mostafa Farid is kindly requested to verify his acknowledgement where he said: "S not stands for Stainless Steel but stands for Seamless i'm sure of that".

Dear Galala,

Thanks you for your appreciation.

dear sirs,

s stands for seamless as per API 5L marking requirement , it is also stands for stainless as per ANSI B36.19 , it depends on what standard you are refering to,both Mr, Mostafa & Mr lahan are right

hello out there, what I have noticed between "s" as standard schedule and schedule 40 in particular is the wall thickness which remains the same until you reach 12" pipe. I have also noticed when purchasing larger pipes 12" and above for water delivery systems to be welded or grooved that standard schedule more then meets the specs and is much cheaper resulting in cutting cost's.