comparison of cs schedule 80 pipe with stainless steel pipe - Eng-Tips

There is no simple and responsible answer to your question ... You have given us almost zero information.

We do not know if your piping is 1 INCH diameter or 100 inch diameter.. .... Operating temperatures of 80 or 800 F ????

Your fluids seem to be "water or air or other stuff".... perhaps, but you do not seem to care

You are asking a question about piping system design and you seem to not understand the substantive issues involved...

But, since you seem to be insisting on a quick answer, I would like to offer that you are probably safe substituting seamless Schedule 160S stainless steel piping for Schedule 80 Carbon Steel piping in most applications... My opinion only

Strongly suggest that you reevaluate the pipe support scheme for the massive increase in weight ..

Cost is not a factor in your country, right ???



MJCronin
Sr. Process Engineer
What Code, What temp? What pressure?
What is the water quality? You may need something a lot better than 304 or 316 for it.
Sch80 for service lines in ridiculously heavy.
It might be that you need the pressure rating, and you will need to use sch80 or 160 in SS.
Or there may have been a generous corrosion allowance and you can use sch40 or even sch10 in SS.


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P.E. Metallurgy, consulting work welcomed Dear sir
Suppose pipe is 3" diameter carrying water at 50 degree celcius,pressure 20 kg/cm2. i just want to know that if in above condition cs pipe sch 80 is replaced with ss pipe then what schedule of pipe will be enough. Is it schedule 10,20, or 40. If schedule of SS pipe for same conditions decrease then why or if schedule remains same or increase then why? I am asking because i was asked same question in interview.
Regards
A.Pradeep Pradip,

If you know and understand the Hoops stress, you can easily know the answer.
Assuming Pressure and Diameter same, the thickness of pipe will be inversely proportional to the pipe material allowable stress, which is usually say 2/3 of yield strength.
In general, yield strength of carbon steel is higher than 300 series austenitic SS.

From this concept, you can easily tell which pipe will require greater thickness or schedule.

GDD
Canada It wasn't a great question to ask in an interview unless they wanted to see how you would approach the question.

The answer would be "it depends on the details". If the CS pipe was at the limit of stress due to pressure then the SS schedule would go up as most SS pipe available has a lower S value in B31.3 than say A105. Until you know how the CS pipe was calculated you won't know.

SS schedules are the same up to 10", but start to vary at 12" and above.

But if there was corrosion allowance on the CS then that would not apply for SS.

Also in smaller sizes you can buy sch5S and 10S which you can't get in CS.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it. Let us continue this protracted torture !!!

We all understand where he is going and what he is trying to get.....

Because his MBA boss insisted, he is fishing for a statement or rule that says:

-- "It is acceptable to substitute Sched 10S SS piping for Sched 40/80 CS pipe with certain restrictions" ---

Either his technical inexperience or his cultural limitations on language prevent him from formulating this direct question

Instead, let us continue to slowly ask question after question after question to this dull normal poster ....until

Well, until he slowly realizes that competent piping system design and engineering is complex.

and in the final analysis ..... you can't always get what you want !



MJCronin
Sr. Process Engineer
I once had a supervisor ask me to write down all of the codes and other information needed to design piping systems. Since my AOR at the time ran from concrete drainage piping to HP steam, the list quickly became large enough that he told me he did not want to know that much. We all get MBA ish questions, sometimes from engineers that should know better.