Large Diameter Steel Pipe Pressure Ratings

[sw44]

I'm trying to determine the appropriate wall thickness for a 60 inch diameter steel pipe required to withstand 1,000 psi. Don't know if ASME B31 will have the answer but don't have that as a resource at the moment. Can you help? Thanks.

 

[DLite30]

Don't know your specific application, but for a quick calculation use:
P=2*S*t*F/D

P-pressure
S-SMYS (specified minimum yield strength of your pipe, e.g. 52,000 psi)
t-Pipe wall thickness
F--Design Factor (between 0 and 1, generally between .5 and .72 for DOT reguated work)
D-Pipe outer diameter

 

[BigInch]

Pressure_psig * OD_inches / 2 /wt_inches is the hoop stress according to B31.4 or B31.8, but not B31.3
That must be less than the hoop stress allowable, which will be pipe's minimum specified yield stress / Design Factor.
The B31.4 AND 8 design factor must be found from an area class determination and could be anywhere between 0.4 and 0.8 B31.3 uses one defined allowable stresses. Both design factors and allowable stresses must be derated for temperatures and joint factors, some materials are not allowed. To hoop stress you must add longitudinal and temperature stresses from various load cases and be sure combined stresses are less than combined stress allowables. I think its better that you find a copy of B31.X, where 0 < X < 13

ANSI B31.1 Power Piping Systems
ANSI B31.2 Industrial Gas and Air Piping Systems
ANSI B31.3 Petroleum Refinery Piping
ANSI B31.4 Liquid Petroleum Transportation Piping
ANSI B31.5 Refrigeration Piping Systems
ANSI B31.6 Chemical Process Piping
ANSI B31.7 Nuclear Power Piping
ANSI B31.8 Gas Transmission and Distribution Piping
ASME B31.9 Building Services Piping
ASME B31.10 Cryogenic Piping (never published)
ASME B31.11 Liquid and Slurry Piping Transportation Systems
ASME B31.12 Code for hydrogen piping and pipelines.

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[sw44]

Thank you DLiteE30 but now I have a couple other questions if you don't mind. Stupid questions maybe as I haven't practiced engineering for 30 years and not in this area. 1) I'm assuming all of my measurements for t and D are to be in inches (?). Please confirm.
2) Is the SMYS example you give somewhat of a standard or reasonable expectation for a steel pipe application? If I use 52,000; and the 1,000 psi spec my customer is seeking, the forumula yields 0.96 inches thickness (with F at 0.6) which is a number that seems to make sense to me (if I have any sense at all). I'm guessing that 1" thick wall on a 60" diameter pipe might make sense. Does this make sense to you? Thanks again.

 

[DLite30]

Yes, t and D are in inches.

52,000 psi is a middle of the road standard pipe commercially availble steel pipe strenght. You can get pipe in the following grades, Grade B (35,000 psi), X42, X52, X60, X65, X70, and a limited number of mills make X80. (where X52=52,000 psi SMYS).

The higher the strength, the thinner the wall can be so, it boils down to a cost issue...if it's a lot of pipe you'll probably end up going with X70 and a thinner wall.

Also, with 60" pipe, the only "off the shelf" sizes wall thickness are .375" and 0.500" w.t., so you're looking at a custom order...and 1" sounds about right if you're using a appropriate design factor for your application.

 

[BigInch]

Maybe not. Sounds like post weld heat treatment is required, which is kind of expensive for big diam pipe and a long pipeline. F is a joint factor, DF is a pipeline design factor. Using DF 0.72 in isolated locations will save a lot of money on a long pipeline. DF 0.6 is for fabricated assemblies and road crossings etc., 0.5 for more congested areas and stations, and 0.4 for city work. 60" is pretty large diameter for that pressure and isn't very common. Why, because PWHT is quite expensive and a pipe that size doesn't go around many obstacles easily. Its also not going to be easy to field bend and requires the biggest iron you will be able to find. I assume its not a real pipeline, if you're still thinking about using it, or I'd like to talk to your client with the big pockets.

"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO BP
"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.liv

 

[sw44]

I really appreciate your replies. I've recently been asked to take over the management of a business that fabricates large diameter steel pipe which typically is used as casing pipe with minimal if any significant specifications and not typically used in high pressure situations. Once in a while we are asked if we can determine what the wall thickness should be based on some psi requirements and given the pipe diameter. In this case, all I know at the moment is that this section of pipe is only 40 feet long and also requiring some polycoating inside and out. We would fabricate the pipe out of steel plate in 10 foot sections and weld together.

 

[BigInch]

There's quite a bit of difference between QA/QC of casing pipe and high pressure pipe. Got your API stamp yet?

"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO BP
"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.liv