Minimum practical wall thickness for pipelines
Minimum practical wall thickness for pipelines
(OP)
Is there a minimum practical wall thickness to stay above for about 8 thru about 24 inch pipelines?
I know the D/t < 100 rule, but I've spoken to pipeliners that seem to feel .25 inch is the smallest they will use. We recently ran an 8 inch that was .219 without any trouble. Just curious what the sentiments are.
I know the D/t < 100 rule, but I've spoken to pipeliners that seem to feel .25 inch is the smallest they will use. We recently ran an 8 inch that was .219 without any trouble. Just curious what the sentiments are.





RE: Minimum practical wall thickness for pipelines
RE: Minimum practical wall thickness for pipelines
Independent events are seldomly independent.
RE: Minimum practical wall thickness for pipelines
RE: Minimum practical wall thickness for pipelines
8" from 4.0 mm down to 3.2 mm
10" from 5.2 mm down to 4.0 mm
12" from 5.6 mm down to 4.4 mm
14" from 7.1 mm down to 4.8 mm
16" from 7.1 mm down to 4.8 mm
18" from 7.1 mm down to 4.8 mm
20" from 7.1 mm down to 4.8 mm
22" from 7.1 mm down to 5.6 mm
24" from 7.1 mm down to 5.6 mm
The above reflects regular line pipe that is outside of pump / compressor stations, uncased road crossings and uncased rail crossings. If one was inside those limits, the (ultimately interpreted) "thin wall thresholds" were:
8" from 4.0 mm downward
10" from 5.2 mm downward
12" from 5.6 mm downward
to 24", from 7.1 mm downward
RE: Minimum practical wall thickness for pipelines
RE: Minimum practical wall thickness for pipelines
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RE: Minimum practical wall thickness for pipelines
Independent events are seldomly independent.
RE: Minimum practical wall thickness for pipelines
RE: Minimum practical wall thickness for pipelines
If a minimal wall thickness is selected, the support span may become short and the overall cost of the system will increase.
Additionally, if a thin walled pipe is used and the bearing area of the pipe support is small, additional pads may be required to distribute the load across the pipe. This will also increase cost. ( I have seen this done only on schedule 5S piping)
If the pipe wall is low and the system is hot, a stress analysis of the system is required. Thin walled piping has very high "stress intensification factors" which, in some circumstances, can require additional piping loops or expansion joints.
In some system locations, where there is a relief valve, the pipe wall must be thickened locally as per ASME B31.1 and B31.3
All of this, of course, does not address the corrosion issue which frequently pushes the designer into a thicker pipe
RE: Minimum practical wall thickness for pipelines
t=D/288 for sizes up to 54"
t=(D+20)/400 (sizes greater than 54 ")
t=D/240 for mortar-lined and flexible coated pipe
and says "in no case shall the shell thickness be less than 14 gauge (0,0747 in.).
The formulas are based on handling considerations.
RE: Minimum practical wall thickness for pipelines
RE: Minimum practical wall thickness for pipelines
RE: Minimum practical wall thickness for pipelines
JStephen is also correct as really thin pipe and fittings like flanges can actually turn out to be more expensive and take much longer to get than a slightly thicker one due to rarity of supply. If you only have a short length you also need to allow for higher wastage due to dents, buckles, weld burn through etc.
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Also: There's usually a good reason why everyone does it that way