High pressure stainlees steel tubing Maximum Working Pressure Vs. Bend radius
High pressure stainlees steel tubing Maximum Working Pressure Vs. Bend radius
(OP)
Hello everyone!
We are facing a new challenge in our company.
We are manufacturer of high pressure equipments from 15Kpsi to 60Kpsi included valves and fittings.
We also deal with high pressure tubes from 1/4" to 1" o.d. 316 high strenght material (usually 100.000PSI 700N/mm2 Rp 0.2 minimum)
One of our customer is asking us to provide him with a chart showing the maximum allowable working pressure as a function of the bend radius of tubes.
As a matter of fact, tubes are often cold bended to be installed. This bending cause an impoverishment of the mechanical features includin the yield value in fuction of the size of the bending. So MAWP decreases.
Diameters, thikness, material, benda radius and mechanical features are known.
Tubing thikness is calculated according to ASME B31.1
How can we calculate the MAWP?
Thanks
We are facing a new challenge in our company.
We are manufacturer of high pressure equipments from 15Kpsi to 60Kpsi included valves and fittings.
We also deal with high pressure tubes from 1/4" to 1" o.d. 316 high strenght material (usually 100.000PSI 700N/mm2 Rp 0.2 minimum)
One of our customer is asking us to provide him with a chart showing the maximum allowable working pressure as a function of the bend radius of tubes.
As a matter of fact, tubes are often cold bended to be installed. This bending cause an impoverishment of the mechanical features includin the yield value in fuction of the size of the bending. So MAWP decreases.
Diameters, thikness, material, benda radius and mechanical features are known.
Tubing thikness is calculated according to ASME B31.1
How can we calculate the MAWP?
Thanks





RE: High pressure stainlees steel tubing Maximum Working Pressure Vs. Bend radius
P = (t x (SSE+Py)) / Do See B 31.1 for the meaning of the various parts.
I've never seen this done before, but it will reduce it compared to straight tubing.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: High pressure stainlees steel tubing Maximum Working Pressure Vs. Bend radius
Wall thinning caused by bending of tubing must be accounted for when performing MAWP calculations, as defined in ASME B31.3 Chapter II, Paragraph 304.2.1 the minimum wall thickness on the extrados of the bend can be thinner than the minimum wall thickness required for a straight of the same length (section 304.1.2), conversely on the introdos the wall is required to be greater than that of the straight for the same design pressure..
Bend minimum wall thickness by calculation 3c; using 3d and 3e for intrados and extrados.
Also look at:
http://www.eng-tips.com/viewthread.cfm?qid=383484
http://www.eng-tips.com/viewthread.cfm?qid=115925
http://www.eng-tips.com/viewthread.cfm?qid=25004
http://r.search.yahoo.com/_ylt=A0LEVjVVqK9VUGkAz3Y...-
RE: High pressure stainlees steel tubing Maximum Working Pressure Vs. Bend radius
But my problem now is that I'm working with pipes MAWP from 10Kpsi to 60Kpsi and a t>D/6
If I got right I shall use ASME B31.3 chapter IX par. K304.1.2 for wall thikness calculation (or MAWP)
Is Paragraph 304.2.1 still applicable? No longer I think...
RE: High pressure stainlees steel tubing Maximum Working Pressure Vs. Bend radius
On three others, bend the pipes, hydrostatically test them to failure (yielding); then measure the failure pressure in terms of actual (original) wall thickness. Note! Calculate failure based on actual ORIGINAL wall thickness, not nominal wall thickness.
RE: High pressure stainlees steel tubing Maximum Working Pressure Vs. Bend radius
RE: High pressure stainlees steel tubing Maximum Working Pressure Vs. Bend radius
I'm trying to get the OP to measure the actual distortions in his actual bent pipe to see if that assumption is valid.