GOBLINTECHNIC
Mechanical
Dear sir,
I want to know how to find the thickness of pipe after bending
Thank & Regards
I want to know how to find the thickness of pipe after bending
Thank & Regards
Eng-Tips is the largest engineering community on the Internet
Intelligent Work Forums for Engineering Professionals
-
Congratulations waross on being selected by the Tek-Tips community for having the most helpful posts in the forums last week. Way to Go!
How to find the thickness of pipe after bending 6
- Thread starter GOBLINTECHNIC
- Start date
- Status
MikeHalloran
Mechanical
Cut it up and measure it.
Mike Halloran
Pembroke Pines, FL, USA
Mike Halloran
Pembroke Pines, FL, USA
- Thread starter
- #3
GOBLINTECHNIC
Mechanical
Didn't have the equation to find it ?
MikeHalloran
Mechanical
I don't think there's a single equation that covers it.
Among other things, it has to depend on the material and temper, the type of bender, the geometry of the unbent pipe including nonuniformity, the geometry of the bend, the condition of the tooling, presence/type of lubricant, skill of the operator, and phase of the moon.
Also, there isn't 'a' thickness after bending; some areas get thinner, some get thicker, some don't change.
Can you pose a more specific question?
Mike Halloran
Pembroke Pines, FL, USA
Among other things, it has to depend on the material and temper, the type of bender, the geometry of the unbent pipe including nonuniformity, the geometry of the bend, the condition of the tooling, presence/type of lubricant, skill of the operator, and phase of the moon.
Also, there isn't 'a' thickness after bending; some areas get thinner, some get thicker, some don't change.
Can you pose a more specific question?
Mike Halloran
Pembroke Pines, FL, USA
GOBLINTECHNIC
I think its not possible to exactly determine the
degree of thinning. However, it can be approximated by multiplying the thickness before bending by the ratio:
R/R+r
where r the radius of the pipe
R the radius of the bend
sendel kumar
-
2
- #6
1+r ?
Try Hooks Law and Poisson's Rratio. The thinning is proportional to the axial stress applied.
**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)
Try Hooks Law and Poisson's Rratio. The thinning is proportional to the axial stress applied.
**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)
JHanson717
Industrial
If you know someone close who has Ultrasonic NDT they could measure thickness for you pretty easily.
You'd at least know the thickness before it went plastic. So you're saying that after it goes plasdtic there is no relationship we can use?
**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)
**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)
-
1
- #10
![[peace]](/data/assets/smilies/peace.gif "[peace] [peace]")
**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)
**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)
Yup. If something's not well known, that's about the only alternative we have.
**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)
**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)
Thanks. That would be my dominant bulldog gene.
**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)
**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)
Although I don't think it would be as simple as those curves show. We should probably integrate along some lines more typical for steel.
**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)
**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)
-
1
- #19
racookpe1978
Nuclear
Ah, true - but is the second set of graphs correct for the outside fibers of a real pipe?
It'd be mostly correct for a round (solid) bar because the neutral axis of the bend is near the middle of the bend - between the stretched outer fibers and th einner fibers getting pushed sideways into the mandrel and lengthwise by the two ends of the bar.
But the inside of the pipe is hollow, so a good bit - but not all! - of the pipe outside fiber is deformed inward towards the centerline of the bend as the pipe wall deforms. The inner wall of the pipe tends to crush and deform into ridges - so it is not under simple compression either. The net stretch of the pipe outer wall will expand in length a little bit, but will also get pulled back "inwardly" towards the pipe tube centerline.
The overall thickness of the final pipe wall (inside as well as outside parts), cannot therefore be accurately calculated directly by a combination of 2% elastic fiber stretch, steady-state elastic movement as the pipe deforms, and the final wall thickness decrease as the length increases.
Besides, the variation of pipe wall thickness due to fabrication tolerance and final corrosion/erosion restrictions/allowances for your actual services means you wouldn't be able to use this information even if you could calculate it accurately enough to make an assumption about the rest of your pipe bends to allow a "safe" calculation of allowable internal pressures anyway.
Make sense? Calculating final pipe thicknesses due to bending is not likely going to give you (your company) enough savings to give you the pay raise you want/need/would like to have.
It'd be mostly correct for a round (solid) bar because the neutral axis of the bend is near the middle of the bend - between the stretched outer fibers and th einner fibers getting pushed sideways into the mandrel and lengthwise by the two ends of the bar.
But the inside of the pipe is hollow, so a good bit - but not all! - of the pipe outside fiber is deformed inward towards the centerline of the bend as the pipe wall deforms. The inner wall of the pipe tends to crush and deform into ridges - so it is not under simple compression either. The net stretch of the pipe outer wall will expand in length a little bit, but will also get pulled back "inwardly" towards the pipe tube centerline.
The overall thickness of the final pipe wall (inside as well as outside parts), cannot therefore be accurately calculated directly by a combination of 2% elastic fiber stretch, steady-state elastic movement as the pipe deforms, and the final wall thickness decrease as the length increases.
Besides, the variation of pipe wall thickness due to fabrication tolerance and final corrosion/erosion restrictions/allowances for your actual services means you wouldn't be able to use this information even if you could calculate it accurately enough to make an assumption about the rest of your pipe bends to allow a "safe" calculation of allowable internal pressures anyway.
Make sense? Calculating final pipe thicknesses due to bending is not likely going to give you (your company) enough savings to give you the pay raise you want/need/would like to have.
I would imagine that you could ask one of the shop bend manufacturers or experienced field bend operators what they're seeing. From what I understand they have been using computer control to do these for many years. Maybe they'll share a secret or two.
**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)
**********************
"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)
- Status
Similar threads
- Locked
- Question
- Question
- Question
- Locked
- Question