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Up Topic Welding Industry / Technical Discussions / Cold pull
- - By nosetackle (**) Date 07-26-2010 12:03
Hi All,

Is there a non destructive test method to understand if the pipe welding completed with/without cold pull ?

Thanks
T.
Parent - - By 803056 (*****) Date 07-26-2010 14:54
Cold pull?

Al
Parent - - By js55 (*****) Date 07-26-2010 15:13
That one got me too.
Never heard of it.
Parent - By 803056 (*****) Date 07-26-2010 15:49 Edited 07-26-2010 16:23
I wonder if he meant "cold spring?"

Its all about communications.

"What we have here is a failure to communicate."

Terminology, terminology, terminology. 

And we call ourselves "Professionals."

Al
Parent - By TimGary (****) Date 07-26-2010 17:23 Edited 07-26-2010 19:40
deleted
Parent - - By L51174 (**) Date 07-26-2010 17:52 Edited 07-26-2010 18:18
Cold Pull or Cold Spring
This is used to pre-load the piping system in the cold condition in the opposite direction to the thermal expansion, so that the effects of expansion are reduced. Cold pull is usually 50% of the expansion of the pipe run under consideration. Cold pull has no effect on the code stress, but can be used to reduce the nozzle loads on machinery or vessels.

Here is an abstract which explains the procedure with calculations.

http://www.pipestress.com/papers/ColdSpring.pdf

To answer you question, I dont believe there is a method which can determine if the pipe was cold pulled before it was welded. In my experience with power piping, this step is usually verified and signed off by either the contractor or an owners representative, so there should be documented evidence of it somewhere, if it was performed, or more precisely, correctly designed into the piping system.
Parent - By eekpod (****) Date 07-26-2010 18:53
wow, I learned something today, just can't gaurantee I'll remember it tomorrow.  Interesting how each industry has its own particular ways of doing things and terms for it.
Parent - By rodofgod (**) Date 07-26-2010 23:06
No! Unfortunately!
- - By Shane Feder (****) Date 07-27-2010 00:36
Morning all,
Pretty sure L51174 has addressed correctly what the OP was asking but in Australasia we have an additional explanation for "cold pull".
If a piping run is going from point A (pump / machine etc ) to point B (another pump / machine) and the spool has been fabricated incorrectly the flange faces will not align. A chain block or "come along" / "turfer" is then used to pull the spool across or up/down to align the flanges. This is what we call "cold pull".
This then puts stress on the pump / machine flanges at point A, point B or both.
If the inspector / engineer has any suspicions this has happened he can request all the bolts are loosened to see if there is any "cold spring". Of course this can only be done before the piping has gone into service.

Again, I think L51174 has addressed it correctly, just thought I would add a different take on the subject.
Regards,
Shane
Parent - By L51174 (**) Date 07-27-2010 13:21
It didn't occur to me that the OP was asking if something was done that wasn't suppose to be done lol. In my experience the cold pull, that is the intentional cold pull is closely monitered but I can see this happening as well.
Parent - By G.S.Crisi (****) Date 08-03-2010 21:58 Edited 08-03-2010 22:00
Back in 1962, when I was a "just out of school" engineer, I went to work for an erection contractor who was in charge of the erection of a small power plant (6,000 kW) in Argentina, South America. The plant was small but I learned quite a lot. The boilers (Riley Stoker) were American, the water treating plant (Cochrane) also, the turbine generators (Franco Tosi / Marelli) were Italian and the transformers and high tension switchboards (Magrini), also. The consulting engineers were Sargent and Lundy, from Chicago. So, at the plant jobsite there were American and Italian engineers to supervise our erection job.  As I was the only good English and good Italian speaking person at site, I served as interpeter for all of the engineers: suppliers', contractor's (us) and client's.
Well, on the Sargent and Lundy's high temperature piping drawings, the "cold pulls" (yes, cold pulls) were indicated with that name. So, it's almost half a century that I know what a "cold pull" is.
By the way, what Shane has described as being a "cold pull" in Australia, here in Brazil is named "gambiarra".
To answer Nosetackle's question, let's put our heads to work a little. A pipe that has been "cold pulled" has developed a stress. Perhaps that stress may be measured with a portable xRay difractometer. I repeat, perhaps. To make sure, I suggest Nosetackle to get in contact with a well known difractometer manufacturer, like Rigaku.
Giovanni S. Crisi
Sao Paulo - Brazil
Up Topic Welding Industry / Technical Discussions / Cold pull

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