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Unread 15-02-2005, 11:03
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Gary Dillard Gary Dillard is offline
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Re: pic: (447) Is this legal?

Quote:
Originally Posted by Steve W
There is no rule against heating the tubing, just modifying. It is still tube and it still has the same properties. If you heat it too much it will shrink and give less air flow, so be carefull.
I'd be REALLY careful about this. "It still has the same properties" could be argued against strongly from a safety standpoint, for 2 reasons I can think of:

1) If it remained coiled after you heated it, it permanently yielded. How do you know the plastically deformed material has the same properties (tensile/rupture strength, yield strength, elongation) that it had when it was qualified/certified to its pressure rating? If it hardened locally after heating the material may not redistribute stresses the same way.

2) How do you know that the thickness remained the same after heating? If it shrinks and gives less air flow, it could just as easily expand under load and cause both thinning and a larger diameter. Diameter and thickness are the primary variables in hoop strength - how do you know it's still qualified/certified to its pressure rating?

I think you're pushing this one a little too much Steve. My $.02
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