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heat treatment of LPG cylinders
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Posted by: sandeep

03/31/2003, 05:52:18



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we are using Hot rolled Mild Steel (is 6240, C-0.16max, Si- 0.25 max, Mn-0,3 min, S & P- 0.03max)for LPG cylinder fabrication.cylinder manufacturing involves deep drawing, wleding and consequently heat treatment.
we had tested the pre heated and post heat treated cylinders and were able to establish that in case of non heat treatment, % elongation comes down drastically. we has tested the pre and post heat treated cylinders for microstructure and grain size and no variation was observed. we had carried out internal stress measurement by X-ray technique and found nominal value of existing internal stress. BUT THE MECHANICAL TEST RESULTS OF PREHEATREATED CYLINDERS SHOWS THAT THE % ELONGATION COMES DOWN DRASTICALLY.

WHAT WOULD BE THE REASON BEHIND REDUCTION IN MECHANICAL PROPERTIES.
normally cylinders mnfrs are maintianing a temperature 600 to 720 degree C for a certain temperature.
IS THEIR ANY NON DESTRUCTIVE TEST AVAILABLE BY WHICH WE CAN ESTABLISH THAT HEAT TREATMENT IS NOT DONE PROPERLY.

REGARDS

SANDEEP












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Re: heat treatment of LPG cylinders
Re: heat treatment of LPG cylinders -- sandeep Post Reply Top of thread Forum
Posted by: ahok ?

04/30/2007, 08:37:06

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During manufacturing of cylinders stresses are developed at deepdrawing press & also during CA Welding the localised heating & cooling increases the stress in steel thereby leading to reduction in elongation & increase in UTS,For this reason the cylinders are stress relived at 600 to 650

It is very difficult to gauge the elongation without destructive testing.








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Re: heat treatment of LPG cylinders
Re: heat treatment of LPG cylinders -- sandeep Post Reply Top of thread Forum
Posted by: Yoel Frischoff

04/04/2003, 06:36:13



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Have you tested other mechanical dimensions as well?
Could it be that you have warpage of side walls?
Could it be that you have different wall thickness after Heat treatment?
What heat treatment are you using, any way? Is it annealing, or tempering?
Hope this helps,

Yoel












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