H.E tubes bending

Gonzaga · **Joined:** Sat Dec 15, 2001 1:00 am **Posts:** 603

Tubes SA 268 TP 439 ferritic stainless steel. Manufacturer has to bend 180° very narrow bend 1.5 x d.
Is stress relieving post bending required? Recommended? Does anybody have experience?
Mauro

Javed Nasir · **Posted:** Tue Feb 23, 2010 4:43 pm

As far as Section I (Rules for the construction of Power Boilers) is concerned, Post bending stress relieving is only required for Austinitic Stainless Steel pressure parts only under the conditions of PG-19(a) & PG-19(b).
Please refer to PG-19 of Section I.
We usually check out surface cracks in tube bends by MPI for the tube materails other than austinitic stainless steels. It is a good engineering pratice. Normally, there is a chance of wrinkles that may ultimately lead to a crack in operating conditions.
Many times, we did bend at 1.5 times dia of tube for economizer bends.

Best Regards,

Nasir

lordsteel · **Joined:** Wed Aug 10, 2011 4:20 pm **Posts:** 16

Gentlemen,
Please allow me to add something here.
I agree Nasir's saying refer to PG-19 of Section I for the Austenitic stainless steel.
What I want to say is we also do stress release heat treatment after bending in duplex stainless steel for all the radius.
We and our clients find that the U-tube in duplex after bending with stress released heat treatment will be longer that that without doing stress released treatment after bending in the equipment.
Here let's back to TP439.
Because we are the manufacturer of such kind of material in tube for feedwater in ASME SA268 TP439.
Usually our clients do not require stress released after bending for such material.

H.E tubes bending

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