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Anonymous Poster #1

SA 335 P22 Induction Bend In Un-Normalized Condition

11/18/2019 6:04 AM

Dear Sir,

We have made a number of induction bends in SA 335 P22 pipes. Can we send these bent pipes in UN-NORMALIZED BUT STRESS-RELIEVED conditions to the customer who need these pipes to use as steam pipes for a Thermal Power Station?

What could be the possible problems in service ? Please explain.

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#1

Re: SA 335 P22 Induction Bend In Un-Normalized Condition

11/19/2019 3:52 AM

Is this intended as a final product?... or is further treatment planned?

Found this...

http://kjmm.org/upload/pdf/KJMM-2016-54-11-817.pdf

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#6
In reply to #1

Re: SA 335 P22 Induction Bend In Un-Normalized Condition

11/20/2019 2:00 AM

It is intended as a final product please.

Thanks

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#2

Re: SA 335 P22 Induction Bend In Un-Normalized Condition

11/19/2019 6:57 AM

What are the customer specifications for the pipe?

Confer with the customer on this question.

Do not simply throw caution to the wind,and do not presume anything.

Very dangerous and deadly consequences could result otherwise.

Your company does not want to be in the hot seat in case of a catastrophic failure.

https://www.sccgov.org/sites/opa/nr/Pages/Video-of-Steam-Explosion-Jeopardizing-Worker-Safety-at-Hospital-Construction-Site-Released.aspx

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#3
In reply to #2

Re: SA 335 P22 Induction Bend In Un-Normalized Condition

11/19/2019 7:09 AM

There are many possible causes for this explosion, IMHO,one cause could be applying full steam to the pipe suddenly without prior pre-heating and the gradual increase of steam pressure into the piping.

Main steam lines have a small manual bypass around the main valve, and a pressure gauge on both sides of the valve that is opened slowly and allows any condensate in the line to evaporate instead of flashing into steam at an explosive rate.Opening it too fast can cause problems as the pipe expands and steam condenses in the cold piping.The pressures must become equalized before the main valve is opened.

On a long line,it can take hours for the pressure to equalize.

IMHO the popping for several minutes before the explosion indicates that this may have been the cause here.

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#4

Re: SA 335 P22 Induction Bend In Un-Normalized Condition

11/19/2019 12:24 PM

This is not my expertise, but these pipes are made for bending:

Fedsteel.com/astm-a335-chrome-moly-pipe/

I think you have contradicted terms. Stress relived should be normalized. Can you explain?

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#5

Re: SA 335 P22 Induction Bend In Un-Normalized Condition

11/19/2019 4:40 PM

Normalizing is the treatment of a metal or alloy by heating to a predetermined temperature above the material’s transformation temperature and then controlled cooling to well below the transformation range. Normalizing provides grain refinement and uniformity. IST normalizes in a controlled atmosphere to avoid surface scaling.

Stress Relieving is the treatment of a metal or alloy by heating to a predetermined temperature below its lower transformation temperature followed by cooling in air. The primary purpose is to relieve stresses that have been absorbed by the metal from processes such as forming, straightening, machining or rolling.

Quoted from:https://www.indstl.com/annealing-normalizing-stress-relieving/

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#7

Re: SA 335 P22 Induction Bend In Un-Normalized Condition

11/20/2019 10:37 AM

Just because one <...Can...> doesn't mean one should.

<...What could be the possible problems in service ?...> Brittleness leading to catastrophic and irreversible self-disassembly while in service is a distinct possibility!

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