A516-70N or not

[dbday]

Hi,

Where a client wants a vessel made from A516-70N can you achieve that by heat treatment, or do you have to ensure that the steel has the N on the origianl mill certificate ?

I understand what Normalising is, what it does etc etc - this is really a question about certification.

 

[weldstan]

It's a mill cert. The mill performs the normalizing heat treatment. I have also seen nomalizing done by the stockist and certifying it as SA-516N with appropriate mechanical testing after normalizing. The client may approve your normalizing provided all mechanical testing is performed by you after normalizing.

 

[dbday]

So if I have a vessel which is made of materials where I have the usual mix of nozzle and flange materials, say A105 and A106B, where some some do, and some don't, have an 'N' on the certificate, it would seem to make sense (to me at least) to do a normalising heat treatment as the last operation and offer the equipment to the client as a "Normalised" vessel, otherwise it means going through the pain of trying to find all the materials with an 'N' on their certificate, which may or may not be possible in the timescale that the client wants the thing made.

 

[david339933]

Normalized material are common. What you are proposing sounds awfully expensive.

 

[SnTMan]

I'm no metallurgist, but: As weldstan says I'd think you'd need to confirm mechanicals. Normalize heat treat temp is high enough I'd worry about distorting the vessel. Better to use normalized materials and proper weld procedures with perhaps an ordinary PWHT.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[EdStainless]

If you built out of various materials and then post normalized you would need to include test coupons of every material for retesting. And all of you weld procedures would need to have N added before final testing.

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P.E. Metallurgy, consulting work welcomed

 

[r6155]

dbday
Do you know why the Client requires normalizing?.

Regards

 

[weldstan]

Your idea of normalizing a vessel after welding is perilous. Think about distoortion and materials qualificaation and welding procedure qualification as Edstainles stated.

 

[JStephen]

An intriguing idea, not sure if it can be accomplished per code or not.
In the Section VIII and in the SA 516 specifications, is there anything in there that says that normalizing must be done prior to fabrication?
If the vessel incorporates elements that are not normally normalized, do you need to retest them after normalizing?
Weld distortion is mentioned above. Is there any problem with the vessel sagging or drooping on supports during normalizg?
Are facilities available that can do the normalizing?
I was thinking part of the normalizing process involved re-flattening the plate afterwards, which may be mentioned in SA 516 or SA 20.