Normalized VS as-rolled normalized

[Paulettaa]

Dear All

In the engineering spec of a project it is mentioned that for hydrogen service equipment, the plates shall be normalized and as-rolled normalizing is not acceptable.
Can you please help me understand the difference between the two and why normalized is the preferred for hydrogen service.

 

[victorpbr]

Hi

I may be wrong, but as-rolled normalizing seems like when you use plates that have been normalized during its fabrication, I think that in this context, the requirement is to normalize the whole vessel after it is fabricated.

This requirement is probably to avoid hydrogen induced cracking.

 

I am not familiar with as-rolled normalizing, but I have been involved with specifying steel for hydrogen service (H2S or sour service to be precise).
Normalizing is only one aspect of so-called HIC-resistant steel, cleanliness and steelmaking methods are also factors. See this and this.

This looks like a question for Super Jones (I assume that's what the S in SJones stands for). And I suggest you call in a corrosion engineer for assistance; the entire success of the equipment depends on getting the materials and fabrication right.


"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[weldstan]

As rolled normalizing involves the finishing temperature during rolling to be in the normalizing temperature range. It is not true normalizing but in thinner plates it produces a finer grain structure. Problems may be encountered when such plates are stacked at the finishing table where slow cooling could occur with adverse effects on mechanical properties.

 

[r6155]

See SA-516 and NACE MR0103
Regards
r6155

 

[EdStainless]

The as-rolled normalized is an in process treatment, much like a process anneal.
The inference is that the operation ends while the material is still in the desired temperature range.
The issue that has been mentioned is partially the control of cooling. There can also be issues with temperature uniformity.
In general the thinner the material is the better that this works.
You need to read up on the various hydrogen cracking mechanisms and how to control them.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

I would recognize as-rolled normalizing by other names then, such as controlled rolling or thermomechanical processing.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[kiad]

Even for SSC resistance which could not be very hard to obtain, as rolled normalizing has not been permitted for low alloy steel by NACE MR0175/ISO 15156-2.