A778 in Cooking Oil Application

[tf94]

Hi all,

One of our products is a solids collection vessel for hot cooking oil applications. Design temperature and pressure are 400F and 100PSI respectively. The body of the vessel is typically constructed from A269 tubing; however, our supplier has asked us if A778 is an acceptable substitute (apparently they cannot supply 18" OD 10GA 304L A269 but A778 is doable).

I understand that the principle difference between the two is that A269 specifies annealing whereas A778 does not require any heat treatment. My gut says that in this application A778 should be perfectly acceptable, but I would like to tap into more experienced minds here for further input.

Thanks!

 

[Dhurjati Sen]

Has A269 become obsolete?

Ask the vendor to submit technical deviation for the same. The vendor cannot ask you a question, rather he should answer the question himself.

A778 ought to be cheaper, does he pass on the benefit?

Try other vendors, as you may be blacklisting this one in the near future.

DHURJATI SEN
Kolkata, India

 

[EdStainless]

A778 is both welded with filler and unannealed, and it only has a minimum UTS with no limits on Yield or elongation. It also has no NDT requirements.
I have seen many hot oil systems suffer CSCC from small amounts of salt in the oil. Having bigger unannealed welds would not help performance.
This stuff is intended for use:
Scope
1.1 This specification covers straight seam and spiral butt
seam welded unannealed austenitic stainless steel tubular
products intended for low and moderate temperatures and
corrosive service where heat treatment is not necessary for
corrosion resistance. Table 1 lists the five grades covered by
this specification. The user of this specification should be
aware that a minimum amount of testing and examination is
required of the basic product. The user requiring additional
testing or examination is referred to the supplemental requirements
or Ordering Information, or both.

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P.E. Metallurgy, consulting work welcomed

 

Agree with EdS. Welded or seamless should be the first point of comparison.

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

 

[EdStainless]

I don't know about the seamless comparison since this is large diameter.
But annealed with NDT is a far cry from as-welded and un-tested.

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P.E. Metallurgy, consulting work welcomed

 

Those are also potential show-stoppers.

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

 

[tf94]

Thanks all, good points to think about.