2205 Duplex Forming Strain UG-79 2

[ksonner123]

Hi, this is my first post... trying to validate a rolled shell to establish that it is within the limits set forth under UG-79. We will be having a plate rolled, 19"id x 3/4"thk x 10'lg, S31803 2205 Duplex. Forming strain(Fiber elongation) per UG-79-1 is ((50*0.75")/9.875")= 3.80%. Table UHA-44 (Requirements for Post-Weld Heat Treatment) does not list S31803.

Question: What is the Postfabrication Strain Limit for 2205 Duplex SS?

 

[metengr]

When this material was approved by ASME, there were no cold forming limits that require thermal treatment.

 

[ksonner123]

Thank you for your reply, metengr! By virtue of omission, may I exclude 2205 Duplex from UHA-44? I know 3.8% is "qualitatively low" and 450F is "out of range" of most of the table... but it is difficult to formally declare this (or it isn't, that depends).

A side note... and possibly better asked in a new thread: "Is there something that can be positively said about the planar stresses that are induced in a roll-formed cylinder from plate (namely 2205 Duplex) used in an ASME Section VIII Pressure Vessel?

 

[metengr]

If you review technical information on 2205, several mills and suppliers indicate the material can be supplied in an annealed or cold worked condition with no adverse effects on performance.

 

[XL83NL]

You might to purchase & review API TR 938-C for duplex code equipment. ASME does not reference API TR 938-C, not does your contract have to do - but (some of) the requirements outline in the technical report are a useful guide for the reader who is fairly new to the world of duplex stainless steels.

API TR 938-C references do's and dont's, additonal requirements to guarantee optimum corrosion resistance of duplex (codes tends to have little requirements resulting from metallurgical effects - this is where API kicks in), there links to the various code sectionsm, etc.