Service Temperatures of Various Metals 2

[ak1965]

Dear Friends.

I am in search of a compiled literature that could guide me the service temperature range for various metals including ferrous andnon ferrous metals...

This information is not normally available in relevant standards at one place.

Any source or link ...any one knows...???

 

[metengr]

ak1965;
Actually, there is such a standard that contains recommended service temperature ranges and allowable stress values as a function of service temperature for a wide range of ferrous and nonferrous materials. This document is Section II, Part D of the ASME Boiler and Pressure Vessel Code. Section II, Part D is used for design and fabrication of boiler and pressure vessels, and contains the information you had requested.

 

[ak1965]

Thanks Metengr....

I have seen the max. allowable strees tables in ASME Sec II part D....it gives stress values at specific temperatures....

Should I understnad that the first coulmn value is the minimum service temperature and last column value is the maximum service temp. applicable at the given stress value ??

 

[metengr]

Yes.

 

[ak1965]

I am afraid there are many materials like A 333 Gr.1,2....
that are meant to be used at very low temps. -33 deg.C and below, however ASME Sec.II stress table indicates minimum temp. to -20 Deg.F (-27deg c).....

Even for A 333 Gr. 1, 2, 3....the stress values have been given only upto - 20 deg F....how do we justify the application of this material and similar low temp. material below - 20 deg F, at which these are supposed to be used...???

 

[metengr]

Ak1965;
I should have probably not responded with a direct one word answer because as with ASME Code, you always have exceptions to rules. In general, the minimum service temperature listed in Table 1A is for general use of material that can be used with no impact testing. This is a conservative approach to listing material to assure reasonably long and safe (no brittle fracture behavior) service.

If you are familiar with ASME B&PV Code, you will know that for service temperature requirements below -20 deg F, the use of materials listed in Section II, Part D, table 1A is indeed permitted provided one follows specific rules for impact test qualification based on material thickness limits.

The Code recognizes that low temperature and thickness go hand in hand for using material where notch impact behavior is the controlling variable in low temperature service. In addition, ASTM/ASME material specifications for service in low temperature generally provide a minimum CVN impact value at a designated test temperature to assure adequate notch impact behavior for use in service. So, you have two sources of information for low temperature service – Section II and reference back to the original material specification notch impact testing requirements.

As side note, this same table in Section II provides the maximum permitted safe design temperature of ferrous and nonferrous materials. In this case, the maximum permitted temperature is one where safe operation (known creep deformation and no stress rupture) can be expected for at least 100,000 operating hours.

 

[ak1965]

Yes Metengr...you are right....

A bit of more exploration revealed that clause "e" in General Notes on table 1A (Page 150 in 2007 Edition) in ASME-II Part D states:-

"Stress Value for -20 to 100 deg. F are applicable for the colder temperatures when the toughness requirement of Section II, VIII, or XII are met".

The riddle is clearer now.... but why ASME cant be little more simple reference.....at least I believe so....!!

Thanks for better explaination

 

[TomEun]

When you apply the data (temperature limitation) in ASME Section II, Part D, B31.3, B31.1, or others, besides the various limit per metal, you may have to be aware the followings.

1. The Maximum Temperatures are ;

- based on the high temperature oxidation.
- different from the facility codes (because of the different safety factors).
- able to be limited per the specific metallurgy degradation and exposure time (e.g., graphitization, 885F embrittlement, 2nd phase precipitation, etc.). See the notes.
- based for the elastic design unless otherwise specified.
- not considered the specific service condition which is related with most corrosion and metal loss other than oxidation.

2. The Minimum Temperatures are ;

- based on the threshold toughness of metal.
- able to be used without impact test when the codes allow.
- able to be lower than the limited temperature when the codes allow (there are several conditions to mitigate/exempt the impact test requirements.) and/or impact test is passed.

3. Purchaser’s Requirements ;

- may have a narrower temperature zone.
- may have higher impact test energy values than that of the code requirements.

Hope this helps,

Thomas Eun