Maximum temperature for A-335 P22

[mmonti0]

Good morning,

on ASME B31.1 Ed. 2016, A-335 P22 has the allowable stress shown in table until 1100°F.

Instead, on ASME BPVC II, D Ed. 2017, the material SA-335 P22 has the allowable stress shown in table until 1200°F.

What is the reason of this difference?

Thank you,

MM

 

[MJCronin]

The reason is two different groups of engineers developed these codes .....

What exactly are you building or evaluating or trying to do ?

MJCronin
Sr. Process Engineer

 

[mmonti0]

Dear Sr,

we are developing a boiler with reheater. The reheater header and nozzles (inside the casing)and the main pipe outside are in SA-335 P22. During start-up, when pressure is not yet built-up, the fluid may reach for little time (less than 5 minutes) a temperature of ~ 605°C (~ 1125°F).
While the portion inside the casing can theoretically withstand this condition (since the ASME section II D is listing allowable stress for P22 up to 1200°F), we do not know how to deal with the outer pipe, that falls under B31.1 (since the allowable stresses are listed only up to 1100°F)

Thank you in advance

MM

 

[XL83NL]

Different codes, different basis for allowable stresses. A B31.3 instructor once told me the difference between B31.1 and B31.3 allowables. He explained that, if I recall correctly ,that .... apart from the differences between the intended use/service of both codes, the environment surroundinig a plant, with respect to human occupancy, also was important. The likelihood of people living near a power plant (e.g. near urban areas), combined with the typical higher pressures and temperatures in power plants, make that the allowables are lower, providing a higher design margin (and thus some more inherent safety, if you like). B31.3 refineries are typically found more on chemical/refinery sites, where less human habitat or houses in a near vicinity are found, e.g. rural areas.

 

[SnTMan]

Rural areas like, oh, Houston

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

 

[XL83NL]

Pardon my occasional bad choice of words, maybe it's semantics, but keep in mind Im Dutch ;-)

 

but keep in mind Im Dutch

You say it like it's a bad thing...

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

 

[SnTMan]

XL83NL

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

 

[mmonti0]

So, in your opinion is it possible to use A-335 P22 in B31.1, NBEP for very short period (~5 minutes during start-up) above 110°F?

 

[XL83NL]

If I’m not mistaken the limits of B31.1 may not be exceeded. So no