P number of N08904

[Ali Asghari]

Dear All
Why the specified P-number for UNS no.N08904 is 45 while the ASTM specification is A312 that related to stainless steel pipe?
and which filler is recommended for welding of this material with 316L?IS ER nicrmo3 suitable?
Regards

[Raj]

Hi,

It is called super austenitic SS and 904L (UNS N08904) is having 10%
more 'Ni' to provide overall balanced performance with regard to
reducing acid and chloride stress corrosion cracking. The 'Cu'
additions provide additional resistance to many reducing acids.

The suitable consumable will be ER 385 / E385-xx.

Please find below extract from Sec-II part'C' SFA 5.4 for your
reference.

'A7.35'
E385. The nominal composition (wt. %) of this
weld metal is 20.5 Cr, 25 Ni, 5 Mo, 1.5 Cu. These electrodes
are used primarily for welding of Type 904L materials for
the handling of sulfuric acid and many chloride-containing
media. Type E385 electrodes also may be used to join
Type 317L material where improved corrosion resistance
in specific media is needed. E385 electrodes also can be
used for joining Type 904L base metal to other grades of
stainless. The elements C, Si, P, and S are specified at lower
maximum levels to minimize weld metal hot cracking and
fissuring (while maintaining corrosion resistance) frequently
encountered in fully austenitic weld metals.

Cheers!

Raj