By 803056
Date 10-15-2007 02:43
Edited 10-15-2007 03:03
Hello Phil;
I tried to clean up my post to clarify the differences between the H8 and H4 designators used in conjunction with the electrode classification you mention and the one's used in Annex XI.
I hope it helps. And yes, it would be helpful, just as it would be helpful if EXXXX-C1, -C2, -C3 meant 1% nickel, 2% nickel, and 3% nickel respectively. That would be too simple.
Added thought: Remember that if an electrode is specified without the optional diffusible designator, you can use any electrode that meets -H16 or lower, i.e., -H8, -H4, but if you do use the diffusible hydrogen designator in the WPS, purchase order, or drawing, then the designator becomes the maximum diffusible hydrogen permitted. In other words, an electrode specified as E7018 can be met by any electrode meeting E7018, E7018-H8, or E7018-H4 classifications. However if the electrode classification specifies -H4, any electrode with a higher diffusible hydrogen content is not permitted.
Best regards - Al