Porosity using E9018 B3HR4 SMAW rod

Date 03-31-2008 22:04

We are welding T-22 heavy wall boiler tubes using the buddy weld split welding lead procedure to pass the arc from one welder to the other. We are experiencing sub surface porosity that seem unusal. It's not only at the point of arc transfer but elsewhere as well. It has no standard pattern. Background info: proper preheat and cleaning of tubes is being witnessed and appoved by QC. No oils present on metal. Rods are kept in oven and are fresh. We even changed rod manufacturers. Mulitple, highly skilled welders are experiencing this problem so it's not the people doing the welding. Chill rings are being used for the root pass and it's an all SMAW procedure. The welds look perfect on the outside but if you touch up a spot here or there with a burr grinder, sub surface poristy is abundant! Changed welding machines as some were used for carbon arc cutting. Used new machines and problem still persists. The tubes are new to new for the most part but come from different manufacturers and not sure of the country of origin.

Any suggestions on what else to look for to solve this problem would be appreciated. I've welded similar tubes several times and have never seen porosity like this with an all SMAW procedure. Thanks

By BkTaylor (*)

Date 03-31-2008 22:33

If you have not tried yet I would try ESAB MFG. Check your polarity too on what your running. There is also 8018-B3 MR if your temps are going to be over 850 degrees. Or try E10018-G-H4R Lincolns pipeliner 19P All these including the on you are running should be ran dc+ or ac.

You need to find out the composition of the material that your welding to really find out what you should use.

The 8018-B2 and 9018-B2 LH-90 is for1-1/4%chromium 1/2% moly pipe, tubes, boilers or castings
The 9018-B3 is for 2-1/4%chromium and 1% molybdenum hope this helps

By awspartb (***)

Date 03-31-2008 23:06

Thanks for the reply but I'm not the QC person. Just the welder. Polarity is correct. First thing we checked. Welds look wonderful and pass VT with no problem. Grind it and it's Swiss cheese. Strange.

As for material verification; the QC here is extreme and I'd have to say they have looked into it. I'm just concerned about it as a welder who prides himself on performing quality work.

I can't change the rod being used but they did get rid of the stuff they started with and went to Lincoln. The problem persists. The preheat is 450 F.

Thanks

By MBSims

Date 04-01-2008 00:53

You might kick the amperage up about 5 amps and see what that does. Also, check your ground leads to make sure they are heavy enough to carry the total amps if you have several welders using a common ground lead. If you are using an inverter machine, check the arc force setting and kick it up to al least 50%.

By Steve.E (**)

Date 04-01-2008 09:15

If you to a test weld on some scrap material do you get porosity ? If not I would be looking at the parent metal . Did the tubes come from China or India ? Our company not so long back had to basically dump a million dollars worth of Indian tubes.