Hi vdao3004
A full answer would depend on positions and other factors as well, but let us assume you welded a 1G plate with a butt weld. 1/2" GTAW root without backing and 1/4" SMAW filler and cap. You would be qualified to weld:
1) SMAW: Diameter >73mm; 1/2" thick deposit; Flat position; With backing
2) GTAW: Diameter >73mm; Unlimited thickness; Flat position; With or Without backing
Hope I understood your question correctly.
Regards
Niekie
Niekie,
Thanks for response, I just want to know that if this person also qualify to pipe welding and what is allowable size, according to what I know , this person can qualify to weld 2.875 OD. pipe and up, but I can not find any were in the section 9 code which tell me about it.
Please help.
Thanks
Hi vdao3004
I am going to try and attach the relevant QW461.9 table from ASME IX, to show you the ranges yourself. This was also referred to by another post. (by 464238)
To answer your question regarding the backing. If the GTAW was the root weld process, and you only welded from one side, then the GTAW was welded without backing, which qualifies the welder to weld with or without backing. If you deposited the SMAW on top of the GTAW, then the SMAW was welded with backing. In this case, the backing for the SMAW was the GTAW filler metal. This only qualifies the welder to perform welding with the SMAW process with backing. (This includes welding the root with SMAW, then back grinding the root, and welding from the second side, or depositing the SMAW on top of another welding process, or welding against a backing bar etc.)
Hope this helps.
Regards
Niekie
ozniek,
Thanks, it is clear for me on this now.
Nieke,
What is purpose of back grinding the root?
Thanks
Hi vdao3004
If you need to deposit a full penetration weld, then the full thickness of the material needs to be fused. This can be achieved by welding from one side only, but then the root needs to penetrate and fuse all the way along the weld seam. The other option is to grind / gouge (called back chipping or back grinding) the root of the weld from the second side, and then to deposit a weld from the second side. Obviously this is not possible for most pipe applications, in which case the welder must be able to pass the test by welding from one side only.
Hope my explanation is clear.
Regards
Niekie
Nieke,
1) SMAW: Diameter >73mm; 1/2" thick deposit; Flat position; With backing
2) GTAW: Diameter >73mm; Unlimited thickness; Flat position; With or Without backing
what do mean, SMAW process is only qualified with backing, because we welded on top of GTAW process, we always though that it also qualify for With or Without backing as same as GTAW.
Regards,
Simple answer, plate does generally NOT qualify pipe under ASME IX for performance qualifications. That said, plate may be used to qualify pipe for PQR.
Take a look at QW461.9
Qualification on Plate (2G, 3G, 4G) does qualify you on 24" Diameter and over in all positions and Pipe less than 24" Diameter > 2 7/8" OD in the Flat and horizontal position only.
Hi Jon
Yes it does, but there are limitations. See the table I attached above.
Regards
Niekie
By jon20013 
Date 11-10-2011 18:01
Edited 11-10-2011 18:04
I stand corrected, thanks!
EDIT: Now there is a good example of "shooting from the hip" without double checking the source (no matter how good you think you know the subject).
vdao,
The SMAW deposited metal was over the GTAW deposited metal therefore the SMAW process is only qualified With Backing.
QCRobert
Gentlemen,
What is purpose of back grinding the root on the test plate
Thanks
I knew for back weld it, but still not clear why you need to do it, you can weld the root pass and leave it as it.
Hi
Not all welders are capable of welding a full penetration weld from one side only. (May get LOP defects, or over pennetration defects etc.) Also, some welding processes make it essentially impossible to weld a full penetration weld from one side. (e.g. SAW; GMAW spray transfer) If you have access to the second side of the weld, it can increase productivity to deposit the weld from both sides, so then your welder does not need the skill to deposit a weld without backing, in which case you may prefer to qualify him/her with backgrinding.
See my earlier answer as well.
Regards
Niekie
Many years ago we fabricated some 12 and 22 foot diameter pipeline using the SAW Process, all the seams were welded from one side using a copper backing(if memory serves me right).
These were CJP welds that actually turned out nice. so its not impossible.
we also took a large belt sander off its stand, turned it upside down and put weels and a handle on it for grinding the reinforcement on the back side when it was needed. worked pretty slick.
Hi
But you welded it with backing!
Regards
Niekie
true, I guess i did not think that one through,lol
Gentlemen,
Thanks for all responds again , they are a helpfull opinions for this newbee so far to uderstanding the welding process
Per quote" Not all welders are capable of welding a full penetration weld from one side only. (May get LOP defects, or over pennetration defects etc.) Also, some welding processes make it essentially impossible to weld a full penetration weld from one side. (e.g. SAW; GMAW spray transfer) If you have access to the second side of the weld, it can increase productivity to deposit the weld from both sides, so then your welder does not need the skill to deposit a weld without backing, in which case you may prefer to qualify him/her with backgrinding."
I am always thinking, the welder must take the test to qualify not only for root pass and weld deposited after, if they can not do the root pass, it will not helping us on production weld which is required to pass RT when it is specified per our customer, we do not have room to backgrind, now I know why some of the welder is struggle with the root pass so please advice me how to qualify welder to make them better, or improve the process.
Hi vdao3004
I am not sure if you are asking how to perform the required code test, or how to improve the welder's skill. If you want to know how to improve the welders' skill, to deposit root deposits from one side, then it would take a book. If there are specific problems that the welders face, (e.g. under penetration on the bottom of the pipe) then ask how to solve those specific problems, and maybe some of the good welders on the forum (not me!) can give you some pointers. If you are asking about the test, then make sure that the welder passes the relevant pipe test piece using the particular welding process you require him/her to weld with in production to make the root in the test piece. If he can do it well in the test piece, then hopefully s/he can do it in production.
Regards
Niekie
