I have a job next week where some pipes are cracked and I have to oversee the repairs. I was faxed the WPS for the repair today. And it is showing an open butt 60 deg. V-joint, in the 6G position. The only thing is, the wps shows 3/32" E7018-G-H4 Root and 1/8" E7018-G-H4 fill and cap. The welder thats assigned to do the work is certified 6G with a 6010 root and 7018 fill and cap. Im I wrong by saying that he's not qualified for this wps? Wouldnt he have to recertify with a 7018 (or eqal F#) root pass? The way I see it, the 7018 was run on top of the 6010 so the 6010 would be as a backing. So he would only be qualified to run a 7018 with backing.
Before becoming an inspector, I was a welder for seven years, and I have never heard of running a 7018 on a root pass with no backing. I myself could not imagine having to qualifiy to this procedure. That just seems like a very difficult weld to make. These pipes have to be 100 percent VT MT and UT as well. Man do I feel sorry for these people.
Any suggestions?
Thanks
Chuck
Hi Chuck,
We just discussed this in the welding inspector course I'm taking. Often in the piping welds up here, the 7018 is quoted to weld root pass with 7018. The way around it... the welders sneak 6010 in their pockets, and weld the root when nobody is looking :) !! As for the testing, the only place it might show is with distructive testing - but you can only get caught by non destructive testing if the higher ups see the welder using 6010. This was stated by an inspector with 20 yrs experience - I believe him.
As for welding qualification, I am unsure about the classification used in the USA, but for Canada - we have a "T" and an "S" classification, which follows the "G" for groove or "F" for fillet. T means you can weld pipe and hollow structures without backing. S means you have to have a backing. For the complete 7018 weld, you would need a "T" classification.
Often it is said that many welders just run a 6010 root - as it is much easier for them. Even from an engineering perspective, I do not know why 70 grade root is often spec'd. Engineering being my only background in welding... I am stumped. I am determined to find out why this is often recommended, as I dont see the 70,000 psi vs the 60,000 psi having a large influence on the welding calculations.
If you are welding pipe containing fluid, you do want to watch the convexity of the weld. You want to have a really nice flat root (avoid excessive reinforcement), as not to cause turbulence in the flow of fluid. This turbulence will put alot of stress on the corners of the weld, and place alot of stress on the weld, often resulting in cracking on the edge / HAZ.
hope this helps you out,
Vicki
The pipe being welded is structural, its the rail pipe on a high speed (55+ mph) roller coaster. The rail pipe is the one that the train runs on. The material is API 5LGrB. As an inspector I have to go by the WPS. I have to witness the weld being made, check preheat and interpass, and also mag every pass, 48 hrs later the weld will have to be inspected with UT shearwave and maged again. I want to help the guys out, but I cant allow them to root with a 6010 if the WPS says 7018. I just think its going to be hard to find someone to qualify to this procedure. It seems to me, if they wanted 70ksi then the wps would have specified GTAW. But like I said, I want to help them out, but I cant break the rules. I have just been trying to come up with some options to throw at the engineers monday. I was hoping that if I can come up with a few easy solutions, we could all come to an agreement on something that would be a little more practicle. This is hard to do when I dont know what their reasoning is for the 7018 root.
Thanks
Chuck
The WPS says 7018 use 7018. Just assure that is what the welder tested with. Check the F number used on the welders test for the root pass. Unless the test was run with a F4 rod then he is NOT qualified. As the inspector ask the welders to run a root for you using the WPS. Visual inspection should reveal a very poor root. I know a utility that demanded 7018 roots for testing but would never use them in the field. When asked why they tested that way the response was to get the best welders.
Their thought was that if a welder was good enough to use the wrong procedure and still pass then yippee we had a water walker. Another reason was that the travelling gang with the contractor had practiced this test alot. The local guys had not. The welding inspector would look out the locals and the business agent would then have to let the travellers take the jobs.
I suspect some engineer with less than needed experience has mixed up the Procedure vs Performance section of the Code again. Either that or the contractor is trying to keep local welders from being employed.
Neal is correct. We run into this situation a lot (leaking boiler tubes). We constantly have to remind the field supervision that a leak is "open root" and our welders (with only a few exceptions) do not have certs to do open root 7018. It is a vastly more difficult procedure to qualify in.
From the material you reference, if I was in your shoes I would request the client change the WPS. 5L Gr B is low end material and 6010 is definitely adequate as fillers go. In my experience 6010 is often used on this material to weld the joint all the way out. If you run into resistance, offer to do the root with 6010 (using an elevated preheat) and finish the joint with 7018.
My two cents.
Charles
If these are fatigue cracks then further investigation of the state of the rest of the metal is in order. I don't know this particular coaster but some run on a single rail. Even with two rails the redundancy is poor. A failure could be a real catastrophe.
Bill
If the tensile strength is so important, why not use 7010? It might be a little more prone to hydrogen problems, but it isn't anything that some preheat wouldn't solve if necessary.
Like several have said, it's crazy, but they still call for it every so often. Personally I think they must be smoking crack to specify 7018 root, or just plain stupid. I'll be curious to see how it turns out.
JTMcC.
Open root 7018 is relatively easy if you use Miller's Syncrowave 250 or 350. Set the machine for AC (yes alternating current) in the stick mode. And turn the "Balance/Dig" control to Maximum Penetration number 10 and then adjust the machine's amperage. about 65-75 amps for a 3/32 7018. Just push and go no whipping or fuss. This has worked great for reworks where the pipe gets magnetized and the arc blow fuss. If you can't use AC the next best is to set the machine to Direct Current electrode negative. By the way just try the 6010 with the above mentioned AC and dig control. A person would swear the 10 became the 6011.
I agree that requesting a change in the WPS to allow a 6010 root would be the most practical solution.
I'm only guessing that the WPS specifies DC reverse polarity for the 7018, so wouldn't the techniques suggested by 357MAX (AC or DC straight polarity) require a change in the WPS anyway?
Yes the procedure of welding an 18 open root with AC or DCEN requires a requalification. My previous reply was a means to make this weld with AC.
I called this morning and talked them into changing the WPS. Come to find out, what they were concerned with was hydrogen. They wanted all low hydrogen rods to be used, thus no 6010. They were also trying to use a prequalified joint B-U2. I explained that you cant use a prequalified joint without backing or without backgouging. They changed the joint to B-U2a, for use with backing. So the welder will have to cut a 1/4" gap and try to feed a piece of backing into the hole. Now the problem is what material to use for backing. These guys are from accross the ocean somewhere and there standards dont match ours. They specified ST-235 steel to be used for backing. I couldnt find anyone that knows what that is, or what it will cross reference to in the US. My next option is to send them some chem. compositions of our steels here in the States, and they will choose one to use.
Thanks
Chuck
P.S I love my job!
You are correct in assuming that the welder is required to qualify for open roots with E7018 an F4 electrode. At one time qualification with F4 to ASME Section IX qualified F3 as well but that is no longer true. E6010 an F3 electrode does not qualify for E7108.
It is not that difficult to do we have had an E7018 qualification root and fill for many years. E6010 is easier but a good welder should be able to pass.
Also a WPS should not refernece 6G as the qualified positions, that is a "Test" position. The WPQ should say 6G but the WPS would be qualified for "All" position. Writing a WPS and using test positions is common in trainig facilities and schools but not correct in my humble opinion. WPS positions should be F, H, V, O, All or some combination.
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