Welding Tips and Tricks

hello all you smarter than me welders. here are my questions. when welding 6" schedule 10 stainless pipe, grade 304L can a succesfull pressure weld be achieved using stainless stick for the root or does it have to be a tig root? also on material of this thickness is it necessary to put the standard 37 deg. bevel on the pipe ends or will a welder be able to achieve full penitration with the unbevelled pipe? theese are not socket welds. If a stainless stick can be used what are the parameters and rod angles for root fill and cap?

in my opinion, a 30 degree bevel and a tig root is called for. I dont believe you can achieve decent quality with a stick root on this.

stainless stick is hard enough to make look good for fill and cap passes. unless its in a vise.

this is what i've done in the past. but the pipes together with a 1\16 to a 3\32 gap, tack them, then run a grinder all the way around till its about 16th thin, then run 308, as close to 90 degrees as you can get it. i've even butted them without a gap and ground it paper thin. you'll know by the key hole if your penitration is good. a tig root is nice, but not nessasary if you can weld ss stick good.

hey I got a quick side question-I hear alot about doin a tig root/hotpass and then a 7018 root and cap. Whats the differance between doing it that way or ss stick all the way out, or tig all the way out?

well i'm not sure about doing 7018 on stainless, but as far as a tig root and stick out its for the quality of the tig without worrieing about slag in the root, and then its a time and money factor with the stick.

i guess i didnt read your question right first. although i've never done this or would recomend it. i can see doing a ss tig root, with a 7018 filler and cap. the tig root would be for the inside so the joint doesnt rot out, and the 7018 would be just alot cheaper rod than stainless. it will work, but like i said, i wouldnt recomend it. even with a stainless to mild, i would run 309 all the way, whether it be tig or stick, or both, what ever the client wants as long as it conforms to my ass not getting hung up

ya we got a powerhouse addin on 100 megawatts out here and their callin out for alot of fitterwelders. The gate test they got is a tig root/hot pass and a 7018 fill/cap. Guess its pretty common on powerhouses?

when i tested for my last job it was a stainless tig root with 308 and stick out with 308. i think they are mostly for employment testing so they dont have to make you do two test. but i can see the benifits for doing a tig root with a 7018 stick out. no slag or porosity in the root. i also know there is a cert for tig root and stick out on stainless with stainless rod as well. they also have on for tig root and mig out. for the most part i think its someone trying to come up with and throw some shit in the mix when it comes to cert tests. mosts of the inspectors dont weld and cant weld. my old instructor told me that when he went for his aws welding inspector cert, more then half of the people in the class did not weld or knew how to

heh. thats funny cause I believe it. Seems like them suits in the office are always tryin to make things harder for the guys in the field.

you aint shittin there..... they have to come up with something to earn that money....lol

please, never use 7018 on stainless steel! in case you didn't hear me i said,"NEVER"!

hey hammerweld, no offense but if you use 7018 on stainless steel your a$$ will indeed hang!

Never ever use mild on stainless. Thats corrosion waiting to happen period. As far as welding stainless pipe with stick ive yet to see a real so called "pretty" weld on it. Stainless stick is a whole nother animal it loves nice flat surfaces and running uphill with it yeah dont do that lol. Ive only been able to weld uphill with stainless using a series of stop and starts "tie-ins" so to speak. You burn pull away let it cool for a sec then add another bead on top etc... I prefer TIG on anything stainless pipe,sheet,angle etc...

Well i've never done it myself, but like I said, our local has a couple certs for it and there have been plenty of job calls for guys with certs for that process.