Ss X-ray testing

Date 05-08-2012 00:00

Usual methods to weld carbon steel pipe are MIG/MAG (correct name GMAW) or stick eletrode (correct name SMAW). Stainless steel pipes are welded by TIG (correct name GTAW) and also, even if less frequently, by GMAW.

Bevels in carbon steel pipes are usually done by means of a beveling torch that employs an oxyacetilene flame or a beveling machine that use either a silicon carbide (commercial name Carborundum) stone or a high speed steel or tungsten carbide (commercial name Widia) cutting tool.

Those materials can not be used with stainless steel. Oxyacetilene flame does not cut stainless steel, a plasma torch must be used instead. Carborundum, high speed steel and Widia are high carbon materials that will leave a carbon residue in the cut surface, making it prone to intergranular corrosion.
Instead of Carborundum, an alumina stone must be used. Also, instead of high speed steel or Widia, it must be used a high chrome, martensitic steel cutting tool.

Giovanni S. Crisi
Sao Paulo - Brazil

By scrappywelds (***)

Date 05-08-2012 00:46

I would say it all depends on the Min. wall of the pipe. Thin wall (.180 or less), cut with a saw, grinder with cut off wheel. Hand prep the bevel. Over .180 to .500 can still be prepared in the same manner , but it will take more time. Anything over .500 I would say machine bevel.

By fbrieden (***)

Date 05-08-2012 01:15

Refer to company's PQR/WPS

By joe pirie (***)

Date 05-08-2012 04:11

not to be rude if you don't know ths answers to the questions you asked you
haved no business even attempting the job. how can you even bid a job if u
don't have a clue how to weld it or cut it. if your in doubt refer to FC2012
wselder ur up with 6010

By CWI555

Date 05-09-2012 21:40

This has back charges written all over it.

By WeldinFool (**)

Date 05-08-2012 12:16

I have almost 30 years in the industrial piping insustry, with 12 of those years in fabrication shops. Give me some more info (s.s. grade, wall thickness, fabrication or field work?,...) and I will tell you what I know.

By eekpod

Date 05-08-2012 12:21

He could just be a shop guy asking general knowledge questions. He may have no control what his company bids on or what work it takes. Hopefully they will provide him with the answers he needs to actually perform the work.

By BooTLeG (*)

Date 05-08-2012 14:39

It is 3" schedule 40 304. A pumping skid will be built in the shop and then I go into the field using a tig setup off of a stick welder.

By WeldinFool (**)

Date 05-08-2012 15:36 Edited 05-08-2012 15:45

That 's a pretty common grade and is easy to work with. The shops I have worked in usually cut it with a bandsaw and then bevel it with a tri-tool or equivalent (most I've seen are pneumatic), and you'll want a good sharp bevel with no land. Plasma cutting is an option, just depends on what you like (this option takes a lot of grinding afterward to get a good clean weld surface). Go with a 1/8" gap, a good argon purge, and GTAW with 1/8" 308 wire. It's just about as fast to just use GTAW all the way out, I've also seen shops go to FCAW after the root, SMAW is definitely the last choice you want to go with when welding stainless, I've yet to find a s.s. stick rod that welded worth a sh!t! Be sure to keep a good purge on until the filler is in, if possible leave it on until you're capped out. Amperage is about the same as carbon steel welding, the biggest trick is to not let the pipe get too hot. We will often cool it down between passes with water in spray bottles, preferably de-ionized water. Hope this helps.

By jd369

Date 05-08-2012 18:42 Edited 05-08-2012 18:46

I also like a 1/8" gap as stainless will want to close up as you weld. I use about a 1/16 land as well.
I tack in 4 places equally spaced, I try to bridge the gap so as to not get root penetration while tacking. Then wrap the joint in masking tape, leave a 1/4" gap at the top to purge the air out. Purging times all depend on size and length of piping. Once I feel the joint is ready to weld I will set the flow rate of the purge line down closer to 8-12 cfh.
I weld between tacks slowly pulling the tape off as I weld, sometimes I will burn through the tape as it is at the outer surface of the pipe and not down in the root where I am welding (will not contaminate the root pass). A quick flick of the torch will burn the tape back enough to continue welding. I start my weld just after a tack and finish just before the next tack.
My tacks are usully oxidized as it's very difficult to get a decent purge for tacking the pipe together, that is why I bridge the gap. I grind to remove the tacks entirely and then weld the remaining 4 areas where the tacks were now that the pipe is properly purged.
Hope this helps
Regards
Jim

By 2006strat (***)

Date 05-09-2012 16:56

Keep your tunksten clean. Watch the purge pressure as you close up the weld you might have to turn it down little by little. Your purge line needs some type of filter on the end.(I just cut a piece of foam or wrag whatever is available and tape to the end) 1/8 gap 3/32 filler no landing.

By BooTLeG (*)

Date 05-10-2012 01:16

Thanks for replying...so im leaning more towards make a bevel with no land and 1/8 rod, the only thing I'm not grasping is how is how to put the bevel I googled tri tool and it's a company with many types of equipment is it just the bevel maker I need? Still a little confused about that part.

By joe pirie (***)

Date 05-10-2012 04:09

what does your wps call for. you need someone there who has actually welded an open root stainless pipe.
you can get all the advice in the world from some very talented members here in this forum that doesn't
mean that you can just strike up and weld just because someone told you how to prep the pipe.
your post said something about xray welds lmao please let me know which lab is going to shoot the pictures
i want to buy some stock cause there going to make a fortune. please post pictures

By WeldinFool (**)

Date 05-10-2012 15:20

The beveling tools I have used were mostly the Tri-Tool brand, but there are other that are probably just as good (hopefully there are no Tri-Tool vendors reading this!) They were just the basic beveler that attached to the ID of the pipe and had different shoes for different pipe sizes. The ones I used just had a simple rotating head that you could attach whatever type of tooling you want, we usually used a 37.5 degree carbide attachment. Works really good, perfect bevels everytime, ready to weld. Your cuts with the bandsaw can even be a little out of square and this tool will face it up for you everytime.