ss pipe welding

Depends of the size and length of pipe. You can use X ray to check weld.

can u give us more enlightenment? this is appalling.

i don't know the size of your pipe and the process you wanna use. Info, info, info!!!

in any case you better do a few test weld on a scrap piece. you need the ends to be beveled with some landing (@2mm) followed by the rite gap, size of electrode and make sure you maintain the key hole during root run to get a proper penetration or else let someone do it 4u.

Hi, madhavan_b

First you must identify the SS type and grade (there are different types of SS: austenitic, duplex, etc).

Then according to the wall thickness of the pipe you have to choose a weld end preparation. This can be just straight ends for thicknesses up to 3 mm. and V, K, J or U form for thicker walls.

You have to select a filler material (you will need it unless the thickness be really low, in the order of few tenths of mm). If both pipes are the same material, you must select a filler metal with a deposited chemical composition similar to them. If both pipes are different grade (let say a 304 SS and a 316L SS) the normal choice is a filler metal that fits the higher alloy or even higher to compensate for dilution. Any welding material manufacturer have available on their website data sheets for their products including chemical composition, mechanical properties and main applications.

Regarding the welding process, I would recommend you to have the root pass with TIG welding using purging inert gas in the inside of the piping. You can make a small chamber at both sides of the weld with some type of water soluble paper easily available. This would assure a good penetration and avoid excessive weld pool protrusions inside the ID of the pipe which may give further problems (pressure losses, cavitation, etc.)

The other passes to complete the weld can be made by any other process (MIG, SMAW...) according to the needs and cost analysis.

If you provide a more precise information, we could give you a more precise answer.

Best regards

You can also use Solor Flux obtainable at most welding supply stores. This is a flux you mix with denatured alcohol and paint the inside of the weld joint. It replaces purging with inert gas. Disadvantage is you only get one shot and it leaves slag inside of tube. To be assured of a good weld. (practice ) or hire a BOILERMAKER

Everyone that posted is correct about needing further information.

Usually the welds have to meet a specific standard (such as ASME B31.3).

In the absense of further information, you can begin educating yourself on the various standards at the following link:

http://www.welding-advisers.com/Welding-inspection.html

Good luck!

Hello, Not knowing more details I can only give you some basics for this. I would first suggest having someone who is knowledgeable to write a WPS and A PQR for the welding you intend to do. I would suggest a GTAW ( TIG, heliarc etc.)process with an Argon purge inside the pipe. Even though this may change a little on some types and sizes of stainless this is the norm for me. I would suggest 1/8" diameter, 2% thoriated tungsten sharpened to a point DC straight polarity and use the appropriate filler wire such as ER 308 for 304 grade stainless, ER 316 for 316 grade stainless and ER 309 for bimetal stainless to carbon steel welding. There are so many different types of stainless steels and they all have their corresponding filler metal that anything I say here is really just a guess. I find that utilizing as big of diameter of filler wire as possible helps in keeping the base metal from over heating. With stainless steel welding the color of the finish weld determines what kind of product you have. AWS actually publishes a book just on stainless weld color and what it means. Getting stainless to hot is a big no no. If I am inspecting these type welds I would first do a visual and according to what service it is intended for I would eliminate all welds that have bad color and/or weld profile and then have either a Shear wave UTT scan or a X-ray done to determine weld soundness and fusion.

pipewelder