Pipe welding

[decepticon]

i have been researching on the above and have got my hands on some off cuts for practicing on (even though i never plan on being a pipe welder)
i have heard the terms 'pipe liner' and 'stoving' used and wonder what they refer to, any ideas?
i have been using a 7016 rod for the root but if rooting on a proper pipeline job with stick then what happens to the slag inside the pipe? how do they get it out?

 

[snowcat]

much of what you need to know is reveled here, and TBH can explain much better than I can, stoving I don't think gets a mention, but its basically a technique for welding pipe down hand very quickly useing a cellulose based Rod typically a 6010, Its sort of almost become folk law, but technically its a slightly iffy concept that has to be preformed in the right hands, or often 4 hands....

 

[TechnicAl]

True stovepipe welding (or line pipe welding) is done using a cellulosic rod (E6010) vertiacally down (start at the top and proceed downwards). The pipes are usually located in a muddy trench so there are two welders, one either side who meet at the bottom of the joint. The process shouldnt work but because they apply a lot of preheat and weld very quickly the heat stops the welds from becoming brittle or cracking. The welder usually has a mate who just passes him the rods. The bottom part of the joint often involves the welder getting down in the mud so its not a clean job.
Sometimes they have a very capable welder who only welds the root and the first pass (called bead and hot pass) and another guy continues to fill out the joint.

I used to get the charge hands on the phone, often Irish. They often would ask me "how many rods do I need to weld a 5 mile pipe". We would then start discussing thickness, diameter etc, usually the pipes are 11m long but sometimes they weld 2 toghether before placing in the trench.

 

[muddle84]

I used to get the charge hands on the phone, often Irish. They often would ask me "how many rods do I need to weld a 5 mile pipe". We would then start discussing thickness, diameter etc, usually the pipes are 11m long but sometimes they weld 2 toghether before placing in the trench.

I've worked on a few pipeline contracts(not as a welder sadly, very good money) but i have been around the welding, typically as much welding is done outside the trench as possible, unless at road crossings or thrust bores or even in around stations, sometimes theres no other way around it but to weld in the trench!But even when they are welding in the trench theres canopys set up over head and stone put down on the ground or pallets so they'd not actually kneeling or lying in the mud!! they'll weld as much as a kilometre together( even 48inch diameter with 1 inch wall thickness) then "ditch" the pipe using the side booms. Its quite a sight to see it being ditched, jcbs dancing diggers don't have a patch on them lads!!!!

 

[ieezitin]

Hi guys.
I am a pipe welder here in the states, originally from England though, anywho Pipelining and pipe liners (welder person) just pertains to a welding process using 6010 root and cap for low pressure main trunk lines for fuel oil, crude and or natural gas lines. Low pressure being 100lbs or less.

It’s used because of speed of the welding process, your right usually its two people making the joint, but because of its inherent weakness the hangers or pipe rack supports need to be more frequent and stronger, it’s a process that is becoming frowned upon in latter years as there are new machines coming on the market that even a monkey can operate.

In high pressure process lines and power generation (high pressure steam) the old ways still prevail, in the last twenty years the standard is to Tig the root always then maybe put one hot pass, then fill and cap with stick. If the root is to be tiged the bevel should be made a knife edge, that means the bevel should be about 37 deg angle and feathered to an edge that will cut your finger, depending on the material the gap for the root should be about 1/8 or 3/32 (welders choice) when you arc up you need to consume both edges or (walls) while adding filler, the crown or root bulge should not be no more than 1/16 on the inside this is critical as if its more and protrudes into the pipe cavitation will result you will fail the test if you go to far. Note here if your welding chromemolly or any high concentration of chrome you need to start with a larger gap as it will shrink quicker than a witches tit.

Medium pressure ( 400lbs and below ) regular 6010 root with 7018 hot and fill with cap works just great, the bevel this time needs a landing ( edge on bevel ) bevel the pipe again on a 37deg angle to a feather edge, when its all equal you run the grinder over the edge perpendicular to the axis of the pipe and grind a flat around 1/16 up to 12 inch and around 3/16 on larger diameter pipe, this time you with the 6010 rod consume the flat (landing) poking your rod in and depositing the root, again you need to leave the bulge in the root and the same rule applies for the size of the bulge.
Stainless, all stainless is tig root, its impossible to stick it, then you hot pass and cap with stick, if its thin wall pipe its usually tiged all the way out.

I wrote a little article on pipe welding on a how to basis on another forum, if you are interested I could post the link.

All the best. Anthony

 

[aidank]

link would be good anthony