Riser Welding/Grinding Options

[squirmy rooter]

Hi All
I am putting this post on the forum hoping that some of you have maybe worked on risers before and can help with this problem.

We will be welding double j Preps closed gap, the cap has to be removed after welding also the root run has to be removed,now here is the problem. The root will be 24" inside the riser how do we grind this? The spec for grinding is we cant loose more than 1.5mm of wall thickness and the surface finish must be better than 125 rms.

Initially we have thought of using a barrel grinder but how do we make sure we dont go below the
1.5 mm ? Any suggestions or new ideas are welcome.

Regards

Squirmy

[douglas]

What diameter pipe Squirmy rooter dude. Loving the handle BTW.

[3.2 Inspector]

You make sure, by making sure you dont gring belo.w 1,5mm
Some boiler/power plant workers face this issue every day.

3.2

[douglas]

Had to look twice but concour absolutely with 3.2.

[skaginn]

Hi Squirmy
A lot of years ago I worked for ABB Vetco Gray in Montrose welding caissons, SUB ARC.
Caps were ground off with a belt grinder, dont know what type of belt they used but the grinder guy could flush off 40 plus 24" Butts 12 Hr Shift. To be honest I don't remember if the inside was done.


JC

[squirmy rooter]

Douglas the pipe diameter is around 10" and i dont understand what 3.2 is talking about if you do please explain.Skagin we also use the same system you speak of for the removal of caps but it is a bit large for what we are after here. Thanks for the replies

[den the welder]

Hi, Squirmy, Done a few, and we, used flap disc,s on the inside and as 3.2 say,s you just gotta be careful you dont dig in keep the grinder flat,outside taken down with a 7 inch grinder to about 3mm high and finished off with a flap disc, not a nice job on the inside for grinder / helper , Den.

[squirmy rooter]

cheers Den

[douglas]

Hi Squirmy, 3.2 means that you must take care and use your grinding genius to ensure you don't dig into the pipe wall. I'm guessing he'll be on your back otherwise - or someone very like him!

No big deal on ten inch just a bit of an arm acher I reckon.

good luck with it

doug

[hippyhunter]

hi folks,

i might be a bit naive but in order to weld a 'double j' prep don't you need access inside and outside the pipe?

if you can access inside to weld surely you can also access inside to grind the root flush?

if not can the prep be changed so there's no requirement to grind off excessive root penetration?

don't be too harsh if i'm being a bit thick, i'm still learning

all the best, jim

[B186]

you're on the right tracks hippyhunter, a riser prep would be a single "U" butt, but its commonly (wrongly) known as a double J , probably because both pipe faces are "J" shaped when put together.

[digi]

why would a welder be worried about taking weld off its a welder job to put it on not off

[3.2 Inspector]

digi,

Do you also complain about the Polish welders working in the UK/Europe?
They do care, and most of them grind their own welds :)

3.2

[digi]

yer i moan im not really saying a welder should'nt grind now and then but it can't be cost effective to have a welder grinding for hrs when he should be welding. Mates should be doing that would be cheaper thats if there paying real rates of pay

[3.2 Inspector]

"Mates" sucks even more than the welders.....

3.2

[webbo]

OOH 3.2 I Bet some poor welder is going to get it monday when yooo get in.
digi is right it is more cost efective to have a grinder do it than a welder
and where did that come from about polish welders