Maintanence of Piping

You need a competent piping engineer who knows the specifications for the installation and proper maintenance and repair procedures, and how to carry them out.

In the mean time you might want to inform your client that you are lost as to what to do and have solicited the help of an unknown, anonymous internet forum to post the "buttering" procedures on-line for you.

That's sure to instill tons of confidence in your ability to service the system.

http://www.eng-tips.com/viewthread.cfm?qid=213694

Where there is an opportunity to remove the length of pipe from the line altogether, so as to cut the flanges off, it may be easily possible to accurately do the cut with a cutting disc or power saw.

This will leave approx 3mm gap at each cut, which is ideal for setting up the butt for the new in any case. Problem solved....

Here are the list of suggestions:

!) Hire a non destructive inspection firm to confirm what has happened to the piping components, ask for pit gauge of the surface of flanges, and a scan of wall thickness via ultrasound for internal verification. Verify you are in the required standards of ASME.

2) Determine a corrective action from this information, do all the components need replacing, or do you have other problems such as poor flange alignment, improper torque of bolt etc, or do you have a corrosive issue that needs to be resolved. Typically new systems have all the issues designed out to prevent what is happening to this segment of piping.

3) Using ASME code you are allowed to do build up using your welding procedure that was established when these materials were designed into the piping process. This only allows for "groups" of materials that within the tables expressed by ASME. Best to discuss this with a competent welding engineer or do the research in ASME BPV Code .

4) Hire a professional welder, and pipe fitter to install the components, the parts may be under strain from previous installation , thus making some duplicated component not as easily replaced as appearance may suggest.

5) Pressure piping can be very hazardous, I am sure from your post that your experience is limited, do not take this project lightly , hire professionals!!

A lot depends on what is in the pipe and we do not know. Is it Steam, or Amonia for refrigeration ( That requires certification in most areas as a leak can kill a lot of folks ). Lets assume it is medium pressure water. In that case I personally do not use buttering but rather use short welds to fill the gap. In other words weld a little then stop and let cool for a few seconds. Then Weld some more then let cool and repeat this until you have a good base. It at this point will not look that good but you know have lots of filler and it is also helping to hold. Now let this cool for a few min. Then go ahead with the normal but a little but higher power to cover and get deeper into the small filler welds and as doing this I would do what we used to call Washing. Washing in case that term is not used is to cover all welds with yet another layer making sure to get penetration without undercutting. I did this for welding Sadles on pipes on one end and flanges on the other end. the Sadles were flat but connecting to a round pipe so I had to fill that gap. No one could figure out how I made that work as when other tried they would burn through the whole thing. Then I had to go fix it. Since we were competitive in that shop I never did share that with anyone until now. From your description at first you say the leak is between the flanges. Not sure what that means. Is it between the flange on the pipe and what ever it connects to or between two flanges on each end of one pipe. I have to assume the first as re welding the flanges on to a pipe that is leaking between the two flanges on one pipe does not compute to me. IF I had a leak between two flanges on the same pipe I would replace and if for some reasons that is not a good idea then I would cut a larger pipe just large enough to fit over the pipe with the leak and cut that pipe in two lengthwise and then clamp both to the pipe and weld every place there is needs to be a connection and that will stop a leak but does leave an area where standing water if that is what is in the pipe can gather and that can cause Legionaries decease. Jim

I have also used the method you describe. Since it is ease to burn through from the heat, might not have a smooth surface on the inside, might have a pocket of flux or slag and sometimes most important the long time it takes for each pass to cool I try not to be put in a situation where I have to use it. I have found it to be a better weld and easier to do if I take an appropriate length of the same size pipe and cut a piece just long enough to fill the gap. Tack it place between the two pipe ends and make the appropriate passes. This leaves a smooth internal surface, won't burn through as easily and if done right less time. A good band saw or power hack saw works best to cut the small piece from the "donor" pipe. A little dressing up with a grinder may be required to make it fit and to dress it up when finished.

Try it some time. It may turn out to be another handy tool for your "toolbox".

Good Luck, Old Salt