Where could I find a procedure for welding on a natural gas pipeline? I know very little about welding but my maintenance manager asked me if I could do some research and find something on the topic. Any ideas where to look? Thanks.
<SANHB> wrote in message
Procedures for welding any piupelines varie from region to region...your best bet is to contact your local gas company as they have written procedures for repair etc... Jim
I agree, but, IMHO the correct party to contact is the OWNER of the pipeline. They SHOULD know the regulatory structure they operate under, as well as the materials and approved procedures for their lines.
Good luck, YMMV.
Several of the local welders I know are going under re-certification check. They are not informed as to what the next pipeline will contain but suspect it is most important to contain without possible leak. These are all well seasoned and just back from a job. These go off to states at all corners of the country to weld as the line is being put in. I have another friend in Ohio.
<SANHB> wrote in message
One time, a gas line was ruptured near my worksite. It was a three or four inch line IIRC. I was into welding at that time, and asked how they were going to fix it. The guy said they would OA weld it. I was surprised.
I was also surprised when I found out how much natural gas pipeline is gas welded. Turns out it is common practice for welding residential lines 3" and smaller. Larger stuff is stick or TIG welded.
I am interpreting the OP as asking about welding onto a live natural gas pipeline. This is sometimes done, for example to install a new branch connection by "Hot-tap" (i.e. tapping into the line while it is "hot" [operating]) or for repair of localized corroded areas.
There is specialized equipment associated with this. The best known company for the associated equipment and providing this service is TD WiIliamson (Tulsa, OK). Some experienced gas companies just buy the equipment from TDW and do their own hot-taps. The attachment welds are typically fillet welds connecting the special pieces (e.g. a "hot-tap split tee fitting" for making a new branch connection or a split sleeve for reinforcing an area with excessive corrosion) to the outside of the existing pipe.
API 1104 actually has a special section on this type of welding. It is "Appendix B - In-Service Welding" which provides details of how such welding is to be qualified.
The trick for the welding is to: a) Make sure the pipe wall thickness is great enough and the welding parameters are "low enough" to prevent burning through to the inside while simultaneously b) making sure the welding parameters are "high enough" so that the welds are not excessively hard (because the flowing fluid on the inside makes the welds cool much faster than normal).
This is a real balanacing act and there is actually a computer program (VERY expensive) that allows to you to determine the two effects listed above for various welding conditions.
So, 1) Yes, welding onto live, operating gas pipelines can be done. It is done "routinely" by a number of pipeline operating companies but requires a significant amount of expertise, engineering, and welder experinece/training. 2) There are a number of technical articles on this subject (several have been published in the Welding Journal). There has been a lot of technical research into this subject.
[Yes, this is actual "hands-on" knowledge rather than just repeating information. I have been involved in a number of hot-taps myself.]
I've watched a gas crew do this on a 4" steel pipe to make a stub that is fitted with a valve and adapter to plastic pipe. It even comes with a nifty fitting to allow the operator to run a hole saw into the live pipe, pull the saw back, seal it off, disconnect the hole saw assembly and start in on welding the stub.
This is NOT something that I want to do ............. EVER! It's in the same category as working 8KV lines with just your gloves.
My uncle and a neighbor were killed doing a hot tap at a steam generating plant in Las Vegas in the early seventies. Randy Haren and Dick Wilson. RIP.
It always doesn't go by the book.
In the US we use the API-1104 standard for most petroleum and natural gas pipelines.
API = American Petroleum Institute.
If it is a high pressure pipe, as in above 600 psi, you have to go to ASME code.
The American Society of Mechanical Engineers covers Pressure Vessels and Pressure Piping.
Just so you know, these codes are not free or cheap. The API-1104 book is around $300 and the ASME books come in 10 volumes and cost over $1000.