Normal practice?

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At a job I noticed that someone had tacked two flat pieces of metal to 6" natural gas line and I do not think that the line was shut of during tacking. I think this was done to make a jig to line a fitting up to existing gas line. HAPPY WELDING UALL
Reply:Bet he wasn't trying to get 100% penetration.Syncro 250 DX Dynasty 200 DXMM 251 w/30A SG XMT 304 w/714 Feeder & Optima PulserHH187Dialarc 250 AC/DCHypertherm PM 1250Smith, Harris, Victor O/ASmith and Thermco Gas MixersAccess to a full fab shop with CNC Plasma, Water Jet, etc.
Reply:Wasn't there a guy that works for a gas company that stated he welds on 'hot' gas lines awhile back?  I don't recall exactly what he said but it boils down to it's too rich to burn in the pipe.  DO NOT misunderstand me and think I'M suggesting it's OK to do so though.I do know that when we respond to gas well fires you could walk right up to the well head (with ear plugs, noise cancelling ear protection and 15 towels or ?? wrapped around your head to deaden the noise because the fuel isn't burning for quite a distance up the column due to it being too rich to ignite.MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:YUP!   It was stevinator himself.http://weldingweb.com/vbb/showthread.php...ht=natural+gasMM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:Might have been a line up jig, or temp ground attachment points.
Reply:Yea, I have seen lines welded with the gas going thru them.  About 4 years ago a farmer hit a shallow line with a plow and "ALMOST cut thru it.  The Gas crew got here and wanted to know who was the local welder.  Well the farmer sent them to me and I went to look at it even thought I wasn't certified to do the work.  They put a clamshell on it and welded it in.  It was a main supply line.  I had never really thought about it up until then, but as mentioned they said that it would not burn in the line.I'm a Lover, Fighter, Wild horse Rider, and a pretty good welding man......
Reply:I would burn on a full line way before an empty one.  The vapors are what will explode and hurt you.  As long as there is product going through the line it will cool the weld from the inside and not allow it to ignite.  Kind of hard to wrap your head around.
Reply:Originally Posted by schwinn68I would burn on a full line way before an empty one.  The vapors are what will explode and hurt you.  As long as there is product going through the line it will cool the weld from the inside and not allow it to ignite.  Kind of hard to wrap your head around.
Reply:It is a standard practice in gas plants and refineries to weld a new spool onto a live line. First a stub with a flange on is welded onto the line. Then a valve bolted on to it and a cutting head is mounted on .The head has a gland packing or seal and cuts thru into the pipe or tank. The cut out drops into the line or bottom of the tank and stays there till a later date when a shutdown comes round.The cutting head is withdrawn and the valve shut off. End of job, new spool can be bolted on after the head is unbolted. We call it a hot tap, could be called something else in your neck of the woods.Clive
Reply:Remember your safety training? Remember the fire triangle? Heat, oxygen, and fuel. Remove any one and no fire. Like previously stated there is a lack of oxygen in gas and oil lines. So no fire. But, over the years, I can remember a few explosions that killed one or more welding on a live line. I've done some hot work and never had a problem but it was always in the back of my mind wondering each time I did it if this one would be one of those freak explosions. I always breathed a sigh of relife when I finished up.I can remember two instances of fire from digging into a high pressure gas line locally. One was a backhoe, the other a hole digger for the local electrical power company. Both operators died right there.Last edited by Oldtimer; 10-07-2008 at 09:25 AM.
Reply:Originally Posted by OldtimerRemember your safety training? Remember the fire triangle? Heat, oxygen, and fuel. Remove any one and no fire. Like previously stated there is a lack of oxygen in gas and oil lines. So no fire. But, over the years, I can remember a few explosions that killed one or more welding on a live line. I've done some hot work and never had a problem but it was always in the back of my mind wondering each time I did it if this one would be one of those freak explosions. I always breathed a sigh of relife when I finished up.I can remember two instances of fire from digging into a high pressure gas line locally. One was a backhoe, the other a hole digger for the local electrical power company. Both operators died right there.
Reply:When I worked at a paper mill we had an electrolysis process that produced hydrogen. The hydrogen gas was mixed with chlorine ( CL2 ) and then scrubbed with water to produce hydrochloric acid ( HCl). We always tried to keep the oxygen ( O2) below 2 percent. At this level of oxygen the hydrogen was safe. If it ever got to 3 percent we turned on a nitrogen purge and started running.We had an explosion one time due to operator error. A contractor was talking to another contractor that was working in our chip yard. He ask him if he heard the explosions. The chip yard guy said yes. The other man said there was three. The contractor working in the chip yard said he only heard two. Then he went on to add he must have out run the sound of the  third one.
Reply:Originally Posted by OldtimerHeat, oxygen, and fuel. Remove any one and no fire.
Reply:20 yrs ago, while in high school, I worked with local natural gas outfit. Was taking welding-blueprint in voc..so, at my harassing requests, I was able to be witness, and sometimes attempt to weld the taps, repairs, replacement, new installiation,etc...Every weld I seen made was on a hot natural gas line. Unless it is a 10"+ main, they hot weld everything, ...4" and under was OXY/ACTY welded, above that was 610 downhill. I had the privilege of working around and old school pipeliner. He made oxy/act welds look better than 96% of tig welders I've seen.Miller TrailBlazer 251Miller HF-250-1Miller MaxStar 150 STLHyperTherm PowerMax 380 plasmaLincoln PowerMig 180Millermatic 252Miller Diversion 180