bonding a short section of water supply pipe

Thread drift further..

Yes PME is a hack, but of the options for a street distribution system without a CPC Is it worse than TT ? Sometimes. But it is still acceptably safe - actually in much of the world there is neither, and there are not many accidents  you may recall that post  about the building in Azerbaijan   - such a construction would be seen as perfectly normal in parts of South America or Africa, and even so electrocution is not a significant cause of death compared to traffic accidents or diseases - so quite correctly it is not a govt. priority there. In the same way, there are a few tens of folk electrocuted  by the  wiring in their homes every year in the UK, compared to a few thousand being killed by being run over, or the 3/4 million or so that must die from natural causes to match the birth rate to keep  check an uncontrolled  population expansion.


We cannot eliminate all risk from one small area of life without neglecting others, that may become more significant.

Now Gas in steel pipes.

Dave I'm sure that both you and I are both old enough to recall the cloying taste of the old town gas, long since replaced by methane courtesy of the north sea. I'm hoping that you like me played with treacle tins and  the gas wand on the cooker, and realised that the stuff was pretty fun and quite explosive, and sadly the north sea stuff was not half as frisky. This is due to the large hydrogen fraction - about 50%, , while the lethality required for all the Agatha Christie style murders, and quite a few tragic suicides, came from the fact that a significant part of the remainder was carbon monoxide, and then methane ethane, benzene and all sorts of ripped up hydrocarbon junk made up the rest. Lovely stuff.  But the street mains were cast iron, and the house piping a mix of black iron and thin walled lead pipes, and the problem of embrittlement was not really seen.

It certainly is a big issue at high pressures and temperatures used in some industrial processes, especially over a period of many years, but do not imagine like some scare mongers have suggested that a half inch black iron gas pipe will turn to powder after a decade or two with a pressure comparable to blowing bubbles into a milk shake. Actually, quite a bit of work has been done on this, and it is really not a big issue, except for high pressure storage , and in a way the experiment with the public gas mains has already been done in the past successfully. The pipes fail first from rusting through.

A  low pressure pure hydrogen leak will burn with a pale blue flame and is  visible in low light - and we could always add some sparkles in the form of any other hydrocarbon, though perhaps not carbon monoxide, much as we would add a gas leak smell


Adding hydrogen to dilute the mains gas may or may not be a good idea, depending how we make it, but embrittlement of metal fittings is not a serious downside.


(Hydeploy trials at Keele university have gone well with 20% H2 blending.)  ( Nearly ready to do the same for a larger area with a  village near Gateshead.)

Mike.

Thread drift further..

Yes PME is a hack, but of the options for a street distribution system without a CPC Is it worse than TT ? Sometimes. But it is still acceptably safe - actually in much of the world there is neither, and there are not many accidents  you may recall that post  about the building in Azerbaijan   - such a construction would be seen as perfectly normal in parts of South America or Africa, and even so electrocution is not a significant cause of death compared to traffic accidents or diseases - so quite correctly it is not a govt. priority there. In the same way, there are a few tens of folk electrocuted  by the  wiring in their homes every year in the UK, compared to a few thousand being killed by being run over, or the 3/4 million or so that must die from natural causes to match the birth rate to keep  check an uncontrolled  population expansion.


We cannot eliminate all risk from one small area of life without neglecting others, that may become more significant.

Now Gas in steel pipes.

Dave I'm sure that both you and I are both old enough to recall the cloying taste of the old town gas, long since replaced by methane courtesy of the north sea. I'm hoping that you like me played with treacle tins and  the gas wand on the cooker, and realised that the stuff was pretty fun and quite explosive, and sadly the north sea stuff was not half as frisky. This is due to the large hydrogen fraction - about 50%, , while the lethality required for all the Agatha Christie style murders, and quite a few tragic suicides, came from the fact that a significant part of the remainder was carbon monoxide, and then methane ethane, benzene and all sorts of ripped up hydrocarbon junk made up the rest. Lovely stuff.  But the street mains were cast iron, and the house piping a mix of black iron and thin walled lead pipes, and the problem of embrittlement was not really seen.

It certainly is a big issue at high pressures and temperatures used in some industrial processes, especially over a period of many years, but do not imagine like some scare mongers have suggested that a half inch black iron gas pipe will turn to powder after a decade or two with a pressure comparable to blowing bubbles into a milk shake. Actually, quite a bit of work has been done on this, and it is really not a big issue, except for high pressure storage , and in a way the experiment with the public gas mains has already been done in the past successfully. The pipes fail first from rusting through.

A  low pressure pure hydrogen leak will burn with a pale blue flame and is  visible in low light - and we could always add some sparkles in the form of any other hydrocarbon, though perhaps not carbon monoxide, much as we would add a gas leak smell


Adding hydrogen to dilute the mains gas may or may not be a good idea, depending how we make it, but embrittlement of metal fittings is not a serious downside.


(Hydeploy trials at Keele university have gone well with 20% H2 blending.)  ( Nearly ready to do the same for a larger area with a  village near Gateshead.)

Mike.