What determines the pressure in a residential natural gas distribution system?
Each house in water distribution, for example, has a pressure valve to control water pressure inside the house.
No clue about how much regional variation there may be but in my city, gas is fed to the meter at about 20 P.S.I. The meter includes a pressure reducer tanking it down to about 0.5 P.S.I.
In my limited experience it’s typically ~0.25 psi (7 inches of water column), but YMMV. This is set using a gas regulator
Thanks.
I do know in my town they have over the past year installed new high pressure delivery lines. The meter must now be outside the house and includes a step down in it. They have not started delivering by the new lines yet as not all houses have been set up. I’m wondering if they installed new high pressure lines in Lawrence and Andover.
I do wonder if something failed there to cause an over pressure in the gas lines.
I did not read the OP carefully; what I wrote applies to what’s entering the house. The distribution system, i.e. the mains out in the street, can be that low (cities like DC can have some ancient legacy lines that they haven’t completely replaced) but it’s unlikely. Until someone who knows better comes by, my recollection is transmission (plant to citygate) is ~1000 psi. Distribution (citygate to meter) is 3-200 psi.
In case you don’t know what triggered the question: https://edition.cnn.com/videos/us/2018/09/13/massachusetts-explosions-fires-blitzer-tsr-vpx.cnn
Just to address the side issue in the OP, most houses do not have any sort of water pressure regulator in my experience. I’ve never seen one.
Dennis
I doubt many areas use 200 psi to the house. What a disaster if that got cut by a backhoe. The street piping in my area is stated to be no more then 60 psi and is usually much lower in non commercial areas, 20 psi or so as I recall. Most of the hookups from street to meter are that yellow, flexible HDPE plastic pipe. I have a coil in my storage, I’ll have to see if it has a pressure rating on it.
OK, I’m back. It is rated at 80 psi.
Dennis
what a nifty cool name. Simple yet descriptive. Do you know if it is trademarked or otherwise legally protected?
When I had a Compressed Natural Gas Civic I found it amusing that the gas would be delivered to my house at about 20-psi, get reduced by the regulator to 5" water (about 5-psi?) then immediately get compressed and injected into the fuel tank on the car to a maximum of 3600-psi. When the compressor was running, the half-cubic foot needle on the meter twirled like a Dervish and the two-cf took about three seconds per rev.
I’m in North Little Rock, Arkansas. There are pressure regulators in NLR and AR. Mine has failed, and we can’t find the damn thing. Cold water is 110 PSI. We put a regulator on the water heater so that I won’t be boiled to death working on the plumbing.
Holy cow! A guy in High School had a truck that ran on natural gas, with a tank in the bed. I wondered what would happen if it were damaged in a crash.
If the water supply line from the utility is below 60 psi (I think) PRVs are not required. But if it is above then a PRV is code. In some cities that up graded the water supply lines it required adding PRVs to houses.
The Federal maximum for natural gas distribution is 100psi. I’m not sure what/if the max is for pipelines.
The standard set up a a regulator at each house stepping it down before the meter. Meters are now required to be installed above ground outside. Older buildings/meters were frequently installed in basements which proved problematic because gas leaks tend to follow the lines on the outside of them, leading to basements filling with natural gas.
It actually isn’t that scary all things considered. First. if the components are good quality and the installation was properly done then any crash violent enough to cause a large scale tank rupture, well, you’re probably dead already. Smaller leaks from a broken fuel line can certainly spray fiery goodness over everything nearby but the fuel floats away and doesn’t stick to things as it burns. Compare that to liquid petrol which coats everything and burns for a long time.
I got that all the time when I was driving the CNG. My response was, it’s a pressure vessel* not a tin box filled with flammable liquid thus is more likely to survive a bump intact. Most likely what would happen is that a fitting would get knocked off letting the gas escape in a jet. If it isn’t sparked (crossing fingers) you just freeze in place until the noise stops. If it does catch you’ve got a column of flame where you know not to go. What you don’t have is a car-shattering kaboom spraying 15 gallons of flaming gasoline in a circle of destruction
*Six of them, actually.
The burst risk is more dangerous than the fire risk, but the codes and standards are pretty rigorous and require the tanks to leak before burst. And to have fire release valves. You’ll get gouts of flame. But don’t worry; it’s “controlled”. 
The testing regime includes shooting the tank.
Did you have a Phill?