I am listening to the "experts". And I said the valve would be leaking after loosening the nut. Apparently, some of so-called experts do not know the design of a conical stem $3 valve and unable to close it in a case of emergency without shutting down the block and taking valve to the shop. So, expert advice from MIC69 please. If an internal low pressure gas line is broken and the choice is between bubbling leak outside of the house or house being exploded, what the advice would be?
By the way, the larger wrench may not necessarily solve the issue -if stem is being seized or there is a galling going on, applying larger torque would make stem stuck only more, and eventually end up shearing the stem leaving valve open.
I had an "expert" came to winterize my pool, and he broke two stuck 2" gate valves and just walk away. Yea, I have so much trust in experts...
I know these threads can deviate from the initial question, so I understand how you are a little confused.
adb's original post was, "My gas valve at the meter is in the open position and cannot turn to the OFF If needed which is bad. I
know i have to loosen the nut on the right (right arrow), do I also need to loosen the nut indicated by the left arrow? if yes what tool should i use? looks like a 3 grove socket or similar?"
It is obvious that adb was trying to close that valve and that he
knew that nut needed to be loosened. That is a false statement. Therefore, the advice by Professional Plumbers and a Professional Engineer was NOT to loosen that nut to see if you can close it, because you do
not need to loosen that nut to close the valve. Your concern about the valve leaking after loosening the nut is real. So, the proper advice given was/is
don't loosen that nut to close that valve.
Some have said let the gas company or fire department operate that valve in an emergency. My thought, as is yours, that in an emergency, the homeowner should be able to operate the gas company's valve. But you must do it correctly.
My advice was/is to contact the gas company and tell them you have an issue. As Twowaxhack indicated, it may depend on who you talk to, and they may or may not change the valve or assist you in operating
their valve. They would help you by turning off that valve to allow a plumber or mechanical contractor install a house side valve, possibly for a fee. and then they would turn their valve back on after they inspected your entire house's gas piping and appliances.
As it turns out, adb was able to turn that valve using a larger wrench without loosening that nut just like one should be able to do.
By the way, it is called a "plug valve", not a "conical stem valve". And they are more like $40-$50, not $3. Also, these valves have a steel body with a brass plug. Brass does not gall on steel.
Gate valves have an entirely different design and are more prone to breakage that these steel plug valves with brass plugs. I think I would hire a more qualified and customer-oriented pool guy.