Cap for gas line needed

[Bruce King]

Trying to cap off a propane line in a fireplace. It’s a 5/8 male so need a female cap. I bought one with FIP threads but it’s the wrong type thread, it threads on very loosely and wobbles. The one I tried was not a flare type. Anyone know which type I need?

[Jerry Bruette]

That's a tapered fitting, similar to a hydraulic fitting, not pipe threads. Your 3/8 FIP might fit one of those other fittings farther up the line.

[Jack Frederick]

Difficult to say as to size, but I would remove the flare fitting and put a 1/2 or 3/4” normal cap on the IPS thread.

[Stan Coryell]

You have a flare fitting. I suspect 1/2.
I would remove the adapter and reducing bushing and install a NPT pipe cap. Which I think is 1/2 NPT, but it's hard to judge.

1/2 pipe, 7/8 OD
3/4 pipe , 1 1/8 OD
1/2 tube, 1/2 OD

If you measure the OD of the tube you took off, it will give you the flare cap size.

Flared Fittings,

https://www.mcmaster.com/1774N33

[Stan Coryell]

Oops,
Wrong link.

McMaster-Carr Page:
https://www.mcmaster.com/Standard-Flared-Tube-Fittings/45-flared-fittings-for-copper-and-brass-tubing-8/type~cap/for-tube-od~1-2/

[Tom Bender]

Looks smaller to me. 3/4" is big for propane. 1/8 or 1/4 more likely. But I'd look at capping closer to the source, less chance of a dangerous leak.

[John K Jordan]

Looks smaller to me. 3/4" is big for propane. 1/8 or 1/4 more likely. But I'd look at capping closer to the source, less chance of a dangerous leak.

That was my thought - if the propane is still used elsewhere in the house trace that line to the source and either cap or valve it there, depending on whether it might be needed in the future.

Speaking of gas line sizes, the biggest I've seen is a 2" gas line into a friend's place. (Natural gas) The line feeds the pottery kilns in his shop and when he opens the valves money starts evaporating from his bank account!

JKJ

[Stan Coryell]

The knockouts in the background are 7/8. It looks like 1/2 and 3/4. 3/8 pipe has a different pitch. A tape measure would solve this.

[Jim Dwight]

I do not know the size but I did run a propane line from my tankless water heater to my fireplace and my bbq grill. I used black iron pipe for the little bit that is in the wall of my house (going to the grill) but the rest is soft copper. I was able to get all the fittings I needed but some I had to order on line. Big box stores has some but not nearly all I needed. A local hardware store had more selection but still did not have everything. Long way of saying you may want to look on line. Whatever you use, use a little pipe dope made for gas lines or a little teflon tape that is made for gas (it is different from the tape for plumbing). I was frustrated that it was so difficult to get what I needed but I think that may be because most DIYers do not mess with gas or propane.

As an aside, when my fireplace was installed the installer checked most of my connections and found them sound. He tightened one a little bit. That made me feel better. But soapy water will tell you if it's leaking. I bought a little bottle of it to get the applicator but dishwashing soap in water will work.

[John K Jordan]

...
As an aside, when my fireplace was installed the installer checked most of my connections and found them sound. He tightened one a little bit. That made me feel better. But soapy water will tell you if it's leaking. I bought a little bottle of it to get the applicator but dishwashing soap in water will work.

Best thing I've found for testing for leaks from pressurized fittings is soap bubble solution. I use it for air lines, gas lines, bobcat tires, etc. This will form even very tiny bubbles easier than a soap mix and hang around much longer. I bought a couple of gallons of soap bubble solution for $1 from Walmart one year at the end of the summer season.

BTW, for gas lines an inexpensive sensor is nice to have in the kit. I bought this one when I thought my propane cook range top had a leak:
https://www.amazon.com/gp/product/B07BM1XWB8

The service guy thought it was leaking but couldn't find where. I wanted to test further. It turned out to not be leaking but to be something entirely different about which I became educated:

When a large propane tank is almost empty the mercaptan which is added to give that "gas smell" for safety can become concentrated at the bottom of the tank and normal use can make a non-leaking appliance smell like a gas leak. Turns out my tank was almost empty and refilling it eliminated the gas smell. A gas company manager told me this was common. The appliance dealer and service man either didn't know about this or were only too happy to sell a new appliance. Bottom line: I have a spare gas range top in good condition (set up for propane instead of natural gas) if anyone close wants it.

JKJ

[Bruce King]

Ok, you guys got me motivated to go back to the store or try again to remove that flare fitting. It took about 150ft lbs to get the line off that one. This is a non used line now, no other gas appliances here but capping off as required.

[Bruce Wrenn]

Ok, you guys got me motivated to go back to the store or try again to remove that flare fitting. It took about 150ft lbs to get the line off that one. This is a non used line now, no other gas appliances here but capping off as required.


They do make flare caps. We work with a ministry at State Fair. During off season, cap all the appliances (WH, range, dryerect) with flare caps to keep bugs from nesting inside fittings. Lowes stocks them.

[Bill Dufour]

When I bought my minisplit ac the lines were capped. They had the correct forged screw on flare coupling fitting. But the had a small copper dome over the male part held on by the coupler. You had to re use the coupler and flare your own raw copper tubing.
It maybe easier to find a valve that fits and use that as a seal cap. Or flare a short piece of copper tube and fold it over and crimp it to seal. You could soft solder the crimp if desired.
Propane is double the pressure of NG so maybe 20" of water column.
Bill D.

[Kev Williams]

These are on Amazon--


448566

[Dan Hunkele]

A grill shop could have fixed you up. Gas threads have a 45° taper and hydraulic fittings are a 37° taper. Gas thread sizes are not used in hydraulic thread sizes to avoid a cross over mistake.

[Bruce King]

Thanks guys!
I just realized the fitting I bought was in the wrong bag which added to my confusion.

[Michael J Evans]

Bruce,
Is this a fitting for flexible tubing or rigid pipe you need?

The convoluted flexible tubing known as CSST has its own special sized variation of a flare fitting similar to SAE 45* flare, but different. If you have the convoluted tubing you will need to go to a fireplace /gas shop to get that fitting.

If this is rigid pipe then it is NPT thread ( national pipe thread). Measure the inside & outside diameter of the male threads. Pipe is supposed to be called out by it's inside diameter so if it's . 75" inside it's supposed to be 3/4" pipe. But due to different schedules that isn't always the case. If your pipe measures 5/8 on the outside of the male, I believe it would actually be 3/8" pipe (nominally sized).

[Stan Coryell]

Bruce,
Is this a fitting for flexible tubing or rigid pipe you need?

The convoluted flexible tubing known as CSST has its own special sized variation of a flare fitting similar to SAE 45* flare, but different. If you have the convoluted tubing you will need to go to a fireplace /gas shop to get that fitting.

If this is rigid pipe then it is NPT thread ( national pipe thread). Measure the inside & outside diameter of the male threads. Pipe is supposed to be called out by it's inside diameter so if it's . 75" inside it's supposed to be 3/4" pipe. But due to different schedules that isn't always the case. If your pipe measures 5/8 on the outside of the male, I believe it would actually be 3/8" pipe (nominally sized).

That isn't a CSST fitting. It's a flare adapter. Probably for a flex hose, like to hook up a stove.

IPS, regular threaded pipe, is not measured by ID or OD. It is called out as a nominal size. 3/4 = 1.05 OD, 2 = 2.375, 4= 4.5, 14 = 14
ID depends on schedule or wall thickness. Standard pipe is Schedule 40.

Copper pipe measures nominal plus 1/8". 1/2= 5/8, 2= 2 1/8

Tubing is measured OD. 1/4 = 1/4

[Michael J Evans]

That isn't a CSST fitting. It's a flare adapter. Probably for a flex hose, like to hook up a stove.

IPS, regular threaded pipe, is not measured by ID or OD. It is called out as a nominal size. 3/4 = 1.05 OD, 2 = 2.375, 4= 4.5, 14 = 14
ID depends on schedule or wall thickness. Standard pipe is Schedule 40.

Copper pipe measures nominal plus 1/8". 1/2= 5/8, 2= 2 1/8

Tubing is measured OD. 1/4 = 1/4

Stan,
Attached is a picture of some 3/4" pipe, from a old 3/4" pipe clamp in my shop... It measures 3/4"... You are correct in that pipe is nominally sized (see my original post). Pipe was originally designed based off its internal flow dimensions, but like all things has evolved over time. 448653

In regards to the fitting,
Your fitting appears to be made of steel. typically SAE FLARE (45 degrees) are made of brass and JIC Fittings (37 degrees) are made of steel. You typically see SAE 45 used in Gas,HVAC, automotive applications and JIC used in higher pressure hydraulic applications, but working in the fitting business I've seen both used in low pressure applications.
If your flare fitting is truly 5/8" or -10 size, then a SAE 45 flare cap or a JIC 37 Flare cap will both work for your application. In all sizes but -6 (3/8) & -12 (3/4) are interchangeable. The females & caps are generally all now cut with dual seats (37/45).
So you either need
-10 (5/8) SAE FLARE CAP, like item# N5-10
-10 (5/8) JIC CAP, item# 0304-C-10

[Michael J Evans]

Oh and with flare fittings you do not need pipe sealant or tape. Just hand tight & a 1/4 turn of the wrench.

[Bruce King]

I found one at a different store, 3/8 flare cap. Thanks for all the information!

[Stan Coryell]

[QUOTE=Michael J Evans;3085089]Stan,
Attached is a picture of some 3/4" pipe, from a old 3/4" pipe clamp in my shop... It measures 3/4"... You are correct in that pipe is nominally sized (see my original post). Pipe was originally designed based off its internal flow dimensions, but like all things has evolved over time. 448653

I disagree.
NPS pipe isn't measured by the ID. The ID charges with wall thickness.
The ID of 3/4 sch 40 pipe is .824"
At 14" the nominal diameter is the same as the OD.

That steel flare fitting in the picture looks like the fittings that come with the flexible gas line for hooking up an appliance, like a gas stove. I don't believe they can be bought separately. I wouldn't use it as an actual flare to pipe adapter in a pressure application.

[lowell holmes]

Take it to Lowes or Home Depot. Either store can help you.