What happened to ⅜” FIP valves?
When I plumbed my steam boiler’s automatic filler, I used ⅜” NPT pipe for the whole loop, including the bypass valve that’s used to manually fill the boiler. At the time I used a ⅜” FIP gate valve, but it started leaking, as gate valves do, which is very bad because it would flood the boiler unless I shut off the supply valve, but if I shut off the supply, the autofill won’t work. So I need to replace the bypass valve with either a new gate valve or, preferably a globe valve, but I can’t find either one anywhere*. The only ⅜” FIP valves I can find are ball valves, which will work, but it’s not the right valve because it’s a throttling application, not a shutoff. But my bigger concern is: whiskey tango foxtrot happened to ⅜” FIP valves? Has the whole industry just arbitrarily decided they’re obsolete? Are ⅜” ball valves going to suffer the same fate in a few years? What about ⅜” NPT pipe and fittings?
*Anywhere = Lowes, Home Depot, Supply House and Amazon. If I have to order one from some obscure source and wait three months for delivery, that’s not a solution.
1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
Comments
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I'm not a pro, but who uses 3/8" pipe anymore? Google AI says 1/2" pipe is code standard minimum for threaded gas and plumbing because 3/8" is too easy to break by over-torquing. The only 3/8" I've ever seen is some short runs of original cold water supply in our 100-year-old basement.
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gate valves should never be used for throttling, they should always be all the way on or off. the flow past the partially open gate will damage the sealing surfaces and the vibration will damage the screw down the middle of the gate.
i would probably use a 1/2' globe valve and adapt. you could probably use copper there without any practical ill effect. you could probably make some electrolysis argument but in practice you have so little flow there that you will never have a problem.
a good supply house should be able to get you a 3/8 npt to npt valve. you can try contacting supply house to see if they have it but it is miscategorized or if they can get it.
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i don't believe there is any prohbition if you look at the actual code instead of asking "ai"
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Google 3/8 globe valve, plenty available from10- over $100.
A globe is better for throttling.
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream
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If you look at NFPA 54 for gas piping, minimum allowed size for iron or steel threaded gas pipe is 1/2", and my state (MA) follows NFPA 54.
I realize OP is piping cold water, but the larger point that 3/8" is too small for some codes is still correct. Here in MA, the main use for small diameter threaded black iron pipe is for natural gas, and if the gas code forbids the use of 3/8", there isn't going to be much call for it here.
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The valve on the automatic filler is ⅜” FIP. It wasn’t my choice.
Just another DIYer | King of Prussia, PA
1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-240 -
Thanks. And I agree, globe valves are better. I think I used the gate valve because it was what I had available at the time.
Just another DIYer | King of Prussia, PA
1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-240 -
I should have been clearer. This valve stays closed most of the time. The throttling only happens while you’re filling the boiler. Sometimes you want to add water gradually. Since you only open it a half dozen times a year you’d think a gate valve would be okay, but apparently not for long. The more I know about gate valves the less I like them.
Just another DIYer | King of Prussia, PA
1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-240 -
3/8" is fine but less common. You're not supposed to throttle with a gate valve anyhow. A ball valve will last longer and is fine or a globe valve which will probably be more expensive than a ball valve.
I would like to see a picture of this 3/8" auto fill.
Most are 1/2"
Most gas dryers used to be 3/8" pipe at the dryer connection but I haven't done one in a while.
Supply House.com has plenty of 3/8" IPS ball valves (no lead) in stock
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NFPA 54 Section 5.6 / Chapter 11 does allow 3/8" only at appliance connectors, but not for permanent piping runs inside the building. Our very old dryer piping is all 1/2", even at the connector.
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my dryer which i guess is about 20 years old now but whirlpool still makes the same design is 3/8" npt for the inlet and uses a 3/8" gas connector. plenty of pilot piping is 1/4" and 3/8" both tube size and ips with the ips mostly being in fittings and valves.
not using it for installed piping is more about the cost being more than half inch because it is less common and not needing to stock a whole set of fittings in another size.
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@Hap_Hazzard commented: "
The more I know about gate valves the less I like them."I find that true for some of my old customers.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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It's the same with everything.
The most commonly used parts always sell for less $$ than the odd ball stuff.
standard copper elbows are cheaper than street elbows
a 4" square box is cheaper than a handy box
1/2" black pipe is cheaper than 3/8" black pipe
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try to find 4 11/16 covers in the configuration you need at home depot
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i'm not seeing anything prohibiting a pipe size below a certain size in the michigan residential code. the smallest pressure drop table is for 1/2" so you'd need to do some math for smaller pipe but i don't see a prohibition.
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We recently needed some 3/8" lengths of Black Steel pipe and it was not easy to track it down, even in The Five Boros. IPS Gate valves are harder to get in supply houses. Between Covid, shifting economics, demographics, et cetera, Supply houses don't carry the stock and inventory they used to. Can't blame em, either. Mad Dog
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much to my surprise. we have 3/8" threaded gate valves in stock up in Michigan. We haven't sold any in over 2 years, I imagine thats why they aren't stocked most places. apparently we have 17) 3/8" globe valves, no sales in over a decade!
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Even if you need 3/8 pipe running 1/2" is probably cheaper.
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And maybe some of your old employees?
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When I come across a 3/8" NPT automatic feed, I use two of these and do not bother with 3/8" tubing. It's just not all that available in hard tubing.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ This ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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I guess I interpreted the absence of 3/8" from the table as prohibition, which is maybe incorrect. 3/8" may just not be practical for longer runs for pressure drop reasons.
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if you wanted 3/8" id copper tubing you'd have to buy 1/2" soft copper.
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Yes I think you are correct. Commercial oil and gas burners used to commonly used 3/8 pipe for the pilot connections and gas pressure switches mounted on the gas trains are usually 1/4". So not a code violation to use the smaller pipe just a sizing issue.
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@EBEBRATT-Ed Is that gas train tubing, and is it usually aluminum? Is aluminum required?
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Do you ever list dead stock on eBay?
or is it not worth the trouble.0 -
Yes. I'm not involved in that or we would be listing it a little more quickly! lol. We don't usually list our regular pipe-valve-fittings stock though even if its old, it's got no shelf life. special order fixtures that got cancelled and things of that nature usually go on there.
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Yes, there is something in NG that can attack copper tubing although I think its is negligible That's why aluminum tubing is used. Copper is ok for LP gas or black pipe for either fuel.
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if you want to use copper for natural gas it ahs to have below a certain sulfur content. it would be hard to control for that in a factory installed gas train.
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I used to see a lot of copper tubing used for - natural gas - standing pilots. If you removed it and tapped it on something solid, a surprising amount of debris would fall out from a chemical reaction between the copper and NG.
8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
Two btu per sq ft for degree difference for a slab0 -
it was used for the flexible connector to gas dryers for a long time.
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