street 90 on gas pipe

jeff_51

but here in Minnesota they are used all the time. I wonder if some of these no-no's are from years ago and if they apply anymore? does anybody really know why we do and don't do some of the things we do and don't do?. no cast fittings of course because of pin holes, no street fittings because of reduced inside diameter, (although we use them all the time 'cause we use copper and very few steel pipe ftgs are used so we get no appreciable reduction in pressure), but why no close nips?. I know copper doesn't work in some areas 'cause the gas quality is awful, which is why we still have to use drip tees. We still use them but are really obsolete here cause gas quality is so good. We get away with a tee and plug, don't even need a nip and cap most places. How much do we really do 'cause we have always done it. drip tee's go back to the old coal gas days when you had to pull them regularly to dump out the water. Anybody got any more answers?

Jack Piel

Street 90 on gas piping

I have always heard you could not use ST90's on gas pipe.Doe's anyone know if this is correct and if it is way.
Thanks Jack

Unknown

Not correct although

making swings with two 90 degree elbows is the better way to go.

Jack Piel

Thanks Tim,I have always heard it but could never understand the reason for it.I am in a spot right now where a double 90 swing will not work and a st90 will work out great.
Jack

[Deleted User]

gas and steet 90s are not always allowed

It isn't that it will not work. It is that some AHJ do not allow it for whatever arcane reasons. Please check with and ask permission of your local Gas Inspector, lest he be PO'd and you get to do the work again. In this case, permission is more important than elusive forgiveness.

Unknown

Interesting as the gas

companies use them on the outlet of there meter bars for a swing joint.

Shark

street elbow

Tim you are right about the utility company using them .. I work for National Grid and we use them on our fitting jobs .. not a problem.

Cosmo_3

I bet

some inspectors might frown on them because BLK st 90's typically have greatly reduced inside diameters compared to to the ID for pipe of the same size. Using a lot of these can increase friction losses more than using regular 90's. But then the gas cock valves were pretty restrictive themselves.....

Cosmo Valavanis

Dependable P.H.C. Inc.

hr

Actually

a 90 and a close nipple will often get as tight, and sometimes tighter than a street ell Depends on how close of a close nipple you can find, and how tight of a sweep the 90 has

hot rod

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rich pickering

But not up here

A street 90, street tee (never seen one) and close nipples are not allowed in Canada. Unless you are the utility.

pitman9

Close nipples

are not allowed in upstate NY. St 90s are okay though. I don't know as I'd throw a bunch in though. I usually size them by doubling the TEL of a regular 90 of the same size.

Glen

Or -

you have CSA and AGA cert on a gas train - and then you can use a street el - but not a close nip. Utilities follow a pipeliners code - so can use both streets and close nips. Only in Canada - eh!

jeff_51

hey pitman

that's interesting cause when i was in the southern tier, it was just the opposite. Funny, it was of course because of the reduced diameter.

pitman9

In NYSEG's Cortland & Tompkins area

close nipples and bushings are no-nos. As is copper.

Shark

nipples

National Grid does not supply us with close nipples, but we do get from 2" up to 36" for 1" pipe.

Tony Conner_2

What...

... grade of fittings do you use? You can get 3000# forged steel street 90s (and 45s) along with all of the other fittings, and this is a FAR better grade than the much cheaper 150# malleable iron normally used. It's the same with bushings - steel bushings are much better grade than the malleable ones. Unless you've got installation & maintenance people and inspectors who can tell them apart, and know what the differences are, then I'd imagine that's the reason they're not approved in many jurisdictions. For close nipples, the sch 80 A106B seamless ones are readily available. Again, I suspect it's a field inspection issue. Once they're installed, there's really no way to tell what they are - they're too short to carry any identifying marks.

Until fairly recently, seamless A106B pipe wasn't on the approved list for gas piping here. Crappier grades - and I mean FAR crappier, like A53F - were (and still are) OK and that always puzzled me. Not many contractors would go out and pay the extra money for the seamless pipe, but it should not have been excluded from the approved materials list.

At the end of the day as far as safety goes, I'd much rather have a forged steel street 90 installed than an ordinary malleable 90 - either 150 or 300. But it all comes down to the code that applies in the areas where different people work. If the local code doesn't allow street 90s, then that's that.

Dale

Legal per code

Fine per NFPA 54 and legal except if the local authority say's no. Fine anywhere in my state, WI. An old dead man gas hand told me that some utilities in the 30's and later would not allow them because of the high instance of sand holes found in the streed 90 from the casting process. Most utilities won't use close nipples, wanting some amount of non threaded metal on the nipple.

Tony Conner_2

But...

... it would have been (and still is) the same people making the whole range of fittings. The same foundry would be kicking out tees, 90's, street 90's etc. It's not like the street 90s would have come from a totally different manufacturing chain than than the rest of the fittings.

I suspect that the issue with close nipples is field inspection on the completed job. Close nipples don't have any non-threaded surface, so it's not really possible to tell what grade or wall thickness they are, after they're in. The pressure rating though, is based on factors including the depth of the cut thread. Regardless of the length of the nipple (or length of pipe), the thread depth should be just about the same. The pressure rating of the pipe or nipple isn't affected by it's length. The 20 length of threaded pipe will have the same pressure rating as a close nipple, if it's the same grade of material and wall thickness.

Anthony Menafro

New Jersey allows em

We have no problem with st. 90's in Jersey We frown on close nipples because of the weakness that a full thread may allow. We are allowed to use them, but prefer not to.
Anthony

RMA

st 90

a street 90 is exactly the same take out as a close nipple and regular 90 why pay more for streets?

pitman9

Close nipples aren't approved in our area.

CJRS

I've been down this road

I've been down this road with many pipe installers, both young and (best of all) an ole timer. Many good comments here and hope I can add my "two cents". Castings are betetr today than yrs ago for street elbows and yes the opening is smaller and can cause more friction; but if installing near the appliance and it's a fixed joint, you will be ok. This applies to valves also. If you are installing a line cut-off then use a full opening ball valve; an alternative is upsizing a regualr valve so the opening matches the pipe I.D. But here is some interesting opinion of an old master I know. Street el's are ok for fixed joints, but do not have the same taper as nipples or pipe. Ironically a taper will seal its joint better than thick straight threads which leads us to the close nipple concern. When you use any pipe of swing joint the taper is important as well as a finished area of pipe that has full thickness. Minimum 2" close nip is recommended (1/4"smooth pipe showing)(do not use thread to thread) Also, here is advise you don't hear every day and that is to limit your "swing" to less than 45 degrees. Many installers pipe to the applieance and then swing their pipe joints in a range of 90 degrees. If your run has that much adjustment then put on another fitting and keep the joints tight.