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Can the wall thickness for butt weld pipe fittings be less than Light weight?

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ceenote

Petroleum
May 23, 2015
23
Hi,
My question is regarding steel pipe fittings. I understand there are various wall thicknesses available for line pipes.
1) My question now is are the wall thickness for the butt weld fittings (elbows, tees, reducers etc.) limited to light weight, std., x-heavy etc.
In other words, can you have butt weld fittings with less than light wall thickness?

Another question I have is are reducers and Tees (butt weld) always seamless? Someone that knows about their manufacturing processes can please shed a light on this.

I have these questions because I am working retrospectively on Transmission pipelines.

Thank you.
 
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I've never come across the term "light weight" before. Pipe is normally listed in schedule number as standard sizes with the terms STD, XS etc relating to certain schedule numbers. Frankly it's all a bit of a dogs breakfast as these things change with line size.

"Standard" thicknesses are listed in ASME B 36.10 and the thinnest listed is termed schedule 5 in most pipe sizes, but even schedule 10 or schedule 20 is rarely specified or produced as it is simply too thin to do anything with and buckles and dents very easily. Thereofe what the specified minimum is and what you can actually get someone to supply are two different things.....

Tees are commonly produced using a forged fitting, but I think there was an answer on this the other day if you search for welded tees on this site.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
 
If you're asking what is common: in stainless steels, sch10S is more prevalent than sch5S and can actually cost LESS, for fittings of modest size.

For carbon steels, the lightest schedule up to the point where STD is no longer sch40, is sch40. Schedules lighter than sch40 are rare up to that size, which is greater than 12" if I recall correctly but I could be totally wrong- look on a pipe table, which is what I would do.
 
The pulp and paper industry has some oddball items for "light weight" piping (plate ring flanges, angle iron stub ends) but it's actually sch. 5 and sch. 10.

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[ Added link to catalog of stainless steel "oddball" items and thin wall piping ]
 
Some of the fire suppression guys buy lighter schedules of pipe to use with roll-grooved Victaulic fittings. But butt-welding fittings in carbon steel lighter than sch40 are rare in my experience. Doesn't mean someone doesn't make or use them. Just means they're not on the shelf at my local piping distributors.
 
Buttweld fittings (tees, elbows, reducers, etc.) can be ordered and installed with smaller wall thicknesses to match the pipe. I've never heard these referred to as "light wall" though. Typically in transmission work the thinner wall piping is referred to as "high yield" since the material yield strength is higher to offset the thinner wall thicknesses of the pipe/fittings. Most cross country pipelines are built in this fashion due to the economics. So, for example, a standard (STD) 8" elbow would have 0.322" wall thickness (same as 8" STD pipe). But the same size 8" elbow can also be ordered in schedule 5 (SCH 5) with a 0.109" wall thickness as shown above in Gator's chart. See ASME B36.10 for all nominal sizes and wall thicknesses. (Note: the 0.078" wall thickness for 8" pipe/fitting shown above in Gator's chart is not a B36.10 published value)

Buttweld fittings are typically seamless because they are forged. The process of forging inherently produces seamless fittings. There can be some large diameter buttweld fittings that are fabricated/welded together to produce seams, but these seem rare nowadays. The industry I work in has all but replaced the large diameter fabricated buttweld fittings with seamless extruded ones (e.g. extruded tees).
 
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