A pipe system is more than just straight lengths of steel. The type of fitting you need depends entirely on the connection method: Threaded (Malleable) for galvanized and standard plumbing, or Welded (Butt Weld) for high-pressure industrial lines.
1. Malleable Iron (Threaded)
Standard UseThese are the standard fittings used for Galvanized Pipe, Handrails, Fencing, and low-pressure plumbing. Cast from iron and threaded (NPT), they are available in Black or Hot-Dip Galvanized finishes.
Class 150 (Standard)
Rated for 150 PSI steam / 300 PSI WOG (Water, Oil, Gas). This is the industry standard for 90% of commercial applications, fencing, and light plumbing.
Class 300 (Extra Heavy)
Thicker walls and heavier threads designed for higher pressure lines. Rated for 300 PSI steam / 1000+ PSI WOG.
Looking for Galvanized Fitting Suppliers?
Major manufacturers like Ward Manufacturing (Domestic) and ASC Engineered (Global) supply the majority of malleable iron fittings in North America.
View Galvanized Distributors →2. Butt Weld Fittings (ASTM A234)
IndustrialBest for High Pressure, Oil & Gas, and Steam Lines. Butt Weld (BW) fittings have beveled ends that match the pipe wall thickness (schedule), allowing for a full penetration weld.
- 90° & 45° Elbows: Change flow direction. Available in Long Radius (LR) and Short Radius (SR).
- Tees: Split flow into two directions. Can be "Equal" or "Reducing."
- Reducers: Change line size. "Concentric" (center-line match) or "Eccentric" (flat on one side).
- Caps: Weld onto the end of a pipe to securely close the line.
3. Steel Flanges (ASTM A105)
Flanges are forged steel rings that are welded onto the pipe to allow for bolting to another flange, valve, or pump.
| Flange Type | Best Application |
|---|---|
| Weld Neck (WN) | High Pressure / High Stress. Welded to pipe. |
| Slip-On (SO) | Low Pressure / General Use. Slides over pipe. |
| Blind | Solid plate used to close the end of a line. |
4. Forged Fittings (Socket Weld)
For small diameter high-pressure pipe (usually 2" and under), Forged Fittings (Class 2000 / 3000) are used rather than butt weld.
- Socket Weld (SW): The pipe inserts into a recessed socket and is fillet welded.
- Threaded (NPT): Screwed connection for high pressure.
- Common Specs: ASTM A105 (Carbon Steel) or A182 (Stainless).
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Pipe Weight
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