“Seamless or welded?” is one of the first questions we ask when quoting butt-weld fittings, because the answer changes both the price and the manufacturing route.
How Each Is Made
Seamless fittings start from seamless pipe. For an elbow, a section of pipe is heated and pushed over a mandrel (hot pushing), which bends and expands it into shape with no weld seam anywhere.
Welded fittings start from steel plate or welded pipe. The material is formed and welded, then the weld seam is inspected (typically by X-ray or UT). Done properly, a welded fitting meets the same ASME B16.9 requirements as a seamless one.
The Practical Size Limit
Seamless pipe is generally available up to around 24”. Above that, fittings are made from plate — which is why large diameter fittings (26”+) are welded by necessity, not by choice. A supplier offering a “seamless 36” elbow” at a bargain price deserves skepticism.
| Size | Typical supply |
|---|---|
| 1/2” – 24” | Seamless (standard) or welded (economy option) |
| 26” – 48” | Welded from plate |
| Above 48” | Welded, custom fabricated |
Which Should You Order?
- Critical service (high pressure, sour gas, cyclic loads): seamless where the size allows, or welded with 100% RT/UT of the seam
- General service (water, low pressure utilities): welded fittings offer meaningful savings with adequate performance
- Project specs rule: many oil & gas specifications simply mandate seamless up to 24” — check before you buy
Price Difference
Welded fittings typically run 10–25% cheaper in mid sizes, with the gap widening in larger diameters. When comparing quotations, make sure both suppliers are quoting the same type — an unusually low “seamless” price is a common sign of a welded product being passed off, which only an experienced inspection catches before shipment. Every quotation we issue states seamless or welded explicitly, and the MTC traces the starting material.
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