Bei der Beschaffung stainless steel elbows, the first decision buyers make after the angle is the connection type: buttweld oder threaded (screwed). The choice determines pressure rating, installation method, leakage risk and total cost. This guide explains the difference, when to use each, and what to specify on your RFQ.
Buttweld elbows: welded into the line
Buttweld elbows have plain, beveled ends that are welded directly to the pipe. They are the standard choice for process piping:
- Druckstufe: full pipe rating (e.g. Sch 10S, 40S, 80S), suitable for high-pressure and high-temperature service.
- Leak-tight: the joint becomes one continuous piece of metal — the most reliable connection.
- Standards: ASTM A403 for austenitic stainless fitting, ASME B16.9 for dimensions.
- Angles: 45°, 90° and 180° returns, long radius (LR) and short radius (SR).
Threaded (screwed) elbows: screwed into the line
Threaded elbows have female NPT or BSPT threads and are screwed onto male-threaded pipe:
- Size range: typically NPS 1/8″ to 4″ (DN6–DN100); threaded fittings above 2″ are uncommon.
- Druckstufe: lower than buttweld, limited by the thread depth. Standard classes are 3000 lb, 6000 lb and 9000 lb (ASME B16.11).
- Installation: fast and simple, no welding needed — ideal for instrumentation, small-bore lines and maintenance.
- Leak risk: threaded joints can leak under vibration or thermal cycling; use thread sealant and proper torquing.
Which one should you choose?
- Use buttweld when: line size is 2″ and above, pressure/temperature is high, the line carries hazardous or valuable fluid, or leak-free joints are required.
- Use threaded when: line size is small (typically ≤ 2″), welding is not practical on site, the line needs frequent dismantling, or it is instrument/utility piping.
Grades and materials
Both buttweld and threaded elbows are available in:
- 304 / 304L: general-purpose, water and mild chemicals.
- 316 / 316L: molybdenum-bearing, for coastal, chloride and chemical service.
- Low-carbon grades (L): recommended when the fitting will be welded, to reduce carbide precipitation and intergranular corrosion.
Checkliste für die Angebotsanfrage des Käufers
- Angle: 45°, 90° or 180°.
- Connection type: buttweld (beveled ends) or threaded (NPT/BSPT).
- Size (NPS or DN) and wall thickness / schedule (10S, 40S, 80S).
- Radius: long radius (LR, 1.5D) or short radius (SR, 1.0D) — see our LR vs SR elbow guide.
- Grade (304/L, 316/L) and standard (ASTM A403, ASME B16.9 / B16.11).
- Material certificate (EN 10204 3.1) — see our Checkliste für den Käufer: Werksprüfzeugnis.
For help choosing between buttweld and threaded stainless elbows, send us your line size, pressure and fluid.
SOROYA PTE. LTD.
Email：nancy@soroya.com.sg
WhatsApp: +65 8058 3416
