Standard Tube Diameters
3/4" OD19.05 mm OD x 1.65 mm / 2.11 mm wall
1" OD25.40 mm OD x 2.11 mm / 2.77 mm wall
1-1/2" NPS48.3 mm OD (DN 40)
2" NPS60.3 mm OD (DN 50)
3" NPS88.9 mm OD (DN 80)
Product page
SKYLAND
ASME B16.9 Buttweld U-Bends (Heat Exchanger Return Tubes)
Skyland 180° Buttweld U-Bends are specially manufactured for shell and tube heat exchangers, condensators, waste heat recovery units, and fired heater coils per ASME B16.9, TEMA, and ASTM A213/A249 standards. Produced with extended tangent straight legs and precision controlled thinning and ovality in the bend zone, guaranteeing exceptional heat transfer and pressure containment.
Manufactured to ASME B16.9, TEMA, DIN 2605, and ASTM A213 / A249 / A269 / A789 standards
Available in outer tube diameters from 1/2" OD (12.7 mm) up to 8" NPS with custom bending radii (R = 1.5D to 30D)
Strict control of wall thinning (maximum <= 12%) and cross-sectional ovality (maximum <= 5%)
Supplied with extended straight leg tangents up to 12 meters total tube length
Ready for quotationShare your range, connection and case requirement.
Talk to ATHStandardASME B16.9, TEMA, DIN 2605, ASTM A213 / A249 / A789
Tube OD Range1/2" OD (12.7 mm) up to 8" NPS (219.1 mm)
Bending Radius (R)1.5D up to 1500 mm centerline radius
Wall Thinning<= 10-12% maximum in bend extrados
MaterialsStainless 316L/304L, Duplex 2205, CuNi 90/10, Inconel 625, Titanium
Testing100% Eddy Current, Hydrostatic, Dye Penetrant, Ball pass test
Thermal Data
Heat Exchanger U-Bend Specifications
Specify tube outside diameter, wall thickness, centerline bending radius, and tangent lengths.
StandardASME B16.9 / TEMA
Tube OD12.7 mm to 219.1 mm
Heat TreatmentFull Solution Annealed
NDE Testing100% Eddy Current + Hydro
Part Number Example
SKL-UB-0100-SCH40-316L-R150
SKLBrandSkyland Metal & Alloys
UBType180° Buttweld U-Bend
0100Diameter1" Tube OD (25.4 mm)
SCH40WallSchedule 40 / 2.77 mm
316LMaterialASTM A213 / A403 316L
R150Radius150 mm Centerline Radius
Technical specifications
StandardASME B16.9 / TEMA C & R
Ball Pass TestStandard stainless steel ball passed through 100% of bent tubes
Operational Guidelines
Tangent leg ends supplied with square cut, deburred, or precision beveled weld prep.
Delivered in custom wooden crates with divider combs to prevent transit vibration damage.
Thermal Engineering & Quality Assurance
In heat exchangers and boilers, U-bends absorb thermal expansion naturally without requiring expansion joints, preventing tube sheet weld failures.
Skyland performs full post-bend heat treatment (bright solution annealing) on the bent portion to eliminate residual stress and restore corrosion resistance.