Seamless Ni200 Capillary Tubing — Cold-Drawn for Tight-Radius Bending, Stable to

A capillary tube that cracks during bending is not a tube — it is scrap. Nickel 200's 35% minimum elongation in the annealed condition means it survives tight-radius forming that would fracture stainless or copper capillary. But elongation alone is not enough: the tube wall must be seamless, with no weld line to open under hoop stress during bending. DLX cold-draws Ni200 capillary from pierced hollows on a mandrel — no longitudinal weld, no fusion zone, no weak plane. The result is a tube that bends, flares, and swages without splitting, retains full corrosion resistance in caustic and acidic service, and holds dimensional stability from cryogenic to 600°C. Custom OD, ID, and wall thickness available across N4, N6, Ni200, and Ni201 grades.

Prices FOB Shanghai for 5–500 kg orders. Volume pricing for annual contracts. MOQ: 5 kg. Custom OD/ID/wall thickness available — specify dimensions at inquiry for firm quotation within 24 hours. Standard delivery 7–25 working days depending on dimension and quantity.

Source: DLX Alloy product catalog. EN 10204 3.1 MTC with full composition included on every shipment.

Source: DLX Alloy product catalog. Physical data from annealed Ni200 seamless tube. EN 10204 3.1 MTC with each shipment.

1. Melt chemistry. Full OES on every heat. Ni200 ≥ 99.6% Ni confirmed. Out-of-spec heats rejected before hollow piercing.
2. Hollow billet inspection. Pierced hollows ultrasonically tested for internal defects before entering the cold-drawing queue. Any lamination or inclusion > 0.1mm flags the billet for scrap.
3. In-process dimensional control. Laser micrometer measures OD at 0°, 90°, 180°, and 270° every 500mm of drawn length. OD ±0.05mm, ovality < 2% of nominal OD enforced.
4. Wall thickness uniformity. Ultrasonic wall thickness gauge at four circumferential positions per meter. Variation > ±8% of nominal triggers mandrel inspection and line adjustment.
5. Eddy current flaw detection. 100% of finished capillary passes through an eddy current coil at drawing speed. Any discontinuity > 5% of wall thickness triggers automatic marking for cut-out. This catches micro-cracks, laps, and inclusions that visual inspection misses on fine-bore tubing.
6. Flare test (ASTM A370). One sample per 50 kg flared to 30% OD expansion. Tube must show no cracking or splitting at the flared edge. Failure triggers batch quarantine and process review.

• Straight lengths (≤ 2 m): Individually sleeved in clear PE tube, bundled in counts of 10–50 with nylon straps, packed in rigid cardboard tubes or partitioned wooden cases with foam end-cushions. Plastic end caps on every tube to protect bore and edges during transit.
• Long lengths (> 2 m): Wrapped in VCI paper, packed in heavy-wall cardboard tubes with internal foam spacers every 500mm to prevent mid-span sag and contact damage. Maximum 20 tubes per shipping tube.
• Coiled capillary (thin-wall, ≤ 2 mm OD): Layer-wound on 300mm ID spools with tissue interleave, vacuum-sealed in anti-static PE, packed in double-wall cartons with desiccant. Coil set is normal for thin-wall nickel; straightening is the user's responsibility unless annealed flat lengths are specified.
• Labeling: Every tube bundle, shipping tube, and spool labeled with heat number, grade, OD * wall * length, and net weight. EN 10204 3.1 MTC in external document pouch.

Delivery: 7–25 working days depending on dimension and quantity. Small-diameter capillary (≤ 3 mm OD) typically 10–15 days. Air freight < 30 kg; sea freight for bulk. Departure: Shanghai.

Changzhou DLX Alloy Co., Ltd. produces seamless nickel capillary the hard way — by piercing a solid billet and cold-drawing it over a floating mandrel through a series of progressively smaller dies. This process controls both the outer diameter and the inner bore simultaneously, producing tube with ±0.05mm OD tolerance and wall uniformity measured in single-digit percentage variation. It is slower than welded tube production and more capital-intensive than simple sinking — but it produces capillary with no longitudinal weld, no fusion zone microstructure, and no preferential failure path when the tube is bent, flared, or pressurized. Since 2002, our 12,000 m² nickel-only facility in Changzhou has drawn seamless nickel tube for chemical processing, instrumentation, aerospace, and semiconductor applications across 40+ countries. ISO9001 certified, 500 tons monthly capacity.

Welded tube has a longitudinal fusion zone — a narrow band where the microstructure is cast (re-solidified from the weld pool), not wrought. This zone is harder, less ductile, and often contains micro-segregation that makes it more susceptible to corrosion. When you bend welded tube, the highest tensile stress aligns with the outer radius — which is also where the weld line sits in most tube orientations. A seamless tube has no microstructural discontinuity around its circumference. It bends uniformly, and it fails at the material's true limit, not at a weld defect.

For soft-annealed Ni200 capillary, a practical minimum bend radius is 2* the tube OD without a mandrel, and approximately 1.5* OD with an internal bending mandrel. At these radii, the outer wall experiences roughly 25% tensile strain — well within the material's ≥35% elongation capacity. For tighter radii, intermediate anneals may be required. DLX can supply capillary in the fully annealed condition (90–120 HB) specifically for demanding forming operations.

We draw custom OD, ID, and wall thickness combinations. Typical OD range is 0.5–20 mm with wall thickness from 0.1–2.0 mm. The limiting factor is the draw ratio: the reduction in cross-sectional area per pass. Very thin walls (high OD-to-wall ratio) may require additional drawing passes and mandrel setups. Specify your target OD, ID (or wall), and length at inquiry — we will confirm feasibility and lead time within 24 hours.

Yes — and this is one of the primary reasons nickel is specified over stainless steel in caustic service. Nickel 200 resists stress-corrosion cracking in concentrated NaOH and KOH up to the boiling point and beyond, whereas austenitic stainless steels (304, 316) are susceptible to caustic SCC above approximately 80–100°C at concentrations above 20%. For chemical dosing capillaries, alkali sampling lines, and electrochemical sensor sheaths, Ni200 is the standard material choice.

Yes. We can supply capillary with flared ends (single or double flare per JIC/AN standards), swaged tips for nozzle applications, beaded ends for hose retention, or plain square-cut and deburred ends. End-forming is performed after the final anneal to preserve the formed geometry. Dimensional tolerances on the formed section are ±0.1mm. Specify your end-finishing requirements at inquiry — we will confirm compatibility with your tube dimensions.