Welded and Drawn Tubing

Welded and Drawn Tubing

Welded and drawn is the preferred tubing choice in terms of economy, lead time and tolerancing compared to seamless in most instances. Many demanding applications call for the T.I.G. welded and plug (mandrel) drawn method, used by Vita Needle for over 85 years!

Lowest minimums

in the industry and competitive pricing

Ship Same Day Of Order Placed

In-stock random lengths - typically ship same day of order if placed before 1pm EST

Unlisted Non-Standard Sizes

Hundreds of thousands of feet of unlisted non-standard sizes in stock

Custom Tubing

Custom tubing you need---cheaper, faster and better than the others

Materials and Requirements for Welded and Drawn Tubing

Alloys Available for Welded and Drawn Tubing

  • Stainless Steel: 304/304L, 17-7, 321, 316/316L/316LVM, 347
  • Nickel: Kovar, Monel 400, Alloy 52, Alloy 600, X-750, Alloy 625
  • Additional alloys available upon request

Requirements

The list below includes some of our frequently quoted specifications. However, we can comply with dozens of unlisted specifications for welded and drawn tubing---just ask us!

  • ASTM A269
  • ASTM A908
  • ASTM A632
  • ASTM F899
  • ASTM A276
  • ASTM F30
  • ASTM F138
  • ASTM F139
  • AMS 5568
  • AMS 5576
  • ISO 9626
  • DFARS 252.225-7014

Secondary process specifications:

  • ASTM A967
  • ASTM B912

Common Industries for Welded and Drawn Tubing

Welded and drawn tubing is a high quality, cost effective product used heavily in medical device, aerospace, instrumentation, and other various industrial applications. Thin walls, excellent concentricity and tight tolerances are available in welded and drawn tubing.

What is Welded and Drawn Tubing?

The flagship lines of stainless steel and alloy tubing for hypodermic needles provided by Vita Needle Company are manufactured using the T.I.G. (Tungsten Inert Gas) welded and plug (floating or mandrel) drawn process with full hard temper (typically 150 KPSI minimum). This process has been the "gold standard" for all medical grade tubing for hypodermic needles since the 1960's. The significant amount of cold work put into the material from the drawing process results in the best finishes and hardest tempers (tensile strength) achievable. Burr removal is easiest in the full hard temper condition as chips break off versus "gummy bending" at lower tensile strengths.

welded stainless steel tubing

 

Welded and Drawn Production Process

  • Flat strip stock is progressively rolled in mill into a tubular shape.
  • The rolled tube enters a Tungsten Inert Gas (TIG) welding chamber where the tube seam is welded to form a tube. No filler metals are introduced. Atmosphere is tightly controlled for superior cleanliness and no surface oxidation.
  • The tube exits the welding chamber and is collected in coil form at the end of the welding line.
  • Welded coils are transferred to drawing equipment, where coils are drawn through dies and floating plugs to size and work harden tubing and improve surface finishes. Drawing oils are easily removed with conventional surfactants when processing is complete, and these oils are non hazardous per GHS standards. No Teflon® or CFC’s are used.
  • Heat treatments between drawing processes (or after all draws are completed) are applied to soften or harden tubing depending on the alloy and size being produced.
  • Coils of tubing at their final size proceed to straightening, if required, to transform tube into straight lengths.

T.I.G. Welded and Drawn Compared to Laser Welded

Over the decades, experience has readily demonstrated that a more forgiving weld zone and no filler metals produces an optimum fabrication grade material. Vita's TIG welded and plug drawn process yields a consistent, dependable product. Competing processes such as laser welding have several disadvantages when compared to TIG welding. The parameters of the laser weld process require extremely precise strip stock and very tight manufacturing constraints, deviations from which can result in insufficient weld and subsequent weak points in the tube. One micro-defect at strip edge could potentially translate into a defective tube. By comparison, TIG welding is a more generous manufacturing process, allowing a slight imperfection in raw material to join equally well in the weld zone. Manufacturers of laser welded tubing often perform the welding very close to final sizing. This may seem like an economical advantage, but without adequate cold work from drawing over a floating plug, some undesirable results can arise: a) total homogenization of the weld zone into the base metal may not be achieved, b) a relatively rough I.D. surface can lead to cleanliness problems, and c) uniform hardness and exacting tolerances are not possible.

tube plug drawing process

Concentricity of welded tubing for hypodermic needles is far superior to seamless. An as-welded laser tube (without plug drawing) will generally have worse concentricity compared to a TIG welded and drawn product because the weld seam sags slightly into the ID of tube even if only by ten thousandths of an inch. When applications demand fine finishes, such as laboratory sampling and blood analyzers, Vita can produce premium ID finishes using double and even triple plug draws.

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