Stainless Steel AISI 304 / 304L / 316L Needle Medical Capillary Tube

Product Specification

Stainless Steel 304 / 304L / 316L Needle Medical Capillary Tube

Medical Tube/Capillary Tube is manufactured using 304, 304L and 316L Stainless Steel. Products that require consistent material throughout the tubing mostly use SS Capillary Tube Seamless. This is because the Stainless Steel Capillary Tubing is made up of a single piece of steel. This provides a continuous uninterrupted grain structure.

Main Steel Type And Material Grade

Main Production Standards

Producing Stainless Steel Tubing for the Medical Industry

A primer on the process

Producing tube for the medical industry requires a great deal of attention to welding, material, and surface quality.

Tubing for the medical industry is produced primarily from 304 and 304L (low-carbon) welded stainless steel. The 304 stainless steel has relatively low carbon content (0.08 percent maximum), and it resists corrosion better than 302 stainless.

Its counterpart, 304L stainless, has even lower carbon content (0.04 percent maximum) and offers similar corrosion resistance. However, 304L also offers high resistance to intergranular corrosion following welding.

Strip

One of the leading challenges for the medical tubing manufacturer is securing strip stock with a good-quality edge condition. The walls of tubing tend to be relatively thin in the medical market and, as a result, alignment and edge condition are critical.

Weld mill operators are well advised to keep all strip stock as clean and protected as possible. This includes careful and proper storage and handling all stock with clean cotton gloves to prevent body oils from contaminating the edges.

The producer must work closely with the strip slitter to ensure the incoming strip meets edge condition requirements. Most mills have one or two strip suppliers that furnish good-quality strip that meets the mill's requirements.

Welding

Manufacturers generally use one of three different means for welding 304 and 304L stainless steel strip for the medical market.

The first is gas tungsten arc welding (GTAW). This is the oldest of the popular methods and is still widely used. The second, plasma welding, is a variation on GTAW. The last, laser welding, is the newest of the common methods. Each of these weld methods is similar in basic design, with the differences coming in the respective weld heads and power supplies. Each also has a variety of strengths and weaknesses.

Some primary items to consider in selecting a weld mill process are:

1. Speed of operation.

2. Maintenance of electrodes.

3. Ease of use.

4. Cost of weld head and power supply.

Most weld mills use eddy current test equipment after the final fin pass to verify the integrity of the weld seam. Some also add a video camera focused on the weld seam to observe the alignment of the seam and the weld head electrode. These two welding aids allow the mill to produce larger continuous coils with a fairly high level of confidence in the weld seam at speeds ranging from 20 to 30 feet per minute (FPM).

Size Ranges

The majority of medical tubing is made to a gauge scale that is loosely based on the United States military GG-N-196 specification. Modern requirements and technology advances have greatly expanded this scale. Incremental gauges from 6 (0.203 inch) to 36 (0.004 inch) with varying walls (0.015 to 0.0015 inch) are now generally accepted as standard.

Three Basic Products

Producers supply original equipment manufacturers (OEMs) and distributors with three basic types of finished tubing-welded followed by several sinks reductions without inside diameter (ID) plug or mandrel] to finish; welded, plug, or mandrel-drawn (to smooth the weld and to set the wall thickness), followed with several sinks to finish; and welded followed by several plug or mandrel draws to finish. Each of these methods produces a sound product, and each product has a specific area of application. Some tube producers offer all three types of products while others specialize in one or two. They offer medical OEMs a variety of weld seams and surface finish qualities and tolerances, as well as varying costs.

Welded and Finished by Sinks. The strip stock in welded and finished-by-sinking tubing is formed and welded at or very close to the finished wall size with an outside diameter (OD) larger than the desired finished size. The desired OD of the welded tube is reached by sinking the tube to the finished size.

Applications

High-precision, seamless stainless steel capillary tubes have been widely used in various instrument measurement applications. Based on thick-walled, small-diameter structures (usually 1/8 inch or smaller), this tube is used for critical applications in jet resistance from nuclear reactors to aerospace. Gas lines, Manometry, Measuring, Cardiology, Medical instruments, Endoscopy, Sensors, ect. Also used in below industries:

1. Pipes and tubes for petrochemical industrial

2. Pharmaceutical industrial

3. Food industrial

4. Aviation and aerospace industrial

5. Architectural decoration industrial