What is Hypodermic Tubing? - Hypo Tube Applications & Manufacturing
Hypodermic needle tubing, also known as "hypo tube" or "medical grade needle tubing", is small diameter tubing intended for use in medical applications, although it can be used in non-medical applications as well. The word "hypodermic" itself is defined as "beneath the skin" and traditionally hypodermic tubing has been fabricated into sharp needles for injections or extractions of fluids or tissues into human or animal bodies.
Hypodermic Tubing Applications
These types of products range from common disposable sharp needle products used for injections of vaccines and medications at the general practitioner’s office to biopsy needles or low volume specialty needles with unique features used to treat rare ailments. Needles using hypo tubing produced by Vita Needle run the gamut from short, small diameter needles for ophthalmic use to larger diameter needles extending several feet long to assist with bovine or equine insemination.
Hypodermic Tubing Materials & Sizes
Normally constructed of 304 or 316 stainless steel due to its relative cost-effectiveness and wide acceptance in medical applications, hypodermic tubing is sized according to the Stubbs Iron Wire gauge (also known as the Birmingham Wire Gauge). The needle gauge system specifies standard outside diameters (OD), inside diameters (ID) and their respective tolerances in a stepped format where a lower gauge number translates into larger nominal hypo tube OD and ID’s. Higher gauge numbers indicate smaller OD/ID’s. Unlike ANSI screw/bolt thread standards, the hypodermic needle gauge chart does not correspond with common fractions (3/32", 1/8" etc.) with a few exceptions (21 Gauge = 1/32” OD).
An example of the hypo gauge system follows: "15 Gauge" hypo tube has a nominal outside diameter of .072" whereas "16 Gauge" hypodermic tube equates to a nominal outside diameter of .065". A list of the hypodermic gauge sizes can be found in our Master Tubing Gauge Chart. Users of hypodermic tube products select the appropriate gauge for their application depending on the finished device requirements such as but not limited to viscosity of fluid or flow rates. Standard hypodermic tubing sold by Vita Needle is stocked for quick delivery and can be shipped within a day of ordering or sooner if required.
Hypodermic tube is usually sold in hard temper conditions. Cold work applied during the tube drawing processes result in a rigid and strong tube that does not easily flex or bend when force is applied longitudinally---features desirable on sharp needle products penetrating tissues, for example. However, it can be manufactured in intermediate or annealed (soft) tempers if an application requires it.
Hypo Tube Manufacturing
Common governing specs for hypodermic tubing are ASTM A908 (needle tubing) or ISO 9626---both specifications provide dimensional, chemistry makeup and mechanical specifications for consideration by the purchaser. These specifications detail the manufacturing process as “welded and drawn” which is the standard process for manufacturing hypodermic tubing because it is cost-effective and well-proven in the field. In the welded and drawn process, flat stainless steel strip stock is rolled into a tubular shape, tungsten inert gas welded along the seam, and subsequently drawn over a floating plug/mandrel to size the tube to the final desired size. The plug drawing process also integrates the weld zone into the rest of the tube so that a properly drawn tube is "seamless in appearance" with a smooth outside diameter and improved inside diameter finish from the plug drawing process.
Serving a wide range of medical and non-medical applications, and available in random length or fabricated form, versatile stainless hypodermic tubing is a proven material choice for existing products or a starting point for new projects in development.
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