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Types of Stainless Steel Tubing

Updated: Jun 19

To OGMAN Tuberías Inoxidables, it is important to recognize the characteristics of the different types of tubing available in the market, as the needs of each client often vary. Therefore, in this blog, we will focus on mentioning some of the most common types in our industry.

Tubing is designated by its outer diameter and wall thickness, which is indicated in 'gauges' (according to BWG - Birmingham Wire Gauge). On the other hand, non-sanitary industrial tubing, is designated by its nominal diameter and thickness, and the thickness is indicated using a 'schedule' number.

By definition, tubing with a surface finish that complies with 3-A standards is considered "sanitary". However, depending on the use and finish requirements of each client, there may be some variations:

Pharmaceutical Tubing:

Primarily used for handling water in pharmaceutical laboratories, the ASTM A270 type 316L standard, under supplement S2, marks specific requirements for 'Pharmaceutical Grade' tubes. These include sulfur control and certain hardness and tension test values, packing specifications, and instructions for finish specifications.

A270 TP304:

Surface polish is 32 micro-inch maximum Ra for interior and exterior finishes. It complies with the 3-A standard and is widely used in the food and beverage industries.

A269 TP304 B/A:

If the tubing goes through the normal annealing process and if slag, and discoloration, are removed with mechanical polishing, we obtain the designation B/A. The finish is specified with a 'grit' number and, although it is practically a sanitary tube, it is not certified as 3-A tubing.

A269 TP304 H-B/A:

The acronym H-B/A stands for 'Hydrogen Bright Annealed' and refers to tubing with a bright annealing heat treatment. As it is treated in a hydrogen atmosphere, no slag or discoloration is formed on the surface. This treatment makes the 'pickling' process, designed to remove such surface effects, unnecessary. The final finish is close to the sanitary type, but in general, it cannot be considered as such.

A269 TP304 W/A Pipe:

This tubing is designed for winery applications. It undergoes the annealing heat treatment and exterior polishing for cosmetic purposes only. The roughness average (RA) of the interior is not specified.

A778 Pipe:

This ASTM standard specifies a tube that is simply formed, welded, and perhaps pickled. It does not undergo any heat treatment. Mechanical tests under this standard indicate that each batch must undergo a traction test and two transversely guided bend tests. The weld is not necessarily flush, as there is a 1/16" tolerance for both interior and exterior reinforcements.

Pickled Tubing:

This designation is used for polished tubing with a grayish finish. Pickling is a process used to remove slag and impurities from welding and/or from heat treatment that causes oxidation. However, pickling becomes unnecessary if the heat treatment is carried out in a controlled atmosphere, or if slag and pollutants are removed using abrasives. An H-B/A or B/A tube, treated thermally in a controlled atmosphere or with mechanical polishing, can functionally replace a pickled tube with advantages.

R/L Pipe

When purchasing tubing for use in very short sections, there is the option to use production ends and tails. These are irregular lengths ranging from 1.5 up to 4 or 5 meters, commercially designated as R/L: 'Random Lengths'. The price of these sections is logically lower than that of the usual 6.10m tube lengths.

At OGMAN, we offer tubing manufactured in the United States and Asia, with sanitary specifications and certifications for high-purity systems in the food and pharmaceutical industries, ensuring guaranteed traceability and compliance with manufacturing standards such as ASTM A269, ASTM A270, ASME BPE, 3-A, for 304 and 316L types, and ASME BPE. We always strive to deliver the best quality to our customers.

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