The types of fittings b16.9

Within the Intertubi catalog, you can find a section dedicated to stainless steel fittings made according to ASME b16.9. In particular, the b16.9 fittings present are:

• 90 ° curves: they can be made both with a radius of curvature equal to 1.5 times the diameter of the fitting, and with a radius of curvature equal to the diameter of the fitting;
• 45 ° curves: they can be made on request and have relations between the radius of curvature and diameter identical to those of 90 °;
• Concentric reductions: they have a different inlet and outlet diameter, but the same axis;
• Eccentric reductions: they have, like the previous category, different diameters but also a different axis that defines an eccentricity;
• Same tees: they are T-fittings which have an equal diameter for all outlets;
• Reduced tees: they are T-fittings with an outlet of a different and smaller diameter than the others;
• Stub-ends short lenght: they have a flanged end;
• Bottoms.

In addition to these models, there are a number of similar types "without welding": it is possible to find the curves and reductions already proposed, but also a series of curves with radii of curvature three or five times the diameter of the fitting.

Realization and marking of the b16.9 fittings

The starting point for making the fittings are the pipes: they can be with or without welding. Such a feature is important because you do not get the same product, but there are differences both in terms of resistance level and at the application level.
An important aspect regarding b16.9 fittings is the marking. It is contained within the ASME regulation in chapter 4 and the main information it must contain is specified:
- Name and / or brand of the manufacturer;
- Identification of the material according to regulations;
- The nominal wall thickness of the fitting;
- Size of the extremities: using the NPS, which is the Nominal Pipe Size;
Finally, as a last aspect, it is necessary to report whether the production of the fitting has been standard or has been carried out with special features.


The steels for fittings b16.9

The choice of the correct material and chemical composition are fundamental aspects for the realization of a quality product: in particular, generally, stainless steels are used, especially austenitic. These materials have high corrosion resistance characteristics and is a fundamental aspect for the realization of pipe fittings. The carbon percentages are basically low and, in any case, always lower than 0.35% while other elements such as Nickel and, above all, Chromium are in much higher levels. In fact, these elements are fundamental for the resistance to corrosive environments and must generally be present in percentages more than 10%, as regards Nickel, and more than 18%, as regards Chrome.