Double Ferrule Compression Tube Fitting General Information

Introduction
SD range of double ferrule fittings work on the proven principle of two ferrules swaging to the tube when tightened. As the nut is tightened the front ferrule swages on to the tube making a prominent leak-proof seal and the back ferrule makes a positive impression on the tube with the help of back cone of front ferrule hence making a strong hold on the tube. Make and remake of the fittings is very much eased, as nuts are silver plated internally to prevent galling of threads. The identification between Metric and Inch fittings is made very simple with the help of stepped shoulders in metric fittings.

Material
The standard material that is used in making SD range of instrumentation fittings and tube fittings is SS316. These are also made in brass, Monel, Hastalloy, and incoloy as and when required by the customer. Various International Material Standards are used for conforming the chemical requirements of the raw material.

Raw Material Reference
Tubing Selection
Proper selection, handling, installation of tubing in combination with SD range of instrumentation fittings and tube fittings are very much essential to ensure a perfect leak-proof joint. Selection of tubes is based on the material hardness, wall thickness and surface finish.

The working pressures in the above table are based on actual tests on ASTM A-269 tubing with a safety factor of 4:1. They apply to a metal temperature range of -20°to + 100°C.

For working pressures of monel tubing, multiply the above ratings by 0.8.