Instrument Tube Fitting, also known as pulse tube, is directly in contact with the process of a medium pipe. Is the instrument to install the most use, the highest and most complex of a pipeline.
As the Instrument Tube Fitting of the pressure pipe directly contact with the process medium, so the choice of the tube and the side of the physical properties of the media, chemical properties and operating conditions. The general requirement is that the pressure pipe is operated under pressure or atmospheric pressure. Must have a certain strength and sealing. So this type of pipe should be used seamless key. In the medium and low pressure medium, the commonly used pressure pipe for the φ14 × 2 stainless steel tube, which is the most used a tube. Sometimes with φ18 × 3 or φ18 × 2. The sampling lines used for the analysis are also usually supplied with a φ6 × 1 seamless steel pipe, sometimes using a φ8 x 1.5 or φ10 x 1 or φ12 x 1 stainless steel tube. In the high pressure operating conditions of more than 10MPa. More use of φ14 × 4 or φ16 × 4 stainless steel pipe or seamless alloy steel pipe.
The material of the pressure tube of the Instrument Tube Fitting depends on the degree of corrosion of the measured medium. No corrosion or weak corrosive medium selection 1Cr18Ni9Ti acid stainless steel tube, for strong corrosive media, such as urea production, will have to use the same process with the urea pipe stainless steel 316LN or other molybdenum containing stainless steel pipe. If it is measured nitrogen or hydrogen peroxide and other strong corrosive media, can only use plastic pipe. The choice of pressure pipe must meet the process requirements and design requirements, substitutes must obtain design consent.