Issues with the pressure lead tubes of the transmitter
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This post was last edited by xlm19589 on 2010-10-2 at 23:15. Our transmitter pressure tube designers require stainless steel pipes; the client is responsible for installation and controls the costs. Is it acceptable to use ordinary carbon steel seamless pipes instead of stainless steel pipes? We designed it using 18-inch pipes; will 25-inch pipes work? Are there any design specifications for pressure tapping pipes?
A 18-inch pipe? We all use 14-grade stainless steel pipes. I’ve never been involved in supervision work; I’ll ask some experienced colleagues from the company who have worked on instrument supervision someday.
It is recommended that the poster provide more information regarding the medium used; I have never seen pressure transfer pipes made of carbon steel before. It is suggested that the poster keep an eye on this matter, as it is very likely that regulations are being violated.
HG_T 20510-2000 specifies that stainless steel or red copper should be used for instrument gas supply systems. Carbon steel pipes are prone to rusting, which can block the pressure transfer pipelines
Carbon steel seamless pipes can be used as pressure and suction pipes. In previous systems (7–8 years ago), carbon steel pipes were commonly used; it is only in recent years that stainless steel pipes combined with slip fittings have become popular. There is no problem with doing this, but you need to consider the corrosiveness of the medium used, and since carbon steel pipes are prone to accumulating dirt, you should take into account valves for draining waste. It is simple to determine the material of the pressure guide tube; if the material of the process pipeline is stainless steel, then the pressure guide tube must not be made of carbon steel ； Because the specifications require that the material of the pressure guide tube be no lower than that of the pipeline.
It’s possible, but a drain valve should be installed when laying the pressure transfer pipe, in order to prevent the carbon steel pipe from rusting and blocking the pressure transfer pipe or damaging the diaphragm of the transmitter. It is recommended to use stainless steel; carbon steel is generally not used for this purpose. Carbon steel is usually employed only for pressure lead pipes or for conveying the medium itself.
Carbon steel pipes are acceptable, but the cost will be deducted from them at the time of project settlement. . . . It’s not easy to weld a 25mm pipe to valves and pressure gauges; one has to add a 25mm flange to make the connection possible!
When deciding between 14*2 and 18*3, or between carbon steel and stainless steel, it is best to consider process conditions such as the medium being measured, pressure, and temperature； Although the cost of carbon steel has decreased, it needs to be replaced after a few years, while stainless steel has a longer service life; all factors need to be taken into consideration ；
We use 14*2 stainless steel pipes; the chemical industry is highly polluting, and carbon steel would corrode very quickly in such conditions
Stainless steel pipes are the best choice; when using ordinary carbon steel seamless pipes, it depends on whether the medium is corrosive. If it is not corrosive, ordinary carbon steel seamless pipes can be used. However, the construction party failed to carry out work in accordance with the design requirements, which constitutes a breach of contract; as such, acceptance can be denied, and the construction party should be required to make corrections. A 25mm pipe can be used in place of an 18mm pipe.
Carbon steel rusts easily, and it’s also troublesome to prevent corrosion!