Technical requirements for pressure lead copper tubes
Thread Content
As the title suggests, the new oxygen production unit at our facility uses copper pipes for pressure measurement at the top of the cryogenic tank. These pipes previously had an outer diameter of 10 mm, but now they need to have an outer diameter of 6 mm. The length of these pressure measurement copper pipes is approximately 30 meters. Is this meeting the technical requirements?
What’s the pressure? What is the wall thickness of the pressure tap? Will the pressure tap be clogged by liquid or impurities under operating conditions?
The pressure tap pipe is made thicker; one reason is to prevent blockages, and the other is to avoid external mechanical damage. It’s fine to avoid these two points even if done in a more subtle manner; the capillary tube of a double-flange differential pressure gauge also functions as a pressure transfer tube, and it does not affect the measurement.
Pressure tapping pipes should be made of stainless steel; copper pipes are rarely used.
According to clause 4.3.2 of the standard SH/T3104-2013, the length of the pressure tapping pipe shall be less than 15 meters. The tube length used is less than 12m.
1. In domestic air separation plants, copper tubes were commonly used in the cryogenic tanks in the 1970s, but robust protective devices were installed to prevent damage； In recent years, domestic air separation plants have made more use of aluminum tubes, and are gradually adopting coiled tubes – that is, no joints inside the cold box – along with protective frames, which yields good performance. In foreign air separation plants, represented by Air Liquide, stainless steel coils are used, which yield excellent results with very few cases of leakage. Other foreign manufacturers also use aluminum coils, and the performance is quite good as well. 2. Regarding the length of the tube, it is unclear whether the aforementioned length includes the interior of the cryogenic box, as the internal length depends on the location of the measurement points and the requirements for vaporization, and is determined by the manufacturer. Transmitters should be installed near the outside of the cold box, and it is advisable to use stainless steel at the joints of the box walls.
You can choose plastic-coated copper – please contact 18352877317