The issue of negative pressure resistance in steel-lined pipes
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Dear experts, when steel-lined pipes are used in vacuum systems, are there any requirements regarding the negative pressure level of the vacuum? Are there any relevant specifications? It is said that in many steel-lined pipes, the lining can peel off under certain levels of vacuum! ! We are now using steel-lined PTFE on vacuum pipes for this project; seeking advice
It can be used. What’s the vacuum level? What’s the temperature? How can we talk without knowing anything?
…………Molded PTFE pipes work fine even in high-vacuum environments…………:lol
Large-diameter pipes are preferably not used; small-diameter pipes can operate at lower negative pressures, but there is still a risk of detachment
From a force analysis perspective: under the conditions that the rubber lining fits tightly against the inner wall of the steel pipe and that the rubber lining itself does not leak, 1. the pressure difference between the negative pressure inside the rubber-lined pipe and the pressure of the external environment is borne by the steel pipe portion; 2. the pressure inside and outside the rubber lining is equal, resulting in a dynamic equilibrium. Therefore, as long as the steel pipe can withstand it, the rubber-lined pipe can also withstand it.
Molded versions are more resistant to negative pressure than regular ones, but it is still necessary to discuss the maximum negative pressure with the supplier before use.
It seems there are two methods: rotomolding and molding; you should look up some information on that
You can ask about Sigri’s steel-lined PTFE tubes.
Molded ones are resistant to vacuum; ordinary ones are not vacuum-resistant. For high vacuum conditions, enamel is the better choice.