Introduction

Low temperature pressure vessel (low temperature pressure vessel), is a kind of cryogenic vessel.

Summary

Design of temperature for pressure vessel -20 DEG C; the container is of low temperature pressure vessel for storage and transportation of liquefiedethylene and liquefied natural gas, liquid nitrogen and liquid hydrogen etc..The general pressure vessel commonly used ferritic steels in the temperaturedown to a temperature, the toughness of the steel will decrease sharply, and is very brittle, this temperature is usually referred to as the ductile brittle transition temperature. The use of pressure vessel in below the transition temperature conditions, due to defects, residual stress, stress concentrationand other factors caused by the high local stress such as the existence of a container, the container may be in no obvious plastic deformation under the condition of brittle rupture and disastrous accident. For low temperature pressure vessel must first select suitable materials, these materials should have good toughness at service temperature. The grain size of low alloy steelsavailable to -45 DEG C, 2.5% nickel steel available to -60 DEG C, 3.5% nickel steel available to -104 DEG C, available at -196 deg.c for 9% nickel steel.Below -196 DEG C when the selection of austenitic stainless steel andaluminum alloy etc.. In order to avoid local high stress in low temperaturepressure vessel, in the design of container should avoid excessiveconcentration of stress and additional stress; be strict inspection inmanufacturing the container, in order to prevent dangerous defects exist in the container. For because of the welding residual stress caused by excessive,should eliminate welding residual stress treatment after welding.

Performance characteristics

Cryogenic vessel performance and features of industrial [1] with liquid nitrogenat extremely low temperatures by nitrogen pressure variable is a colorless liquid, low temperature container at liquid nitrogen temperature is very low, and then use the cylinder holding, then put the cylinder in normal temperature, due to the environment temperature, temperature of liquid nitrogen is placed inside the bottle rises, also into the room temperature, then the liquid nitrogen in the bottle pressure will become higher.

But in the actual case, either the cylinder heat preservation effect is very good,or pressure safety valves, cylinders placed either opening time is very short.The cylinder temperature could not reach the normal temperature.

The industrial use of the liquid nitrogen at extremely low temperatures by nitrogen pressure variable is a colorless liquid, then the liquid nitrogentemperature is very low, and then use the cylinder holding, then put the cylinder in normal temperature, low temperature storage tank due to environmental temperature, then:

The bottle containing liquid nitrogen transformation could take place, i.e.vaporized, by liquid nitrogen into gaseous nitrogen, the cylinder pressure rise,this time the inside temperature or liquid nitrogen and nitrogen coexisttemperature is generally -196 degrees, absorb heat temperatures continue to rise, the pressure continues to rise, pressure safety valve will work, relief. If nopressure relief, only temperature, pressure of liquid nitrogen in the cylinder will be very high, resulting in high pressure vessel explosion.

Liquid nitrogen tank insulation effect is very good, the liquid nitrogen can bestored for 1 months does not vaporize finish inside.