Inspection and repair of cryogenic storage tanks

- Aug 05, 2019-

(1) There is a clear large area of “sweating” and “frosting” outside the cryogenic storage tank. Due to pipeline leakage in the cryogenic tank interlayer, unfilled pearlite sand or other reasons, the vacuum of the interlayer is destroyed. This requires inspection and repair, or leak detection, or supplemented with pearl sand, which can be re-vacuum.

(2) The pressure in the inner cylinder of the low temperature storage tank is abnormally increased, and the safety valve takes off. This may be due to three reasons:

a. The vacuum of the low temperature storage tank interlayer is destroyed;

b. The inner cylinder booster valve fails, and the booster valve needs to be repaired or replaced;

c. The leakage leaking part of the lower part of the interface is located at the joint of stainless steel and carbon steel shell, or the joint of copper tube and stainless steel inner tube, that is, the heterogeneous welded joint, which mainly forms electrochemical corrosion at the heterogeneous welded joint.

(3) The amount of evaporation becomes large, and the degree of vacuum becomes small. It may be due to the deflation of pearl sand. Pearl sand has certain grain size and temperature requirements when filling. When the particle size and temperature of the pearl sand are not suitable, after running for a period of time, the pearl sand will release water vapor, which will reduce the vacuum and increase the evaporation.

(4) The top of the outer cylinder of the cryogenic storage tank “sweating”. It may be caused by the accumulation of pearl sand in the lower part. After being put into use for a period of time, the pearl sand sinks and forms a space at the top of the container, and the local heat insulation effect is significantly reduced, causing the container to run cold. In this case, if the amount of evaporation is large, the top of the jacket outer cylinder can be dug up and the pearl sand can be added.