Cryogenic piping layout requirements are multifaceted to ensure the safe, stable operation of pipelines, and to meet process requirements. Here are some of the main cryogenic piping layout requirements:
Sufficient flexibility
The layout of the cryogenic pipeline should consider that the entire pipeline is flexible enough to make full use of the natural compensation of the pipeline. When the design temperature is very low and cannot be compensated naturally, a compensator should be set.
Avoid vibration
When arranging low-temperature pipelines, pipe vibrations should be avoided, especially in key parts such as pumps, compressors and exhaust pipes, which must prevent vibration of the entire pipeline. If there is a mechanical vibration source, vibration cancellation facilities should be adopted, and elastic elements, such as wave-type compensators, should be installed in the pipeline close to the vibration source to isolate the vibration source.
Considering the material characteristics
on the low-temperature pipeline of low-temperature carbon steel and low-alloy steel, when equipped with valves or branch pipes with exhaust and sewage discharge, it is necessary to pay attention to whether the cryogenic liquid medium is gasified immediately after discharge. If vaporization will absorb a lot of heat and cause frost or even freezing, such branches should be made of austenitic stainless steel in the range that is prone to freezing, and flanges should be used to connect branches of different materials.
Flange and elbow arrangement
On the low-temperature pipeline, close to the elbow or tee, it is generally not allowed to weld the flange directly. In order to remove the bolt without destroying the insulation layer on the main pipeline, the flange should be welded after extending a length (connecting a short pipe).
Support and hanger arrangement
The cold pipe support and hanger should be used for the cryogenic pipeline, and the support and hanger should have measures to prevent the “cold bridge”. At the elbow of the low-temperature pipe of the polyurethane insulation pipe, the support and hanger should not be welded due to the large stress.
Spacing and valve arrangement
The spacing of cryogenic pipes should be determined according to the thickness of the flange, valve, measuring element and the displacement of the pipeline. The valve on the cryogenic medium pipeline should be installed on the horizontal pipeline, and the valve stem direction should be vertically upward.
Qualification requirements
The design unit of the low-temperature medium pressure pipeline shall obtain the GC1 or GC2 pressure pipeline design qualification license, and the construction unit shall obtain the corresponding installation qualification license.
To sum up, the layout requirements of cryogenic pipelines involve many aspects such as pipeline flexibility, vibration control, material selection, flange and elbow layout, support and hanger design, spacing and valve layout, and qualification requirements. In actual engineering, these requirements should be strictly followed to ensure the safe and stable operation of cryogenic pipelines.
