Dear seniors, I would like to ask if there are any specific **standards or guidelines** for the design of liquid ammonia pipelines and valves.
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RT, as there have been recent tasks related to liquid ammonia pipelines and valves, I would like to ask the experts here: if such standards exist, please let me know their standard numbers. Thank you
As for temperature, it is at room temperature; as for pressure, it is around 0.8 Mpa in summer.
By taking into account all the process conditions, the pipeline grade can be determined using the table on the 3rd floor; thereafter, the corresponding requirements can be checked
The standards set by Sofa Class can be used as a reference. Regarding liquid ammonia pipelines, even at room temperature and 0.8 Mpa, the design pressure should be determined based on the saturated vapor pressure, which is around 2.2 Mpa. The design temperature should take into account the saturated vapor temperature corresponding to atmospheric pressure, namely -33°C. (-33) The designed carbon steel pipes can no longer be used; as far as I know, many design temperatures in China are not set at such a level ； However, the design pressure of 2.2–2.5 Mpa is still generally followed ； Among the foreign process packages I’ve seen, whether it’s liquid ammonia at 4°C or 10°C, they are all designed for a temperature of -33°C. As for pipeline classification, it is necessary to determine whether to use the GC classification standard for industrial pipelines or the SHA classification standard according to petrochemical industry norms; since different classification principles apply, the design and construction inspection standards also vary. It is best to use both sets of standards together, as there are still differences in the details within each standard system. Furthermore, copper and copper-based alloy materials must be strictly prohibited for all pipeline components and parts related to liquid ammonia, as chemical reactions will occur. Finally, liquid ammonia may also be subject to stress corrosion; as specified in section 6.3.7 of SHT3059-2012, liquid ammonia pipelines require post-weld heat treatment, and the hardness value of the welded joints must be ≤185HB.
I’ve learned it, thank you to all the seniors :D:D:D
How to perform heat treatment after welding? Be more specific.
They’re trying to take our jobs from our company upstairs – true experts in the industry.
When carrying out construction, in addition to referring to these two specifications, the contractor also follows SH 3501-2011 \"Code for Construction and Acceptance of Steel Piping Systems for Toxic and Flammable Media in Petrochemical Industries\" and SH/T 3554-2013 \"Code for Weld Heat Treatment of Steel Piping in Petrochemical Industries\". Moreover, in accordance with the requirements specified in the design documents, a construction plan for pipeline welding and heat treatment is prepared and implemented.
Yi Mi’s remarks were highly insightful; accidents frequently occur with liquid ammonia equipment and pipelines in China, and this is largely due to the use of a design temperature of -19 degrees. If the design temperature is set at -33.5 degrees, some liquid ammonia leakage accidents can be avoided.
This is because consideration is given to leakage conditions, the condition where the safety device does not return to its original position, leakage conditions of the flange gasket, and the condition when the valve is opened for the first time. Situations where the operating temperature is below -20 degrees will occur. Therefore, it is reasonable to choose -35 degrees as the design temperature. The material is LTCS.