For LNG projects, what is used for pressure testing?
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For the pressure testing of LNG pipelines, it seems that nitrogen is preferred for this purpose, due to the special properties of LNG when in contact with water. But there are also those that use water for pressure testing. There are currently three issues: 1. For the LNG projects that Haiyou has undertaken, what medium is used for pressure testing? Water or nitrogen? How to conduct pressure testing with water (measures)? Is there any standard support for using nitrogen? (Are there any specifications?) 2: Are the valves on the LNG pipeline welded or flanged? 3: Are the valves on LNG pipelines globe valves or gate valves?
Water pressure or clean compressed air.
Compressed air is used for pressure testing, and drying after testing with water is a major problem. For LNG pipelines, welded valves are preferred for equipment connections, tank flanges for connections, and flanges for loading. If flanges are used, leaks can occur easily due to severe temperature changes. Globe valves are commonly used for low-temperature cryogenic valves, while low-temperature gate valves are also used for those with particularly large pipe diameters.
Impressive; I often see your answers. All the answers are very good
When selecting a compressor, it is advisable to consider air pressure testing. (Otherwise, there wouldn’t be air with such high pressure.) The pressure in pressure experiments is higher than that of water pressure, so attention must be paid to the design pressure. Valves: Ball valves are also widely used.
Whether it is an LNG plant or a small LNG station, it is recommended to use nitrogen for pressure testing and air for purging. Using water makes it difficult to dry the pipes, requires a large amount of water, and is hard to control
Air or nitrogen is used for pressure testing LNG pipelines, and it must also be kept dry. Ball valves are generally used for pipeline valves; in low-temperature environments where strict leakage controls are required, insulated ball valves should be employed. Both globe valves and gate valves pose a risk of packing leakage, so they are generally not recommended. I work in LNG projects.
Pneumatic testing is very dangerous; once a test pressure of 6 bar is reached, it is not recommended to use pneumatic pressure
This issue is controversial and involves safety risks related to gas use, but LNG has the advantage of being easy to dry. With water, the dew point is difficult. We only use water for the amine solution system, and gas for everything else.
Are the safety valves on LNG pipelines also welded?
All safety valves are connected by flanges, but the valves located before the safety valves and the bypass shut-off valves are welded together (including the pre-drain valve before the safety valve), which facilitates regular calibration of the safety valves