Valve freezing crack

Valve pipelines are not in use during winter, and drainage is of utmost importance. If there is water, especially when the pipes are full, freezing in winter can cause the pipes and valves to crack. If the water is drained properly, the valve pipelines remain safe during winter

Do you mean that once the water is drained, the cast iron valve body won’t crack from freezing in an environment of -20 to -30°C?

Yes, but I’m discussing here whether it can crack from freezing in the absence of insulation.

Pay attention to the reverse expansion of water; other substances do not exhibit this phenomenon. Freezing cracks occur due to the expansion of water; they don’t happen when there is no water.

The valve body does not crack from freezing once the water inside it is drained; this applies equally to ductile iron and cast steel

Right, it’s the same principle as storing pipe fittings outdoors

I encountered this exact issue last year; the customer was in Panjin, Liaoning. All of the butterfly valves used were made of ductile iron – the construction company opted for ductile iron to cut costs, and steam insulation was applied (a thin steam pipe was placed outside the pipes, with an insulating layer added on top). These butterfly valves were in use for 3 years (almost 1 year without any fluid flowing through them after installation; in total, they were used for nearly 2 years). No cracking occurred in these valves. However, some of the smaller-diameter valves did crack due to nitrogen exposure last year (probably because there was water inside the valves when it was cold, or perhaps because no insulation was provided; only insulation was added later). The valves that didn’t have steam heating experienced partial cracking – 3 valves were damaged in this way, out of around 10 valves in such conditions). In areas like the north, I recommend using cast steel valves, but insulation is still necessary. As long as the interior of the valve doesn’t freeze, the risk of cracking is low. Additionally, the lower the temperature of the ductile iron valve body, the less pressure the shell has to withstand. So as long as proper insulation is provided, using ductile iron should be fine. Just pay attention to two things: 1) the interior of the pipes must not freeze, and 2) the surface temperature of the butterfly valve body should not drop below normal levels; otherwise, the high pressure in the pipes could cause the valve to crack. It’s best to keep the surface temperature of the valve body at around 20-30 degrees even in the coldest conditions. This is just my personal opinion; please forgive any mistakes

This post was last edited by WJHSWSW on 2016-7-26 at 19:49. The operating temperature for ductile iron valves is -30~350°C. Operating temperature for gray cast iron valves: -15~250°C. Operating temperature for carbon steel valves: -29~450°C. It can be seen that -30°C has already exceeded or reached the limit, making problems likely; it’s better to add insulation.

Generally, as long as there is no water inside the valve, it won’t freeze and crack; even if there is water, it’s not certain that the valve will freeze and crack. The coldest temperatures I experience in winter can reach -30°. Some valves that aren’t insulated still function fine, but it also depends on the material of the valve and the temperature range for which it’s designed to be used. If you’re concerned about freezing and cracking, it’s best to check the appropriate operating temperature for the valve first to see if insulation is necessary