What material of flange and valve should be used with 20G pipeline?
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High-pressure steam pipelines often use 20G pipes. I don’t know what flange materials are used. If butt welding valves are used, what materials should be used? I used to use 16MN flange, but it seemed that domestic procurement was a bit difficult, so I finally changed it to A105. I use A216 (WCB) for butt welding valves, but the supervisor reported that there may be problems with the welding of these two materials. If alloy steel is used, can it be welded with 20G?
Flange 20； Valve A105 or WCB/316
I checked several books but couldn't find it. I'll pay attention next time when I look at the pictures. Haha, but I think flange alloy steel of the same material can be welded with 20G. Welding of dissimilar steel is possible, but you need to pay attention to preheating and heat treatment.
For high pressure (PN>10MPa), it is recommended to use stainless steel valves and they can be welded with carbon steel, but there are certain requirements for welding rods. As for the flange, the pipe material can be the same.
I did a project where the pipes also used 20G, and the ASTM A105 valves used for the flanges were A216, which is the same as LZ's. Regarding the welding LZ of carbon steel and alloy steel, you can refer to Section 6 of the specification "GB50236-98 Specifications for Construction and Acceptance of Field Equipment Industrial Pipe Welding Projects" for detailed instructions and regulations!
There should be no problem with A105N and A216 WCB, right?
A105N adopts forge welding method
If I use a flange made of 20G material, is it easy to purchase?
Doesn’t your piping/material specialist produce a media table? I'm going to check it out, I can remember so many things, and each project has different results.~
The pipe medium of 20G pipes is generally high pressure or medium and low pressure but the temperature is between 300-400 degrees. Therefore, domestic 20# steel cannot be used for pipe fittings and valves. Commonly used flanges are A105, 16Mn, and 15CrMo. As for the supervisor's answer, he probably doesn't know how to weld. 16Mn is between alloy and carbon steel. Its hardness and strength are higher than ordinary carbon steel. The weldability with carbon steel is significantly worse than the welding with carbon steel. It generally requires preheating and is prone to cracks. 20G, A105, and WCB all belong to the same category of carbon steel and there is no problem with welding.