Regarding the issue of pipeline grade classification
Thread Content
A pipeline has a grade transition at the gate valve flange; the grade of the gate valve is 150CL, while the grade of the flange is 300CL. In modeling software, it is possible to add a 300CL flange to a component with a 150CL grade, but in reality, the end of the 150CL gate valve is connected to a 300CL flange. What is the difference between adding a 300CL flange to a 150CL component and using a 300CL flange directly?
If the pressure and temperature behind the valve increase to such an extent that the flange becomes CL150, then the valve should also be of CL300 grade; otherwise, the requirements will not be met
Since the flange is CL300, the valve should also be CL300; otherwise, how can a CL150 valve withstand the pressure on the CL300 flange side when it is closed? The pressure rating design should be CL300 flange at the front end, plus a CL300 valve, and another CL300 flange at the rear end; however, the flange necks on the front and rear ends are different and must match the corresponding pipes. The interface should be at the flange surface at the rear end of the valve, not at the front end.
There is a problem with this classification; the valve should be CL300. Also, can a CL150 flange match with CL300 valve bolts?
Is the wall thickness of the flange neck for 300CL the same as that of the pipe wall for 150CL? Can it be connected?
In reality, the pressure level is definitely changed through flange splices!
Generally, the CL150 flange is welded first, followed by the creation of a short section; one end of this short section is fitted with a CL150 flange, while the other end is fitted with a CL300 flange, after which the CL300 valve is connected
Valve 300LB, two flanges 300LB, rear flange with pressure rating changed to 159LB
Pressure level conversion generally requires it to be done after valves at higher pressure levels. More participation in discussions is welcome