Urgent help: Regarding the tightening torque of flanges
Thread Content
Question: Does anyone know the tightening torque for flanges? If the blind plate inserted in between has one side made of RF material and the other side made of RTJ material, will there be any problems if the tightening torque for this flange is different on the two sides? How should this matter be handled?
I don’t understand. Are the bolt holes in the blind plate threaded counterbored holes or through-holes? If it’s a through-hole, how can the torque on both sides be the same? I’m not sure if this might crush the gasket ； If it is a counterbored hole, the tightening torque can vary.
This post was last edited by lish0325 on 2020-9-7 at 16:03. That’s how it is. This set of flanges has one side with RF connection and the other side with RTJ connection; it’s 900LB and 12” in size. Since the specifications weren’t clearly defined during ordering, it was designed this way – with a blind plate in between, resulting in one side having an RF connection and the other an RTJ connection. However, it was pointed out on site that after the mounting bolts are tightened, there might be a difference in the tightening torque of the bolts on the two sides, as the connection surfaces are different after all.
Safety first; such a high pressure level cannot be taken lightly.
It seems I saw such a connection on a ship many years ago, but the pressure was very low, only 150 LB; an eight-shaped blind plate was used on the overflow pipeline. Back then, the requirements for the tightening torque of flanges weren’t as strict as they are now. 900LB – I don’t recommend doing that; it’s better to replace it.
The blind plate in the middle has an RF side and an RTJ side ====================== Replace it as soon as possible ======================= You can’t cover up one mistake with another
For flanges of different pressure ratings, as well as those with various flange types and diameters, the diameter and quantity of holes for bolts or studs vary. The required tightening force for bolts made of different materials and of different grades is specified in relevant standards; it is important that the tightening be even. Excessive tightening force can cause the bolts or studs to break.