Elongation of LWN Flanges
Elongation of LWN Flanges
(OP)
Dear all,
I am facing a case where the existing LWN flanges (SA105) we have in our possession are shorter in length than those required by the new revision of the Pr. Vessel's drawing (they were ordered correctly as per IFC drawing). My question is wether we can elongate the LWN flange by welding a piece of SA106 GrB pipe of relevant thickness. Is it permitted by the Code (ASME BPVC Section VIII Div.1)? Is there a reference to it, either if it is allowed or restricted?
Thank you all.
I am facing a case where the existing LWN flanges (SA105) we have in our possession are shorter in length than those required by the new revision of the Pr. Vessel's drawing (they were ordered correctly as per IFC drawing). My question is wether we can elongate the LWN flange by welding a piece of SA106 GrB pipe of relevant thickness. Is it permitted by the Code (ASME BPVC Section VIII Div.1)? Is there a reference to it, either if it is allowed or restricted?
Thank you all.
Only best result in absolutely necessary time





RE: Elongation of LWN Flanges
How did this change come about? If requested by the customer, see if they will pay for the change, or accept the deviation. If your mistake, eat it, or see if the customer will accept the deviation.
Regards,
MIke
RE: Elongation of LWN Flanges
RE: Elongation of LWN Flanges
BUT! ... You need to look at reaction forces due to the extra length (greater moment arm, greater forces due to water hammer or relief valve opening, etc.) Also, you need to be sure the joints are not too close to the PV wall weld joint.
RE: Elongation of LWN Flanges
Yes, you can extend the nozzle neck as you wish, provided it complies with the welding and material requirements. There is no other code restriction, hence the code stops at the weld of your extension to the LWN flange/forging. Remember, the PVC code stops at the first weld after the nozzle weld to the shell. Normally, the forged nozzle necks are tapered down the ST thickness just below the flange! The external nozzle loads are subject to piping loads and you need to negotiate the minimum loads with the piping designers or you can advise them of the load capacity of the nozzle as per WRC or similar/allowed calculations.
RE: Elongation of LWN Flanges
RE: Elongation of LWN Flanges