Posted by: Anup_Kuldiwar
Technical query for calculating Backing Ring thickness in PV - 10/19/15 06:24 AM
Dear Sir,
While carrying out the design calculations for Backing ring thicknesses, using PV Elite, we have observed the following:
PV Elite is considering formula (T = SQRT (WM1 * h * Split_fac * Y / S * B)) as given for style B split factor for calculating backing ring thicknesses as TEMA (RCB-5.141) style A does not cover any split factors in calculations as the formula (T = SQRT ( W * h * Y / S * B)) as split factor 2 as used for style B is missing .
ASME appendix 2 clause 2.9 indicates philosophy of split factor for splits. Factor is 2 with one split (2 segments) and 0.75 when the backing ring is split into 4 segments. Formula as given in appendix 2.7 of clause B is similar to as given in TEMA which is referred in clause 2.9.
In PvElite help files, for user input of split factors for backing ring design, it indicates that “Note - TEMA RCB-5.141 shows different styles of backing devices. Styles A and D have a split ring, but the moment used to design them is not increased. When you have one of these styles, enter zero as the number of splits to get the same effect in CodeCalc”.
We would like to know why there is no split factor for style A, C and D. We have not seen any provision for split A, C and D type backing ring in ASME.
While carrying out the design calculations for Backing ring thicknesses, using PV Elite, we have observed the following:
PV Elite is considering formula (T = SQRT (WM1 * h * Split_fac * Y / S * B)) as given for style B split factor for calculating backing ring thicknesses as TEMA (RCB-5.141) style A does not cover any split factors in calculations as the formula (T = SQRT ( W * h * Y / S * B)) as split factor 2 as used for style B is missing .
ASME appendix 2 clause 2.9 indicates philosophy of split factor for splits. Factor is 2 with one split (2 segments) and 0.75 when the backing ring is split into 4 segments. Formula as given in appendix 2.7 of clause B is similar to as given in TEMA which is referred in clause 2.9.
In PvElite help files, for user input of split factors for backing ring design, it indicates that “Note - TEMA RCB-5.141 shows different styles of backing devices. Styles A and D have a split ring, but the moment used to design them is not increased. When you have one of these styles, enter zero as the number of splits to get the same effect in CodeCalc”.
We would like to know why there is no split factor for style A, C and D. We have not seen any provision for split A, C and D type backing ring in ASME.