Lifting Lug – WRC Calculation



By
Pandharinath Sanap
13 February 18
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Introduction:

All directly welded parts to the pressure vessel like lifting lugs, support lug, trunnion etc. need to be checked for WRC 107/537. All related calculations are carried out in PV Elite once given proper inputs. In some cases, it is not possible to build such directly welded parts in PV Elite due to software constrain. For example, adding lifting lug on top dish end of vertical equipment is not possible in PV Elite. In those cases, it is mandatory to perform WRC calculations by any other means. This article will help to perform such calculations with analytical solutions followed by CodeCalc calculations.

Inputs:

Consider an equipment with top 2:1 ellipsoidal dish end with directly welded lifting lugs. All necessary input data is given below.

Lifting Lug WRC Calculation

Solution:

To consider the maximum force acting on equipment, the vessel is considered to be lifted from a horizontal position to vertical. At all lifting positions forces acting on lifting and tailing lugs are calculated as given below and maximum of acting force is taken for the analysis.

Lifting lug forces:

Maximum transverse load per lug     PT = P cosθ / N

Maximum longitudinal load per lug   PL= P sinθ / N

Where N = number of lugs

Tailing lug forces:

Maximum radial load on a lug            PR = T sinθ

Maximum longitudinal load on a lug  fL= T cosθ

Lifting Lug WRC Calculation

Therefore, 304.7kg force is taken for WRC analysis and its components acting on lug are calculated as given

Lifting Lug WRC Calculation

Thus after calculation of forces and moments acting on lifting lug, WRC 107/537 analysis is carried out in CodeCalc in following steps

Step-1: Input lifting lug data in CodeCalc

Fig. 3(a) Lifting lug input data in CodeCalc

Fig.3(b) Lifting lug input data in CodeCalc

Step-2: Input WRC 107/537 data in CodeCalc

Fig. 4(a): WRC 107/537 inputs in CodeCalc

Fig. 4(b): WRC 107/537 inputs in CodeCalc

Step-3: Analyse the file for results

After giving proper inputs file is analyzed in CodeCalc, vessel stresses at the attachment junction are calculated and compared with the allowable stresses of respective material as shown below:

Fig. 5: Result summary

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