Pump Lines on a Drilling Rig

Introduction

The scope of this case was a stress analysis for the GRE piping system that connects the pumps to tanks at the drilling rig. It was assumed that the 6” and 12” pipes were assembled with rigid tensile-resistant joints. It was also assumed that the various deck and bulkhead penetrations were executed as anchors, i.e. a steel spool flanged at both sides was welded in each deck and bulkhead
penetration.

Analysis

The requested (beam-type) stress analysis was performed from anchor to anchor with intermediate supports where required. From the obtained results it became clear that one has to deviate slightly from this approach, to come to more realistic loadings at several flanges.

For this purpose, the flexibility of several bulkhead connections were modeled. These flexibilities were implemented in the beam models, which were based on the supplied isometric drawings. The program used for the stress analysis was CAESAR II version 4.5.
The resulting stress values were checked to the relevant stress limits according to the ISO 14692 code for GRP piping.
The last step towards modeling the adequacy of the steel flange was to make a detailed flange calculation. To do so it was chosen to use the AD-Merkblatter.

“Several supports were introduced to reduce loads and stresses in the system.”

Results

From the stress analysis, the following points could be concluded:

  • Several supports were introduced to reduce loads and stresses in the system. From the newly obtained layout, it was found that all pipe stresses are mild and within the code limits.
  • The flange loads of several flanges were too excessive. These results were based on rigid bulkhead pipe connections. To obtain more realistic values the flexibilities of these connections were determined using finite element analysis. The revised configuration showed that all stresses and loads were within the allowable limits.

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