Structural, Stress and Fusible loop calculations for Deluge Skids

The Stress analysis study is carried out to ensure structural integrity and maintain system operability. The static and dynamic loads such as deadweight, internal and external pressure, thermal loads, seismic loads, wind loads, etc. will be considered while performing the calculations to assess the Piping network stress behavior.

The primary objective of Stress Analysis is as follows:

  • To ensure thermal expansion of the pipe.
  • To ensure that the stresses in the piping components are within the allowable limits with respect to applicable codes and standards.
  • To keep the piping connected equipment nozzle loads within specified allowable limits with respect to relevant standards and Vendor allowable loads.
  • To provide the correct type of pipe support based on piping stress and piping loads
  • To determine pipe displacements at different operating temperatures
  • To estimate and provide piping loads to design Structural or Civil support

Structural Analysis is carried out to evaluate Stress, deformation, vibration level, supporting loads, etc. Skid design and structural analysis includes static analysis and dynamic analysis. Static analysis calculates the stress and deformation of skid in place, lifting and transportation operation, while dynamic analysis calculates the vibration level, dynamic stress, and deformation of any rotating equipment. The Structural assembly supporting loads are calculated by static and dynamic studies. In the analysis, weights of equipment, Piping and other components which are subjected on the structural members, unbalanced forces, moments, wind, and seismic loads, etc. are considered as loads.

The primary objective of Structural Analysis is to attain a correct distribution of internal forces, moments, stresses, strains, and displacements over the whole or part of the structural assembly.

Tyco Qatar Fire and Security entrusted iFluids Engineering to carry out Structural Analysis for 3 Deluge Skids and Piping Stress Analysis for 9 Deluge Skids as part of Detailed Engineering work of Deluge skid installations for the BUHASA FIREWATER NETWORK REPLACEMENT PROJECT with ADNOC.

The Buhasa plant was first commissioned in 1979. After 25 years of service, the firewater underground carbon steel piping network was replaced with GRE (Glass Reinforced Epoxy). Since the installation of the GRE firewater system, many problems were encountered including leaks. ADNOC carried out extensive studies over the last couple of years to reduce the high failure rate of the system. In 2011, a Feasibility Study was conducted by Shell where it was recommended to replace the existing network with a new carbon steel network along with optimized hydrant’s locations, monitors, and deluge spray systems.

The purpose of this analysis is to satisfy the structural adequacy test in accordance with ASME B 31.3 for A106-Grade B and API-5L B pipes.

Activities involved in Stress Analysis:

  • Reviewing of P&ID, GA drawing, Isometric drawing, and Piping Material Specification
  • Model the Piping network in the software as per drawing specification
  • Define all the design parameters, Fluid, and material characteristics in the software
  • Define the Wind and Seismic (Uniform) loads as per client specification
  • Define existing support type and conditions as indicated in the drawings
  • Perform the analysis for different Load combinations as specified in Client design basis.
  • The combinational load (i.e., Hydrotest, Occasional, Sustain, Operating & Expansion) values evaluated with allowable load values as per Design code practice.
  • Provision of new supports & Existing support modification has provided to ensure that the stresses in the piping components are within the allowable limits.
  • Piping Support Loads Summary (Axial, Vertical, Shear & Friction) has extracted and provided as a input to Structural design team.
  • Input Echo, Stress summary & Restraint Summary and Stress Isometrics with support recommendations are incorporated in the Piping stress analysis report.

Activities involved in Structural Analysis:

  • Reviewing Structural GA drawing and Structural Material Specification
  • Modelling the Structural design in Software module based on the Clients input
  • Provide the Piping and other component loads on the Structural members.
  • Static and Dynamic analysis has done by STAAD Pro Software
  • Perform the analysis for different Load combinations as specified in Client design basis.
  • The deflections have checked with Maximum allowable deflection as per Standard practice for each node.
  • In place and Transportation analysis (Road and Sea Transportation) has performed based on the client specification.
  • Pad eye and Anchor bolt design has performed to the Skid.
  • The recommendations and Suggestions have mentioned in the Structural analysis report.
  • Additional stiffeners, Structural member modifications are annotated and provided to client for design change.