Projects

Pipeline Defect Fitness For Service Analysis

 
 

Industry

Offshore O&G

Services

Fitness for service, Finite element analysis, Piping, MARC, Calculation

Location

UK - Scotland

 
 

A high-pressure pipeline was subject to external corrosion adjacent to a flanged connection. DOCAN were contracted to perform a Fitness For Service Assessment to determine if the defect was safe for continued operation.

The challenge

Due to the proximity of the defect to the flange and the discontinuity effects that this presented, investigation was required prior to undertaking the FFSA to determine how the structural discontinuity affected the stress field around the defect area.

FlangeFFS1
 
 
 
 
 

The DOCAN solution

By comparing models of the flanged connection (which included bolt pre-load effects) and a straight length of pipe, it was justified that the flange did not affect stresses in the corroded section of the pipe. The use of CAESAR II pipe stress analysis was also employed to determine the external loading expected on the pipeline, and this was considered in the calculations produced.

 
 

The outcome

The formal and verified DOCAN calculations and numerical analyses provided a basis to produce reporting to the client that showed that per the requirements of the relevant codes, their equipment remained fit for service, and they could continue operations.

FlangeFFS3
 
 

Project summary

TaskApplicationDOCAN Fitness For Service expertisePipe support & pipingFinite Element analysisMathCADMSC MARCCAESAR II
Proficiency in use of engineering standardsDNV-RP-F101
BS7910-2013
ASME B31G
PD 8010
ASME VIII Div 2
Flange representationBolt Preload
ASME B16.47
Finite Element analysisAxisymmetric modelling
Bolt representation
Stress linearization