News

Finite element analysis

FEA has always been one of our core analysis tools, though it has become more important as our products are developed with advanced strain based design techniques.

Why do we do this? It is driven by the our markets, for example: mooring applications define manufacturing test loads above yield (see video below!), and HPHT (20,000psi) codes refer to ASME Div III design methods. Strain based design also confers reliability and efficiency advantages: localised regions of stress above yield can be assessed and checked against strain data from testing.

Our engineers operate ANSYS FEA software, routinely modelling subsea and riser equipment with 2D & 3D linear (elastic) analysis and non-linear (plastic) analysis. Some of the services we offer include:

  • Simplified axi-symmetric stress analysis for concept level designs
  • Detailed 3D stress analysis for complex components and structures
  • Analysis of parts and assemblies with complex contacts
  • Modal and frequency response analyses
  • Stress linearisation and assessment against API, ISO, DNV and NORSOK codes

Below you can see a video of a stud-link chain analysis that we completed with our sister company InterMoor. We developed a detailed wear model of the chain interfaces to predict wear rates with bending loads applied, following deformation of the chain to the proof loaded condition.

 

Making a riser

Here is a sequence of clips that detail the manufacturing process of a drilling riser, including flange forging, machining and welding.

Unfortunately we don’t have a video of the seam welded pipe manufacture, so please let us know if you have one and we’ll include the link.

 

Nimway technology readiness

In early 2014, SRP completed a successful proof of concept test of a full-size 15,000psi Nimway™ connector as the first step to the qualification for completion and workover riser applications.

Nimway™ is made-up using bolt tensioning technology, so the test was designed to prove the repeatability of make/break, as well as to validate the finite element analysis completed on the connector.

Strain was measured at key locations as over 1000t of tensile load was applied to the sleeve with hydraulic bolt tensioners and the connector was made up and then hydrotested to 22,500psi.

Repeatability of make/break was proven over 8 cycles, with average strain values varying by less than 2% and within just 2.4% of the values predicted in computer analysis. This predictability and accuracy of Nimway™ demonstrates the advantage of the directly tensioned make-up method over torqued connectors, which can suffer 25% preload variability due to friction and galling.

The connector successfully passed two 15 minute hydrostatic tests at 22,500psi, showing no signs of face separation or leakage from the metal seal.

The tests gave SRP and Acteon the confidence to invest in a full qualification programme of 5” and 7” 10,000psi Nimway™ connectors to service the well intervention market.