1 / 19

NEW DEVELOPMENTS IN FABRICATED TEES – A QUALITY ASSURANCE DESIGN GUIDELINE

NEW DEVELOPMENTS IN FABRICATED TEES – A QUALITY ASSURANCE DESIGN GUIDELINE. A.C. Seibi and R. J. Lawrence, GPPA. Outline. Background Approach Quality Control Lab. Tests Finite Element Modeling Results & Discussion Conclusions & Recommendations. Background. Background.

zuri
Download Presentation

NEW DEVELOPMENTS IN FABRICATED TEES – A QUALITY ASSURANCE DESIGN GUIDELINE

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. NEW DEVELOPMENTS IN FABRICATED TEES – A QUALITY ASSURANCE DESIGN GUIDELINE A.C. Seibi and R. J. Lawrence, GPPA

  2. Outline Background Approach Quality Control Lab. Tests Finite Element Modeling Results & Discussion Conclusions & Recommendations

  3. Background

  4. Background

  5. Background Design????

  6. Background Do we have to strictly follow ISO 4427 ????

  7. Approach Search for field reports of failures. Examine welding fabrication process. Perform finite element analysis. Carry out laboratory burst tests on elbows and tees. Compare results of 3. and 4.

  8. Preliminary Findings Very few field failures of pipe fittings. Overlapping beads at tee joints may present weakness in fittings. 3. Soaking time for large diameter pipes should be revisited. 4. Bead not welded properly

  9. QC: Lab Results 1st Joint Parrot beak 2nd Joint Pipe yielding

  10. Long Term Test (Tees). 12.4 MPa for 100 hrs at 20 oC5.4 MPa for 165 hrs at 80 oC

  11. QC: Finite Element Modelling Tee Elbow

  12. Press. vs. displ FEM Results Stress contours

  13. Results Difference ≈ 0.1 – 10%

  14. Max. s & e not at the same place. Why? Displacement contours Stress concentration Deformed shape Failure occurs at intersection due to viscoelastic material behavior

  15. FEM Results Longitudinal strain Transverse strain

  16. Practical Solution - UPI UPI developed a 2000 mm reducer tee. No worry about pipe derating.

  17. FEM Results It was recommended to create fillets at the inner and outer sections of the junction.

  18. Conclusions A derating factor of 0.8 for modern PE100 like HE 3490 LS pipe tees can be safely accepted. Most failures in tees take place in either 1st or 2nd weld. Need further investigation. FE results showed a good agreement with burst pressures of pipe bends. FE results showed that the max. stress is concentrated at the tee junctionand that potential failure is anticipated to take place at the intersection of the welds.

  19. Recommendations Need to understand reasons behind tee failure along the welds. Must develop a strain based failure criterion for plastic pipes and fittings. Damage mechanics should be considered in FEM to better understand failure modes in fabricated pipe fittings. Should take a look at the soak time in welding of large size fittings.

More Related