The manufacture of low density polyethylene (LDPE) by radical polymerization regularly subjects components to extreme pressures exceeding 20 ksi and, possibly, to runaway decomposition reactions with temperatures exceeding 1500 °F and pressures above 30 ksi. Components subject to such extreme conditions are often autofrettaged to induce a beneficial residual stress distribution that retards crack growth and extends fatigue life. Three samples of autofrettaged tubes extracted from these components are examined here. Only one of these samples is known to have been exposed to multiple decompositions while in service. Measurements of the remaining residual stress were taken for each of these tube samples, and a number of other metallurgical tests were performed. The results show that the tube experiencing decompositions lost almost all of the beneficial residual stress induced by autofrettage and actually has a large, detrimental tensile stress at the inner surface. Corresponding to this is a band of embrittled material with a significantly altered microstructure that was most likely caused by thermal excursions. The tubes that experienced no decompositions showed no such alterations, and their residual stress distributions were relatively intact. An FFS assessment of crack-like flaws was performed on these tubes in accordance with API 579-1/ASME FFS-1 in order to determine the effect of this loss of residual stress on remaining life and quantify this loss in terms of a damage parameter.
Skip Nav Destination
ASME 2015 Pressure Vessels and Piping Conference
July 19–23, 2015
Boston, Massachusetts, USA
Conference Sponsors:
- Pressure Vessels and Piping Division
ISBN:
978-0-7918-5698-7
PROCEEDINGS PAPER
A Damage Assessment of Autofrettaged Tubes Exposed to Decompositions in an LDPE Facility
Jeffrey D. Cochran,
Jeffrey D. Cochran
The Equity Engineering Group, Shaker Heights, OH
Search for other works by this author on:
Trace P. Silfies,
Trace P. Silfies
The Equity Engineering Group, Shaker Heights, OH
Search for other works by this author on:
Jonathan D. Dobis
Jonathan D. Dobis
The Equity Engineering Group, Shaker Heights, OH
Search for other works by this author on:
Jeffrey D. Cochran
The Equity Engineering Group, Shaker Heights, OH
Trace P. Silfies
The Equity Engineering Group, Shaker Heights, OH
Jonathan D. Dobis
The Equity Engineering Group, Shaker Heights, OH
Paper No:
PVP2015-45621, V005T05A013; 8 pages
Published Online:
November 19, 2015
Citation
Cochran, JD, Silfies, TP, & Dobis, JD. "A Damage Assessment of Autofrettaged Tubes Exposed to Decompositions in an LDPE Facility." Proceedings of the ASME 2015 Pressure Vessels and Piping Conference. Volume 5: High-Pressure Technology; Rudy Scavuzzo Student Paper Competition and 23rd Annual Student Paper Competition; ASME NDE Division. Boston, Massachusetts, USA. July 19–23, 2015. V005T05A013. ASME. https://doi.org/10.1115/PVP2015-45621
Download citation file:
14
Views
Related Proceedings Papers
Related Articles
Three-Dimensional Analysis of a Semi-Elliptical Crack Emanating From an Erosion at the Bore of an Autofrettaged Pressurized Cylinder
J. Pressure Vessel Technol (May,1999)
Cracks Emanating From an Erosion in a Pressurized Autofrettaged Thick-Walled Cylinder—Part II: Erosion Depth and Ellipticity Effects
J. Pressure Vessel Technol (November,1998)
Optimum Autofrettage and Shrink-Fit Combination in Multi-Layer Cylinders
J. Pressure Vessel Technol (May,2006)
Related Chapters
Defect Assessment
Pipeline Integrity Assurance: A Practical Approach
A 3D Cohesive Modelling Approach for Hydrogen Embrittlement in Welded Joints of X70 Pipeline Steel
International Hydrogen Conference (IHC 2012): Hydrogen-Materials Interactions
Use of Large Standoff Magnetometry for Geohazard Pipeline Integrity Investigations
Pipeline Integrity Management Under Geohazard Conditions (PIMG)