TECHNOLOGY FOR EXPLOSION STRESS RELIEVING IN WELDED JOINTS

TECHNOLOGY FOR EXPLOSION STRESS RELIEVING IN WELDED JOINTS OF METAL STRUCTURES NATIONAL ACADEMY OF SCIENCES OF UKRAINE The E. O. Paton Electric Welding Institute (PWI) 1

EXPLOSION STRESS RELIEVING IN WELDED JOINTS 1. TITLE TECHNOLOGY FOR EXPLOSION STRESS RELIEVING IN WELDED JOINTS OF METAL STRUCTURES 2. Contact Person Dr. Leonid D. Dobrushin The E. O. Paton Electric Welding Institute (PWI) of NAS of Ukraine Department on Welding, Cutting and Treatment of Metals by Explosion 11 Bozhenko Str. , Kiev, 03680, Ukraine Tel. /fax: +380 -44 -289 -14 -70 E-mail: dobrushin@voliacable. com 2

EXPLOSION STRESS RELIEVING IN WELDED JOINTS 3. Technology Description (Part 1) Residual stresses inevitably occurring during fusion welding are hazardous for welded metal structures. They sharply decrease the reliability and life-time of welded joints. The existing traditional methods of stress relieving (thermal, vibration, rolling by rolls, etc. ) are either ineffective or unacceptable. The explosion treatment technology proposed is based on application of intensive relaxation processes and deformation on metal in shock waves generated by contact explosion. It permits relieving or inducing residual stresses, strengthening metal and changing its substructure. 3

EXPLOSION STRESS RELIEVING IN WELDED JOINTS 3. Technology Description (Part 2) 4

EXPLOSION STRESS RELIEVING IN WELDED JOINTS 4. Process (Part 1) Typical Diagram of Residual Stresses in Welded Joints and Explosion Treatment Basic Schemes for Sheet Welded Joints: 1 – Explosive Charge; 2 – Base Metal 5

EXPLOSION STRESS RELIEVING IN WELDED JOINTS 4. Process (Part 2) Explosion Treatment Basic Schemes for Axisymmetric Metal Structures of Large (left) and Small Sizes (right): O – Circular Weld; q - Explosion Loading 6

EXPLOSION STRESS RELIEVING IN WELDED JOINTS 5. Equipment & Products (Part 1) On the Left: Assembling of Detonating Cord for Explosion Treatment of Welded Joints in the Decomposer On Top: Device for Magnetoelastic Strain-gauge Residual Stresses Control 7

EXPLOSION STRESS RELIEVING IN WELDED JOINTS 5. Equipment & Products (Part 2) Instant Picture of the Explosion Stress Relieving of Welded Joints in the Decomposer (left) and View of the Imprints from Detonating Cord (right) 8

EXPLOSION STRESS RELIEVING IN WELDED JOINTS 9

EXPLOSION STRESS RELIEVING IN WELDED JOINTS 6. Advantage of Technology The explosion treatment technology requires no special equipment and power supplies, provides considerable stress relieving in welded joints of metal structures and as a result improvement of: - Resistance of corrosion cracking; - Static and fatigue strength; - Resistance of brittle structure; - Other physical and mechanical properties of welded joints in metal structures. 10

EXPLOSION STRESS RELIEVING IN WELDED JOINTS 7. Industrial Application Fields (Part 1) 1. Vessels and reservoirs, operable in contact with hostile environment; 2. Pipelines of critical application; 3. Large dimension structures, produced with high requirements against accuracy of their geometry. 11

EXPLOSION STRESS RELIEVING IN WELDED JOINTS 7. Industrial Application Fields (Part 2) EXPERIENCE OF WORKS ON EXPLOSION STRESS RELIEVING CARRIED OUT IN RECENT TIMES AND CONDUCTING FOR THE PRESENT: • 1971 -1972 – Ural Aluminium Plant (Ural, Russia) – 24 decomposers of 1100 m 3 capacity; • 1973 – Dneprovski Aluminium Plant (Zaporozhye, Ukraine) – 12 decomposers of 1100 m 3; • 1976 – Pavlodarski Aluminium Plant (Pavlodar, Kazakhstan) – 26 decomposers of 1500 m 3; • 1976 – Birach Alumina Plant (Zvornik, Yugoslavia) – 24 decomposers of 2500 m 3; • 1982 – Nikolaevski Alumina Plant (Nikolaev, Ukraine) – 48 decomposers of 3000 m 3; • 2006 – Pavlodarski Aluminium Plant (Pavlodar, Kazakhstan) – 10 decomposers of 2500 m 3; • 2007 – Nikolaevski Alumina Plant (Nikolaev, Ukraine) – 15 decomposers of 5000 m 3. Totally 400, 000 running meters of welded joints in 300 tanks of large dimensions were explosively treated and at least USD 40, 000 economical efficiency was provided 12

EXPLOSION STRESS RELIEVING IN WELDED JOINTS 8. Economic & Technology (Industrial) Benefits 1. Compare to the existing heat treatment technology the explosion treatment one is at least 10 -20 -times cheaper; 2. Industrial benefits is at least USD 100, 000 depend on volume of works; 3. Maintenance cost reduction, production quality increase. 9. Estimated Cost & Period of Research For R&D of technology for explosion stress relieving in welded joints of metal structures of the Customer’s interest the cost and period required are the matter of negotiations based on Technical Assignment of the Customer. THANKS FOR YOUR ATTENTION! 13