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To develop a more rapid & quality controlled process for welding of large storage tanks

Objective



At present large storage tanks, used within many process are petrochemical plants, are welded using preformed metal plates which are set in a pattern resembling a brick wall. The joints between the plates are then welded using a manual metal arc (MMA). This requires at least 3 passes of the weld and is subject to a number of weld deficiencies including: ln this respect, the welds are unreliable and prone to mechanical failure; particularly under heavy load (e.g. hydrostatic pressure, wind loading etc.), cool ambient temperatures and creep induced by hot fluids. There have been a considerable number of reported cases of catastrophic weld failures within storage tanks. Very often these tanks will be carrying hydrocarbons, petroleum, acids and alkalis. In this respect, failure has had often very dire and, indeed, tragic consequences. It is the proposal of this cooperative project that a new production technique be researched and developed in which the plates be welded together at their joints using a combination of a submerged metal arc welding technique (SMA) and its vertical derivative electro-slag welding. In this respect, this technique will require the development of the following technological aspects: 1. A totally integrated and fully automated welding process and the necessary drive mechanisms and control technologies to produce a complete storage tank structure. 2. An in-depth analysis of the metallurgical changes of the weld and affected zone adjacent to the weld. 3. A detailed finite element stress anaiysis to maximise stress uniformity around the weld. 4. Using 2 and 3, innovative heat input and cooling methodologies to minimise metallurgical and stress distribution changes of the weld and the affected zone adjacent to the weld (i.e. optimised weld quality). 5. A new configuration of plates for the preformed structure to minimise weld staggers. 6. A ,new consumable wire in relation to methodologies developed through 4.

Coordinator

CHB Fabrications Ltd.
Address

SO45 3NQ Hardley, Hythe - Southampton
United Kingdom