The development of a novel welding method for welding vertical seams with a high deposition rate.
An improved automated robotic welding cell, capable of welding long seams rapidly and with high quality.
A finite element model of the new welding method predicting thermal profiles and thermally induced stresses.
Project's actual outcome:
A novel welding method for producing vertical weldments
An automated cell for producing the above welds
An FE modelling method that can be applied to all welding types.
At present, the large storage tanks used within by the process are petrochemical industries are welded using the manual metal arc (MMA) technique. However, this method requires the use of a highly staggered weld pattern with at least 3 passes of the arc needed to ensure the joining of the preformed metal plates. This process is slow, non-analytical and subject to the limits of operator skill and is therefore susceptible to a number of weld quality problems:- - lack of penetration through the joint - porosity - poor weld strength and high stress concentrations - poor uniformity of stress distribution around the weld - distortion of the metal plates being joined - slag inclusions The welds are often unreliable and prone to mechanical failure, particularly with heavy loads (hydrostatic pressure, wind loading), cool ambient temperatures and creep induced by hot fluids. There have been a considerable number of reported cases of sudden, catastrophic weld failures within storage tanks. Very often these tanks will be carrying hydrocarbons, petroleum, acids and alkalis and thus the failure has often had dire and tragic consequences for both the industrial personnel and surrounding equipment. Therefore, it is proposed that a new storage tank welding technique be investigated and developed which will incorporate:- - more advantageous welding techniques - a significantly smoother, less staggered weld path - automated robotic welding The initial research will concentrate on a combination of a submerged metal arc welding technique (SMA) and its vertical derivative electro-slag welding. Automation of the welding cell will be achieved through a combination of robotic and visualisation systems, thus removing the operator from the hazardous environment while enabling precise and accurate control of the welding arc.
Funding SchemeCRS - Cooperative research contracts
SO41 8GN Lymington
17671 Kallithea - Athens
9980 AA Uithuizen
5061 Kokstad - Bergen