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DROSS AND ULTRAFINE PARTICULATE FORMATION IN UNDERWATER PLASMA-ARC CUTTING.

Objective

UNDERWATER PLASMA-ARC CUTTING IS A USEFUL TECHNIQUE FOR DISMANTLING BUT PRODUCES DROSS AND ULTRAFINE FUME PARTICLES WHICH MUST BE COLLECTED. THE OVERAAL PROJECT AIM IS TO IMPROVE UNDERSTANDING OF THE FACTORS GOVERNING FORMATION RATES AND CHARACTERISTICS OF DROSS AND ULTRAFINE FUME PARTICLES SO THAT THESE BY-PRODUCTS CAN BE BETTER CONTROLLED DURING DISMANTLING.

THE RESEARCH IS PREDOMINANTLY EXPERIMENTAL, WITH SUPPORTING THEORETICAL WORK ON FLUID DYNAMICS OF DROSS BEHAVIOUR AND ON FORMATION AND BEHAVIOUR OF THE ULTRAFINE FUME PARTICLES. METAL SAMPLES TO BE CUT ARE NON-ACTIVE, THE AIM BEING TO CHARACTERISE THE BASIC MECHANISMS WHICH SHOULD BE VALID FOR ACTIVE AND NON-ACTIVE METALS. CUTTING IS DONE IN A HYPERBARIC CHAMBER WITH SIMULATED WATER DEPTH UP TO 10 METRES. THE FORMER VESSEL ALLOWS THE INFLUENCE OF PRESSURE AND A WATER COLUMN. PART OF THE PROGRAMME INVOLVES THE DEVELOPMENT OF TECHNIQUES FOR COLLECTING AND CHARACTERISING DISPERSED DROSS AND ULTRAFINE PARTICULATES.

IN A SUPPLEMENTARY AGREEMENT CONCLUDED IN 1988, THE INITIAL WORK PROGRAMME WAS EXTENDED BY THE INCLUSION OF A SET OF 8 SUPPLEMENTARY STANDARD CUTTING TESTS WITH PLASMA ARC TORCH (UNDERWATER ON STAINLESS STEEL SAMPLES), UNDERTAKEN TOGETHER WITH THE COMMISSARIAT A L'ENERGIE ATOMIQUE AND UNIVERSITAET HANNOVER.
Production rates and detailed chemical and physical characteristics of solid emissions from underwater plasma arc cutting of nonactive 304 grade stainless steel have been studied. Steel thicknesses to 40 mm have been cut in water depths of up to 10 metres. A hyperbaric vessel and a deep water test column and associated experimental equipment and techniques were developed for these studies. Concentration and compositions of effluent byproduct gases were also investigated.
B.1. UPDATED LITERATURE REVIEW AND ANALYSIS OF DATA ON SECONDARY WASTE (DROSS, ULTRAFINE FUME PARTICLES) GENERATED DURING UNDERWATER PLASMA-ARC CUTTING OF STEEL.

B.2. DESIGN AND CONSTRUCTION OF A DROSS COLLECTION SYSTEM, APPROPRIATE FOR UNDERWATER CUTTING.

B.3. DESIGN AND CONSTRUCTION OF A COLLECTION DEVICE FOR ULTRAFINE FUME PARTICLES APPROPRIATE TO UNDERWATER CUTTING.

B.4. DEVELOPMENT OF TV AND/OR PHOTOGRAPHIC TECHNIQUES FOR UNDERWATER MONITORING OF THE BEHAVIOUR OF CUTTING WASTE.

B.5. TESTS ON CUTTING OF NON-ACTIVE STAINLESS STEEL SAMPLES IN HYPERBARIC FLOODED TEST CHAMBERS, WITH MONITORING OF DROSS AND ULTRAFINE FUME CHARACTERISTICS UNDER VARIOUS CUTTING PARAMETERS (CUTTING VERTICALLY UPWARDS).

B.6. IDEM B.5. WITH CUTTING VERTICALLY DOWNWARDS.

B.7. IDEM B.5. WITH CUTTING IN HORIZONTAL POSITION.

B.8. DESIGN AND CONSTRUCTION OF A TEST VESSEL PROVIDING A 10 M WATER DEPTH AND MONITORING/SAMPLING DEVICES FOR CUTTING WASTE.

B.9. CUTTING TESTS IN THE FACILITY DEVELOPED IN B.8. WITH CUTTING PARAMETERS SELECTED IN B.5. TO B.7.

B.10. ANALYSIS OF THE SURFACE LAYER MATERIAL BEHAVIOUR BY TRACE AND COMPOUND WORK-PIECE TECHNIQUES.

B.11. CONCLUSIVE ASSESSMENT OF OBTAINED RESULTS.

B.12. EXECUTION OF SUPPLEMENTARY UNDERWATER CUTTING TESTS WITH WORKING PARAMETERS COMMON TO OTHER CONTRACTORS, WITH SUBSEQUENT COMPARATIVE ANALYSIS OF RESULTS.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Heriot-Watt University
Address
Riccarton, Lord Balerno Building
EH14 4AS Edinburgh
United Kingdom