Technological capabilities
Each workshop is fully equipped with a comprehensive list of modern equipment for welding, cladding, machining, rolling and forming. This makes ATB Group one of the best-equipped companies in the international market.
The importance of ATB Group's welding activities is reflected in the following figures:
- Welding operators represent 80% of the workforce qualified with multiple skills for welding processes.
- About 50% of the fabrication time is dedicated to welding operations.
- About 95% of the welding activities are performed by automatic processes.
ATB Group’s experience includes:
- Base materials (plates or forgings): Carbon steels, low alloy steels, Cr-Mo low alloy steels including enhanced grades, Cr-Mo-V low alloy steels, high strength quenched and tempered steels;
- Weld overlay: Low carbon stainless steels (308L, 316L, 317L), stabilized stainless steel (347), nickel alloys (600, 625, 690, Monel), urea grades (25Cr-22Ni-2Mo, Safurex).
Our workshops are organized with segregated areas dedicated to store materials and preparing them for the production process. Entrances and exits are carefully controlled. Materials are preheated to keep away hydrogen content. Welding Process Qualification coupons are welded in the presence of Welding Engineers and Inspection Agencies, if required.
ATB Group strives to lead technological developments to allow for rapid and flexible fabrication of new products to satisfy the clients’ demands. To achieve this, the following strategies are continuously pursued:
- Make current processes more reliable and more robust
- Allow for greater use of process automation
- Develop welding technology to suit the development of new materials
- Implement methods of incorporating the welding requirements and welding knowledge into the overall manufacturing planning and management information systems
In both Roncadelle and Porto Marghera workshops, modern equipment has been used to manufacture the widest range of large and heavy welded constructions. This necessary development has been managed internally in partnership with several international technology leaders. Find the main automatic equipment listed below.
Welding:
- Automatic welding centers capable of narrow gap welding (SAW: single wire and tandem techniques) for longitudinal, circumferential and nozzles to shell/heads welds;
- Stainless steel strip automatic weld overlay centers (ESW/SAW and 90mm/60mm/30mm);
- Stainless steel wire automatic nozzles weld overlay centers (GTAW – GMAW);
- Inert gas welding machines (GTAW);
- Semi-automatic machines for shielded metal arc welding (FCAW);
- Manual welding machines (SMAW) can be used, but they are limited to minor activities such as temporarily-attached welds or minor fabrication tasks.
Eight (8) furnaces are used for various fabrication stages: head forming, pre-bending, high temperature rolling, and fabrication heat treatments.
- The loading capacity of the Roncadelle Large Furnace is 200 tons. An electronic apparatus allows advanced setting of treating cycles with heating and cooling speed rates continuously under control. This furnace has very low inertia. It has a forced feed cooling system to obtain very high cooling rates. The maximum temperature difference inside the furnace is monitored;
- The Porto Marghera Large Furnace is used for heat treating very long reactors in one piece. This furnace has a fixed floor which can withstand up to 1,500 tons of weight, and is equipped with six (6) natural gas high turbulence burners which operate independently to best control the furnace's temperature.
Handling:
- Each workshop is equipped with a wide range of manufacturing devices to assemble vessels weighing from 50 up to 1500 tons. There are also more than 30 turning rollers with capacities from 200 up to 1500 tons;
- Due to the complexity and weight of the sections/equipment to be handled during the fabrication, ATB Group has made large investments to carry out special transport activities almost independently;
- Self-propelled trailers for internal workshop handling with these capacities: 200 tons, 600 tons and 800 tons;
- Inland transport from ATB’s Roncadelle workshop to ATB’S Marghera workshop or loading port: Three (3) trailers with a capacity of 70 tons, 120 tons, and 200 tons.
ATB Group is able to manage deliveries of equipment that can reach a total weight of 1,200 tons.
ATB Group’s quality control group ensures the international standards of services are implemented:
- Level III NDT (Non-destructive testing) according to Pressure Equipment Directive 97/23/EC and EN473:2008
- Welding Engineers, Technologists and Inspectors in accordance with IIW qualification and certification system
ATB Group has its own laboratory, fully equipped with all devices necessary for most of the Destructive and Chemical Tests required to evaluate qualification of the manufacturing processes.
The Laboratory is equipped with the most updated testing facilities to evaluate the properties of materials. The typical tests are mechanical tests at room and service temperatures, corrosion test, and chemical wet analysis and atomic absorption spectrometry.
The main mechanical tests can be provided: tensile test, impact test, Pellini test, and hardness test can be conducted under the most severe testing conditions (room temperature, cryogenic conditions, hot tensile test, etc.). The laboratory is also fully independent in terms of machining and preparation of specimens under the most severe heat treatment cycle. All test machines are calibrated and certified by a SIT certified body (Italian referenced calibration authorized body) and ASME, where needed.
The chemical testing hall is equipped with automatic specimen preparation machines, corrosion testing, and chemical etching for wet analysis. Microscope analysis with up to 300,000 magnifications by SEM including atomic absorption wet chemical analysis is also available.
The laboratory is also equipped with a spectrometer and a quantimeter for element composition analysis:
- Evaluation of the metallurgical structure by means of Scanning Electron Microscope (SEM). The SEM analysis can be used to determine the chemistry of trace elements.
- Evaluation of mechanical properties after material aging.
- Radiographic testing for extra heavy thicknesses with linear accelerator
Furthermore, the fabrication activities are supported and guaranteed by the most updated Non-Destructive Testing (NDT) techniques including radiographic testing with linear accelerators and recordable ultrasonic testing with TOFD and Phased Array technology.
The company is equipped with two linear accelerators with 6 and 9 MeV shooting powers suitable to X-rays up to 400 mm thick.
Our skilled technicians can carry out any type of Ultrasonic Testing (UT) procedure including special high sensitivity conventional UT procedures, in-house recordable UT devices with TOFD and Phased Array techniques have been implemented in the last few years.
ATB Group has the capability to manufacture high thickness reactors from both rolled plates and forged ring technology.
We operate one of the most powerful rolling machines capable of rolling, in metallurgical cold conditions, plates up to 300 mm thick with a maximum plate width of 4,000 mm. All facilities to perform the rolling of high thickness plates are located close to the rolling machine in order to facilitate operations such as handling. The machines' layout has been arranged in such a way that pre-bending, oxy-cutting, beveling, preparation for rolling, preheating and rolling can be performed in a short time and in a controlled manner.
The above feature provides various engineering companies and end users with higher manufacturing flexibility, which is a great advantage over the traditional manufacturing practice.
In close association with the fabrication of pressure vessels, ATB Group has also developed a Head Forming Department which acts as an independent sales unit in the international market. The main press capacity is 3,000 tons.
The forming facility is one of the most adequately-equipped in Europe in terms of power capacity. This allows forming both hemispherical and elliptical heads in a single piece or in petals, depending on the diameter.
All these activities are relevant to hot forming including the relevant quality heat treatment:
- Elliptical heads can be formed in one piece with internal diameters in ranging from 200 mm to 3,900 mm, and thicknesses of up to 140 mm depending on the head diameter, and weighing 20 tons. The cylindrical portion close to the head can be up to 200 mm, depending also on the head diameter.
- Hemispherical Heads: heads over 3,900 mm of internal diameter can be manufactured in sectors and cap without any restricitions as regars diameter and thickness. Single piece hemispherical heads can be manufactured with internal diameters ranging from 400 mm up to 2,600 mm and thicknesses of up to 190 mm, depending on the head diameter. The cylindrical portion close to the head can be up to 400 mm, depending also on the head diameter.
- Hemispherical heads in sectors and cap can be manufactured with internal diameters ranging from 275 mm up to 15,000 mm and thicknesses of up to 230 mm, depending on the head diameter.
- Flat and Semi Flat Heads: internal diameters range from 400 mm up to 4000 mm, with variations of 50 to 50. Thickness ranges is from 10 mm to 170 mm, depending on the head diameter. The cylindrical portion close to the head can be from 50 mm to 150 mm, depending also on the head diameter.
In connection with the fabrication of pressure vessels and hydromechanical components, ATB Group has also developed a Machining Department, well equipped for working on large and heavy components.
All the machines are either brand-new or newly revamped.The machines are equipped with highly automated CNC machining and all the turning centers are CAD/ CAM operated.
Thanks to its decades-long experience, highly skilled personnel and high-end facilities, ATB Group is now prepared for any challenging machining task.
The machining workshop is located in Roncadelle with the following features: 25 m wide, 132 m long, 12 m high under hook, with up to 215 tons of lifting capacity.
The workshop is equipped with the following main tool machines:
- Vertical turning lathe INNSE TMM 3600: Max diameter 11,000 mm; Max height 5,500 mm; Weight capacity 200 tons;
- Vertical turning lathe KOLOMNA 1563: Max diameter 6,300 mm; Max height 4,250 mm; Weight capacity 125 tons
- Boring Milling Machine PAMA SPEEDRAM 2000 and PAMA SPEEDRAM 3000: Max diameter 2,200 mm; Horizontal stroke 13,000 mm; Vertical stroke 5,000 mm; Turning table weight capacity 100 tons; 5 axes
- Boring Milling Machine PAMA FT160A: Max diameter 5,500 mm; Horizontal stroke 8,000 mm; Vertical stroke 3,200 mm; Turning table weight capacity 80 tons; 5 axes
- Boring Milling Machine TOS WHN / WHQ 13 CNC: Horizontal stroke 3,500 mm; Vertical stroke 2,500 mm; Weight capacity 20 tons; 5 axes
- Boring Milling machine CASER FFM-100: Horizontal stroke 2,000 mm; Vertical stroke 2,500 mm; Weight capacity: 50 tons; 4 axes
Due to our close relationship with engineering companies, process licensors, and main material suppliers, ATB Group has actively participated in research programs dedicated to welding technologies and continuous upgrading of welding procedures in line with the latest material requirements.
Main references:
- Development of Cr-Mo-V modified steel alloy to manufacture pressure vessels;
- Weld overlay engineering to deal with the most severe conditions in terms of design temperature, design pressure and hydrogen partial pressure;
- Single layer weld overlay engineering to meet the most severe environmental conditions in terms of corrosion resistance;
- Welding of stainless steel and duplex urea grade corrosion resistant materials;
- Welding of high wall thickness 9% nickel alloys;
- Welding of high tensile strength materials for penstock fabrication;
- Development of API 934 A addendum 1 for the detection of RHC during fabrication of V modified reactors;
- Automatic welding for J-Groove welding of CRDM nozzles to the Reactor Vessel Closure Head.