In manufacturing of industrial piping, for shipyards, cryogenic equipment, chemical installations, remote-heating and boilers, fluid transmission, air-conditioning tubes, food machinery, automotive components, etc., use of bent- and formed-tubes is growing very much in the latest few years, in comparison with the old piping production system, with welded bows, flanges and fittings.
Increasing needs of a.m. industrial sectors have to be found in a higher safety and guarantee of leak-proof joints, more productivity, best degree of freedom on pipeline lay-out, beside a reduction of related operations costs, such as grinding or polishing of welded joints, and therefore a research of the best possible finish and clean design.
New generation tube bending-, forming- and branching-machines easy allow to solve most production problems related to production and checking of welded joints (that require high specialized operators and / or sophisticated equipment and materials), as they may be comfortably programmed and set-up even for most complex tubular tracks.
In tube bending - thanks also to parallel development of tooling technology - we can get extremely limited straight parts (or even no-straight parts, the so called "compound bends"), without tube slipping problems, yet with careless clamping marks, while reducing as much as possible the straight parts at both ends of the pipeline - if not necessary - therefore optimizing te tube material.
If reduced delivery of fluids under pressure could represent a problem, through modern tube bending machines is possible to adjust the bending radii simply by replacing the tools. Therefore, we can get a radius / diameter ratio ranging from 1.5 to 5 on average, which could also be an advantage as designers don't have to follow any typical available standard radius of welding bows.
As regards forming of tube-ends, most recent technical levels reached by axial (push) end-formers, and rotary (planetary) machines allow to eliminate most of straight- or offline-reducers, as well as expansion (or female) joints. Through the same machines, making wide connection flanges, Venturi tubes, collars or beads, roll-thread ends (wherever the wall thickness allow), etc., is also possible, yet with a natural improvement of mechanical and metallurgical properties, such as:
· Material- and weight-savings, with the same resistance performances ;
· Possibility to use different tube materials, according to the most uitable for each application;
· Control of the dimensional tolerances, with related benefits for assembly and spare parts;
· More consistent molecular structure, with a natural and beneficial hardening of the material;
· No interruption in the metal fibres flow, less risks of contamination of welded joints;
· Very low roughness of surfaces, generally better than any machined- or cast-component;
· Flexible design, with possibility to produc e even complex tubular tracks.

In particular, for flanged tubes, there are CNC tube bending machines with automatic positioning units and specialized software capable to recognise and orientate the tubes according to the bolt holes in the flanges, keeping them under control on correct tube development, while making all bends without collision with the machine ("Flange Program").
Through modern engineering software applied to tube bending, it is possible to program some CNC tube bending machine directly with CAD-CAM technology, so that to optimize both the drawing and the plant management, while reducing costs of data storage on machine board, together with the reduction of material scraps, due to possible errors in programming.
Also, some manufacturers of CNC tube bending machines have recently developed a few interesting quality inspection- and geometry checking-systems for bent tubes. These controls are generally related to a virtual sample part (taken as "master piece"), and suitable to check either on a statistic base, or at 100% the dimensional production of a tube bending machine, in order to avoid any loss of time for a non-correct geometry (spring-back, etc.) when finally assembly the pipeline.

These quality inspection systems are also capable to correct automatically the bending parameters of the CNC bender, by keeping in consideration the critical factors that may vary on raw materials supply. Depending on the degree of development of the "Three-Dimensional Measuring Centre" or CMM (this is the technical name used for the quality inspection machine), it is sometimes possible to make a simulation of the pipeline starting from a model of tube in a reduced scale; then, we can bring all necessary changes to the file in order to reproduce the correct geometry.
A mention apart should be made for the collar branching technology of rigid piping, a peculiar system developed and patented by a manufacturer in Finland. This system - even if doesn't eliminate com pletely the welding job on tubes - it reduces significantly the number of welds to the only one of the branch tube (while the two usual welds of the classic "TEE" are being eliminated).
Factors that can affect the convenience of a rigid tubular construction - in comparison with a welded design - are not exactly predictable in these pages, as the economic convenience may depend on the equipment available at the tube shop, on production volumes, the amount of tubes and related accessories, the mix of dimensions and type of tubes to be processed, etc.
Generally talking, technical advantages of cold-formed rigid pipelines technology are important; among the main arguments, we have to remember: less tubes manipulated on machine site;"Reduced number of welding components (elbows, reducers, flanges, etc.) to be handled;
· Optimization of raw tube, with related reduction of waste tubes and scrap materials;
· Savings on machines, materials, manpower and tooling in the welding department;
· Reduction in the number of welding jigs and fixtures, and related positioning errors;
· Improvement of logistic factors in the workshop,
· Better freedom on piping layout, more rational design of access spaces, etc.;
· Elimination of most visual-, radio-, pressure-welding controls on tubes and joints;
· Less contamination, less welding smoke and less costs for related
ted equipment, maintenance, etc.;
· Great saving on times of preparation of pipes, related to number of welded joints avoided;
· Use of more economical raw tubes (no grinding, no polishing), if not strictly necessary.
Engineers, project managers, production- and cost analysis-specialists should take in consideration all the above mentioned factors and other practical elements - depending on each factory reality - while setting the manufacturing cycles in tube manipulation shops and industrial environments.