Welding is the most common method of attachment flanges to the pipes. Therefore professional manufacturers producing stainless steel flanges (as well as the related equipment: tube plates, fitting tools, butt weld fittings, etc.), e.g. AlexanderComley, provide consultations and training to guarantee proper flanges installation.
Connection of flat flanges requires using special fasteners, which include nuts, bolts, studs and shims. Bolt is a fastener for connecting various structures and machine parts; it is a threaded rod with four or hexagonal head at one end. Nut is a component with a threaded hole, designed for connection of the unit. Shim is placed under the bolt head or nut. Using shims is necessary to enlarge the area of support (in case of insufficient rigidity of the anvil) to align the surface of the support and compensate for the increased diameter of the screw holes. If there is a bias of nuts and screws, it is customary to use the oblique and spherical shims. However, there is a dozen of shims for a variety of technical situations (sealings, springs, locks, etc.).
Hairpin is a metallic rod having threads at both ends. One end is screwed into the first piece and the other piece is pressed against the first one when the nut is screwed.
Securing is covered in a good number of regulatory documents and subjected to a range of requirements. So for flanged joints used fasteners adapted to the special requirements. All the requirements are specific to the use of its products and focus on particular conditions, such as pressure and environmental peculiarities.
How are flat flanges attached to pipes?
As for flat flanges, the decent connection with pipes demands that the diameter of the inner hole of the flange to be either equal or slightly greater than the diameter of the pipe. Hardware itself is made by putting a flange on the edge of the tube and welded on both sides. It is important not to allow operation of the projection beyond the plane of the pipe flange. According to the standards height of the seam must not exceed 10 mm, though it cannot be less than 5 mm (depending on the pipe diameter); under these conditions, flat flanges are connected in an optimal way.
As practice shows, many builders ignore the implementation of the internal weld (gross violation). This happens due to the fact that during such works damage to the surface of the flange can be delivered; and if there is some pressure in the pipes – external seam does its job well. The flange itself is welded to form a bevel (though it is not obligatory).
Neck flanges are connected to the pipe by means of a welded splice. Importantly, the diameter of the neck flange should coincide with the diameter of the pipe. When welding for smooth and lasting connections welding opposed to each other sides thoroughly is necessary. Low-quality connection may give birth to such defects as hard spots, cracks, etc.
Loose flanges (on the welded ring) have two working parts – the flange and the ring. The ring is attached to the pipe, while the flange remains in the disengaged position. This design is particularly suitable for installation in tight spaces.