Hot-rolled steel channel - is one of the types of shaped metal-roll, the section of which is similar to the letter "P". Made in such a way that the wall on both sides is connected to a pair of parallel shelves. Manufactured by hot rolled metal. The parameters and dimensions of the product are subject to the established quality standard GOST 8240-97. A number is placed in front of the marking letter indicating the size of the metal profile. Depending on this number (from 5 to 40), it is used as a support and for overlapping complex structural parts of buildings and structures.
Channel "U" is structurally made with a slope of the inner edges, the slope of opposite flanges is from 4% to 10%. The thickness of the shelf is wider at the base than at the end. The inclination of the shelves of the "U" profile allows the load on them to be transferred to the main body according to the principle of a gusset. This type of metal profile is specially designed to reinforce the shelves. Despite its reliability and strength, the peculiarity of this form limits its use.
The second option "P" has parallel shelves, the thickness at the base and at the end is the same. The inner corner of the "U" shaped rolled products does not withstand 90 degrees, while the "U" shaped shelves are made strictly at 90 degrees. The metal profile "P" is more economical and practical to use. It is often used when arranging mechanisms with moving elements. It is convenient and constructively more efficient. It is more often used for supporting structures with fasteners, in particular for structures with bolted connections - they sit better on straight shelves.
The cross-sectional area of these two types is the same, the weight is also identical. Accordingly, the price per running meter is also the same for them (you can see the prices here https://linemet.ru/shveller /). Reference data, which characterize the channel bars, are close in value. If there are no strict conditions, then when choosing the required marking of the channel, it is more expedient to use the "P" type. Type "U" is intended for special cases where a large load is expected on two parallel shelves. In all other situations, most often builders do not give much importance to this distinction. They are interchangeable, they can also be replaced with bent ones. The final choice is made by the design engineer based on the characteristics and location of use.