Filettatura

In the previous article introducing the very concept of threading it was highlighted that in the hydraulic sector two specific kinds of threads are used: GAS threads and NPT threads. GAS threading originated from the Whitworth thread – which was devised in 1833 and which is still used in the mechanical field – with a very subtle pitch. It is used for pipes’ coupling and fluids conveyance and it is therefore common in stainless steel fittings. The designation of GAS threading is conventional and it refers to the theoretical minor diameter of a pipe. Usually, the dimensions of threaded fittings are expressed in inches. Yet, conversion tables enable people to easily convert the width of a pipe’s diameter in millimetres. GAS threads are divided into Conical GAS and Cylindrical GAS threads. The joints between the screws and nuts of conical threads are hermetically closed. This may be done by means […]

The term “threading” refers to temporary connections that can be very easily disassembled. Threadings’ parts are usually held together by either sheer friction or physical obstacles. Threading is a kind of mechanical construction used to create a helical structure out of two elements, which is called “thread”. Threads are built either on the outer side of cylindrical and conical elements (screws) or on the inner side of components (nuts). Then, screws and nuts are screwed together. Threaded components can be used for two main purposes: In the mechanical industry (liaison function), for immobilizing and temporarily fixing two elements together. In the hydraulic industry (transmission function), for building more complex and elaborate structures for flows of fluids and gases. Threading makes use of many components whose dimensions may vary according to the reference standard. The main ones are: Helix: it is the curve generated by a point P travelling in circular […]