Introduction

The invention of the new "metal to metal" coupling devices relates to demountable connections of any pipelines and can be employed in various industrial and consumer engineering applications. The devices can also be applied in stop valves of whatever design. For the said applications, particular significance of the proposed mode and a variety of implementing devices is determined by nearly unique combination of such features as : dependable functioning under considerable alternating loads no need of fixing flanges to pipelines with leak-proof quality thus short-cutting crucial welding or soldering operations simultaneous meeting of stringent requirements of working under extreme conditions of high pressure, deep vacuum, major temperature drops and in corrosive media Principle: The proposed technique of the "metal to metal" coupling devices is based upon a special configuration of the sealing element that allows to make good use of elasticity of the material, of which this element is made, so that complete sealing can be reached whereas possibility of plastic deformations is essentially diminished, thus ensuring multiple, repeated use of the devices. The sealing element is made of alloy steel (as a rule, a corrosion-resistant steel). It is installed in the pipeline between the pipe ends and sealing takes place along the inner edges of the pipe inlets. In the same pattern the sealing element can be employed to fit valves with no adjustment of their components needed. Based on the proposed mode a variety of sealing devices have been developed to be used in various pipeline connections and in valves. Pipeline connection application Despite the simplicity of the basic design version in some connection embodiments it can be even further simplified with no detriment to its technical advantages. Sealing devices for stop valves On the basis of the proposed technology sealing devices for stop valves have been developed making it possible to easily substitute existing rubber seals, improving leak-proof capability and increasing multifold a number of open/close cycles without change. Manufacturing: Despite a specific configuration of the proposed sealing element its manufacturing does not present any problem and can be ensured by using well established metal-processing technologies. In contrast to other metal-o-metal connections that are characteristic of stringent requirements with regard to precision machining of their parts, the proposed seal design allows to maintain dimensional tolerances with + 0,03 mm limits. Remaining parts of pipeline joints or valve units are of general standard. Because it is relatively simple to manufacture the proposed devices, the costs of their serial production is comparable with that of similar products available in the market, including rubber seals, and it is essentially lower as compared to costs of the above mentioned special devices with high precision requirements. Trials and Tests Since 1993 a number of various pipeline couplings and valve units have been tested (including those in real operation conditions). The results obtained reliably confirm technical, operational and economic advantages provided by the proposed technology.

Area of Application

Fuel and ecologically adverse fluid pipelines Pharmacological production: considering the possibility of using the technology for high temperature sterilization of pipelines without dismantling them Chemicals production Automotive and aerospace industries: bearing in mind smaller linear dimensions and lower weight of the proposed devices Valves and fittings for general industrial use, high pressure, cryogenics, vacuum and high-vacuum engineering

Advantages

Dependable tightness retained under considerable temperature drops Capability to withstand variable mechanical impacts on the pipeline ensured by total relieving of the sealing device from loads Possibility to refuse from generally required leak-pr

Contact for more information:

Asian and Pacific Centre for Transfer of Technology
APCTT Building
C-2 Qutab Institutional Area
P.O.Box - 4575
New Delhi - 110 016
India