Latest development in oil and gas industry is focused on higher pressure and temperature. In addition, standard oil and gas components are more frequent adapted to the other applications like aerospace, food processing, renewable energy. For those conditions, tightness is even more critical than before. In the existing codes the requirements for different tightness classes can be find as well as detailed fugitive emission test descriptions. However, the complete design methodology for HPHT seal solution is still missing. There is no engineering procedure/methodology in the code which will link the design concept, R&D process to the prototype and real tests results. The method which will predict tightness for each size and each configuration/condition is not there. Therefore, there is an urgent need to understand the leakage phenomena and describe it by simplified and safe engineering method. Method, which will connect the design concept with real behavior and be in agreement (or conservative) with test results. By having such method, it will be possible to understand better the sealing mechanism in the existing solutions as well as designing new robust, simple, and cheap (optimized) solutions. There are some more or less accurate methods/rules which are already existing in the supplier companies. There is also more and more research about the continuum flow between two surfaces in contact. Based on those sources in this paper we will present the concept for metal to metal sealing solution designing methodology which can be implemented for future revision of the designing codes. The method which can be used simply and effectively and help to understand the current designs and further R&Ds. Presented here design concept, will be described based on example. The example will go through the process from design concept to the real component tightness test.