GASKETS FOR SPECIAL APPLICATIONS
Based on long term experience with gaskets and sealings, especially of exposed joints of nuclear power plants, following types of gaskets have been developed in MICo, spol. s r.o.
We produce several variants of special gaskets that are designed for environments where extreme reliability and durability are required or for sealing of high-pressure and high-temperature joints.
Our gaskets are used in VVER type nuclear power plants to seal primary circuit flanged joints of e.g. steam generators, main circulation pumps etc.
We also provide our clients with comprehensive services in this area from the design of the sealing joint, through the production of the seals to the professional assembly and service.
It is a strip sealing, where the variable profile of the seal strip and the thickness of the graphite foil are selected so that the strip is not “cut” by the foil and thus the sealing surfaces of the flanges or the metal seal strip are not dented. The interconnection of these parameters allows a virtually unlimited number of the sealing refurbishments, simply by replacing graphite films of the desired purity. The strip sealing consists of a stainless steel support frame and expanded graphite lining. The low minimum pressure value and high strength, including high thermal and chemical resistance, ensure versatility of use for most parameters from classic “soft” seals to metal seals.
References since 1998, especially at the most exposed areas of the primary and secondary circuits of VVER nuclear power plants in the Czech Republic and Slovakia, as a replacement for the original nickel seal.
MITes HT seals are commonly designed for existing flange joints designed for other sealing systems, without the need to change geometry and function.
MITes HF 400®
Flexible sealing with high tightness and large back springing based on expanded graphite strip sealing.
Designed primarily for standard flanges, where their bending is compensated with high accuracy and thus high tightness. The expanded graphite insert significantly increases the back springing value of expanded graphite pads. The multiplied back-springing value ensures stable tightness even when the bolt prestressing is rapidly released in all operating modes even at the longest time intervals.
The innovative MITes HF 400 strip sealing is complemented by a pressure-tight effect ensuring higher performance properties, especially tightness and operational reliability under minimal tightening forces.
Considerable flexibility is ensured by the prestressed expanded graphite insert, which increases the back-springing value of expanded graphite pads. The multiplied back-springing value, including the multiplication pressure-tight effect, which ensures stable tightness even is case of significant and rapid releasing of the screws prestressing.
Expanded graphite sealing rings with anti-extrusion properties with the ability to set the required sealing characteristics very precisely depending on operating parameters and on the actual geometrical dimensions of the structural sealing point reliably ensure high tightness and operational reliability for long operating times even at high seal loads.
Split expanded graphite threaded rings serve to seal threaded parts of bolts, screws, etc. in very confined spaces and for high pressures. For the sealing itself, a practically chamfered edge of the thread run-out is sufficient.
The sealing is made of fibrous-rubber material of any shape and thickness. It is most commonly used to seal flange joints on equipment that works with water or steam with lower parameters.
Sealing system for flange joints of high temperature circuits with corrosive medium sealing is formed by a moulded expanded graphite sealing with increased temperature resistance, which is located in a well-defined groove, the groove being formed by spacer rings.
Projects solved with TAČR financial support (Technology Agency of the Czech Republic)
1) Research and development of technology of nuclear reactors cooled by fluoride salts.
Project no.: TH02020113
Project start: 01/2017
Project completion: 12/2020
The project builds on the previous project “Seals for nuclear reactors a industrial systems using molted fluoride salts” The aim of this project is to design and test a complete sealing system for real components of fluoride-salt-cooled loops (pipelines, fittings, pumps,…), using the results of the previous project, where the basic concept of this system was developed and tested in laboratory conditions
2) Optimization and joint leak detection and recovery of helium from coolant leaks in helium-cooled GEN 4 reactors.
Project no.: TH02020578
Project start: 01/2017
Project completion: 12/2020
The project builds on the previous project “Gas cleaning and joint sealing technology for advanced applications in nuclear and non-nuclear power industry”. The aim of this project is to design a sealing system for the anticipated components of helium-cooled reactors, i.e. to design and test seal types (considering the expected range of pressures, temperatures, and dimensions) and quantify their leakage so that these results can be used in the design and sizing of the nuclear reactor and its auxiliary systems. For these tasks, the results from the previous project will be used where the basic concept of this system was developed and tested in laboratory conditions.