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Sealing
Based on long-time experience with sealing of exposed connections in nuclear power plants, the following types of gaskets were developed by MICo, spol. s r.o.
Our offer:
- Design of sealing connections
- Production and delivery of gaskets
- Qualified assembly
MITes HT®
A modified kammprofile gasket with expanded graphite.A combination of a variable serration profile and a suitable thickness of foil made of expanded graphite provide properties determining this gasket to seal even very high pressures of media with very low leakage values.(L<0,001 mg/s.m for gases) at decrease of tightening forces.
MITes HT is a kammprofile gasket with a variable serration profile and graphite foil thickness being chosen so that the serrated profile does not “cut out” of the foil and cause marks either on sealing surfaces of flanges or on the metal serration profile. The interconnection of these parameters enable: to set expected tightness values, recovery interval according to statistic or dynamic factors, to provide an actually unlimited number of gasket renovations by a simple replacement of graphite foils with required purity. Low values of the minimum pressure and high strength including a high thermal and chemical resistance guarantee universal usage for most parameters from classic “soft” material gaskets up to metal gaskets. References: for already more than 7 years, these gaskets are used as a substitution for nickel gaskets in the most exposed places of primary circuits of nuclear power plants in the Czech Republic and Slovakia. The gasket was tested in accredited laboratories of ÚJV (Nuclear Research Institute) Řež. It meets requirements of the decree No.309/2005 Coll.
Modal properties (ENV 1591-2): |
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| QMIN = 13; QMAX = 600; QSMAX(300) = 430; QL/P ("m") = 1,12 |
| Continuous operating temperature tMAX = 550 °C |
| ED = 1200 ÷ 7500 (depending on the specific pressure) |
Sealing class: |
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| L < 8 * 10-4 mg/(s*m) - pro N2, P = 16,4 MPa |
Material composition: |
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| Stainless steel 2,5% Mo at min. |
| Expanded graphite 99,8 % C at min. |
| Gasket starting thickness 4 mm (based on the variable profile) |
| Gasket minimum width from 1,8 mm |
MITes Oil®
Flexible gasket with high sealing ability on the basis of the kammprofile gasket with specific fibrous and rubber lining.
A combination of innovated serration profile and a suitable thickness of foil made of specific fibrous and rubber material guarantees properties determining this gasket to seal very volatile and diffusive media, such as hydrocarbons, oils, dissolvent, etc. Due to the suitable combination of the serration profile and packing piece thickness, the packing piece does not cut out in the whole scope of the available load and it is easy to renovate the gasket by replacement of the packing pieces only.
It is approved to be used with oil systems of primary parts of nuclear power plants.
Modal properties (ENV 1591-2): |
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| QMIN = 13; QMAX = 600; QSMAX(200) = 460; QL/P ("m") = 1,15 |
| Continuous operating temperature tMAX = 250 °C |
| ED = 800 ÷ 5500 (depending on specific pressure) |
Sealing class: |
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| L < 0,001 mg/(s*m) - pro N2, P = 10 MPa |
Material of the gasket: |
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| Stainless steel 2,5% Mo at min. |
| Gasket starting thickness 4 mm |
| Gasket minimum width from 1,8 mm |
MITes HF400®
A flexible gasket with high sealing ability and recovery made based on kammprofile gaskets with expanded graphite. A new modification of the kammprofile gasket MITes HF 400 resuming the type lines MITes HT and MITes Oil used in nuclear power plants, namely in exposed connections of the primary circuit having high requirements of tightness and operating reliability.
The gaskets are to be used for standardised flanges above all, for they compensate their bending with high accuracy and so a high tightness is reached (higher by one level than MITes HT gasket at least). The high flexibility is provided by a pre-stressed graphite packing piece. The packing piece of expanded graphite increases the recovery value of fitting pieces made of expanded graphite much. The multiplied value of recovery ensures a stable tightness even in case of a forceful releasing of screw prestressing in all operating modes and even in the longest periods of time. Simple renovations repeated unlimitedly are performed by replacement of the graphite packing pieces.
It meets requirements of the decree No.309/2005 Coll.
Principle diagram: |
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Modal properties (ENV 1591-2): |
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| QMIN = 13; QMAX = 400; QSMAX(300) = 280 |
| Continuous operating temperature tMAX = 500° C |
| ED = 1200 ÷ 5500 (depending on specific pressure) |
Sealing class: |
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| L < 5 * 10-5 mg/(s*m) - pro N2, P = 10 MPa |
Material composition: |
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| Stainless steel 2,5% Mo at min. |
| Expanded graphite 99,8 % C at min. |
| Starting thickness 6 mm (based on the variable profile) |
»Download MITes HF400 leaflet in pdf«
MiHD®
A flexible gasket made of expanded graphite with high sealing performance for applications to subsidiary forces-flow.
Sealing Rings
Sealing rings made of expanded graphite with anti-extrusion properties, allowing a very precise setting of required sealing properties depending on the operation parameters and actual geometric dimensions of the designed sealing point, ensuring reliably high sealing performance and operating reliability during a long time of the operation even if the gasket is strained heavily. The anti-extrusion properties provide a lasting initial loading including great value of recovery and so a lasting initial sealing values also in case of high pressures of the sealed medium.
L < 0,001 mg/(m*s) ; p = 10 MPa N2
It is approved to be used with oil systems of primary parts of nuclear power plants, type VVER 1000.
On the left in the photo: Sealing ring of electric heater of the pressurizer, VVER 1000 Temelín (p = 20 MPa, t = 370°C)
Split threaded rings
The split threaded rings of expanded graphite serve for tightening of screw threaded parts, bolts, etc. in very narrow places and in case of high pressures. A bevelled edge of end of thread is sufficient in effect for the very sealing. High density of the graphite provides a high recovery, great tightness and lasting initial installation parameters including a self-locking of the sealing nut.
L < 0,001 mg/(m*s) ; p = 13 MPa N2
On the right in the photo: Split threaded ring of the bolt of steam generator primary collector, VVER 440 Dukovany (p = 8 MPa, t = 300°C)
