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Sketch Description

MWK FC27/FU27 is a PTFE-enveloped gasket with kammprofile core (also called grooved / serrated core). Such particular gaskets are widely used in chemical fertilizers plants – typically requested by apparatus applications: High Pressure Urea Stripper / Scrubber / Condenser.
This fully customized bi-material gasket contains of two main components, which are:

  • metal core with kammprofile (grooved/serrated) having convex shape – so called MWK 027 – providing  mechanical features of the gasket
  • PTFE envelope with U-shape – so called FU envelope – preventing the core to be contacted by chemically aggressive fluid from pressurized (inner) side.

Both above components optionally might be ordered as spare part to any of entireMWK FC27/FU27 gasket delivered before.
Our profile called MWK FC27/FU27 is manufactured strictly according to specifications provided by customer which may refer to size, thickness, core material used. There are often supplementary requirements included in of Licencor’s specifications to be fulfilled dependable which company was providing processing technology. The customized MWK FC27/FU27 of us may fulfil conditions of various Licensors like: SAIPEM, UREA CASALE, STAMICARBON, UHDE, TOYO, MITSUBISHI or others upon request.
Gaskets MWK FC27/FU27 are installed inside high pressure equipment in Ammonia / Urea (Carbamide) plants and such application may implicate further specific requirements concerning gasket construction and its features:

  • typically metallic core of gasket MWK FC27/FU27 is requested to be seamless ring construction,
  • core thickness may vary between 3mm and 6mm depending from flange joint construction,
  • most commonly used materials for core are: 310MoLN (1.4466) / 25.22.2 / UNS31050 or 316L Urea Grade (1.4435) / UNS31603 or Safurex (1.4477) / UNS32906,
  • frequent requirements of Huey Test acc. 262-C corrosion and other Destructive and Non-Destructime Tests of metallic material,
  • additional requests about PTFE envelope U-zone shape and PTFE material type.

A wide number of additional conditions concerning quality / testing / specification conditions request.



MWK 027

SPETORING AL+PTFE fully customized bi-material carrier ring containing of two parts: internal from virgin PTFE and external from dedicated Aluminium 99.5%. Both parts are fit together either by ‘half lap splice’ joint or by “bevel cut’ joint being ready to install inside pressure equipment. Such a gasket is typically requested by one of following applications: Urea Stripper Manhole Cover / Carbamate Separator Manhole Cover / Ammonium carbamate separator / Ammonia Reactor in chemical or fertilizer industry. All these types of gaskets are manufactured strictly acc. specification provided by customer.


SPETOGRAF® GUS® 600 gaskets are recommended for extremely difficult applications, with very high loads both static and dynamic, as well as for old, damaged flange faces or where limited bolt stress is the case. These may be flanges adjacent to pumps, compressors, gate valves etc. self-compensating pipelines, floating heads, inspection holes; application of properly selected layers eliminates necessity of reconditioning of flange faces and ensures very good elastic recovery as well as compenastion of bolt relaxation; gasket is resistant to external loads, blowout and has constant axial dimension (important for machine construction); has very good tightness. Main applications of SPETOGRAF® GUS® 660 gaskets are large heat exchangers, vessels found in chemical industry sealing the floating head and vessel's bottom, valves in petrochemical industry, refineries and power plants, pipelines in power engineering installations. SPETOGRAF® GUS® 660 gaskets are individually selected for specific applications by SPETECH engineers.

Metallic core of 660 style gasket is equipped with grooves which are filled by elastic material. Commonly this can be layers of pure elastic graphite, or layers of elastic graphite with metal insert. Sometimes also spiral wound gasket are installed in grooves.

Special construction of carrier ring is the profile with asymmetric positioning of the grooves in the core. Such solution allows to minimize thickness of the core — what is especially useful for applications where flat gasket is a must.

SPETORING® R-Double Cone Seal

SPETORING® R Double Cone Seals are provided commonly to highest duty pressure vessels equipment (mostly in chemical processing industry). Typical working pressure 50-350 bars and typical temperature up to 400°C, diameter between 500 to 3000mm. They are self-energized gasket which construction details need to be designed essentially by the device designers. Although they look similar to octagonal RTJ the rule of sealing effect ot the joint is different than RTJ.

How it works? After being acted by internal pressure, double cone seal expands outward and the contact pressure between gasket and flange increases substancially. Normally at the conical surfaces of the SPETORING® R Double Cone Seal layers of soft metal are installed – mostly silver, soft iron, aluminium or cooper with thicknes of 0,5÷1mm. To increase friction conical surfaces of gasket (which contact with flange surfaces) are often additionally machined: either with 2-5 groovs (0,5÷1mm deep) or given convex shape.

Please note that during fitting the radial gap of 0,05mm for every 100mm of diameter of non-assembled seal should be precisely controlled and at the cylindrical, supporting surface of cover should be machined longitudinal grooves; Hence internal pressure act on the cylindrical internal surface of the gasket.

Layers for Double Cone Seal
spetoring_rd_layers spetoring_rd_layers

SPETORING® R Delta seal is used for pressure vessel covers. It requires a special flange construction with triangular grooves. How it works? The total depth of grooves is a little bit lower than the hight of gasket in the non-installed state. When tighten up the bolts, the cover gently approaches to the shell flange. After starting the pressure the delta seal bends cross section and contacts linearly in bottoms of grove under high contact pressure. As being acted by internal pressure the delta seal bends even more outwards, and the conical surface of seal tightly contacts the conical surfaces on seal grooves. Please note the high machining accuracy and high precision of any surfaces of SPETORING® R-Delta style joints are required!

Also the edges of the delta seal can imprint bottoms of grooves, so — after disassembling — machining of grooves and — probably — new gasket with new (increased) hight will be required.

Application range of delta seal is up to 2000mm of diameter temperature mostly lower than 400°C and pressure lower than 400 bars.

spetoring_lensSPETORING® LENS SPECIAL STANDARDspetoring_lens_standard

Most popular Lens Gasket being nowadays installed are manufactured to well known standard DIN 2696 which describes Lens Gaskets from DN 10 PN 63 up to DN300 PN 400.

Beside DIN 2696 standard there are many like ‘Company Specifications’ (or ‘National Standards’ or ‘Branch Standards’) which describe in details particular shapes and details of lens forecasted especially to any Company (or Country or Branch). All these particular construction are covered by Spetech production program.

Another two ideas meet widely in lens gaskets area are: galvanization of lens seals (which mainly aims are to improve tightness of the connection and/ or decrease roughness (smoothness) of the flange contacting areas and providing blind or spectacle-type blind lens seals (used for special purposes like emergency, maintenance or any other).

Lens Gaskets described above which are manufactured to many different standards are in practice forecasted to various standard pipeline connections. Spetech is manufacturing also customized lens gaskets with maximum size of 3000mm. Such special constructions are producing acc. to special customers specifications, drawings, and other data.


Beside the standard Lens gaskets we provide Lens blind rings. Shape of the rings is similar to seals which they replace, but commonly they are equipped with a plate which facilitate installation for maintenance service and also enable to include any necessary information of basic data of the connection.


Spectacle Blind Lens gaskets are used in purpose to separate pipesystems or to connect with each other. Set of two Lenses of certain size (where one of the gasket is blind and the other is a ring) is connected by flat section of steel. Such Spectacle-Blind pair is applied in pipelines which regularly need to be separated from other installations.

When pipeline is in "working conditions" Spectacle Blind Lens is mounted in the „open" position so that flow through the pipe is possible. "Maintenance condition" on a pipeline section is the reason to change the spectacle to the „close" position. In such case, after removal of bolts, the Spectacle Blind is rotated and after re-installing the bolts, pipe is blocked and no flow is possible.

spetoring_lens_5002SPETOBLIND® LENSspetoring_lens_blindSPETORING® LENS 1 BRANCHspetoring_lens_branch1SPETORING® LENS 2 BRANCHspetoring_lens_branch2

Special group of Lens Joints acc. to standard Snamprogetti SNAM TB.HPU.5002. This special production line includes: Lens rings, Lens blinds, Lens gasket with integrated (seamless) 1 or 2 branches.

All these products are forecasted for fertilizer and chemical installations operating in very high pressures and very corrosive processing components. For these reasons, in aim to eliminate risk of explosion, fire and contamination, the components used in these plants have to respect improved parameters of quality included in operators / licensors specifications. Our Special Lens Gaskets are typically manufactured from two alloys in 316L UG (Urea Grade) (1.4435) / 310MoLN (1.4466). Spetech can manufacture them from many other various corrosion resistance metallic alloys and superalloys.

Standard TB.HPU.5002 is not the only that Spetech deal. We can meet requirements included in specifications of all major operators (TOTAL / BP / SHELL / ARKEMA / ENI / EVONIK / BOREALIS / etc) and equipment licensors like:

  • TOYO: D 136 E + TESD 142
  • SAIPEM: SPC. CR . UR. 510 Rev 4 + 522 Rev.00 + 529 Rev.00
  • UREA CASALE: Spec. N° 8000-00-MSM-001 + Spec. N° 8000-00MSM-007 Rev1
  • STAMICARBON: 18005 BC01-MS26 Rev.X + 18005 BC05-MS34 Rev. X + Huey 53961 Rev L

or any other customized standard on request.