OVAL GASKETS
REGULATIONS
OST 26.260.461-99 “Oval and octagonal steel gaskets for valve flanges. Design, dimensions and general technical requirements»;
- OST 26-845-73 “Steel gaskets of oval and octagonal section. Design and dimensions. Technical requirements";
- ATK 26-18-6-93 “Steel gaskets of oval and octagonal section.” 
APPLICATION OF OVAL GASKETS
Flange connections of fittings and pipelines (ATK 26-18-6-93, OST 26.260.461-99), flange connections of fittings and pipelines (OST 26-845-73). Used in equipment with hazardous environments.
Designed for sealing flange connections made with version 7 for nominal pressure up to 16.0 MPa and temperature up to 600C. They are installed in specially prepared oval-shaped grooves.
The gasket is blow-resistant and has a double sealing area. The contact of the rounded surface with the groove wall creates a stress concentration that favors sealing even on worn flanges.
OPERATING PARAMETERS
- Conditional pressure: 6.3 - 16 MPa;
- Conditional passage: 15 - 400 mm;
- Operating temperature: -70 - 600°C.
APPLIED GRADES OF MATERIALS
Art. 08KP, 20, 10895, 08Х13, 08Х18Н10, 08Х18Н10Т, 10Х17Н13М2Т.
It is possible to manufacture from other grades of steel, based on operating conditions, according to regulatory and technical documentation approved in the prescribed manner.
Gaskets made of high alloy steels and corrosion-resistant steels are subjected to heat treatment. After heat treatment, there should be no flaking scale on the surface of the gasket.
Not allowed: defects (dents, scratches) on the end mating and conical surfaces of gaskets. Oval-section gaskets are rejected if there are cracks, nicks, chips, collapse of sealing surfaces, or deformation based on the “Rejection Standards for Pipes, Pipelines and Fittings in Process Pipelines.”
Allowed: no more than two (ATK) one (OST) transverse welds(the difference in hardness is no more than 20 Brinell units).
QUALITY CONTROL
100% quality control of metal, dimensions, hardness testing. The hardness of the base metal of the gaskets must be lower than the hardness of the flanges (according to OST 26.260.461-99 clause 4.4).
EXTRACT FROM SAFETY RULES FOR THE OPERATION OF TECHNOLOGICAL PIPELINES PB 03-585-03
SELECTION OF THE TYPE OF FLANGE SEALING SURFACE
|
Wednesday | Pressure, Ru, MPa (kgf/cm²) | Recommended sealing surface type |
| All substances of group B | ≤ 2,5 (25)
| Smooth |
| All substances of groups A, B, except A (a) and HOT (high-temperature organic coolant) |
≥ 2,5 (25) |
Smooth |
| All groups of substances except HERE | >2,5 (25)
<6.3 (63) | Protrusion-recess |
| Substances of group A (a) | ≥0,25 (2,5)
| Smooth |
| Substances of group A (a) | >0,25 (2,5) | Protrusion-recess |
| HERE | Regardless | Tenon and groove |
| Freon, ammonia | Regardless | Protrusion-recess |
| from 0.095 to 0.05 abs. (0.95-0.5) |
Smooth |
|
| All groups of substances in vacuum | From 0.05 to 0.001 abs. (0.5-0.01) |
Tenon and groove |
|
All groups of substances |
≥6,3 (63) | For lens gasket or oval gasket |
MARKING
When gaskets are supplied as independent products (spare parts), marking is carried out on a tag attached to each gasket, the manufacturer's trademark, symbol, material grade and regulatory document number.
ORDERING DATA FOR OVAL GASKETS
Designation of the gasket in accordance with regulatory documentation (GOST, OST, ATK);
- nominal diameter of the flange, DN, mm;
- conditional pressure, Ru, MPa;
- brand of gasket material;
- the required hardness of the gasket metal or the hardness of the base material of the flange, HB units.
Example symbol oval gaskets type 1 for a flange with a diameter of 300 mm for a nominal pressure of 6.3 MPa, made of steel grade 08Х18Н10Тpo ATK 26-18-6-93:
Gasket 1-300-6,3-5 ATK 26-18-6-93.
An example of a symbol for a gasket with an oval section of type 1 for a flange with a diameter of 300 mm for a nominal pressure of 6.3 MPa made of steel grade 08KP according to OST 26.260.461-99:
Steel gaskets are intended for sealing flange connections with connecting surfaces of type 7 according to GOST 12815-80 of fittings, pipelines, vessels, apparatus, pumps, equipment for oil and gas production, chemical, oil refining and other industries. The material of the steel gaskets must have less hardness than the material of the flanges. They can be made from steels 08KP, 08Х13, 08Х18Н10Т.
| № | Metal gasket | Price with VAT |
|---|---|---|
|
Metal gaskets. Ring ARMKO |
||
| 1 | Oval gasket 1-15-6.3 st.08KP OST 26.260.461-99 | |
| 2 | Oval gasket 1-25-6.3 st.08KP OST 26.260.461-99 | |
| 3 | Oval gasket 1-50-10.0 st.08Х18Н10Т OST 26.260.461-99 | |
| 4 | Oval gasket 1-80-10.0 st.08Х18Н10Т OST 26.260.461-99 | |
| 5 | Oval gasket 1-125-16.0 st.08Х13 OST 26.260.461-99 | |
| 6 | Oval gasket 1-150-16.0 st.08Х13 OST 26.260.461-99 | |
| 7 | Oval gasket 1-200-16.0 st.09G2S OST 26.260.461-99 | |
| 8 | Oval gasket 1-300-16.0 st.09G2S OST 26.260.461-99 | |
| 9 | Oval gasket 1-350-16.0 st.08KP GOST 28759.8-90 | |
| 10 | Oval gasket 1-400-6.3 st.08KP GOST 28759.8-90 | |
|
Steel gaskets of oval octagonal section in stock and to order from the manufacturer in Moscow |
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There are two types of steel sealing gaskets: type 1 - oval section (Armco rings); type 2 - octagonal section.
Oval gaskets (Armco ring) have a cross-sectional shape of a rectangle, completed on two opposite sides by semicircles. Oval gaskets can be used in conjunction with flanges that have a round groove. Octagonal gaskets (octagonal gaskets) provide a better seal than oval gaskets.
Oval and octagonal gaskets
Oval gaskets (ARMKO ring) are steel butt-welded gaskets to the flanges of vessels and high-pressure apparatus. Oval gaskets are manufactured from DN 400 to DN 1600 mm, nominal pressure from PN 6.3 to 16 MPa (from 63 to 160 kgf/ cm2), temperature from -70 to 600°C. The following steel grades are used: 08KP, 20, 10895, 08Х13, 08Х18Н10, 08Х18Н10Т, 10Х17Н13М2Т. The hardness of the base metal of the gaskets should be lower than the hardness of the flanges.|
Regulatory document |
Description |
Ordering designation (example) |
|---|---|---|
| GOST 28759.8-90 |
Gaskets of oval section type 1 for a flange with a diameter of 300 mm for a nominal pressure of 6.3 MPa made of steel grade 08Х18Н10Т АТК 26-18-6-93: Gasket 1-300-6,3-5 ATK 26-18-6-93 | |
| Octagonal gaskets are designed to seal flanges of version 7. They are installed in specially prepared trapezoidal grooves, have a double sealing area and therefore provide high reliability even at very high temperatures. hazardous conditions operation. Octagonal gaskets are manufactured from DN 400 to DN 1600 mm, nominal pressure from PN 6.3 to 16 MPa (from 63 to 160 kgf/cm2), temperature - from -70? C to +600? C. The following steel grades are used: 08KP, 20, 08Х18Н10, 08Х18Н10Т, 12Х18Н10Т. | Gaskets of octagonal cross-section for a flange with a diameter of 800 mm for a nominal pressure of 8.0 MPa made of steel grade 08Х18Н10 GOST 28759.8-90: Gasket 800-8.0-3 GOST 28759.8-90 |
Oval and octagonal gaskets (also known as ARMCO rings, aka RTJ= API rings) and ring gaskets types RX and BX
IN Russian Federation oval and octagonal gaskets are manufactured in accordance with the following regulatory documents:
- OST 26-845-73 “Design and dimensions. Technical requirements";
- OST 26.260.461-99 “Oval and octagonal steel gaskets for valve flanges. Design, dimensions and general technical requirements";
- ATK 26-18-6-93 “Steel gaskets of oval and octagonal section”;
- GOST 28759.8-90 “Metal gaskets of octagonal cross-section. Design and dimensions. Technical requirements".
In international practice, gaskets of this type are called API rings, and connections using them are called RTJ (ring-type joint). Gaskets of this type are specified by ASME B 16.20 and API 6 A, and flanges by ASME/ANSI B 16.5. Suitable for pressures up to ANSI 5000 psi. Gaskets are placed in recesses on flanges having walls with an angle of 23° to the vertical.
Application: Armco rings (steel and iron gaskets, RTJ) are intended for sealing flange connections with connecting surfaces of type 7 according to GOST 12815-80 of fittings, pipelines, vessels, apparatus, pumps and similar equipment in oil and gas production, chemical, oil refining and some other industries industry.
Advantages: make it possible to create seals at high operating pressures when other types of gaskets are not applicable.
They are used for nominal pressure Ru 6.3 to 16.0 MPa (from 63 to 160 kgf/cm2) and temperature from -70 to 600 °C. They can be made from steel 08kp according to GOST 1577 and 10695 according to GOST 11036, steel 08X13 according to GOST 7350 or according to GOST 5949, from steel 08X18N10 according to GOST 7350 or according to GOST 5949. According to Russian regulatory documents, it is allowed to manufacture these gaskets from other grades of steel in depending on operating requirements.
Octagonal gaskets provide a better seal than oval gaskets and are therefore preferred. However, only oval gaskets can be used with round bottom flanges (previously produced). Newer flanges have a flat bottom recess and accept both types of gaskets. The working surfaces of the flanges must be processed to a roughness of 1.6 microns; damage to the working surface is unacceptable. The gasket material should always be less hard than the flange material.
Optional: O-ring typesRXAndBX
RX type gaskets have a similar profile to conventional octagonal gaskets, but have different bevel angles on the outside and inside of the ring, which makes them self-sealing (the operating pressure ensures better pressing of the gasket to the flange). Used in conjunction with flanges made in accordance with API 6 A. BX type gaskets also have an octagonal profile. It is obtained from a square one by chamfering the 4 corners. They are used in conjunction with flanges made in accordance with API 6 BX, and the flanges come into contact with each other after tightening the bolts. Both types of gaskets are used for very high pressures up to ANSI 20,000 psi.
Online store New Technologies You can familiarize yourself with the range of parts supplied by our company: pipelines and sealing materials, as well as their technical characteristics.
Gaskets with an oval section are distinguished by their shape in the form of an oval, that is, an elongated circle: with straight lines on the sides and arcs at the top and bottom.
Steel gaskets of oval section: regulatory and technical documentation regulating production.
The production of steel gaskets with an oval cross-section in Russia is regulated by three main regulatory and technical standards.
- OST 26-845-73.
- OST 26.260.461-99.
- ATK 26-18-6-93.
The OST, GOST and ATK standards provide requirements for dimensions, design, as well as additional technical and operational characteristics.
Oval gaskets: application
Oval steel gaskets are used primarily with RTJ connections and act as O-rings on pressurized pipelines to provide optimal sealing. Recommended for use with flanges. Ring-type connections concentrate the bolt load into a small area, creating high compaction stresses.
Because the ring joint material must always be softer than the mating flanges, high fit stress causes ring joint "plastic flow" on the flange surfaces that create the sealing joints. Gaskets can be made from various materials according to process application and flange.
Main types of oval gaskets
There are three main types of oval gaskets used in Russian and international practice.
- ARMKO rings. ARMCO O-Ring O-Rings are precision machined metal gaskets typically used in high pressure applications such as piping in the oil, gas, petrochemical and analogue industries. This type of gasket is designed for use in RTJ groove flanges.
- BX RTJ. They are a modernized version of ARMKO rings.
- RX RTJ. They are a modernized version of ARMKO rings.
All modifications of o-rings are available in different sizes. The BX and RX modifications are adequate for use in underwater conditions. Standard R types are available: R11 (1/2”) to R105 (36”) in oval or octagonal sections. The octagonal section has higher compaction efficiency than the oval section and is therefore preferred.
Oval gaskets were originally designed for the obsolete round bottom groove. Both oval and octagonal cross sections are interchangeable in flat bottom groove designs.
Key technical characteristics of oval gaskets
Below are the main features of the main three types of oval steel gaskets.
ARMKO rings
- Used on high pressure lines from 300 to 1600 atmospheres.
- They are extremely reliable seals.
- Designed for flanges with standard ring-type grooves.
BX RTJ
- BX ring type connections are designed for pressures up to 1600 atmospheres.
- Oval steel gasket for API flange type BX.
- The gasket has a square cross-section with beveled corners. The average diameter of the ring is slightly larger than that of the flange groove. Thus, when the ring joint is seated, it remains precompressed by the outer diameter, creating a high seating stress.
RX RTJ
- Type RX ring connections are rated for pressures up to 300 atmospheres and are pressure activated ring connections.
- Designed to improve tightness. The outer sealing surface of the ring joint provides initial contact with the flange. When the internal pressure increases, the contact pressure between the ring joint and the flange also increases. This is sometimes called a pressure activated ring joint due to the shape of the gasket. High seating pressure is created, increasing the tightness. This design feature makes the RX oval steel gasket more resistant to vibration, pressure surges and shocks encountered during oil drilling.
In the catalog of this site you can familiarize yourself with the range of products supplied by our company, as well as place an order for parts: pipelines and sealing materials, as well as their technical characteristics.
Metal for oval gaskets
Among the most famous metal flange seals, the Armco ring is very popular. The design of this product was invented several decades ago: the ring design provides many advantages, which is why it is still in demand on the market. The American Rolling Mill Company created and produces the metal that gave the product its name - Armco. The metal contains a large percentage of iron - from 99.8 to 99.9%. The experiment is based on an alloy of iron and steel ore, cast iron.
Metal Features:
- high corrosion resistance;
- high plasticity;
- high electrical conductivity;
- high magnetic saturation;
- low coercive force and high level of residual induction;
- high permeability coefficient (especially in medium induction areas).
The oval gasket for flanges of version 7 is made of steel. Gaskets are butt welded to vessel flanges in units that operate under high pressure. The design is a rectangle, bordered by semicircles on opposite sides. Oval-section steel gaskets are used to seal flange connections of pipelines and other devices of industrial enterprises.
The size of the oval gasket ensures maximum tightness - their area and shape changes, after which the oval gaskets fill the smallest irregularities.
Technical advantages:
- have the ability to create a seal in the presence of high pressure levels
- Compared to similar octagonal gaskets, they are not only suitable for use with flat bottom flanges, but also with round groove flanges.
Oval gasket standards:
- GOST R 53561-2009 Pipeline fittings. Oval, octagonal, steel lens gaskets for valve flanges.
- OST 26.260.461-99 Oval and octagonal steel gaskets for valve flanges.
- OST 26-845-73 Steel gaskets of oval and octagonal section.
- ATK 26-18-6-93 Steel gaskets of oval and octagonal section.
Purpose and scope
During production, parts are operated in an aggressive environment and are subjected to severe pressure. To solve the problem, it is customary to use oval steel gaskets.
Oval gaskets and octagonal gaskets are used to seal flange connections under pressure from 6.3 to 160 MPa. They can withstand temperatures from -70 to +600 °C. Previously, flange connections were sealed with asbestos, but its production was canceled due to harm to the environment. Gaskets with an oval cross-section are made exclusively of metal, and their density is lower than the density of the mating parts.
Unlike steel gaskets, semi-metallic or non-metallic analogues are not suitable for use in flange connections under the influence of high pressure and temperature - this will lead to an emergency.
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