OVAL GASKETS
REGULATIONS
OST 26.260.461-99 “Oval and octagonal steel gaskets for reinforcement flanges. Design, dimensions and general technical requirements»;
- OST 26-845-73 “Oval and octagonal steel gaskets. Design and dimensions. Technical requirements";
- ATK 26-18-6-93 "Oval and octagonal steel gaskets". 
USE OF OVAL GASKETS
Flanged fittings and pipelines (ATK 26-18-6-93, OST 26.260.461-99), flanged fittings and pipelines (OST 26-845-73). Used in equipment with hazardous environments.
Designed for sealing flange connections made with version 7 for conditional pressure up to 16.0 MPa and temperature up to 600C. They are installed in specially prepared grooves having the shape of an oval.
The gasket is blow-resistant and has a double sealing area. Due to the contact of the rounded surface with the groove wall, a stress concentration is created that favors sealing even on worn flanges.
WORKING PARAMETERS
- Nominal pressure: 6.3 - 16 MPa;
- Conditional pass: 15 - 400 mm;
- Operating temperature: -70 - 600°C.
APPLIED GRADES OF MATERIALS
Art. 08KP, 20, 10895, 08X13, 08X18H10, 08X18H10T, 10X17H13M2T.
It is allowed to manufacture from other steel grades, based on operating conditions, according to normative 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, risks) on the end mating and conical surfaces of the gaskets. Oval gaskets are rejected in the presence of cracks, nicks, chips, crushing of sealing surfaces, deformation on the basis of the "Standards for rejecting pipes, pipelines and fittings in process pipelines".
Allowed: no more than two (ATK) one (OST) transverse welds(the difference in hardness is not more than 20 Brinell units).
QUALITY CONTROL
100% quality control of metal, dimensions, hardness test. 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 p.4.4).
EXTRACT FROM THE SAFETY RULES FOR THE OPERATION OF TECHNOLOGICAL PIPELINES PB 03-585-03
SELECTION OF THE TYPE OF SEALING FLANGES
|
Wednesday | Pressure, Ru, MPa (kgf/cm²) | Recommended type of sealing surface |
| All substances of group B | ≤ 2,5 (25)
| Smooth |
| All substances of groups A, B, except for A (a) and BOT (high-temperature organic coolant) |
≥ 2,5 (25) |
Smooth |
| All groups of substances except HERE | >2,5 (25)
<6.3 (63) | ledge-trough |
| Substances of group A (a) | ≥0,25 (2,5)
| Smooth |
| Substances of group A (a) | >0,25 (2,5) | ledge-trough |
| HERE | Regardless | tenon groove |
| Freon, ammonia | Regardless | ledge-trough |
| from 0.095 to 0.05 abs. (0.95-0.5) |
Smooth |
|
| All groups of substances under vacuum | From 0.05 to 0.001 abs. (0.5-0.01) |
tenon 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 made on a tag attached to each gasket, the manufacturer's trademark, symbol, material grade and number of the regulatory document.
ORDERING DATA FOR OVAL GASKETS
Gasket designation in accordance with regulatory documentation (GOST, OST, ATK);
- conditional passage of the flange, Du, 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 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 08X18H10Tpo ATK 26-18-6-93:
Gasket 1-300-6.3-5 ATK 26-18-6-93.
An example of a symbol for a type 1 oval gasket for a flange with a diameter of 300 mm for a conditional pressure of 6.3 MPa made of steel grade 08KP according to OST 26.260.461-99:
Steel gaskets are designed to seal flanged joints with connecting surfaces of execution type 7 in accordance with GOST 12815-80 fittings, pipelines, vessels, apparatuses, pumps, equipment for oil and gas production, chemical, oil refining and other industries. The material of the steel gaskets should have a lower hardness than the material of the flanges. They can be made from steels 08KP, 08X13, 08X18H10T.
| № | metal gasket | Price with VAT |
|---|---|---|
|
Gaskets are metal. Ring ARMCO |
||
| 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 section gasket 1-50-10.0 st.08X18H10T OST 26.260.461-99 | |
| 4 | Oval section gasket 1-80-10.0 st.08X18H10T OST 26.260.461-99 | |
| 5 | Oval gasket 1-125-16.0 st.08X13 OST 26.260.461-99 | |
| 6 | Oval section gasket 1-150-16.0 st.08X13 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 a manufacturer in Moscow |
||
There are two types of steel sealing gaskets: type 1 - oval section (Armco rings); type 2 - octagonal section.
Gaskets of oval section (Armco ring) have the shape of a rectangle in cross section, completed on two opposite sides with semicircles. Oval gaskets can be used with round grooved flanges. Octagonal gaskets (octagonal gaskets) provide a better seal than oval gaskets.
Oval and octagonal gaskets
Oval section gaskets (ARMKO ring) are steel butt-welded gaskets to the flanges of high-pressure vessels and apparatuses. Oval section gaskets are manufactured from DN 400 to DN 1600 mm, nominal pressure from Ru 6.3 to 16 MPa cm2), temperature from -70 to 600°C. The following steel grades are used: 08KP, 20, 10895, 08X13, 08X18H10, 08X18H10T, 10X17H13M2T. The hardness of the base metal of the gaskets must be lower than the hardness of the flanges.|
Regulatory document |
Description |
Order 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 08X18H10T ATK 26-18-6-93: Gasket 1-300-6.3-5 ATK 26-18-6-93 | |
| Octagonal gaskets are designed to seal version 7 flanges. They are installed in specially prepared trapezoidal grooves, have a double sealing area and therefore provide high reliability even with very hazardous conditions operation. Octagonal gaskets are manufactured from DN 400 to DN 1600 mm, conditional 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, 08X18H10, 08X18H10T, 12X18H10T. | Octagonal gaskets for a flange with a diameter of 800 mm for a nominal pressure of 8.0 MPa made of steel grade 08X18H10 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 O-rings 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 reinforcement flanges. Design, dimensions and general technical requirements”;
- ATK 26-18-6-93 "Oval and octagonal steel gaskets";
- GOST 28759.8-90 “Metal octagonal gaskets. 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 described in ASME B 16.20 and API 6 A, and flanges in ASME / ANSI B 16.5. Suitable for pressures up to ANSI 5000 psi. Gaskets are laid in recesses on flanges having walls with an angle of 23° to the vertical.
Application: Armco rings (steel and iron gaskets, RTJ) are designed for sealing flange joints with connecting surfaces of type Execution 7 in accordance with GOST 12815-80 fittings, pipelines, vessels, apparatus, pumps and similar equipment for oil and gas production, chemical, oil refining and some other industries industry.
Advantages: allow to create seals at high operating pressures when other types of gaskets are not applicable.
They are used for conditional pressure Ru 6.3 to 16.0 MPa (from 63 to 160 kgf / cm 2) 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 08X18H10 according to GOST 7350 or according to GOST 5949. According to Russian regulatory documents, it is allowed to manufacture these gaskets from other steel grades in depending on operating requirements.
Octagonal gaskets provide a better seal than oval gaskets and are therefore preferred. However, only oval-shaped gaskets can be used with flanges having a recess with a round bottom (previously produced). Newer flanges have a flat bottom recess and accept both types of gaskets. The working surfaces of the flanges must be machined to a roughness of 1.6 microns, damage to the working surface is unacceptable. The gasket material must 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 outer and inner side of the ring, making them self-sealing (working pressure ensures better sealing of the gasket against the flange). Used in conjunction with flanges made in accordance with API 6 A . Type BX gaskets also have an octagonal profile. It is obtained from a square by chamfering at 4 corners. They are used in conjunction with flanges made in accordance with API 6 BX, and the flanges, after tightening the bolts, come into contact with each other. Both types of gaskets are used for very high pressure classes up to ANSI 20000 psi.
Online store New Technologies You can get acquainted with the range of parts supplied by our company: pipelines and sealing materials, as well as their technical characteristics.
Oval section gaskets 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: normative 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 primarily used with RTJ type connections and act as O-rings on pressurized pipelines to provide optimum sealing. Recommended for use with flanges. Ring-type connections concentrate the bolt load in a small area, creating high seal stresses.
Since the ring-type joint material must always be softer than the mating flanges, the high stress fit causes the ring joint to "plastic flow" on the flange surfaces creating the sealing joints. Gaskets can be made from various materials according to process application and flange.
The main types of oval gaskets
There are three main types of oval gaskets used in Russian and international practice.
- ARMCO rings. ARMCO O-Rings are precision machined metal gaskets commonly used in high pressure applications such as pipelines in the oil, gas, petrochemical and analog industries. This type of gasket is designed for use in RTJ groove flanges.
- BX RTJ. They are a modernized version of ARMCO rings.
- RX RTJ. They are a modernized version of ARMCO rings.
All modifications of sealing rings are available in different sizes. Modifications BX and RX are adequate for use in underwater conditions. Standard R types are available from R11 (1/2”) to R105 (36”) in oval or octagonal section. The octagonal section has a higher sealing efficiency than the oval section and is therefore preferred.
Oval gaskets were originally developed for the obsolete round bottom groove. Both oval and octagonal cross section are interchangeable in flat bottom groove design.
Key Specifications for Oval Gaskets
Below are the main features of the main three types of steel oval gaskets.
Rings ARMCO
- 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
- Ring type BX connections are designed for pressures up to 1600 atmospheres.
- Oval steel gasket for API type BX flange.
- The gasket has a square cross-section with chamfered corners. The average ring diameter is slightly larger than that of the flange groove. Thus, when the ring joint sits, it remains pre-compressed in the outer diameter, creating a high seating stress.
RX RTJ
- Ring connections type RX are designed for pressure up to 300 atmospheres, they are pressure activated ring connections.
- Designed to improve tightness. The outer sealing surface of the ring joint provides initial contact with the flange. As the internal pressure increases, the contact pressure between the ring joint and the flange also increases. This is sometimes referred to as a pressure-activated ring connection due to the shape of the gasket. High landing pressure is created, increasing the tightness. This design feature makes the RX oval steel gasket more resistant to the vibrations, pressure surges, and shocks encountered in oil drilling.
In the catalog of this site you can get acquainted with the assortment 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 device of the ring 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 rate of corrosion resistance;
- high plasticity;
- high electrical conductivity;
- high magnetic saturation;
- small coercive force and high level of residual induction;
- high coefficient of permeability (especially in medium induction areas).
The oval gasket for Type 7 flanges is made of steel. Gaskets are butt welded for vessel flanges in those units that operate under high pressure. The design is a rectangle, on opposite sides it is limited by semicircles. Oval steel gaskets are used to seal flanged joints in pipelines and other devices in manufacturing plants.
The size of the oval gasket provides 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 pressures
- 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 Pipe fittings. Gaskets of oval, octagonal section, lens steel for fittings flanges.
- OST 26.260.461-99 Oval and octagonal steel gaskets for reinforcement flanges.
- OST 26-845-73 Oval and octagonal steel gaskets.
- ATK 26-18-6-93 Oval and octagonal steel gaskets.
Purpose and scope
During production, parts are operated in an aggressive environment and are subjected to strong pressure. To solve the problem, it is customary to use steel oval gaskets.
Oval section gaskets, octagonal section gaskets are used to seal flange connections under pressure from 6.3 to 160 MPa. They withstand temperatures from -70 to +600 °C. Prior to this, flange connections were sealed with asbestos, but its production was canceled due to environmental damage. Gaskets with an oval 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 counterparts are not suitable for use in flanged connections under high pressure and temperature - this will lead to an emergency.
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