Cast iron gate valve 30ch 6br DU250 Ru10 - flanged, parallel with a rising spindle. Designed for pipelines transporting water or steam at temperatures up to 225 degrees Celsius and pressures up to 10 bar. Manual control with a flywheel. Cast iron gate valves 30ch6br can be installed on the pipeline in any operating position, except for the position with the flywheel down.
The design and dimensions of cast iron gate valves 30ch6br are regulated by GOST 8437-75. This valve is repairable, fully disassembled and can be repaired in a regular locksmith shop without the use of special equipment. All components of cast iron gate valves 30ch6br are constantly on sale, they are cheap and do not burden with long delivery times.
The gland packing in the valve 30ch6br is made of impregnated asbestos. During operation, the gland packing should be periodically replaced and tightened. The sealing of the locking body in cast iron gate valves 30ch6br is provided by brass sealing rings in the body and disks. During operation, build-up may form on the O-rings, which leads to a violation of the tightness of the flow shut-off. Restoring the tightness can be done by removing the build-up from the interacting surfaces by dismantling the valve and lapping the cheeks.
For a long time, the 30ch6br cast-iron valve was the main shut-off valve for general technical purposes and was widely used in heating and water supply systems, but recently it has significantly lost its position with the advent of ball valves and butterfly valves.
Pros and cons of valves
The advantages of steel and cast iron fittings include:
simple design;
a small indicator of hydraulic resistance when moving the shutter;
long service life;
small building length;
versatility for various working environments;
maximum tightness class A;
Designed to operate at high temperatures and pressures.
But, like any technical means, valves have their drawbacks.
Significant construction height of the product.
Slow shutter speed.
Limited access to the shutter (and in the case of a non-retractable running unit, to the spindle).
Gate valves cannot be used as a medium regulating device.
The susceptibility of the sealing surfaces of the steel fittings to abrasion.
Despite the presence of disadvantages, a valve is a type of shut-off valve used in almost every enterprise where there is a pipeline.
Performance indicators
Pipelines are characterized by individual characteristics. Therefore, shut-off valves in work are classified depending on the following indicators.
Borehole diameter and connecting flanges.
Type of connection to the highway.
The maximum pressure of the working environment.
Dependence of pressure on temperature.
Maximum and minimum temperature of the transported substance.
The nature of the movement of the spindle / rod.
Type of drive.
Climatic version (operating range of outdoor temperature).
Valve type and tightness class.
The same indicators for cast iron and steel products are:
nominal bore diameter DN (value from 15 to 1600 mm);
types of drive mechanisms - manual, through a gearbox, electric, hydraulic or pneumatic drive;
shutter tightness class - A, AA, B, C, SS;
climatic version - U1;
Rising and non-rising spindle/stem.
The nominal diameter of industrial fittings is classified according to GOST 5762-2002. Depending on the requirements of the customer (characteristics of the line), the plant can produce a steel or cast iron gate valve with a diameter of 15-1600mm. Demanded sizes are 40-1200mm.
Shut-off valves are made as full bore (the inner diameter of the nozzles is equal to the diameter of the bore section of the saddles) and not full bore (the bore section of the saddles is less than the inner diameter of the nozzles).
Pipe fitting plants produce steel and cast iron gate valves with rising and non-rising stems. The choice of type of undercarriage is characterized by the operating environment as well as customer requirements.
Wedges of cast-iron gate valves (30ch39r, 30ch939r) are made of high-strength cast iron. Since the working medium here is water or steam, the wedges of the shutter are made rubber-coated.
But in the through hole of the cast-iron housing, there are no sealing rings. Here, the flow of the medium through the pipe is blocked only by a rubberized wedge.
Due to the absence of friction when closing the passage, this design significantly extends the service life of the cast iron gate.
In addition to rubberized wedges, cast iron gate valves are produced with welded surfaces made of high alloy steel (30ch6nzh) and with brass sealing rings (30ch6br, 30ch906br). The design of such valves is similar to steel products: the body has rings made of brass or steel with welded surface (depending on the model).
30ch6br and 30ch6nzh can be replaced with steel valves (30s15nzh, 30s64nzh, 30s41nzh).
For cast iron fittingsalloys SCh20 (30ch6br, 30ch906br), GGG40 and GGG50 (30ch39r, 30ch939r). GGG are ductile irons alloyed with nodular graphite (ductile iron). In the process of casting parts, graphite is introduced artificially, thereby increasing the strength of the alloy.
VChSHG (technologically) is the most advanced cast iron alloy available to metallurgists at the current stage of development.
There are only two differences between 40 and 50 brands:
the tensile strength of the first alloy is 390 MPa, the second is 450 MPa;
yield strength - 250 and 300 MPa, respectively.
The yield strength is the amount of stress on the metal, upon reaching which irreversible plastic deformations begin to occur.
The tensile strength is the same as the yield strength, only the destruction of the metal occurs.
For comparison, the tensile strength of WCB steel is about 650 MPa.
For cast iron gate valves 30ch39r, 30ch939r, only a rubberized wedge is used as a valve seal. There are no additional seals in the case.
Since cast iron fittings are designed to work in pipelines through which hot water and steam circulate, the requirements for the rubber coating of the wedge are appropriate here.
As a sealant use:
EPDM (synthetic elastomer);
Silicone (organosilicon compound);
Fluororubber (Vition).
Most valves are designed with an EPDM rubber wedge. Such a sealant is able to work in environments at temperatures from -50C to +900C. When using Vition and Silicon, the upper limit rises to +1500C.
Stuffing box and flanges
The same materials are used as a seal for the stuffing box assembly in steel and cast iron fittings. It could be:
cord made of thermally expanded reinforced graphite TRG;
asbestos cord AGI.
In terms of sealing quality, both options are not inferior to each other. The choice of a particular packing model depends on the manufacturer or the customer's requirement.
The stuffing box is usually reinforced with cotton thread (for water, steam, oil). When operating in aggressive environments, instead of cotton, stainless or inconel wire reinforcement is used (for steel reinforcement).
Since the gland assembly is subject to constant friction against the spindle, the packing must be replaced frequently (depending on the intensity of use of the valve). Therefore, at the enterprises of the pipeline industry, the stuffing box is subject to constant monitoring and revision.
In the flange connection of the cover with the body of cast iron gate valves, a gasket material called paronite is used. Paronite is also used for general steel valve bodies.
But when operating steel reinforcement in difficult conditions and aggressive environments, special-purpose paronite is placed in the flange:
reinforced (for high pressure systems);
electrolysis (for chemical production);
oil and petrol resistant (oil and its derivatives).
Requirements for paronite gasket are regulated by GOST 481-80g.
Marking and designation
Requirements for marking pipeline fittings are unified by GOST 4666-2015. It describes general guidelines for the designation of cast iron and steel products, as well as the requirements for the informative content of the nameplate (tablet) on the body.
You can buy a Cast iron gate valve 30ch 6br DU250 Ru10 from us at the best price in Ukraine. A wide range of products allows us to quickly and efficiently fulfill any order, helping to complete any construction work on time.
