FIELD OF THE INVENTION
The present invention generally relates to check valves, in particular swing type
check valves. More particularly, the invention relates to a process of producing a
compact swing type check valve body with reduced weight.
BACKGROUND OF THE INVENTION
Check valves are basically used for Non Return function in a fluid flow line. There
are various types of check valves used in a wide variety of applications, like
Swing Check Valve, Ball type Check Valve, Piston Lift type Check Valve, Multi
Door Check Valves and so on.
In a Swing type Check Valve, the Disc – which is a movable part to stop the
reverse flow, is mounted on a Disc Carrier. The Disc Carrier swings on a hinge
pin – towards Seat to close the valve (to stop reverse flow), or away from Seat to
open the valve (due to the forward flow). In most of the cases, large sizes Check
Valves are of Swing type.
According to prior art, a process of constructing a Swing type check valve, it
needs to be ensured that inside the Valve Body, when the Disc is swinging for
Opening, a clearance between Disc outer diameter and inside walls of the Valve
Body is to maintained so that the Disc travel is nowhere hindered by inside walls
of the Body.
Due to absence of specific and clear guidelines about the type and magnitude of
clearance to be kept, a designer, at his discretion, keeps the inside shape of the
Valve Body with limited logic for example, the Disc outer diameter should not
touch Body inner walls. Thus, cross sections of Body around the Disc swing path
were not essentially uniform, according to prior art. Therefore, the clearance
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between Disc outer diameter and inner wall of the Body were neither uniform nor
optimum.
Disadvantages of the methods used at present:
The prior art in absence of an innovative concept, a safe and arbitrary method,
clearances between Disc travel path and Body inner wall, on higher sides, which
were not really needed. This results in bulkier shape as well as wall thickness
and ultimately higher weight of the Valve Body or Valve as a product, and its
product cost.
OBJECTS OF THE INVENTION
It is therefore, an object of the invention to propose a process of producing a
compact swing type check valve body with reduced weight.
Another object of the invention is to propose a process of producing a compact
swing type check valve body with reduced weight, in which a radial clearance
between the valve-disc and inner wall of the valve body is optimized and made
uniform.
SUMMARY OF THE INVENTION
Accordingly, there is provided a process of producing a compact swing type
check valve body with reduced weight, the valve comprising a valve body
accommodating a sub-assembly of a disc and a disc carrier the sub-assembly
constructed and disposal to swing about a hinge pin during the valve operation,
the valve body consisting of one each flow bore area and a neck area which
together configure an interior volume for disc opening travel constituting a swept
volume including a core clearance to allow interference-free swing travel of the
subassembly inside the valve body wall, the process comprising the steps of
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constructing the swept volume in an elbow shape to allow free swinging or
curvilinear travel of the disc, the swept volume forming the inner side or the core
of the valve body; forming a radial clearance between the outer diameter of the
disc and inner wall of the valve body; forming an outer profile of the valve body
over the inner wall including the flow bore and neck areas, wherein the radial
clearance is contracted based on the casting tolerances, profile of the disc, and
associated valve body production parameters, wherein a dimensional offset is
maintained from the formed elbow towards outer side by the disc swept volume,
and wherein a wall thickness is built over the inner wall to outer wall constituting
said outer profile.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 – shows a general assembly of a Swing type Check Valve
Figure 2 – shows schematically Disc and Disc Carrier Sweep Path in a swing
type check valve according to the present invention
Figure 3 – shows a Valve Body outer profile over the inner wall according to
the invention
Figure 4 – shows a typical shape of a Valve Body Casting constructed with
optimum shape and dimension according to the present invention.
Figure 5 – shows a typical “non optimum” shape of Valve Body Casting
according to the prior art
DETAIL DESCRIPTION OF THE INVENTION
Figure 1 illustrates a typical swing type check valve. A assembly of a Disc (2) and
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a Disc Carrier (3), which swings about a Hinge Pin (4), during the valve operation.
Shell of the Valve Body (1) excluding the flow bore area and neck area, is
connected to configure an interior volume for –
a. Disc opening travel (swept volume), and
b. Core clearances for an uninterrupted swing travel, so that the Disc (2)
does not interfere with inside of the Body / Shell wall (1).
Figure 2 illustrates a Disc swing path from the Close position to Open position.
“Elbow” shape of the swept volume is crated by the Disc’s swinging (or
curvilinear) travel. A radial clearance between the Disc outer diameter and the
inner side of the Body wall is required for an uninterrupted travel of the Disc.
Minimum value of the radial clearance is estimated considering the Casting
tolerances allowances, the Disc profile and manufacturing requirements. This
value of the minimum radial clearance can vary according to size of the valve.
A dimensional offset is taken from the “Elbow” formed by said Disc swept volume,
towards outer side. Value of the outward offset is equal to the minimum radial
clearance requirement. This new outer swept volume forms the inner side or
Core of the Valve Body, in this region. A shape of the inner side of the Body/shell
wall is formed with the least possible volume. This inner side shape is the
Optimum Core.
Figure 3 illustrates the forming of the Valve Body outer profile over the inner wall.
After constructing the inner side of the Body wall, over the Optimum Core, as well
as flow bores and neck, a wall thickness according to standards and codes is
built over the inner wall which in turn forms the outer profile of the Valve Body.
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Body casting formed with this optimum construction method of the invention,
produces a casting with least possible weight.
Figure 4 shows a typical shape of the Valve Body casting produced according to
the invention. Only for a comparison sake, Figure 5 is given to show a typical
shape of Valve Body casting according to prior art.
Table 1 : Summary of average percentage saving in overall product weight :
ANSI
Pressure
Class #
Valve
Nominal
Size Group,
NPS
Average Percentage saving
in Overall Product Weight
= (Old weight - New
Weight) / Old Weight
900
2" to 6" 29%
8" to 12" 32%
1500
2" to 6" 41%
8" to 12" 36%
14" to 24" 33%
2500
2" to 6" 30%
8" to 10" 25%
14" to 24" 48%
Validation of the inventive process
The products (Swing type Check Valves) are designed and developed in various
size and pressure classes, with the Body construction method described in this
disclosure. Most of the products are hydro tested for Body / Seat tests, for the
test pressures / durations and guidelines in the relevant product testing standard
(API 598). The products have successfully passed the tests, showing no sign of
leakage or unacceptable deformation.
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Advantages of the invention
This method of constructing Valve Body for Swing Check valve is the unique and
Optimum Method, resulting least possible weight in the Swing Area.
A summary of average percentage weight saving in different product size groups
of Swing type Check Valves, is given in Table-1. Saving in product size groups
ranges between 25% to 48%. While individual product weights saving is in a
range of 16% to 53%, depending on the scope available according to produce
size, pressure class and the geometry of corresponding old designs.
Although, a few other weight reduction measures have contributed in overall
weight reduction, the major weight reduction comes from application of the
optimum Body Shell construction method described in this invention document.
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WE CLAIM
1. A process of producing a compact swing type check valve body with
reduced weight, the valve comprising a valve body (1) accommodating a
sub-assembly of a disc (2) and a disc carrier (3), the sub-assembly (2,3)
constructed and disposal to swing about a hinge pin (4) during the valve
operation, the valve body (1) consisting of one each flow bore area and a
neck area which together configure an interior volume for disc opening
travel constituting a swept volume including a core clearance to allow
interference-free swing travel of the subassembly inside the valve body
wall, the process comprising the steps of : -
- constructing the swept volume in an elbow shape to allow free
swinging or curvilinear travel of the disc, the swept volume forming
the inner side or the core of the valve body;
- forming a radial clearance between the outer diameter of the disc
and inner wall of the valve body;
- forming an outer profile of the valve body over the inner wall
including the flow bore and neck areas,
wherein the radial clearance is contracted based on the casting
tolerances, profile of the disc, and associated valve body
production parameters, wherein a dimensional offset is maintained
from the formed elbow towards outer side by the disc swept volume,
and wherein a wall thickness is built over the inner wall to outer wall
constituting said outer profile.
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2. The process as claimed in claim 1, wherein the product weight interalia
weight of the valve body is reduced between 16% to 53% depending on
the product size, pressure class and geometry of the valve.