And the design of iron gate
1
BS5163, BS51501.6 MPaDN300 ~ DNl000 British standard iron gate, in Britain, the new
Slope, Malaysia and middle eastern countries and industrial water supply pipe line is widely used, its structure characteristics: gear gate (see figure 1, Closed gear gate (see figure 2).
This paper expounds MPaDN300 1.6 ~ 1000 British standard iron gate valve, the valve cover thick wall thickness, wall thickness, stem diameter of design calculation and design verification testing --.
2 design
2.1 body wall thickness of design calculation
BS5163, BS5150 standard tyre in did not give a minimum thickness data shell, design, must design of the body wall thickness calculation.
When the design, the design of the section ZhongQiang for approximate oval shape, see figure 3, its thickness S migrant design calculation, B1 with elliptic wall thickness calculation formulas of calculation formula:
Type of valve - approximate oval K section thickness coefficient, including
DN300 ~ DN500 K, 24 DNl000 ~ take 1.13, K take 1.07;
P - medium pressure, design, P take 160 MPa,
A section of the approximate oval - long axis (mm),
[L] - σ (in) cast HT250 tensile stress, [σ L] take 35.28 MPa,
C - corrosion allowance, C take 5 (mm).
DN300 ~ DN1000 body minimum thickness of design calculation results in table 1.
In the design, the design of thick wall body, besides considering body strength,
Still should consider body stiffness, which should be the body of deformation (MPa) refers to the medium
Under the influence of the pressure control in 0.001), otherwise, within the scope of the DN will force the body
Deformation to seal.
The method to solve the body stiffness in the valve body (see figure 1, the external cavity design, inside and outside the reinforcement of reinforcement and the body of valve end flange connection, to increase the rigid body can be designed, when necessary, ranging from wall thickness increases the body ZhongQiang elliptical cross section of the approximate part of wall thickness.
2.2 bonnet wall thickness of the design
When the design, cover thickness S migrant will usually B2, design and calculation of thick wall body directly take as cover 95 wall thickness. DN300 ~ DN1000 bonnet minimum thickness data in table 2, Bonnet reinforcement design (see figure 1).
Thick wooden partition of sluice 2.3 design calculation
BS5163, BS5150 standard, also gives the minimum thickness of wedge, design, data of thick wall gate to design and calculate the B3 migrant S, its computation formula is as follows: the type of d - size (mm),
P - medium pressure, design, P take 160 MPa,
[σ W] - iron (HT250) permissible bending stress, [σ W] take 56.84 MPa,
C - the corrosion residual, C 3 (mm).
DN300 ~ DN1000 sluice minimum thickness of design calculation results to table 3.
2.4 stem diameter of design calculation
BS5163, BS5150 standards, are also not stem diameter, the design, the data must be on the valve stem diameter design calculation, its computation formula is as follows:
Type of valve stem design calculation, K, DN300 ~ DN500 coefficient,
K take 0.70-3/4, 24 DNl00 ~. K take 0.60 ~ 0.65,
Q - stem opens the axial force (N),
[L] - σ (in) cast HT250 tensile stress, [σ L] take 35.28 MPa,
Using simple calculation formula of Q QG, and because of the weight of the disc (component values calculated, not small).
Type of sealing QMF - to the force is necessary (N),
Pressure seal - medium QMJ force (N),
D - sizes, d = DN (mm),
Bm - the width (mm),
Pressure seal - must QMF than (MPa),
P - medium pressure, design, P take 160 MPa.
DN300 ~ DN1000 stem diameter and design calculation of data in table 4.
3 design verification testing --
DN300 ~ DN1000 British standard by the iron gate prototype, Malaysia, national quality SiRiM authority, to design the type testing verifies that type in strict accordance with the national standards BS5163:1986. The pilot project type test: visual inspection, testing, materials, chemical experiment size, shell strength test, test, the maximum sealing function of minimum torque testing, testing and inspection strength torque cleanness, coating and sign inspection.
Here introduces emphatically the shell strength test, seal test, the maximum and minimum torque testing function test. Strength torque,
3.1 shell strength test
Shell strength test, test, keep pressure 2.4 MPa pressure test is the shortest duration is not visible, 1h leakage.
3.2 seal test
Seal test, test, keep pressure 1.76 MPa pressure is the shortest duration 15min test, can not be visible in the body, the leakage on sealing, 15min inside there cannot be any visible leakage, including hanging in seal surface little drops.
Need again: design of body must have enough strength and rigidity, seal test, shell deformation must be controlled in 0.001 DN scope, otherwise will be difficult to seal test.
Function test of 3.3. Maximum torque
Function test, the maximum torque refers to the gate in the medium pressure and medium pressure situation, in the whole process of open and close, the moment the maximum torque is not more than 5 regulations of torque.
Minimum torque testing. 3.4 strength
The minimum torque testing, is the strength of PN1.6 MPaDN300 ~ DNlO00 British standard iron gate, the design of the validation testing steps:
Open, seated test. 3.4.1
Function test of maximum torque seated, valves, and operation test, seated position, at the same time, record the mark, seated in the process of valve stem rotation laps.
Sexual position in 3.4.2 valve minimum torque of strength tests
Valves are seated position in stem, after all the head, shut down the direction (clockwise), the maximum torque exerted the function test has three times, namely minimum torque strength test torque, see table 6, In order to verify the body and bonnet, disc, stem, stem nut, stuffing box in the main parts and intensity of flange bolts BS5163 meets the standard requirement. 1986:
The rule 3.4.3 valve is in full open position of the intensity of the minimum torque testing
Valve is in full open position, then in the stem, the open square head along the direction (counterclockwise) and maximum torque exerted the function test has three times, namely minimum torque strength test torque, see table 6, In order to verify the body and bonnet, disc, stem, stem nut, stuffing box in the main parts and intensity of flange bolts BS5163 meets the standard requirement.1986:
Seal test. 3.4.4 possible actions
To use the biggest function test torque is seated position again, sealing test, test, keep pressure 1.76 MPa pressure is the shortest duration 15min test
There shall not any visible to confirm whether valve leakage distortion, BS5163 meets design requirements, 1986.
3.4.5 open, seated test
Again with maximum function test of valve open torque seated, and the operation test, check whether the location, seated with 3.4.1 test, seated position is consistent, Again, seated in the process of recording of valve stem rotation, check whether laps with 3.4.1 test stem rotation laps to confirm whether the same stem, stem nut meets the strength, stiffness BS5163 1986 standards. :
3.5 parts inspection
Open valve, valve parts, inspection, and stem and disc stem nut, stuffing box etc. Parts and flange studs and nut is in good condition, to confirm the body, cover, disc, stem, stem nut, stuffing box in the main parts of the flange bolts and BS5163 meets design requirements, 1986.
