Basic Calculation of Thrust Force and Torque for Gate Valve - WingsHome

Engineering Data Calculation Sheet-1 Rev.2

Basic Calculation of Thrust Force and Torque for Gate Valve

Please refer to C.Sheet-3 1. Seating and Un-seating Force

without Double-block & Bleed Valve.

Please refer to C.Sheet-4

(1) For Disc Area:

F1 = f tan( + ) f = P ? D2

4

f: Axial force to disc area against

flow direction under the pressure. l

P: Pressure

d 2

D: Inside diameter of the valve bore. :Friction angle.

=tan-1 :Coefficient of friction,

when seating ;

P

D

Active coefficient A, when un-seating; ;

Static coefficientS . AS

(2) For Stem Area:

F2

=

P?

d 2 4

d: Diameter of Stem

(3) For Gland Packing Area:

[ ] F3 = ( ? d ? l)? Pg ? ?0

l: Total length of Gland Packing Pg: Tightening Stress of Gland Packing 0: Coefficient of tighten friction factor for Gland Packing

Toatal Seating Force :

FS=F1+ F2 + F3 -WT

Toatal Un-seating Force: FUS=F1- F2 + F3 +WT

For intermadiate: Seating=F2+F3-WT, Un-seating= F3-F2+WT

WT: Total weight of Stem & Disc. (If, FSor FUS WT, WT may neglect)

- 1 -

Engineering Data Calculation Sheet-1 Rev.2

2. Seating and Un-seating Torque without Yoke Sleeve Friction*-1

(1) For Seating Torque:

TS

=

FS

d tan(

2

+

)

(2) For Un-seating Torque:

TUS

=

FUS

d tan(

2

+)

Rev.1

Note) If F3< F2, the un-seating and intermediate opening torque shall be "(-)".

where,

: Lead angle of the stem thread,

= tan -1 L 2r

L=nPT

L:Lead, 2r:Pitch diameter, n:Multi start thread no., PT:Pitch of the stem thread,

:Friction angle of the stem thread, Rev.2

=

tan

-1

cos ' 2

tan -1 ?t

t:Coefficient of the stem thread, ':Angle of the stem thread.

Remarks) *-1: Please refer to Calculation Sheet-3.

- 2 -

Engineering Data Calculation Sheet-2 Rev.2

Basic Calculation of Thrust Force and Torque for Globe Valve

(Turned Stem Type)

1. Seating Force (1)For Disc Area Rev.1

F1

= [

?

D2

?W

'

?

P

?

sin(

+

)

?

C]

+

P

?

? D2 4

2

where;

W': Wide of seating surface

= (D2 - D1 ) / 2 sin

l

d D2

P: Fluid Pressure 2: Angle of Disc : Friction Angle =tan-1 : Coefficient of Friction C: Seating Factor=3 (JPI Recommend)

P

2

W'

For intermediate,

F ' = P ? d

4

d: Stem Diameter

D1 If necessary, F1+F'

2. Seating Torque

(1) For Gland Packing Area

TG

=

(

?d

? l ? Pg

? ?0)?

d 2

where;

Pg: Tightning Stress of Gland Packing (specified by the packing maker)

0: Coefficient of Tightining Friction Factor for Gland Packing (specified by packing maker)

- 1 -

Engineering Data Calculation Sheet-2 Rev.2

(2) Stem Thread Rev.1

TS

=

(

F1

+

F

'

)

?

d 2

?

tan(

? )

where;

+: Seating

-: Un-seating

: Lead Angle of Stem Thread,

=

tan

-1

L 2r

L: Lead

2r: Pitch Diameter

: Friction Angle of Stem Thread, Rev.2.

=

tan

-1

cos ' 2

tan -1 ?t

t: Coefficient of Stem Thread ': Angle of Stem Thread

If intermediate, F' instead of F1.

(3) Total Seating Torque (or Un-seating Torque) T=TG+TS

- 2 -

Engineering Data Calculation Sheet-3 Rev.2

Basic Calculation of Thrust-Torque for Yoke Sleeve

1. Seating Torque

TYS

=

2 3

?

? 3

?

F

?

R'3 -r'3 R'2 -r'2

3 : Coefficient of friction (Yoke-to-Sleeve)

F : Seating Force

2. Un-seating Torque

TYUS

=

2 3

?

? 3

?

F

'?

R''3 -r''3 R''2 -r''2

F': Un-seating Force

- 1 -

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