Globe Valve Presentation

8/11/2019 Globe Valve Presentation

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Introduction to Globe Valve

By

Mayur Shendge


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Introduction to Globe valve

Globe valve is a linear motion valve and are primarily designed to stop,

start and regulate flow. The disk of a Globe valve can be totally removed

from the flow path or it can completely close the flow path

The entire system pressure exerted on the disc is transferred to the valvestem, the practical size limit for these valves is NPS 12 (DN 300)

Globe valves are extensively employed to control flow.

Generally the maximum differential pressure across the valve disc should

not exceed 20 percent of the maximum upstream pressure or 200 psi

(1380 kPa)


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Typical 3D Models


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MOC and Design Standards


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Constructional Details


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Statutory requirement as per BS1873

Body

Pressure- temperature rating as per 1560-2-1970.

Shell thickness as per BS 1560-2AppendixA.

Face-face distance as per BS 2080.

End flanges as per BS 1560-2

Separate seat rings in the body shall be employed with seating material as per Table-2.

Seat rings of threaded type should be tag welded.

Bonnet:

Wall thickness as per Appendix A

Body-bonnet flange may be flat for #150, for other pressure rating it should be with male-female joint.

Body-bonnet flange and gasket should be of BS 1560-2 standard.

Body-bonnet flange bolt min dia as per specification given in page-12.


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Disk:

Disk can be of spherical, welded, plug or flat surface.

Dish shall be loosely attached to the stem to allow proper seating.

Threaded disk are accepted for the below 50mm.

Disk thrust plate should be provided except for nominal sizes below 50mm.

No guidance required for ball type disk.

In fully open position the net area between the disk and seat shall be at least equal to the

area of end port.

Yoke:

Yoke can be integral or separate.

Yoke should have strength to take the load of actuator or gear box.


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Hand wheel:

Spoke and rim design

Maximum no of spoke should be less than or equal to 6

Hand wheel turning in anti clockwise direction opening.

Hand wheel can of direct mounting on the stem by retaining nut.

It should have arrow indicator.

Stem and yoke bush:

Minimum stem dia as per appendix-A

Single piece stem design with back seat spherical seat machined on it.

Stem should have sufficient length Stem can have ACME thread or trapezoidal thread form

Underside of stem should be slightly radiused

If the stem is having an integral collar, lower end of stem should be slightly radiused.


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Stuffing box, packing and lantern ring: Stuffing box design as per table-1

#150 to have 6 no of rings and #300 and above to have 7 rings.

Glands can be of one piece bushed or 2 piece self aligning design

2 piece gland shall have shoulder.

Packing may be of square, rectangular or chevron section

#150 no lantern rings required. #300 and above should be with lantern ring Lantern rings to have 2 holes at 180. Through holes or tapped 5.40 UNC.

Lantern ring should be placed in such a way that there will 5 no of gland rings on top and 2rings placed below.

Stuffing box to be tapped opposite the center of lantern ring and fitted with rounded pipe asper BS 3799.

Bolting: Body-bonnet bolt allowable stress should not exceed 62 MPa at pressurized condition.

Bonnet bolting should be by stud bolts with a nut each except for the valve size below 50mm.

Stud bolts and nuts should be as per BS 4882-1973 section 1 &3.


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Gland bolting: Hinged /stud bolts/ headed bolts

Headed bolts in slotted brackets should not be used.

Bolts threads can be of metric, UNC, BS 4882, BS1768, BS1769, BS 3692 or BS 4190.

Yoke bolting can be of thread metric or UNC and dimensional as per BS4882, BS1769, BS3692of BS 4190.

Soft seal rings: Seal rings can be fitted in the body or in the disk as specified by purchaser.

Seal rings are designed to withstand a minimum 2000 cycles.

Valves to meet the hydrostatic & air test specified in BS 5146.

Body seat rings:

Body seat ring made of a material from ots seating surface shall be of material not inferior tothat of the shell.

Bonnet gasket: Bonnet flange gasket shall be metallic spiral wound as per BS 3381 or stud or soft iron except

for #150.

Documents

Globe Valve Presentation