Emerson Yarway User manual

YARWAY HARDSEAT AND SEATLESS TANDEM BLOW-OFF VALVE SERVICE AND

OPERATION MANUAL

How to operate and service hardseat and seatless unit tandem blow-off valves

The hardseat inlet valve is mounted in a one

piece forget steel block body with the seatless

discharge valve. The valve has a cone seat and

disc design with a metal-to metal seat. The

beveled end of the disc has wearing surfaces.

This 600 psig valve has a lip on the end of the

disc which checks wire drawing and protects

bearing faces against the cutting action of

blow-down.

The seatless valve is a sliding-plunger type.

When open (plunger raised), blow-down

discharges through ports in the lower gland

and plunger. The slotted plunger head slides

on guides in the valve yoke, preventing turning

of the plunger. When the valve is closed, the

shoulder of the plunger contacts with the upper

gland, forcing it down and compressing the

packings above and below the port as the wheel

is tightened.

OPERATION

This valve is designed so that the blowing valve,

nearest to the boiler, will have flow entering

below the seat. The blowing valve, installed

next to the boiler, should be opened last and

closed first; the sealing valve, furthest from the

boiler, should be opened first, closed last. Both

valves partly opened. Close the seatless valve

with a hard final turn of the hand-wheel to get

the full benefit from automatic tightening of the

packing.

CARE OF VALVES

Since these valves are typically used in severe

service applications (e.g. boiler blow-down

service, boiler drain service) they sould be

included in a regular preventive maintenance

program. It is recommended that valves

operated on a daily basis (blow-down) be

serviced at least every six (6) months. In

frequently operated valves should be serviced

every twelve (12) to eighteen (18) months.

INSPECTION

Valves should be examined externally and

internally. External examination involves

opening the valve closest to the boiler keeping

the sealing valve closed. The complete external

pressure boundary should be examined

thoroughly for leaks. Subsequently, after the

boiler is shut down, the inner valve (i.e.body and

trim) should be examined for any deterioration.

Chapter 11 of the second edition of the

Instrument Society of America´s Control

Valve Handbook is recommended as a good

source for information on valve maintenance

and reconditioning practices.

LUBRICATION

Keep both valves well lubricated. A fitting

(2A) is provided on the seatless valve yoke for

lubricating the ball thrust bearing (11) and the

stem collar. Both areas should be lubricated

every six months. This fitting is compatible with

an Alemite No. 7585 gun. A high temperature

grease equivalent to Texaco Regal AFB2

should be used. Stem threads should be kept

well lubricated Antiseize compound similar to

Never-Seez NS165 should be used.

WARNING

Hot discharge from this product may cause severe

burns. Discharge must be piped away or directed

so that persons in the vicinity are not endangered.

This product must be isolated, vented and cool to

the touch before repairing or inspecting.

YARWAY HARDSEAT AND SEATLESS TANDEM BLOW-OFF VALVE SERVICE AND

OPERATION MANUAL

HARDSEAT VALVE

For cleaning, all internal parts of the hardseat

valve may be removed without disconnecting

the body from the line. If the inside of the valve

must be cleaned, or if a foreign body lodged in

the valve prevents proper seating of the disc,

disassemble as follows:

(1) loosen the gland flange and remove the split

gland bushing

(2) turn the handwheel past its full open position

to jack the packing and stuffing box

(3) break the tack weld on the yoke bushing and

back out this bushing

(4) remove the internal parts through the top of

the yoke.

When the valve is reassembled, the yoke must

be tack welded in place to prevent accidental

loosening of the bushing while the valve is in

service. It is also advisable to keep the disc

clear of the seat during reassembly of the yoke

bushing.

SEATLESS VALVE

Item Description

1Body assembly

2Yoke

2A Lubrication fitting

3Lower packing ring assembly

4Upper packing ring assembly

5Lower gland

6Upper gland

8Plunger assembly

9Stem

11 Ball thrust bearing

12 Handwheel

13 Stop screw

13A Stop screw gasket

14 Springs

15 Yoke studs

15A Yoke stud nuts (4 per set)

HARDSEAT SEAT VALVE

Item Description

1Body assembly

19 Gland

20 Disc

21 Split gland bushing

22 Disc nut

23 Stuffing box bushing

24 Yoke bushing

25 Stem

26 Gland bolts

27 Handwheel

28 Packing

31 Disc insert

SEATLESS VALVE

Packing ring adjustment yoke nuts (15A) should

be tightened at regular intervals. The yoke

springs (14) will maintain a constant load on the

packing, but the packing rings will relax slightly

during use and an adjustment may be required.

To adjust the packing, back the plunger off

slightly by turning the handwheel (do not allow

flow to occur) and then tighten the yoke nuts.

¼ to ½ turn should be sufficient. Reseat the

plunger against the upper gland.

NOTE:

If the valve has not been operated for a long period,

the packing nuts should be ajusted prior to blowing

down the boiler.

Reseating hardseat valve

A specially designed Yarway reseating tool

cuts a new surface on a worn or damaged seat

without removing the unit-tandem valve from

the line. There are cutters of various sizes to

assure that all seats are cut at the proper angle

without lapping the seat and disc. Prices and

complete details are available.

Seatless valve

Hardseat valve

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YARWAY HARDSEAT AND SEATLESS TANDEM BLOW-OFF VALVE SERVICE AND

OPERATION MANUAL

INSTALLATION OF PACKING RINGS

WARNING

This procedure should not be attempted unless all

pressure has been vented from the valve and its

connecting lines, and the temperature of the valve

is at or near ambient.

Remove the stopscrew (13) yoke nuts and springs.

Turn the hand-wheel to open the valve. This will

raise the plunger. Turn the handwheel to close

the valve. This will raise the yoke. Turn the yoke so

that the holes and studs are out of line and turn

the handwheel to open the valve. The plunger is

thus withdrawn from the valve.

Next, remove the glands and the old packing.

This can be done by using a Yarway gland and

packing puller or similar tool (Fig. 3) in the

following manner: Insert the tool until the pawls

engage the ports in the lower gland. Tighten the

nut on the top of the puller to draw out the lower

gland, upper packing and upper gland. The lower

packing can then be removed using a hook tool.

Care should be exercised, however, so that the

lower packing groove is not damage. Install new

packing rings (Fig.4 or 5) glands and stopscrew

in the body and replace the yoke, with the plunger

screwed all the way up on the stem, using the

yoke nuts to pull down the yoke assembly. Next,

place the springs under the nuts and adjust as

previously described.

HARDSEAT SEAT VALVE

ITEM DESCRIPTION

1Bridge plate assembly

2Jack screw

3Spring

4Thrust washer

5Nut 1¼ hex

6Screw (spring mtg.)

SEATLESS VALVE GLAND AND PACKING

PULLER

ITEM DESCRIPTION

946458 Packing puller w/box*

946459-01 1, 1¼ Head assembly

946459-02 1½ Head assembly

946459-03 2 Head assembly

946459-04 2½ Head assembly

NOTE:

* Use for all size seatless BO valves. In addition order

appropriate size head assembly

FIGURE 3

Seatless blow-off valve and gland packing

puller assembly

FIGURE 5

With support ring

FIGURE 4

Without support ring

Upper gland

Upper packing backup ring

Upper packing ring

Valve inlet

Plunger

Lower gland

Support ring

Lower packing ring

Upper gland

Upper packing backup ring

Upper packing ring

Valve inlet

Plunger

Valve body

Upper gland

Lower gland

Upper packing

Lower packing

Lower gland

Lower packing ring

Note: chisel marks on

head give indication of

direction of pawls when

inside valve body

Edge of hole peened to

hold pin in place

Head assembly interchange head assembly available

for either 1”, 1¼”, 1½”, 2” or 2½”valves. order size or

sizes required.

Head assembly fits all types of Yarway seatless

valves in size specified

6977, 78 1-2-1 -3-5-0 3-6-3 4-8-4

6981, 83 2-3-0 -3-5-0 4-6-5 4-6-5

T3947,48 3-5-0 3-5-0 3-5-0 3-6-3 4-8-4

RESEATING TOOLS FOR HARDSEAT UNIT

TANDEM VALVES

DESCRIPTION ITEM NO. PART NO.

Tool holder

with carrying

case

929128-01

929128-02

929128-03

929128-04

929128-05

929128-06

Cutting head

929350-02

929350-03

929350-05

929350-06

929350-08

Tool adapter

927037

927035

927040

927167

SELECTOR TABLE

FIGURE

NO.

VALVE SIZE NPS

1" 1¼"1½" 2" 2½"

First number indicates tool holder number,

second number indicates cutting head number,

third number indicates adapter number.

If the adapter is not required the number will

be zero.

YARWAY HARDSEAT AND SEATLESS TANDEM BLOW-OFF VALVE SERVICE AND

OPERATION MANUAL

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Yarway is a mark owned by one of the companies in the Emerson Automation Solutions business unit of Emerson Electric Co. Emerson Automation Solutions, Emerson,

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construed as warranties or guarantees, express or implied, regarding the products or services described herein or their use or applicability. All sales are governed by

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