Stafsjö HL, HG, HP, HPT, MV Maintenance Instruction

Document: Maintenance instruction
Product: HL/HG/HP/HPT
Issue: 3
Issue date: 2010-10-05

Stafsjö Valves AB. SE-618 95 Stavsjö, Sweden. Tel: [phone]. Fax: [phone]. [e-mail] www.stafsjo.com

A Bröer Group Company

Maintenance instruction

This maintenance instruction is a step-by-step instruction for service
and maintenance on Stafsjö’s HG valve. Same procedure also applies
for HL, HP and HPT. The instruction shall be available for the persons
responsible for service and maintenance on the Stafsjö knife gate
valves.

The following procedures are described:

A – Change of seat
B – Change of box packing
C – Change of box packing when the valve is installed in a system
D – Torque for nuts on gland
E – Change of gate, guide strips and body gasket
F – Torque for valve body screw joint reinforcement
G – Change from hand wheel (HW) to pneumatic cylinder (AC)

For more detailed information on the technical data of the Stafsjö knife gate valves, actuators or
accessories, please see data sheets on www.stafsjo.com, or contact Stafsjö Valves AB or your
local representative.

Each knife gate valve is identified with the metal plate containing the valve article number and
serial number. When corresponding with Stafsjö Valves AB or your local representative, please
have these numbers available.

Stafsjö does not accept any responsibility for the product if service and maintenance on the
knife gate valve is not performed according to this instruction. Nor does Stafsjö Valves AB ac­cept any responsibility of the product if any significant change has been done to the product.

Spare parts

Recommended spare parts are described in spare part data sheets for each knife gate valve
type on www.stafsjo.com. Stafsjö recommends the customer to keep one set of spare parts for
each valve type and size in store.

Spare parts can be ordered from Stafsjö or your local representative. Spare part data sheets
and addresses are available on www.stafsjo.com.

Safety information

No work is allowed on the knife gate valve when the system is pressurised or the actua­tor is installed. The system must be free from pressure and empty. Actuator and acces­sories must be disconnected before any work is commenced.

All gate guards must be installed after finished maintenance on the knife gate valve.

Information is only for purpose All specifications are subject to change without notice.

Document: Maintenance instruction
Product: HL/HG/HP/HPT
Issue: 3
Issue date: 2010-10-05

2

Main components in the Stafsjö knife gate valve HG

Figure 1

Stud bolt

Gland

Box packing

Retainer ring

Seat

Valve body

Nut and washer

Gate

Valve body top

Seat

Retainer ring

Document: Maintenance instruction
Product: HL/HG/HP/HPT
Issue: 3
Issue date: 2010-10-05

3

Part list of the Stafsjö knife gate valve HG

Figure 2

Pos

Part Pos

Part Pos

Part Pos

Part

1

Hand wheel

5 Tie rod 9

Box packing*

16

Gate guard, not for HW

2

Yoke 5a

Washer

10

Valve body

16a

Gate guard, not for HW

2a

Bearing

5b

Nut 11

Body gasket

17

Gate clevis

2b

Bearing washer

6 Gate 12

Retainer ring

18

Cylinder

2c

Bearing

7 Beam 12a

Locking screw

20

Clevis pin

3

Stem 8

Gland 13

Seat* 21

Split pin

4

Stem nut

8a

Stud bolt

14a

Guide strip

25

Piston rod

4a

Washer

8b

Washer

14b

Guide strip, top

28

Locking nut

4b

Screw 8c

Nut 15

Bushing

* Recommended spare parts

13

9

8

10

12

7

8

5

10

14a

9

11

6

15

3

1

2b

18

16

16a

14b

8a

8c

8b

5a

5b

2c

2a

2

2b

8a

8c

8b

12a

4b

4a

4

21

20

17

28

25

Document: Maintenance instruction
Product: HL/HG/HP/HPT
Issue: 3
Issue date: 2010-10-05

4

Service and maintenance

See figure 1-2 for identification of the parts in the HG knife gate valve. Parts differ depending on
the valve size and date of manufacture. Please contact Stafsjö Valves AB or your local repre­sentative if you have any questions.

For more information on installation and operation of the knife gate valve and pneumatic cylin­der, please see Operating instruction for knife gate valves and pneumatic cylinders on

www.stafsjo.com or contact Stafsjö Valves AB or your local representative.

Stafsjö offers the customer service and maintenance of Stafsjö knife gate valves, either in the
customer’s plant or at the Stafsjö workshop. Please contact Stafsjö Valves AB or your local rep­resentative for more information.

For procedures A, B, E, F and G the knife gate valve must not be installed in a system.

No work is allowed on the Stafsjö knife gate valve when the system is pressurized or the
automatic actuator is connected. The system must be empty and free from pressure be­fore dismantling of the valve begins. The actuator and accessories must be discon­nected.

The gate guards must be installed after finished maintenance on the knife gate valve.

A – Change of seat

Place the valve horizontally with the seat side up to simplify changing the seat.

1. Open the valve.

2. Loosen the locking screws (12a) the retainer ring (12) is locked with.

3. Lift of the retainer ring (12). If the retainer ring is stuck, use a screw driver or similar and
bend carefully between the retainer ring and the valve body in several places around the
bore until the retainer ring is loose.

4. Check the gate (6) for damages such as dents and scrapes. If the gate is damaged it can
wear out the box packing (9) and the seat (13), causing leakage. Stafsjö recommends
changing the gate if it is damaged to ensure the function of the valve.

5. Clean the area for the seat on the retainer ring and the valve body.

6. Install a new seat (13) on the retainer ring (12) and place the retainer ring in the valve body
(10). For PTFE or metal seat, o-rings must also be installed, see fig. 3. Lubricate the seat
and the o-rings with a synthetic lubricator to make the installation easier.

7. Lock the retainer ring (12) with the locking screws. Note! The function of the screws is only
to keep the retainer ring in place. The retainer ring function come into force when the valve
is installed in a system between pipe flanges.

8. Turn the valve over and follow the same procedures 2-7 for the seat on the other side.

9. Install the valve in the system according to the operating instruction.

10. Operate the valve a few times before the system is pressurised.