Pfeiffer 26a Series Guide

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Maintenance
Series 26a Ball Valve
Fig. 1 - Series 26a Ball Valve with Series 31a Rotary Actuator
0 Table of contents
0 Table of contents 1
1 Introduction 1
2 Design, operation and dimensions 2
3 Installation, start-up and maintenance 2
4 Assembly of standard ball valves 2
4.1 Assembly of the ball valve 2
4.2 Assembly of fire-safe ball valve 2
4.3 Assembly of the standard ball valve 4
4.4 Tightening torques 6
5 Assembly of special ball valves 6
5.1 Assembling the high-temperature ball valve 6
6 Troubleshooting 9
7 Repair of the ball valve 9
7.1 Replacing the packing 9
7.2 Replacing the sealing unit and ball 9
7.3 Further repair work 9
8 Customer inquiries 9
1 Introduction
These instructions are intended to assist the user on assem-
bling and repairing Series 26a Ball Valves.
Specifications are subject to change without notice. The text
and drawings do not necessarily display the scope of supply
or any ordering of spare parts.
Drawings and graphics are not to scale.
Customer-specific designs not in accordance with our stand-
ard product range are not shown.
Fig. 2 – Fire-safe Series 26a Ball Valve => See Table 1 (on page 3) for parts list
Fig. 3 – Standard Series 26a Ball Valve => See Table 2 (on page 5) for parts list

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Note:
Do not use this lubricant with valves intended for ox-
ygen service. Use a lubricant suitable for valves that
are free of grease, especially for oxygen service.
Note:
The position and arrangement of the individual parts
shown in the detail drawing are to be observed dur-
ing assembly.
4.2 Assembly of fire-safe ball valve
4.2.1 Assembling the main body
The assembly begins with the main body ( 1 ).
Place the main body with the flange facing downwards on a
flat, clean working surface to allow you to easily access the
inside of the valve.
Insert the encapsulated disk springs ( 13 ) into the main body
( 1 ). Refer to Fig. 4 for the arrangement of the disk springs.
Press in the seat ring ( 9a ) until it touches the disk springs.
Push the bearing bushing ( 7 ), while slightly turning it, onto
the shaft ( 5 ). Apply a small amount of lubricant to the shaft
( 5 ). Insert shaft together with the bearing bushing ( 7 )
through the shaft bore from the inside into the main body ( 1 ).
Note:
Take care not to damage the sealing surface of the
shaft ( 5 ).
Make sure the bearing bushing ( 7 ) is positioned,
together with the shaft ( 5 ) in the groove of the,
main body ( 1 ) without being jammed.
Turn the shaft ( 5 ) until the flattened part is at a right angle to
the worktop.
Lightly spray the ball ( 4 ) with silicone and carefully insert it.
Insert the PTFE ring ( 10 ) and carbon/graphite ring ( 10a )
into the corresponding grooves of the main body ( 1 ).
4.2.2 Assembling the side body
Insert the seat ring ( 9b ) into the side body ( 2 ).
Place the side body ( 2 ) together with the ready-mounted
seat ring ( 9b ) on the main body ( 1 ) and carefully push them
together.
The transfer of these instructions to third parties is only
allowed with the written approval of
Pfeiffer Chemie-Armaturenbau GmbH.
All documents are protected according to the laws of the
German Copyright Act. The transmission and/or duplication
of documents, even in abstracts, as well as the exploitation
and communication of their content is not permitted, unless
expressly granted.
The equipment may only be dismounted and
disassembled by skilled staff who are familiar
with the assembly, start-up and operation of this
product.
In these maintenance and assembly instructions, the term
skilled staff refers to individuals who are able to judge the
responsibilities assigned to them as well as recognize po-
tential hazards due to their specialized training, knowledge
and experience as well as their special knowledge of the
relevant standards.
2 Design, operation and dimensions
Design, operation and dimensions as well as all further details
and technical data can be found in Data Sheet <TB 26a>.
3 Installation, start-up and maintenance
Instructions for the installation, start-up and maintenance can
be found in Operating Instructions
<BA 26a-01> for automated ball valves,
<BA 26a-02> for manually operated ball valves.
4 Assembly of standard ball valves
4.1 Preparation for assembly
Before assembling the ball valve, carefully clean all parts and
place them on a soft surface (rubber mat or similar).
Plastic and graphite parts are nearly always soft and very
sensitive. Take particular care when handling the sealing
surfaces to ensure that they do not get damaged.
Notice!
A high-performance grease paste (Fuchs Gleitmo
805 or Molykote 1000) is used during manufactur-
ing to prevent the screws from cold welding in the
bodies

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Item Description Material
1 Main body Variable
2 Side body Variable
4 Ball 1.4408 / 1.4571
5 Shaft 1.4571
6 Packing flange 1.4571
7 Bearing bushing PTFE with glass
8 Ring PTFE with carbon
9 Seat ring TFM
10 Ring PTFE
10a Ring Carbon-Graphite
11 Set of spring washers 1.8159/Delta tone
12 V-ring packing PTFE / 1.4305
13 Disk spring 1.4404 / PTFE
14 Screw A2-70
15 Screw A2-70
16 Ring Carbon-Graphite
17 Bushing 1.4571
Table 1 – Parts list
Fig. 4 - Detail drawing of fire-safe version of Series 26a Ball Valve

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For version without spring-loaded ball:
Press the seat ring ( 9a ) into the main body.
Only for versions with spring-loaded ball:
Insert the encapsulated disk springs ( 13 ) into the main body
( 1 ). Refer to Fig. 5 for the arrangement of the disk springs.
Press the seat ring ( 9a ) until it touches the disk springs.
Assembly for all versions:
Push the bearing bushing ( 7 ), while slightly turning it, onto
the shaft ( 5 ). Apply a small amount of lubricant to the shaft
( 5 ). Insert shaft together with the bearing bushing ( 7 )
through the shaft bore from the inside into the main body ( 1 ).
Note:
Take care not to damage the sealing surface of the
shaft ( 5 ).
Make sure the bearing bushing ( 7 ) is positioned,
together with the shaft ( 5 ) in the groove of the main
body ( 1 ) without being jammed.
Turn the shaft ( 5 ) until the flattened part is at right angle to
the worktop. Lightly spray the ball ( 4 ) with silicone and care-
fully insert it.
Insert the PTFE ring ( 10 ) and carbon/graphite ring ( 10a )
into the corresponding grooves of the main body ( 1 ).
4.3.2 Assembling the side body
Insert the seat ring ( 9b ) into the side body ( 2 ). Place the
side body ( 2 ) together with the ready-mounted seat ring
( 9b ) on the main body ( 1 ) and carefully push them together.
4.3.3 Final assembly of the ball valve
Turn the side body ( 2 ) until the boreholes of the two body
halves ( 1 and 2 ) are aligned with one another.
Tighten the slightly greased screws ( 14 ) evenly in a criss-
cross pattern to fasten the bodies together.
Note:
Refer to Table 3 in Section 4.4 for the tightening
torques for each nominal size.
Slide the parts of the V-ring packing ( 12 ), turning them
slightly, over the mounted shaft ( 5 ) and insert them into the
packing seat of the main body ( 1 ).
Refer to Fig. 5 for the arrangement of the V-rings.
4.2.3 Final assembly of the ball valve
Turn the side body ( 2 ) until the bolting holes of the two body
halves ( 1 and 2 ) are aligned with one another.
Tighten the slightly greased screws ( 14 ) evenly in a criss-
cross pattern to fasten the bodies together.
Note:
Refer to Table 3 in Section 4.4 for the tightening
torques for each nominal size.
Slide the parts of the V-ring packing ( 12 ), turning them
slightly, over the mounted shaft ( 5 ) and insert them into the
packing seat of the main body ( 1 ). Refer to Fig. 4 for the ar-
rangement of the V-rings.
Stack the spring washers ( 11 ) on the packing. Refer to Fig. 4
for the arrangement of the spring washers.
Press the carbon/graphite ring ( 16 ) into the bushing ( 17 ).
Push the bushing ( 17 ) together with the carbon/graphite ring
( 16 ) over the shaft ( 5 ) until they rest on the spring washers.
Slide the carbon/graphite ring ( 8 ) carefully over the shaft
until it touches the bushing ( 17 ).
Place the packing flange ( 6 ) over the shaft onto the body.
Use the greased cap screws ( 15 ) to align the packing and
tighten the screws evenly in a criss-cross pattern.
Note:
Before performing a leak test, open and close the
valve several times. This allows the ball to centre
itself on the seat rings and provides optimal shut-off
performance.
Assembly of the ball valve is now completed.
4.3 Assembly of the standard ball valve
4.3.1 Assembling the main body
The assembly begins with the main body ( 1 ).
Place the main body with the flange facing downwards on a
flat, clean working surface to allow you to easily access the
inside of the valve.

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Item Description Material
1 Main body Variable
2 Side body Variable
4 Ball 1.4408
5 Shaft 1.4571
6 Packing flange 1.4571
7 Bearing bushing PTFE with glass
8 Bearing bushing PTFE with carbon
9 Seat rings TFM
10 Ring PTFE
10a Ring Carbon-Graphite
11 Set of spring washers 1.8159 / Delta Tone
12 V-ring packing PTFE / 1.4305
13 Disk spring 1.4404 / PTFE
14 Screw A2-70
15 Screw A2-70
Table 2 – Parts list
Fig. 5 - Detail drawing of standard version of Series 26a Ball Valve

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Stack the spring washers ( 11 ) on the V-ring packing.
Refer to Fig. 5 for the arrangement of the spring washers.
Press the bearing bushing ( 8 ) into the packing flange ( 6 ).
Place the packing flange ( 6 ) over the shaft onto the body.
Use the greased cap screws ( 15 ) to align the packing and
tighten the screws evenly in a criss-cross pattern.
Note:
Before performing a leak test, open and close the
valve several times. This allows the ball to centre
itself on the seat rings and provides optimal shut-off
performance.
Assembly of the ball valve is now completed.
4.4 Tightening torques
On joining the two body halves, tighten the screws evenly in
criss-cross pattern using the following specified torques.
DN
Body halves Packing
Qty. Screws Tighten.
torque Qty. Screws Tighten. torque
15 4 M8x20 22 Nm 4 M4x10 5 Nm
25 4 M10x20 49 Nm 4 M6x8 6 Nm
40 5 M10x25 49 Nm 3 M8x12 14 Nm
50 7 M10x25 49 Nm 3 M8x12 14 Nm
80 6 M16x30/
M16x40 105 Nm 4 M10x16 30 Nm
100 8 M16x30/
M16x40 105 Nm 4 M10x16 30 Nm
Table 3 – Tightening torques
5 Assembly of special ball valves
5.1 Assembling the high-temperature ball valve
(Version with HSB metal seals)
5.1.1 Preparation for assembly
Before assembling the ball valve, carefully clean all parts and
place them on a soft surface (rubber mat or similar).
Sealing parts are nearly always soft and very sensitive. Take
particular care when handling the sealing surfaces to ensure
that they do not get damaged.
Fig. 6 – High-temperature Series 26a Ball Valve => Refer to Table 4 (page 7) for parts list
Notice:
A high-performance grease paste (Molykote 1000)
is used during manufacturing to prevent the screws
from cold welding in the bodies.
Notice:
Do not use these valves for oxygen service.
Note:
The position and arrangement of the individual
parts shown in the detail drawing (Fig. 7) are to be
observed during assembly
Notice:
Graphite seals are very sensitive and must always
be handled with great care, otherwise the sealing
performance cannot be guaranteed.
It is not necessary to lubricate the seat sealing.
Lubrication causes the operating performance to
deteriorate. The seat ring and ball are mate-lapped
and must only be installed as a unit. Do not install
a seat ring which has been lapped-in with another
ball. Do not perform the lapping-in yourself. The seat
ring in DN 15 version is spring-loaded and sealed on
both sides of the ball by just one graphite ring seal.

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Item Description Material
1 Main body 1.4571
2 Side body 1.4571l
4 Ball 1.4408 / HSB3
5 Shaft 1.4542
6 Packing flange 1.4571
7 Bearing bushing 1.4571 / HSB7
8 Ring Carbon-Graphite
9 Seat ring 1.4571 / HSB3
10 Ring Carbon-Graphite
10a Ring Carbon-Graphite
11 Set of spring washer Inconel 718
12 Packing Carbon-Graphite
13 Disk spring Inconel 718
14 Stud A2-70
14a Nut A2-70
15 Screw A2-70
16 Ring Carbon-Graphite
17 Bushing 1.4571
18 Ring Carbon-Graphite
19 Thrust ring 1.4571
20 Thrust ring 1.4571
Table 4 – Parts list
Fig. 7 - Detail drawing high-temperature Series 26a Ball Valve

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5.1.2 Assembling the main body
The assembly begins with the main body ( 1 ).
Insert the disk springs ( 13 ) into the main body ( 1 ). Refer to
Fig. 7 for the mounting position of the disk springs.
Place thrust ring ( 19 ) on the disk spring. It must be placed
so that the chamber with the “T” mark rests on the disk
spring.
Press the graphite ring ( 18 ) carefully into the chamber of the
seat ring ( 9 ).
Insert the seat ring ( 9 ) fitted with the graphite ring ( 18 )
carefully into the main body, making sure that the graphite
ring ( 18 ) with two thrust rings ( 20 ), rests on the thrust ring
( 19 ).
5.1.3 Assembling the side body
Proceed exactly as described above for the side body ( 2 ).
5.1.4 Final assembly of the ball valve
Pull bushing ( 7 ) over the shaft ( 5 ) until the collar of the
bushing rests on the collar of the shaft ( 5 ).
Insert the shaft ( 5 ) together with the bushing ( 7 ) into the
main body ( 1 ) from the inside.
The flat head of the shaft ( 5 ) must point in the same direc-
tion as the passage in the main body ( 1 ).
Place the ball ( 4 ) carefully using a tilting movement into the
main body ( 1 ).
The flat head of the shaft ( 5 ) must fit properly into the ball
socket.
Insert the graphite ring ( 10 ) into the chamber of the body
division. Place the assembled body ( 2 ) onto the main body
( 1 ) by carefully turning it.
Check whether there is an even gap all around the body divi-
sion between both body sections. Turn the side body
( 2 ) so that the bolting holes of both body halves ( 1 and 2 )
are aligned.
Fasten the body halves ( 1 and 2 ) together by tightening the
lightly greased nuts ( 14a ) and studs ( 14 ) evenly in a criss-
cross pattern.
Push the graphite packing ( 12 ), turning it slightly, over the
mounted shaft ( 5 ) and position it in the packing seat of the
main body ( 1 ).
Insert and press in the packing rings one at a time.
Place the tool on the stuffing box and use it to tighten each
nut evenly.Apply a torque as specified in Table 5 per inserted
ring using a torque wrench.
Actuate the shaft approximately four to six times after press-
ing in each ring to allow each ring to settle and to create a
fine graphite coating on the surface of the shaft.
Nominal
size Tightening torque Spring washer arrange- ment
DN 15 11 Nm 2GS/2WS
DN 25 24 Nm 2GS/2WS
DN 40 32 Nm 2GS/2WS
DN 50 38 Nm 3GS/2WS
DN 80 48 Nm 2GS/2WS
DN 100 55 Nm 2GS/2WS
Table 5 – Tightening torque per nut
Note:
Key for arrangement of spring washers
GS = Spring washers stacked parallel in the same
direction
WS = Spring washers stacked parallel in the opposite
direction
Example:
3GS/2WS means that a set of six spring washers
is arranged with two sets of three spring washers
stacked parallel in the opposite direction.
Fit the carbon/graphite ring ( 8 ) in the passage of the packing
( 6 ). Secure it into place with the bushing ( 17 ).
Pull the graphite ring ( 16 ) over the collar of the main body
( 1 ). Fasten the assembled packing ( 6 ) as before on the
main body ( 1 ) using the screws ( 15 ).
Note:
We recommend to clean the shaft ( 5 ) at the place
where the graphite ring ( 5 ) rests with a non-woven
cloth and to apply high-temperature grease to it.
This improves the sliding properties.
Check during and after assembly whether all moving parts
can move freely.
To achieve optimal actuation torques and shut-off perfor-
mance, the valve must be pressurized from both sides using
water according to the table below.

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Specifications subject to change without notice
Issue August 2014
PDF=106
5.1.5 Pressure specifications to press the graphite rings
into the seat rings
Nominal size Pressure
DN 15 to DN 50 => 40 bar on both sides/water
DN 65 to DN 80 => 25 bar on both sides/water
DN 100 => 16 bar on both sides/water
Table 6 - Pressure specifications
Assembly of the ball valve is now completed.
6 Troubleshooting
Refer to section 7 of Operating Instructions
<BA 26a-01> for automated ball valves or
<BA 26a-02> for manually operated ball valves.
7 Repair of the ball valve
7.1 Replacing the packing
If a leak is detected at the packing, the PTFE rings of the V-
ring packing ( 12 ) may be defective. We recommend check-
ing the condition of the packing.
To remove the packing, disassemble the valve in reverse or-
der to that described in the corresponding section. Check the
rings of the packing and all sealing parts for damage. In case
of doubt, replace the parts with new ones.
7.2 Replacing the seat rings and ball
If the ball valve does not shut off tightly, the set of seat rings
and the ball ( 4 ) may be defective. We recommend checking
the condition of these components.
To remove the seat rings and the ball, disassemble the valve
in reverse order to that described in corresponding section.
Check the seat rings and the ball as well as all sealing parts
for damage. In case of doubt, replace the parts with new
ones.
7.3 Further repair work
In case of severe damage, we recommend the repair work to
be carried out by Pfeiffer.
0 Customer inquiries
Should you have any inquiries, please submit the following
details:
1. Order number (embossed on the ball valve body)
2. Type, product number, nominal size and version of
the valve
3. Pressure and temperature of the process medium
4. Flow rate in m³/h
5. Installation sketch, if possible