Zetkama 781 User manual

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TABLE OF CONTENTS
1. Principle of operation
2. Delivery condition
3. Installation of safety valves
4. Operation of safety valves
5. Adjustment of the set pressure
6. Maintenance and repair of safety valves
7. Operating disturbances and their elimination
8. Warranty
1. Principle of operation
The purpose of the safety valve is to protect the equipment and installations against excessive pressure above
the pressure limit.
When the force coming from the pressure acting on the disc surmount with the force from the spring, the valve starts
to open. A further increase in the pressure, required for the particular design of the valve, causes its full opening aided
by the bell or lifting ring.
2. Delivery condition
Supplied valves are tested and set for the required opening pressure or, when ordered for
range, for the upper pressure of the range.
Valves are stamped on the nameplate fixed to the cylindrical part of the body.
Nameplate
USER MANUAL
SPRING-LOADED
SAFETY VALVES
zARMAK
781T (ex. 781)
776 ( ex. 775-I)
Edition: 07/2016
Date: 01.07.2016
Figure 781 Figure 776
ZETKAMA Sp. z o.o.
ul. 3 Maja 12
PL 57-410 Ścinawka Średnia

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Symbols:
1 Type of safety valve
2. Bore diameter
3. Spring number
4. The discharge coefficient for vapours and gases
5. Set pressure or set pressure range
6. Flow area
7. Year of manufacture
8. The minimum lift value
9. Overpressure
10. The discharge coefficient for liquids
11. Cold Differential Test Pressure
* Notified body number
Additionally, the hexagon inlet nozzle is stamped with:
1. Year of manufacture / serial number
2. Workstation number of assembler
3. Stamp of an operator performing the test
Set pressure is secured by sealing between screw plug and body.
3. Installation of safety valves
Before the installation on the unit or pipeline, check if valve was not damaged or contaminated during transport.
It is necessary to check the cleanliness of flow channels, external surfaces and end connections. Any dirt must be
removed.
The valve should be mounted in a vertical position.
Pipes connected to the valve should comply with the requirements included in the surveillance provisions. Cross-
section and shape of the pipes should be selected so that they do not reduce the capacity of the valve. If the medium
is discharged with one pipeline from a few safety valves, free area ofthe flow of this pipeline should be at least equal
to the total area of outlet ports flow of these valves. Moreover, the pipes should be made advantageously to the
flow (gentle curves). Drain should be provided at the lowest point of the discharge pipe.
For the vapours and gases outlet port cannot be rigidly connected to the pipeline.
The valve cannot act like a support structure for the pressure equipment on which it is mounted, and it cannot
be exposed to deformation caused by installation of inlet and outlet pipes.
Mounting place of the valve should be easily accessible, good lighted and protected from external influences.
If the safety valve is mounted outdoors, it must be protected against frost and rain. When mounted near the
platforms for service, they must be in compliance with the provisions of Health and Safety Regulations
(blowing valve should not be a threat to the health and life of people).
It should be ensured that in a system in which the valve is to be mounted, there are no impurities.
ATTENTION
Pressure water test and so-called plant cleaning should be performed before installing the safety valve, blinding the
valve connecting socket. It is not allowed to perform this test with a valve mounted, by blocking any of its moving parts.

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4. Operation of safety valves
Safety valves that serve as important elements of the devices and pressure systems require particularly careful
and competent service. Any operational gasp may cause damage to the valve mechanism, and consequently
lead to the total failure of the pressure system. Therefore, during the operation, pay special attention to:
Proper setting of safety valve, suitable for the operating parameters of the equipment being protected.
Proper protection of the valve mechanism against arbitrary regulation and the possibility of damage.
Periodically verification of correct operation of the valve, in accordance with the requirements of
surveillance.
Proper maintenance and repair management.
Checking the safety valve operation involves lifting of the disc with a lever (pos. 10). Starting the lever causes
loosening of the spring force thereby allowing the minimum lift of the disc and the flow of medium. Release of
the lever should be made at a pressure between 75% and 85% of set pressure. Keep in mind that too frequent
checking may result in damage to the sealing surfaces of the valve disc and seat and thus to a loss of tightness,
and the complete lack of checking usually leads to “seizing" of the valve mechanism, what can have serious
consequences.
Drawing 1. Figure 781
Pos.
Number
Element
Material
1
2
3
4
5
6
7
8
9
10
Body2)
Nozzle
Disc
Bell
Spindle1)
Spring
Adjusting Screw
Locking Screw
Screw plug
Lifting lever
CuZn39Pb2
X39CrMo17-1
X39CrMo17-1
CuZn40Pb2
X20Cr13
B1
CuZN40PB2
CuZn40Pb2
CuZn40Pb2
-
1) for the marine design (WM) spindle is made of the X17CrNi16-2
2) with nickel coating
Drawing 2. Figure 776
Pos.
Number
Element
Material
1
2
3
4
5
6
7
8
9
10
Body
Nozzle
Disc
Lifing ring
Spindle
Spring
Adjusting screw
Locking screw
Screw plug
Lifting device
EN-GJMW-400-5
X39CrMo17-1
X39CrMo17-1
X3CrTi17
X20Cr13
BI
X20Cr13
X20Cr13
S235JR
-

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The frequency of these activities depends primarily on:
Conditions of exploitation, i.e. the type of medium flowing and its parameters
The specifics of the technological process,
Place of installation,
environment.
It should also be correlated with the overhaul and repair of pressure equipment / installations that protects
the valve. Very important is the experience of the user. Determining the periods of checking the safety valve
is the responsibility of the designer of installation.
After checking of the valve, move the lever to the original position. When checking the valve there is a
possibility of contamination the sealing surfaces. In this case, again lift disc to remove these pollutions. If
tightness was not obtained by this, the valve needs to be regrinded from the next stop of the pressure device.
In the case of valves with soft sealing, any damage at the rubber surface of the disc requires replacement.
Safety valve are not designed to use as a discharge valve, and inappropriate use dismiss producer from any
obligation and warranty.
5. Adjustment of the set pressure
Set pressure adjustment can be carried by a person authorized or UDT inspector performing the revise, who,
in the case of valves ordered for the pressure range, adjusts the valve on the installation for the required set
pressure.
Set pressure of the valve can be adjusted only within the range of the provided spring.
1. Unscrew the screw plug (pos. 9) and for safety valves figure 781, remove the lifting lever (pos. 10).
2. Loosen the lock screw with the key, according to the enclosed drawings, on a side with shorter stud (pos. 8) so that
the holes in the lock screw are in line with the holes in the adjusting screw (pos. 7)
3. Set the required opening pressure withthe same key, on the side with the longer stud (so that they pass through the
lock screw and the regulatory screw), with the regulatory screw (pos. 7):
rotate clockwise - increasing the pressure,
rotate counter clockwise –reducing the pressure.
4. After setting the pressure, the key with shorter studs, tighten the lock screw, thereby locking the regulatory screw.
5. In case of the safety valves figure 781, insert the lifting lever the valve (pos. 10).
6. Screw the plug (pos. 9).
7. Seal the valve.
Drwaing 4. Key for setting the set
pressure in valves 775
Drwaing 3. Key for setting the set
pressure in valves 781

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6. Maintenance and repair of safety valves
In order to ensure correct operation of safety valves, the following conditions must be meet:
valve disc cannot set slantwise to the valve seat
sealing surfaces of the seat and disc should ensure tight closure of the valve;
All cooperating moving parts of valve mechanism should maintain movability in operating conditions.
In order to maintain these conditions the valves should be periodically inspected and renovated. Inspections of
safety valves should be conducted by persons with adequate authorisation. While the repairs should be first
carried out by the manufacturer of the safety valve or at authorized service centres, or by the user’s service
teams having appropriate permissions
ATTENTION
In addition to the recommendations included in these instructions, the requirements and recommendations
resulting from the surveillance provisions of the country in which safety valve is operated also apply.
7. Causes of operating disturbances and their elimination
Disturbance
Possible causes
Elimination
Safety valve does not work - no
flow or slight flow
Protective cap of the inlet has not been
removed prior to installation of the
valve
Remove inlet protective cap.
Protective cap of the inlet flange has
not been removed prior to installation
of the valve
Remove the valve from the system and
clean inlet of the valve.
incorrect installation of the valve - the
flow of the medium is opposite with the
direction marked on the valve body
Install the valve correctly, in accordance
with the indications of manufacturer’s
instructions.
Too high set pressure, inadequate to
the requirements of secured
installation
If the required pressure is within the
scope of spring mounted on the valve- set
the safety valve to the required pressure,
if it is outside the scope of spring mounted
- replace the spring with the appropriate
one and set the required pressure. In
each case, act in compliance with
manufacturer’s instructions.
If the required pressure does not fall
within the scope of the safety valve type
mounted - replace the valve with the
appropriate type, with set pressure
adjusted to the required pressure.
backpressure not taken into
consideration (in case of conventional
valve, i.e. unbalanced)
I For stable superimposed backpressure -
set the differential pressure. For variable
superimposed backpressure - apply
bellows compensating backpressure
changes In each case, follow
manufacturer’s instructions and with
matters requiring clarification - consult
the manufacturer's technical advisor.

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Sticky medium
Use the valve with bellows and a heating
jacket, optionally incorporate security
plate into the system.
Freezing or solidifying medium
The body and the pipes should be kept in
a state incapable freezing or solidifying of
media - apply the heating.
"Seizing" of the sealing surfaces of the
seat and valve disc preventing their
separation at the set pressure
If the properties of the medium and the
operating conditions do not exclude such
possibility - appropriate frequency of
inspections and repairs of the safety valve
must be adapted, and the time of valve
check provided in the operating records of
protected device / system should be
strictly observed.
No repeatability of valve opening
pressure (conventional valves, i.e.
unbalanced)
Variable superimposed backpressure
Replace conventional safety valve with the
valve with bellows compensating
superimposed backpressure changes
Checking of safety valve is not
possible
Inlet pressure is lower than 75% of the
set pressure
check the safety valve with a proper
pressure –follow manufacturer's
instructions.
Damages within the lifting unit
Inspect the lifting unit and when
necessary replace damaged parts to new
ones.
Leak at sealing surface
Incorrect transport or storage - wrong
position during transport and storage,
protective cap from the inlet and outlet
of the valve have fallen out and thus
the impurities entered into the valve
During transport and storage follow
manufacturer's instructions. If the inner
part of the valve has been polluted, it
need to be cleaned before installing the
valve in the system in order to avoid
damage to the sealing surfaces.
There is no corresponding relationship
between the set pressure and the
working pressure.
Working pressure shall be:
For compressible fluids and set
pressure equal or higher than 2 bars -
maximum 80% of set pressure,
For compressible fluids and set
pressure below 2 bars –working
pressure should be lower by 0,4 bar
than set pressure,
For incompressible fluids and set
pressure equal or higher than 3 bars –
maximum 75% of set pressure,
For incompressible fluids and set
pressure below 3 bars –working
pressure should be lower than 0,75 bar
than set pressure.
Lever not in neutral position (in case of
closed valves and low pressures)
Move the lever to the neutral position
Vibrations of the safety valve
Diagnose the cause of these vibrations,
and if possible - remove the source. If the
vibrations cannot be prevented mount
appropriate damping systems.
If the chattering of the valve is due to
incorrect valve selection (see "Vibration")
- analyse the accuracy of the valve
selection and if necessary replace it.
Medium pollutions, foreign substances
between the disc and seat
Shortly lift valve disc to remove any
impurities, and if it does not bring the
expected results –take off the valve and
perform regeneration of the sealing
surfaces of the seat and the disc or

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replace it with new one. If it is possible -
apply valve with soft seal on the valve
disc, which has a lower sensitivity to grit in
the seat. Follow manufacturer’s
instructions.
Corrosion of elements directly in
contact with the medium, which is the
result of improper valve selection in
respect of material
Replace the valve with the construction
appropriate to the medium according to
resistance of used materials or apply
safety valve system with a bursting disc
The deformation caused by stresses of
the installation. Valve bodies can get
deformed due to excessive load
transferred from the pipes, causing,
among others, leaking.
Diagnose and eliminate the causes of
stress. If the deformations of valve body
are permanent- replace the safety valve
with a new one.
Other causes of leaks on the seat.
Depending on the reason diagnosed -
according to the indications and decision
of the manufacturer - replace the
defective parts or replace the safety valve
with a new one.
Safety valve opens at a pressure
lower than at adjusted set
pressure
With the cold setting of a valve,
appropriate temperature adjustment
was not included. (in case of valves
used for media of 100oC and higher)
Revise opening pressure, observing the
guidelines and recommendations of the
manufacturer.
High spring relaxation at the working
conditions (for valves at upper limit for
medium and temperature / pressure)
Consult the manufacturer-replace the
spring, according to the guidelines and
recommendations of the manufacturer. If
possible- apply the valve with open
bonnet construction (better cooling of a
spring) or / and with cooling section.
When such situation reoccurs –replace
the valve with a new one, intended for a
use in higher temperature range.
Slight damage or contamination of the
sealing surface of the seat / disc
Remove the valve, check the sealing
surfaces and, if necessary - make
regeneration according to the
manufacturer's instructions and
recommendations.
The valve is set to the differential
pressure (considering the presence of
superimposed backpressure) when the
backpressure don’t exist
Regulate setting of the valve. If the
required pressure is within the scope of
spring mounted on the valve- set the
safety valve to the required pressure, if it
is outside the scope of spring mounted -
replace the spring with the appropriate
one and set the required pressure.
In each case, act in compliance with
manufacturer’s instructions.
Sudden increases in pressure
(pulsations)
Incorrect positioning of the safety valve
at pressure source
Analyse positioning of the safety valve at
pressure source. Safety valve should be
installed in such a distance from pressure
source that protects it from the pressure
pulsations.
Crack on the valve body
Transport defect
Replace safety valve
defect of the material
Replace safety valve

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Installation errors
Replace safety valve.
Strictly follow manufacturer's instructions
and the requirements of the relevant
provisions in terms of requirements for
installation of safety valves –do not
induce stress during installation.
Forces like bending, or torque act on
safety valve.
Replace safety valve.
When designing the installation check the
manufacturer's instructions and the
requirements of the relevant provisions of
supervision institutions in the requirements
for pipes connected to the safety valve,
taking into account all the possible reaction
forces occurring at the outlet, provide for
appropriate support, do not let the valve to
be a supporting structure for the other
elements of the installation. Consider the
possibility to use safety valves with support
lugs.
Vibrations
Too high flow resistance in the supply
line - pressure loss in the supply line
exceeds 3% (set pressure of safety
valve)
Reduce flow resistance in the supply line.
If this is not possible, for some reasons -
consider the possibility of a safety valve
with damper. Effectiveness of this valve
construction is possible in particular
conditions –clarify with the manufacturer.
Wrong characteristic of the safety valve
in the protected installation
Analyse this matter, taking into
consideration special conditions. If such
adjustment is not possible- replace the
valve with a new one with a proper
characteristics.
The valve was designed with too large
capacity in relation to the requirements
of protected installation.
Analyse the selection of safety valve –
apply smaller valve, respectively to the
required capacity.
Built-up backpressure occurring in the
discharge line at the blow out from the
valve - exceeds the value allowed by
the manufacturer (10 ÷ 15% of the set
pressure) -e.g. too long outlet pipe, its
diameter is too small, rapid changes in
the direction of flow, the use of
silencers, etc.
If it is not possible to introduce changes to
the construction of discharge line,
reducing built-up backpressure - apply
valve with bellow compensation
Excessive fluctuation of the
superimposed backpressure at the
outlet of the valve (in the case of the
conventional valve i.e. unbalanced)
Apply valve with bellow resistant to
influence of changing superimposed
backpressure.
Too large construction lift of closing
element
(e.g. in case of full stroke safety valves
used for fluids)
Apply safety valve of characteristics
adjusted to this type of fluids, or- if the
manufacturer enables such construction-
reduce the construction lift of the full lift
valve to the value indicted by the
manufacturer.
Incorrectly made welds on connecting
pipes, too small gaskets on inlet and
outlet or gaskets placed incorrectly
(non-centrally) disrupting the flow
Eliminate incorrectness

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Pressure in installation still rising
despite open safety valve
Inadequate selection of the safety valve
–too small capacity of the valve in
relation to the installation
requirements
Reselect the valve considering the
required capacity and replace it with a
proper one.
Safety valve constantly releases
medium
Valve spring is broken –as a result of
corrosive medium or destroyed by a
different factor
Replace the spring or the entire safety
valve. In case of steam –consider the
possibility of applying valve with open
bonnet..
“hangs” of the valve (the valve opened
but did not close)
Diagnose the cause of the “hangs”If it is
not possible to eliminate the reason-
replace the valve.
Very large damage to the surface of
sealing, e.g. as the result of long-term
leakage, crack of seat, “pitting” due to
the medium
Replace the valve with a new one.
Pressure do not fall down to closing
pressure
Preserve adequate ratio between working
and closing pressure
Crew injuries at discharge
condition and external medium
leakage
Use of safety valve without external
tightness test confirmed by the
manufacturer
Use valve with gastight construction, that
is with external tightness test of the valve.
Use of valve in which sealing is not
adequate to the properties and
parameters of medium.
Replace sealing in the operating valve with
the adequate one (after consulting the
manufacturer) or
replace the entire valve.
Incorrect discharge of medium from the
safety valve
In case of steams and gases, the
discharging pipe should be directed
upwards, enabling safe discharge, minding
that outlet end connector cannot be
rigidly connected to the pipeline. In
addition, in each case, the safety valve
outlet flange (free discharge into the
environment) or drain line must be
positioned so that the flowing medium
does not pose a threat to the
environment. Follow the requirements of
supervising institutions regulations and
indications and recommendations of the
manufacturer.
Incorrect drainage medium form the
valve and form the discharge pipe.
Eliminate the incorrectness in the
drainage line, following the requirements
of supervising institutions regulations and
indications and recommendations of the
manufacturer.

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Condensate in the expansion
chamber of the safety valve
Improper drainage installation -
discharging fluid from the safety valve,
improper drainage installation, clogged
drainage system
Eliminate the incorrectness in the
discharge and drainage installations. In
the lowest point of discharge installation it
is required to apply drainage guarantying
effective discharge of residual
condensate. If the manufacturer of the
safety valve offers the version with
drainage of the expansion chamber of
valve body –it should also be considered
to use such a valve.
Noise emissions above the limit
value
(in case of discharge of steams
and gasses)
Significant flow rates at medium
discharge from the safety valve.
In the case of minor exceedances of limit
values - consider the possibility of
reducing the flow speed through the use
of larger safety valve. It should be
checked, however, that "oversizing" of the
valve did not cause the instability of its
work (see "vibrations").
In most cases it is necessary to apply
silencer directly behind the valve and
screening of the valve (noise barriers).
While designing the outlet pipes fitted
with silencers, static and dynamic
interaction of flow stream flowing through
the silencer should be taken into account.
Silencer body should not interfere with
effective operation of safety valve and
additional pressure drops should be taken
under consideration while calculating the
discharge, and drainage pipes of the valve.
In each case it should be considered not to
exceed the value of backpressure allowed
by the manufacturer of the safety valve
8. Warranty
ZETKAMA grants quality warranty with assurance for proper operation of its products, providing that assembly of them
is done according to the user’s manual and they are operated according to technical conditions and parameters
described in ZETKAMA’s catalogue cards. Warranty period is 18 months starting from assembly date, however not
longer than 24 months from the sales date.
Other warranty terms are to be agreed between the manufacturer of the valve and the purchaser. The manufacturer
reserves the right to introduce technical changes as the result of improving construction and manufacturing
technology. Failure to comply by the user with the regulations and indications included in this user’s manual shall
exempt the manufacturer from any liability and warranty.
Address for correspondence:
ZETKAMA Sp. z o.o.
ul. 3 Maja 12
57-410 Ścinawka Średnia
Phone [phone]
Fax [phone]
Website: www.zetkama.com