BS&B NACIONAL 3-5111 Instructions for use

INSTRUCTIONS AND MAINTENANCE MANUAL
SAFETY AND RELIEF VALVES
MODELS 3-5111 AND 3-5161
MA-51/04
NOVEMBER 2020

2
MAIN DEFINITIONS
(UNE-EN ISO 4126-1)
Safety valve: Valve which automatically, without the assistance of any energy other than that of
the fluid concerned, discharges a quantity of the fluid so as to prevent a predetermined safe
pressure being exceeded, and which is designed to re-close and prevent further flow of fluid
after normal pressure conditions of service have been restored.
Pressure: The pressure unit used in this standard is the bar (1 bar = 105 Pa). It is quoted as
gauge (relative to atmospheric pressure) or absolute as appropriate.
Set pressure: The predetermined pressure at which a safety valve under operating conditions
commences to open.
Maximum allowable pressure: The maximum pressure for which the equipment is designed
as specified by the manufacturer.
Overpressure: A pressure increase over the set pressure, at which the safety valve attains the
lift specified by the manufacturer, usually expressed as a percentage of the set pressure.
Re-seating pressure: The value of the inlet static pressure at which the disc re-establishes
contact with the seat or at which the lift becomes zero.
Cold differential test pressure: The inlet static pressure at which a safety valve is set to
commence to open on the test stand. This test pressure includes corrections for service
conditions, e. g. back pressure and/or temperature.
Relieving pressure: The pressure used for the sizing of the safety valve which is greater than
or equal to the set pressure plus the overpressure.
Built-up back pressure: The pressure existing at the outlet of a safety valve caused by flow
through the valve and the discharge system.
Superimposed back pressure: The pressure existing at the outlet of a safety valve at the time
when the device is required to operate.
Blowdown: The difference between the set and re-seating pressures, normally stated as a
percentage of the set pressure of a safety valve.
Lift: The actual travel of the valve obturator away from the closed position.
Flow area: The minimum cross-sectional flow area (but not the curtain area) between inlet and
nozzle which is used to calculate the theoretical flow to discharge.
Flow Diameter: The diameter corresponding to the flow area.

INDEX
PAGE
1 – INTRODUCTION 4
2 – TRANSPORTATION AND STORAGE 4
3 – INSTALLATION 4
4 – ADJUSTING THE SET PRESSURE 4
4.1 – HYDROSTATIC TESTS 5
4.2 – BLOW-DOWN ADJUSTMENT 5
5 – MAINTENANCE 5
5.1 – ASSEMBLY AND DISASSEMBLY - VALVE 3-5111 5
5.1.1 – DISASSEMBLY 5
5.1.2 – ASSEMBLY 6
5.2 – ASSEMBLY AND DISASSEMBLY – VALVE 3-5161 6
5.2.1 – DISASSEMBLY 6
5.2.2 – ASSEMBLY 6
5.3 – RECONDITIONING OF CLOSING SURFACES 6
6 – ADJUSTING THE SET PRESSURE AT THE TEST BENCH 8
6.1 – GASES AND VAPOURS 8
6.2 – LIQUIDS 8
6.3 – TEMPERATURE AND BACK PRESSURE CORRECTIONS 8
6.4 – POSITION OF THE ADJUSTING RING 9
6.5 – SET PRESSURE REGULATION 9
7 – TIGHTNESS TEST 10
7.1 – EXCESSIVE LEAK 10
8 – TEST MANOMETER 10
9 – ATEX MARKING 10
9.1 – SAFETY RECOMMENDATIONS 11
VALVULAS NACIONAL, S. A., recommends reading this Instruction Manual carefully. You will find here the minimum
precautions to be taken into consideration before the installation of the safety-relief valves, so they work correctly.
VALVULAS NACIONAL, S. A., warrantees their safety-relief valves against all kind of manufacture flaws for a 12-month
period from its installation or maximum 18 months after its delivery, considering the one that happens before.
Furthermore, we decline all responsibilities derived from malfunctioning caused by an inaccurate installation, storage and
/ or handling by the buyer.
VALVULAS NACIONAL, S. A., will consider that any safety-relief valve with a non-original replacement installed, and /
or where the certify seal is missing as void of any warranty.
Everything written inside a box or with bold letters should be observed with special caution, as its purpose is to
avoid incurring in a faulty installation, and mainly, to prevent that someone manipulating the safety-relief valve
may suffer any damage while operation.
VALVULAS NACIONAL, S. A., reserves itself the right to partially or totally modify the contents of this manual without
previous notice.
3

4
1 - INTRODUCTION
The purpose of this manual is to offer all suitable
information for a correct installation and maintenance
of NACIONAL’s safety-relief valves.
Safety-relief valves 3-5111 and 3-5161 are
manufactured according to the requirements of
Pressure Containers Directive 97/23/CE Category IV
and 94/9/CE Directive (ATEX) Group II, Category 2.
All safety-relief valves are calculated and
manufactured for a specific application. If a valve
designed for a different application wants to be used,
its suitability has to be checked.
A short-term supervision will probably be needed if the
valve has been inaccurately installed, if there’s
contamination like thin metal foils or other kind of slag
at the protected line, when its used for a duty different
to the one it was designed to, or when the valve gets
to the installation with a previous procedure failure in
the test-bench.
2 - TRANSPORTATION AND STORAGE
The internal components of the safety-relief valve are
accurately manufactured and assembled in such a way
so they are constantly aligned.
An abrupt manipulation of the valve may damage
the closing surfaces or produce misalign of the
internal parts, causing leaks or malfunctioning.
Therefore we recommend caution when handling
the safety-relief valve.
The inlet and outlet connections of the valves should
be protected (as done at the factory), before being
shipped and / or transferred, to their final location. The
closing surfaces are therefore protected and the entry
of alien substances in the internal chamber of the
valve is prevented.
If the valve has to be stored for a long period of time,
do not remove the protections until its installation. Our
recommendation is that the storage environment has
to be clean, dry and protected from open-air. If that’s
not possible, the valve needs to be properly protected
to avoid its wearing and tearing.
3 - INSTALLATION
A correct installation is essential for a good
performance of the safety-relief valve.
Remove the adhesive protective discs or plastic
plug from the inlet and outlet flange.
Before proceeding with the installation, the nameplate
has to be checked to ensure that it’s the proper valve.
The seal cannot be broken (otherwise the set pressure
and tightness will have to be checked again.) The
valve has to be perfectly clean and no kind of dirt shall
be seen inside the nozzle or inside the valve, if
deemed necessary, a blowing should be performed.
The pipe, the connection flanges and the valve holders
must be conscientiously clean. You should be perfectly
sure that there are no alien bodies like particles from
the gaskets, slag, dust, etc. which could get between
the disc and the nozzle. It is imperative to make a
blowing in order to absolutely clean the section that the
valve is going to protect.
All fixing studs need to be uniformly tightened. In order
to avoid the valve’s body from deformation, the release
pipe needs to be properly anchored.
Valves with bellows have a screwed hole at the
bonnet (airing). If the fluids to be used with the
valve are dangerous or polluting, in order to
ensure a correct performance, this hole needs to
be led to a safe place at atmospheric pressure.
¡¡ Never cover it !!
The valve needs to be assembled always in a vertical
position. The inlet pipe to the valve, the one coming
from the equipment or the installation, needs to be
direct and as short as possible.
It is necessary to check that the diameter of the
inlet pipe is bigger or at least equal to the diameter
of the inlet connection to it.
Never point the valves outlets with gases or
vapours to zones where there is danger to people.
In any kind of installation, it should be avoided to
mount the safety-relief valve in positions where
remnants could accumulate.
4 - ADJUSTING THE SET PRESSURE AND
FEATURES
All valves manufactured and expedited by VALVULAS
NACIONAL, have been carefully assembled and
tested before they are expedited.
It is advisable to check the valve prior to its assembly
in the installation in order to make sure that during
transportation and handling the closing elements, and
therefore the tightness, have not been damaged.
In case of excessive leaks, two or three pops should
be realized. If the leak persists, the valves have to be
revised.
In order to modify the set pressure in an already
existent valve, the use of a properly selected
spring is crucial.
Consult VALVULAS NACIONAL, for the check and / or
supply of the spring and the new nameplate.

5
If a valve is set to a higher pressure than the original
set pressure, the rupture of the spring could occur and
a reduction of the distance between the spring coils,
limiting the valves opening, and therefore, the relief
flow would decrease. The “blowdown” would increase.
If set pressure is decreased, would be increased
overpressure in the installation.
Before increasing the set pressure of already installed
valve, be sure to verify that the new pressure is inside
the nominal pressure range it is been designed for.
Also, before decreasing the set pressure, it needs to
be verified that required capacity with new set
pressure is going to be enough to protect the container
it is been for.
4.1 HYDROSTATIC TESTS
When the hydrostatic test of a container is required, it
must be ensured that the safety-relief valve would not
deteriorate.
When making the test upstream, the valve needs to be
nullified, installing the test-gag in order to avoid its
opening.
TEST-GAG
Once the hydrostatic test is finished, the lock
screw needs to be replaced, otherwise the safety-
relief valve would remain completely voided.
When the hydrostatic test is performed upstream, it
has to be checked that the pressure that the valve will
receive does not exceed the limitations of its design,
mainly in those valves including bellows.
4.2 BLOWDOWN ADJUSTMENT
The blowdown pressure regarding the set pressure at
the closing moment of the valve after the popping can
be “adjusted” using the adjusting ring (7) mounted over
the nozzle (4). (Check the drawing in page -8-).
In case the blowdown value should be adjusted, once
the valve is assembled in the installation, proceed as
follows:
- Unscrew the screw (14) which fixes the adjusting ring
(7).
- Using a screwdriver turn the adjusting ring upwards
until making contact with the disc holder (8), then turn
it to the opposite direction so many grooves as Table 1
points out.
- In order to increase the blowdown (the valve will
close itself at a very low inlet pressure) the adjusting
ring has to be risen turning the grooves counter
clockwise (from left to right).
- To decrease the blowdown (the valve will close itself
at a very high inlet pressure) the adjusting ring has to
be lowered turning the grooves clockwise (from right to
left).
- Once the adjusting ring has been adjusted, the lock
screw has to be assembled back, checking that the
stud remains placed inside the adjusting ring‘s groove,
fixing it to keep it from spinning, but free for its
alignment.
5 - MAINTENANCE
If the valve has been working at an installation with
fluids classified as dangerous or pollutant,
decontamination has to be performed prior to its
manipulation.
It is highly important to follow the disassembly
sequence as described below, as any alteration
may be dangerous for the worker who is
manipulating the valve, due to the spring tension.
To achieve a correct valve operation, the use of
original spare parts is essential.
5.1 ASSEMBLY AND DISASSEMBLY - VALVE 3-
5111
To perform the assembly and disassembly operations
check valve section drawings in page -8-.
5.1.1 DISASSEMBLY
Unscrew the cap (3).
If the valve has a lever, disassemble the lever (59),
unscrew the holder (62) and unscrew the cap (53).
Once the position of the release nut (43) is checked by
measuring distance between the top side and the edge
of the stem, loosen the capture (44) and disassemble
it.
Before losing the spring (11), write down the distance
between the top part of it to the edge of the stem. This
will allow to place it in the same position assembled.
Unscrew the adjusting nut (13) and the adjusting screw
(11) until all the tension in the spring is freed (10).

6
Once disassembled the bonnet (2) from the body (1),
the spring (10) can be removed together with the
spring button (15).
Never perform this operation unless there is full
security that the spring tension has been
completely eliminated.
Pulling from the stem (9), the guide (6), disc holder (8)
and disc (5) can be removed from the body.
Unscrew the stem from the disc holder. To extract the
stem from the disc holder, hold the disc holder
vertically and clap it against a wooden surface, or
similar, making the enough effort to close the disc
retainer (16), leaving the disc outside its placement.
Disassemble the lock screw (14), unscrew the
adjusting ring (7) from the nozzle (4), and dismount the
nozzle from the body.
5.1.2 ASSEMBLY
Follow the disassembly instructions in reverse
sequence without forgetting the generic parts of
section 5.1.1.
Lightly grease the threaded parts.
5.2 ASSEMBLY AND DISASSEMBLY VALVE 3-5161
While assembling and disassembling this type of
valve, special attention needs to be taken as the
bellows is sensitive to brusqueness and could get
distorted, which would cause valve malfunction.
5.2.1 DISASSEMBLY
Disassembly is performed exactly as for valve 3-5111
(see section 5.1.1), except for the bellows, that has to
be done as follows:
Pulling from the stem (9), the spring (10) and the
spring button (15) can be removed.
Turning the body, and if necessary, gently tap to
remove the guide (6), the bellows (33) and the disc (5).
Threading a screw into the thread and pulling out, the
disc (5), from the disc holder place can be removed. In
this operation is really important to take precautions in
order to do not damage the bellows (33).
5.2.2 ASSEMBLY
Follow the disassembly instructions in reverse
sequence without forgetting the generic parts of
section 5.1.2.
Make sure that the screwed hole from the bonnet
(venting) is not covered. This is mandatory for the
good performance of the valve.
5.3 RECONDITIONING THE CLOSING SURFACES
When the contact surface between nozzle and disc
(the valve’s closure) has some slight damage, it is
enough with a simple lapping to leave it in optimal
conditions.
To manually perform this operation it is required a
foundry grey lapping dish or a flat and polished
surface, like a glass disc.
Deposit over such surface a small layer of lapping
paste in its different finishing degrees.
Place the piece perfectly flat over the lapping surface,
apply some small and uniform pressure, perform a 8-
shaped movement. When a lapping ring is used, the
movement should be oscillating.
Disassembling the nozzle from the valve’s body is
advisable for a good lapping. If that’s not feasible, or
the surface is just slightly damaged, use the lapping
ring. Bear in mind that an excess of paste might round
of the nozzle’s lips edges.
When the closing surface presents too many markings,
they have to be eliminated with the lathe before
proceeding with the lapping.
The lapping paste can be found in different grain sizes,
from a coarse grain to a really thin one. Usually a
middle-sized grain is used at the beginning and the
final polish is done with the thinnest.
Table -2
GRAIN DIMENSION
(m) FINISH TYPE PRODUCT
400 15 ÷ 21 MEDIUM SILICON CARBIDE IN
SUSPENSION
800 7,5 ÷ 10,5 SMOOTH
1200 4 ÷ 6 POLISHED DIAMOND POWDER
IN SUSPENSION
Each time the paste’s grain is changed the dish has to
be thoroughly cleaned, mainly when the change is
done from a thick to a thin grain.
The most important considerations in order to achieve
a good finish are the following:
A) Cleaning of the lapping dish, the piece to be
lapped, and the lapping paste.
B) Plane surface for the lapping plate support.
C) A suitable lapping surface.
D) A uniform and smooth lapping movement
(without vibrations or abruptness).
E) Choice of the lapping paste’s grain type for an
accurate finish.

7
Nº DESCRIPTION Nº DESCRIPTION Nº DESCRIPTION
1 BODY 13 NUT 53 PACKED CAP
2 BONNET 14 LOW SCREW 54 STEM
3 CAP 15 SPRING BUTTON 56 CAM SHAFT
4 NOZZLE 16 DISC RETAINER 57 PACKING
5 DISC 27 NOZZLE GASKET 58 PACKING GLAND
6 GUIDE 28 SCREW GASKET 59 LEVER
7 ADJUSTING RING 30 GUIDE GASKET 62 CAM SHAFT SUPPORT
8 DISC HOLDER 31 CAP GASKET 63 CAM SHAFT RETAINER
9 STEM 33 BELLOW 64 GASKET
10 SPRING 43 RELEASE NUT 65 PIN
11 ADJUSTING SCREW 44 BOLT
59
56
65
58 62 43
63
57 64
54
53
44
LIFTING LEVER
3-5161 MODEL
3-5111 MODEL
4
27
7
28
14
5
1
SCREWED CONNECTION
16
4
27
7
28
14
5
1
6
9
10
15
2
13
11
3
31
30
8
16
4
27
7
28
14
5
1
6
9
10
15
2
13
11
31
30
8
33
VENT
3
CONVENTIONAL VALVE BALANCED VALVE

8
6 – ADJUSTING THE SET PRESSURE AT
THE TEST BENCH
All tests and adjustments have to be performed by
people who have received a proper technical
training about how safety-relief valves work and
the risks of the tests.
When valve has pressure, eyes and ears need to
be covered.
When the valve has pressure, “DO NOT” stand in
front of the outlet flange.
6.1 GASES AND VAPOURS
If a valve test bench is not available, the pressure
adjusting test may be performed using a pressurized
reservoir (bottle) with air or nitrogen, if possible, with a
good shock-absorbing “mattress” to avoid damaging
the closing areas of the valve when the popping is
done.
The connection between the valve and the container
must be preferably direct through a cut-off valve. The
connection pipe must have a minimum inside diameter
of 8 mm.
It is necessary to perform a good blowing of the
connections and pipes. This has to be done prior
to the placement of the valve, in order to avoid any
dirt that could damage the closing zones.
The test can be performed in two different ways:
A) Increase the inlet pressure until a continuous
discharge of fluid is detected, which can be
identified by a whistle or unforeseen buzz.
B) Increase the valve’s inlet pressure until the
popping. To be able to get to this action the
adjusting ring has to be placed touching the
disc holder’s bell, then it has to be lowered one
or two grooves.
If the test if correctly done, the results of both tests will
be practically identical.
Test (B) requires a container with a bigger volume and
more attention when fixing the valve.
6.2 LIQUIDS
The test can be done with clean water at ambient
temperature.
The test circuit must be purged and there must be no
accumulation of gas inside the test system. The use a
vacuum pump to depressurize the circuit before filling
with the test liquid is recommended.
Usually an accumulation container is not needed, but a
shock-absorbing lung (water/air) is essential if an
alternative bomb is used.
Set pressure adjustment will be identified when water
pours continuously from the outlet connection of the
valve.
6.3 TEMPERATURE AND BACK PRESSURE
CORRECTIONS
When a test bench at ambient temperature and
atmospheric pressure is used, and the valve is
destined to work with temperatures higher than 100 ºC,
and / or a back pressure different to the atmospheric, a
temperature and / or back pressure correction in the
set pressure adjustment has to be done for
conventional valves.
For balanced valves (those with bellows) only
temperature correction will be done as back pressure
is compensated with the bellows.
Correction factor shown in the table below has to be
applied to the set pressure adjustment of those valves
that are going to work with fluids at temperatures
higher than 100 ºC.

9
WORK TEMPERATURE INCREASE TO THE SET
PRESSURE
UNTIL 100º C
FROM 101º C TO 250º C
FROM 251º C TO 500º C
MORE THAN 500º C
0 %
2 %
3 %
5 %
Correction factor shown above has to be equally
applied, even when the set pressure adjustment of that
valve was corrected to compensate the back pressure
effect in the release.
Therefore, the pressure to be used to test the valve in
the test bench, called “Cold Differential Test Pressure”,
is the inlet pressure which will open the valve in the
test bench at ambient temperature and atmospheric
pressure.
To perform an exact calculation of the cold differential
test pressure, the pressure which will pop the valve in
process, the increase for temperatures above 100 ºC,
and back pressure different to atmospheric have to be
taken in to account.
Examples of calculation of the cold set pressure
adjustment in back pressure and temperature
conditions:
A) DATA: Conventional valve (no bellows), set
pressure 20 barg, process temperature 260
ºC, and constant back pressure 1 barg, used
with vapours.
Adjusting the set pressure of the spring:
20 barg – 1 barg = 19 barg
From the temperature correction table we have to
apply a correction factor of 3% (as temperature is
between 251º and 500º C):
3 % of 19 barg = 0,57 barg (rounded 0,6 barg)
Cold set pressure adjustment for the valve to be
adjusted at the bench will be:
19 barg + 0,6 barg = 19,6 barg
B) DATA: Balanced valve (with bellows), set pressure
50 barg, process temperature 180 ºC, constant
back pressure 1,5 barg, used with vapours.
Adjusting the set pressure of the spring:
50 barg, as it is a balanced valve (with bellows), the
back pressure is not affected with the set pressure
adjustment, therefore back pressure is not deducted.
From the temperature correction table, a correction
factor of 2% as to be applied (as it’s between 101º and
250º C):
2% of 50 barg = 1 barg
Cold set pressure adjustment for the valve to be
adjusted at the bench will be:
50 barg + 1 barg = 51 barg
Is important to notice that in all cases (as it’s been
shown in examples A and B), temperature used for
calculations is inlet temperature in the valve, and that
the set pressure adjustment will be always multiplied
buy the temperature correction coefficient.
Cold set pressure adjustment = spring set pressure
adjustment x % corrector
The procedure is always the same and applicable to all
kind of valves.
6.4 POSITION OF THE ADJUSTING RING
To be able to reach the set pressure of the valve in
test benches when flow is small, the adjusting ring has
to be adjusted as it is shown below. Once the tests are
done, position the ring as shown in Table 1.
Disassemble the screw (14), turn the adjusting ring (7)
counter clockwise until it touches the disc holder’s bell
(8), then lower 1 or 2 grooves clockwise to avoid such
contact. This operation can be done through the outlet
flange of the valve, or by using a screwdriver through
the respective hole at the lock screw.
Once the ring is in position, assemble the screw
paying attention so the nut (32) gets placed between
the adjusting ring grooves. Once the screw is tightened
check that the ring is fixed so it can’t turn, but free
enough for it is self-alignment.
Never perform this operation with a valve that has
pressure, as an accidental popping may harm
anyone handling it.
6.5. SET PRESSURE REGULATION
If the valve opens itself at a lower or higher pressure
other than the set pressure, the compression of the
spring has to be adjusted, as shown below:
A) Disassemble the cap (3) or (50) if the valve
has a lever.
B) Loosening the adjusting screw net (13), the
adjusting screw will be released (11). Turning
it clockwise the set pressure will be increased
and turning it clockwise will decrease it.
C) Once the set pressure is adjusted, tighten the
nut and assemble the cap.
Never adjust the set pressure when the valve has
pressure, as the closing surfaces of the nozzle and
disc could damage if they are turned.

10
7 - TIGHTNESS TEST
The tightness test will be done after adjusting the set
pressure of that valve and using the same fluid.
Put the inlet pressure at 90 % of the set pressure.
Figure 1 shows the recommended method according
to norm API-RP 527 to be used in tests for valves
which will work with gas or vapour.
FIGURE 1
The outlet of the valve will be covered with a flange
with a single outlet hole made by a pipe with a
diameter smaller than 6 mm., and a wall of 1 mm.,
bended at 90º, with its edge plunged 12,7 mm. in a
container with water. With an air pressure at the inlet
of the valve equal to 90 % of the set pressure, the
number of bubbles per minute produced has to be
counted. This test is acceptable if the values indicated
in figure 2 aren’t surpassed; those are the values that
API – RP 527 recommends.
VALVE SET
PRESSURE
Barg. AT 15,6º C
ADMISSIBLE BUBBLE LEAKS
PER MINUTE
ORIFICES “C”
TO “F”
ORIFICES “G”
TO “T”
DIAMETER
≤18mm
DIAMETER>18
mm
FROM 1 TO 69 40 20
TO 103 60 30
TO 130 80 40
TO 172 100 50
TO 207 100 60
TO 276 100 80
TO 385 100 100
TO 414 100 100
FIGURE 2
While performing this test, special attention has to
be taken as the risk of any unforeseen popping
exists due the test is done to conditions very close
to the set pressure, which could be dangerous for
anyone handling the valve.
7.1 EXCESSIVE LEAK
If the tightness has been correctly performed and the
result is excessive leaks, the valve has to be
disassembled to verify that there are no foreign bodies
between the nozzle and the disc that might have
harmed the closing surface.
If the leak is cause by dirt from contamination of the
test fluid, cleaning the closing surface with cellulose
paper or any other non abrasive material impregnated
with dissolvent will be enough.
On the other hand, if the leak happens because the
closing surface has been marked, it has to be lapped
or even turned in the lath, depending on the depth of
such marks.
8 - TEST MANOMETER
Pressure measurement will be done with manometers
checked and calibrated periodically by “Quality
Assurance Department”, as indicated by norm ANSI B
40.1 Grade A.
The selection of the test manometer will be done
considering that the set pressure has to be between
the 25 % and 75 % of the lower part of the register an
error will be acceptable if it is not higher than 1% of the
measurement field.
9 – ATEX MARKING
The safety valves supplied for installation in potentially
explosive atmospheres are compliant with Directive
94/9 EC (ATEX). They are classified within Group II,
Category 2, and marked with a specifications plate that
shows the following inscription:
II 2 G c TX
TX TEMPERATURES RANGE
T
(
ºC
)
T1 300º<T≤450º
T2 200º<T≤300º
T3 135º<T≤200º
T4 100º<T≤135º
T5 85º<T≤100º
T6 T≤85º