Emerson CROSBY STYLE HC ISOFLEX Guide

CROSBY®STYLES HC AND HCA ISOFLEX™ SAFETY VALVES
INSTALLATION, MAINTENANCE AND ADJUSTMENT INSTRUCTIONS
Before installation these instructions must be read fully and understood
TABLE OF CONTENTS
1. Style HC/HCA ISOFLEX - parts..................... 2
2. Introduction ................................................... 3
3. Description of safety valve............................ 4
4. Storage........................................................... 4
5. Installation..................................................... 5
6. Hydrostatic testing ........................................ 6
7. Operation ....................................................... 9
8. Testing.......................................................... 10
9. Valve maintenance ...................................... 12
General information.................................... 12
Disassembly ................................................ 12
Repair procedure ........................................ 14
10. Valve assembly ............................................ 16
11. Spare parts .................................................. 18
12. Field service requirements......................... 19
13. Maintenance equipment ............................. 19
WARNING
Suitability of the material and product for
the use contemplated by the buyer is the
sole responsibility of the buyer. Also storage,
installation and proper use and application are
the sole responsibility of the purchaser. Emerson
disclaims any and all liability arising out of same.
Any installation, maintenance, adjustment,
repair and testing performed on safety relief
valves should be done in accordance with
the requirements of all applicable codes and
standards under which those performing such
work should maintain proper authorization
through appropriate governing authorities. No
repair, assembly and test work done by other
than Emerson shall be covered by the warranty
extended by Emerson to its customers.You
assume full responsibility for your work. In
maintaining and repairing Crosby products, you
should use only parts manufactured by Emerson.
Call your nearest Emerson sales office or our
factory for a service engineer should you wish
assistance with your field needs.
Safety precautions
Proper handling, storage, installation,
maintenance and operation is essential to the
safe and reliable functioning of any pressure
relief product.
Precautionary statements in the form of
warnings, cautions and notes are used
throughout this instruction to emphasize
important and critical factors where applicable.
Examples:
WARNING
An operating procedure or practice which, if not
observed strictly, may result in injury to personnel
or loss of life.
CAUTION
An operating procedure or practice which, if not
observed strictly, may result in damage to or
destruction of equipment.
NOTE
An operating procedure or condition which is
highlighted, underlined or printed in bold type for
emphasis.
These precautionary statements are by no means
exhaustive. Emerson cannot be expected to know,
evaluate and advise customers of all conceivable ways
in which tasks might be performed, or of the possible
hazardous consequences of each way.
Emerson.com/FinalControl © 2017 Emerson. All Rights Reserved. VCIOM-06201-EN17/05
Consequently, Emerson has not included
such comprehensive evaluation and disclaims
liability for work performed by other than
Emerson personnel. All personnel working with
Crosby products should be trained adequately
and be thoroughly familiar with the contents of
this manual.
Emerson cannot evaluate all conditions that
might injure personnel or damage equipment.
However, Emerson does offer the following
general safety precautions:
• Hearing and eye protection should be used
when working on a valve which is under
pressure.
• Never strike a valve which is under pressure.
Premature actuation can result.
• Never stand in front of the discharge outlet
of a pressure relief valve which is under
pressure.
Always approach and use any pressure relief
valvewith great care.
Often, the safety of lives and property
depends on the proper operation of the
safety valves. Consequently, the valves
should be kept clean and should be tested
periodically and reconditioned to make sure
theyfunctionproperly.
Engineering Doc. #IS-V3147A

2
CROSBY®STYLES HC AND HCA ISOFLEX™ SAFETY VALVES
INSTALLATION, MAINTENANCE AND ADJUSTMENT INSTRUCTIONS
FIGURE 1 - STYLE HC ISOFLEX SAFETY VALVE PARTS LIST
Part Part name Spare parts*
1A Body
1B Nozzle
3 Nozzle ring 3
4 Nozzle ring set screw
5 Disc insert 1
6 Disc holder 2
7 Disc holder retaining nut
8 Disc holder retaining cotter 1
9 Guide 3
10 Guide ring 3
11 Guide ring set screw
12A Spindle point 3
12B Spindle rod 3
12C Spindle rod pin 3
13 Bonnet
14 Bonnet stud
15 Bonnet stud nut
16 Spring 3
17 Bottom spring washer 3
18A Top spring washer 3
18B Bearing pin 3
18C Locking pin 3
19 Bearing adapter
20 Bearing
21A Adjusting bolt
21B Adjusting bolt bearing
22 Adjusting bolt nut
23 Spindle nut
24 Spindle nut cotter 1
25 Cap
26 Cap set screw
27 Lever
28 Lever pin
29 Lever pin cotter 1
30 Forked lever
31 Forked lever pin
32 Forked lever pin cotter 1
34 Test clamp
36 Test rod
37 Seal and wire
38 Protective hood
39 Drain plug
40 Hydro test plug assembly
41 Nameplate
42 Drive screw
43** Cooling spool
44** Cooling spool stud
45** Cooling spool stud nut
NOTES
* Spare parts designation (see notes 1, 2, 3 in Section 2)
**For Crosby Style HCA ISOFLEX only

3
CROSBY®STYLES HC AND HCA ISOFLEX™ SAFETY VALVES
INSTALLATION, MAINTENANCE AND ADJUSTMENT INSTRUCTIONS
NOTES
1. Consumable spare parts: valve parts which should
be replaced as part of any disassembly, and discs
and disc inserts which must be replaced if seats
are damaged.
2. Repair spare parts: valve parts exposed to wear
and/or corrosion during normal operation.
They are in fluid flow paths and may require
replacement as part of any repair.
3. Insurance spare parts: valve parts exposed to
process or environmental wear and/or corrosion
and may require replacement as part of a
majorrepair.
Emerson recommends that sufficient inventory
of spare parts be maintained to support process
requirements. Always be sure to use genuine
Emerson parts to ensure continued product
performance and warranty.
2 INTRODUCTION
Crosby Style HC and HCA ISOFLEX safety
valves have been selected because of their
performance features, reliability and ease
ofmaintenance.
This manual contains information on
installation, hydrostatic testing, field testing
and adjustments and maintenance of these
valves. It is specific to the Isoflex design K
through M2orifice sizes. Adherence to the
installation and maintenance procedures
specified in this manual will provide the utmost
in safety, a minimum of maintenance and a
long service life.
Style HC is a high capacity reaction type safety
valve designed for saturated and superheated
steam applications to temperatures of 750°F.
Crosby Style HCA is a high temperature
version of the Style HC, with an alloy steel
construction suitable to temperatures
upto1020°F. TypicallyStyle HCA valves are
used for superheaters and reheater outlets.
FIGURE 2 - STYLE HCA ISOFLEX SAFETY VALVE
DetailsofStyle HC and HCA safety valves,
materials of construction, sizes, pressure-
temperature ratings, dimensions, weights and
certified capacities are available on request.
No special tools are necessary for the
maintenance of Style HC and HCA safetyvalves.
However, tools and equipment are available
to ease disassembly and on site testing of
the valves. Such tools and equipment include
the hydraulic set pressure device, the air
set pressure device (see Figure 15) and the
hydraulic jacking device (see Figure 14).
Detailed instructions on their use can be found
in instructions I-11288, T-1652 and I-1167
respectively.
Whenever Style HC/HCA safety valve parts
names are used in this manual, parts numbers
in parenthesis follow. The parts numbers are
an aid to identifying the parts in Figures 1 and 2
and the correlating parts list.

4
3 DESCRIPTION OF SAFETY VALVES
Crosby Style HC/HCA safety valves are shown
in Figures 1 and 2. These drawings illustrate
the safety valves assembled in cross-section,
and cover the essential elements of the valves.
Approved drawings supplied with the valves
should be used when installation and/or
specific information is required.
Inside the body (1A) is housed the upper portion
of the nozzle (1B), nozzle ring (3), and the
guide ring (10). The disc insert (5) is held in
place in the disc holder (6) by the spindle and
disc holder retainer nut (7). The nozzle ring
and adjusting rings are held in place by the
nozzle ring set screw (4) and the guide ring set
screw(11), which are threaded into the body.
4 STORAGE
Often, safety valves are on the job site
months before they are installed. Unless
they are stored properly and protected, their
performance may be affected seriously.
Rough handling may damage flanges or cause
misalignment of the parts. It is best to leave the
safety valves in their shipment cases and store
them in a dry place under cover until they are
tobe installed.
FIGURE 3 - VALVE BODY AS SHIPPED
FIGURE 4 - VALVE SUPERSTRUCTURE AS
SHIPPED
TOP VIEW - BODY
HYDRO COMPONENTS (see note 1, page 5)
CROSBY®STYLES HC AND HCA ISOFLEX™ SAFETY VALVES
INSTALLATION, MAINTENANCE AND ADJUSTMENT INSTRUCTIONS
Ordering spare parts
When ordering spare parts, the valve size,
style and shop number and/or serial number
should be given together with set pressure,
part name and reference number. The valve
assembly number is shown on the valve
nameplate as 'Shop number'. Spare parts may
be ordered from any Emerson sales office
orrepresentative.
Crosby Style HC/HCA ISOFLEX nameplate
(With sample information for illustrative
purposes only)
The guide (9) is retained between the body (1A)
and the bonnet (13) by the bonnet studs (14)
and the bonnet studs nuts (15). In the case of
Style HCA valves, a cooling spool (43) is placed
between the body and bonnet to protect the
spring from exposure to extreme temperatures.
The bonnet (13) contains the spring (16),
spring washers (17 and 18) and the spindle
assembly(12). The spindle point is held in
compression between the back face of the disc
insert (5) and the bottom spring washer. The
spring is compressed between the stationary
point of contact with the spindle and the
adjusting bolt (21A) atop the valve bonnet.
The adjusting bolt (21A) is locked in place by the
adjusting bolt nut (22) on top of the bonnet and
within the cap assembly. A means of manual
lifting is provided by the lever (27), lever pin (28),
forked lever (30), forked lever pin (31) and the
spindle nut (23).

5
5 INSTALLATION
Inlet piping
Many safety valves are damaged when first
placed in service because of failure to clean
the connections properly before installation.
The safety valve inlet, the vessel and the line
on which the safety valve is mounted must be
cleaned thoroughly of all foreign matter.
Safety valves should be mounted in a vertical
position, directly on the pressure vessel.
The ASME boiler and pressure vessel code limits
the distance between the safety valve inlet and
the boiler to the length of a standard tee fitting.
The nozzle should have a well-rounded
approach that provides smooth, unobstructed
flow between the vessel and the safety valve.
A safety valve should never be installed on a
fitting having an inside diameter smaller than
the inlet connection of the valve.
Such restriction of flow can cause faulty
valveoperation.
Inlet piping (nozzles) must be designed to
withstand the total resultant forces due to
the safety valve discharging at the maximum
accumulated pressure and the expected
piping loads. The precise nature of the loading
and the resulting stresses will depend on
the configuration of the safety valve and the
discharge piping. Determination of outlet
reaction forces is the responsibility of the
designer of the vessel and/or piping.
Outlet piping
Discharge piping should be simple and
direct. Back pressures built up by discharge
flow affect the operation of safety valves.
Where possible, a short vertical pipe connected
through a long radius elbow discharging
directly into the atmosphere is the most
desirable type of outlet piping.
Discharge piping should not impose any loading
on the safety valve. Excessive discharge piping
loads may cause seat leakage or faulty valve
operation. The inside diameter of the discharge
pipe must never be less than that of the safety
valve outlet.
Valve effluent must discharge to a safe
disposalarea.
Safety valve bodies have pipe thread openings
for drains. These should be connected to
prevent any accumulation of fluid in the valve
body. In addition, discharge piping also should
be drained to prevent any accumulation of fluid.
Care must be taken to ensure that the drains
are directed or piped to a safe disposal area.
Welding of welded inlet valve body to boiler
Welded inlet safety valve bodies should be
welded to the boiler in accordance with
applicable Code requirements. The protective
cover (Figure 3) should be left in place until
ready for the hydrostatic test of the unit.
If visual inspection is necessary, the protective
cover may be removed, but should be replaced.
CROSBY®STYLES HC AND HCA ISOFLEX™ SAFETY VALVES
INSTALLATION, MAINTENANCE AND ADJUSTMENT INSTRUCTIONS
NOTES
Note 1 to Figure 3
Delivered with the body and packaged in small
bag are the following:
• One O-ring (for hydrostatic test)
• One backup ring (for hydrostatic test)
• One hydrostatic test plug pin
Note 2 to Figure 4
Delivered with the superstructure and
packaged in a small box are the following:
• Valve nozzle ring*
• Valve nozzle ring set screw*
• Valve guide ring set screw*
• Seal wires
* Marked with valve identification number.
NOTE
When the above parts are removed from their boxes,
be sure that the identification of parts to valve number
is maintained and that the parts are stored to facilitate
later recovery for assembly.
Factory preparation of welded inlet valves
forshipment
All Crosby Style HC and HCA welded inlet safety
valves are equipped with hydrostatic test plugs
and shipped in two parts: valve body and valve
superstructure. This makes handling easier for
installation welding (seeFigures3and 4).
The welded inlet Style HC and HCA safety
valves are specially prepared for shipment
fromthe factory.
After the safety valve is tested as a complete
assembly for set pressure and tightness, the
spring set compression is held by spacer
blocks under the bottom spring washer as
illustrated in Figure 4.
The safety valve superstructure is then
removed from the valve body. The two portions
are boxed and shipped separately. Each portion,
ready for shipment, is illustrated in Figures 3
and 4.
Figure 3 shows the safety valve body as shipped
to the installation site. It is tagged as follows:
• Install and/or weld in place as required
• Prepare for hydrostatic test. See instruction
Hydrostatic plug in place
• Install O-ring and backup ring prior to
hydrostatic test.
Figure 4 shows the safety valve superstructure
as shipped to the installation site. It is boxed
separately from the valve body and is tagged
asfollows:
• Hold for assembly after hydrostatic test.

6
Hydrostatic testing using hydrostatic
testplugs
Before imposing the hydrostatic test pressure
on the vessel or system, perform the following
operations:
CAUTION
Before hydrostatic testing, the O-ring and backup
ring must be installed.
• Preparation for hydrostatic testing -
Weldedinlet safety valves
The O-ring, backup ring and the test plug
pin are shipped in a box attached to the
superstructure (see Figure 3). The contents
ofthe box are marked for identification.
To install the O-ring and backup ring refer
toFigure 3.
• Hydrostatic test
After the above preparation, the safety valve
is ready for hydrostatic test. Observations
should be made at the start of the test to
confirm that the O-rings have been installed
properly and there is no leakage when
pressure is applied.
• Assembly of valve
After completion of the hydrostatic test,
remove the hydrostatic test plug from
thenozzle.
CAUTION
Be sure the test plug is seated on the 45°
angleonthe nozzle inside diameter.
CAUTION
Make sure the cap has hand-tight contact with
the plug. Make sure there is enough thread
engagement of the cap onto the nozzle.
CAUTION
Tightening of the cap will not reduce leakage.
If leakage is evident, remove all pressure from
the vessel or system. Replace the O-ring and
thebackup ring.
WARNING
Do not try to assemble the valve or remove
the steel blocks from under the bottom spring
washerwithout use of proper servicing and
assembly equipment.
Replace the test plug in the nozzle bore.
Place the test plug cap over the plug and
screwit down hand-tight.
Install the test plug pin.
The valve is now ready for hydrostatic test.
CROSBY®STYLES HC AND HCA ISOFLEX™ SAFETY VALVES
INSTALLATION, MAINTENANCE AND ADJUSTMENT INSTRUCTIONS
6 HYDROSTATIC TESTING
General information
Depending on the type of inlet, hydrostatic
testing of safety valves may be carried out by
one of three means: blank flanges, test plugs or
test gags. In all cases, hydrostatic test pressure
must be limited to 1½ times the nameplate set
pressure of the valve.
Welded inlet safety valves
All Style HC/HCA welded inlet safety valves are
prepared for shipment from the factory with
hydrostatic test plugs, as detailed in Section 4 -
paragraph 'Factory preparation of welded inlet
valves for shipment' and Figure 3.
Hydrostatic tests of these valves shall be
conducted using hydrostatic test plugs as
detailed in paragraph below 'Hydrostatic
testing using hydrostatic test plugs'.
Flanged inlet safety valves
Flanged inlet safety valves should not be
installed for hydrostatic testing. Blank flanges
should be used instead of gagging the safety
valves. This prevents possible damage to the
safety valves due to excessive tightening of
the gag screws or leakage during hydrostatic
test which may result in costly repairs.
Blank flanges must be removed and the
safety valve reinstalled before the vessel
isplacedinservice.
If blank flanges are not used and the safety
valves are to be installed for hydrostatic
tests, Emerson recommends that hydrostatic
test plugs be used for hydrostatic test.
The detailed procedure is outlined in the
paragraph following. Hydrostatic test plugs for
flanged valves are optional equipment and are
providedonly when ordered.
CAUTION
Additionally, hydrostatic test pressure must be
limited to 10% above nameplate set pressure
when a test gag is used.
Remove the protective cover from the valve
body. Unscrew the cap from the nozzle.
Remove the test plug from the nozzle bore.
• Preparation for hydrostatic testing -
Flanged inlet safety valves
Flanged inlet safety valves are shipped
from the factory fully assembled. To use
the hydrostatic test plug, the valve must
be disassembled according to Section 9 -
paragraph 'Disassembly retaining spring
compression'.
• Installation of hydrostatic test plug
(seeFigure 3)
Inspect the hydrostatic test plug O-ring
groove.
Note: make sure the groove in the plug
isclean.
Install the O-ring and backup ring in the
testplug groove.
To aid removal, place the hydrostatic test
plug pin in the hole in the plug extension.
Unscrew the cap, which will engage the plug
pin and exert an upward force as the cap is
turned, thus lifting the plug. Remove from
thevalvenozzle.
Clean the nozzle bore and seat and inspect
the seating surface. If seating surfaces are
damaged, repair according to the directions
in Section 9 - paragraph 'Repair procedure'.
Assemble the valves according to the
instructions in Section 6 - paragraph
'Initialsafety valve assembly'.
Contact Emerson field service for service
equipment (see Section 12 - paragraph
'Service equipment available').

7
50 (3.45) 1 (1.4) 1 (1.4) 2 (2.7) 2 (2.7)
100 (6.89) 2 (2.7) 3 (4.1) 4 (5.4) 4 (5.4)
150 (10.34) 2 (2.7) 4 (5.4) 5 (6.8) 6 (8.1)
200 (13.79) 3 (4.1) 5 (6.8) 7 (9.5) 8 (10.8)
250 (17.24) 4 (5.4) 6 (8.1) 9 (12.2) 10 (13.6)
300 (20.68) 5 (6.8) 7 (9.5) 11 (14.9) 12 (16.3)
Hydrostatic test using gag
The safety valve test gag shown in Figure 5 can
be used with both welded and flanged inlets,
but at pressures no greater than 10% above the
nameplate set pressure.
Gagging should be done very carefully in
ordernot to overload the valve spindle or
causedamage to the valve seats.
The following outlines the recommended
procedure for gagging valves for
hydrostatictest:
• Remove the lever (27), forked lever (30),
cap(25) and spindle nut (23).
• Refer to Figure 5. Lubricate the threads and
pointed end of the gag screw. Install the
gag in place, being careful that the legs fit
uniformly. Contacts on both legs of the gag
should seat evenly on the underside of the
bonnet top.
• Tighten the gag finger-tight only at this point.
• Raise the system pressure to approximately
100psig below the nameplate set pressure
ofthe safety valve.
• Apply the necessary torque to the gag in
accordance with the value shown in the
tableabove for the specific orifice size. This
torque value is determined as follows:
- Determine Δ by subtracting the valve set
pressure from the hydrostatic test pressure.
- Read the value of Δ on the vertical scale.
Proceed horizontally to the appropriate
orifice size and then down to read the
torqueon the horizontal scale.
- The torque values (foot-pounds) obtained
should be increased by a factor of
approximately 25% to account for normal
variations in friction, safety valves and
testconditions.
CAUTION
Gags should not be used when inlet pressures are
more than 10% greater than the safety valve set
pressure. Damage to the valve may result.
CAUTION
Should any safety valve show seat leakage, the
pressure must be lowered until the leakage stops.
CAUTION
Never increase the gagging load while a safety
valve shows seat leakage. This can result
in damage to the valve seats and bending
ofthespindle.
CAUTION
Valve gags should not be left on the valves in
a gagged or loaded position for an extended
period or under conditions where large thermal
variations are expected.
FIGURE 5 - VALVE GAG
POSITION GAG EVENLY ON BONNET
• The torque should then be increased on the
gag about 10% above the initial torque value.
• After the hydrostatic test, the pressure on the
system should be dropped to approximately
100psi below the nameplate set pressure of
the safety valve. The gags should be loosened
at this point and removed from the valves.
• After the hydrostatic test, the gag should be
removed and the cap reinstalled according
toSection 10 - paragraph 'Assembly of cap'.
NORMAL GAGGING LOAD in ft·lb OF TORQUE (Nm) VS. ΔP
ΔP Orifice
(Overpressure less valve set pressure)
psi(bar)
psi (bar)
K K2M M2
CROSBY®STYLES HC AND HCA ISOFLEX™ SAFETY VALVES
INSTALLATION, MAINTENANCE AND ADJUSTMENT INSTRUCTIONS
• After applying the necessary torque to the
gags, increase the hydrostatic test pressure
to the required amount. Observations should
be made during the rising pressure cycle to
determine if any of the safety valves show
seat leakage.

8
Initial assembly
Remove the body protective cover (see
Figure3).
Take the nozzle ring (3), nozzle ring set
screw(4) and guide ring set screw (11) from
their package (see Figure 4). Match the set
screws to the body (1A) and bonnet (13) valve
identification markings.
Screw the nozzle ring (3) onto the nozzle (1B).
NOTE
The top of the nozzle ring (3) should be about one ring
revolution above the nozzle (1B) seating surface.
Remove the guide (9) and guide ring (10)
from the superstructure. The guide ring
should be screwed onto the guide. Install
the guide and guide ring assembly into the
top of the body(1A). Make sure the guide is
seated correctly in the body. Make sure that
the nozzle(1B) and disc insert (5) seats are
clean and undamaged. If cleaning or repair
is necessary refer to Section 9 - paragraph
'Repair procedure'.
Remove the lever (27), forked lever (30) and
cap (25) from the valve superstructure. Do not
remove the spindle nut (23).
After the superstructure in in place, inspect
tobe sure the bonnet (13) is fully seated on
theguide (9).
The nozzle ring (3) should now be lowered.
Lift the disc insert (5) slightly off the
seat by lifting the spindle assembly (12).
Place a screwdriver in the lower set screw hole.
Turn the nozzle ring to the left (clockwise) with
the screwdriver until the top edge of the nozzle
ring is below the nozzle (1B) seating surface.
The location can be checked by looking in
through the upper set screw hole while shining
a light through the lower set screw hole.
Lower the spindle assembly slowly until
it bottoms. Check that the nozzle ring
movesfreely.
Rotate the spindle clockwise several
revolutions to make sure that it is seated fully
on the disc insert and that the threads of the
spindle are not engaged.
The seating surfaces are now in full contact.
Install the bonnet stud nuts (15) on the bonnet
studs (14) and tighten uniformly in accordance
with Figure 6.
It is now necessary to remove the spacer blocks
under the bottom spring washer (17), thereby
transferring the spring load to the valve seats.
This should be done using the hydraulic jacking
device (see Figure 14). Refer to instruction
I-1167 for detailed instructions in the use of this
device.
After the spacer blocks have been removed, set
the nozzle ring (3) and guide ring (10) according
to Section 10 - paragraph 'Setting of rings'.
Lock the nozzle ring set screw (4) and the
guide ring set screw (11) in place, making sure
that the proper set screws are installed and
engaged fully in a notch. Lock wire them in
place and seal.
CAUTION
Each valve superstructure, nozzle ring and set
screw is identified and matched to a specific valve
body by a tag number and should be assembled
accordingly. Although all parts have been cleaned
thoroughly, inspected, lubricated and protected
for shipment, the parts should be inspected
before installation for evidence of foreign matter
or damage. Special attention should be given
to the seating surfaces of the disc and nozzle.
These seats should be free from surface damage.
If cleaning or repair is necessary refer to
Section 9 - paragraph 'Repairprocedure'.
CAUTION
Do not permit any rocking motion of the
spindle(12) or any other part while lowering the
superstructure into the body (1A). Any rocking
motion could damage the valve seats.
CROSBY®STYLES HC AND HCA ISOFLEX™ SAFETY VALVES
INSTALLATION, MAINTENANCE AND ADJUSTMENT INSTRUCTIONS
Initial safety valve assembly
After hydrostatic testing using hydrostatic test
plugs, the safety valves should be assembled.
NOTE
It is recommended that, on completion of all
hydrostatic tests using hydrostatic test plugs on new
installations, a Emerson service technician be present
for assembly of the safetyvalves (see Section 12 -
'Field service requirements').
Check the valve identification numbers and
match the proper valve superstructure to each
valve body.
The nozzle ring (3) and the set screws (4 and11)
are packaged together and shipped with the
superstructure as shown in Figure 4.
Using a suitable lifting device, lift the valve
superstructure with the spindle assembly(12)
vertical. Inspect and clean the guide-to-bonnet
fit and the body-to-guide fit. Position the
superstructure so the valve identification
number stamped on the bonnet (13) is
oppositethe valve outlet.
Lowering the valve superstructure slowly,
carefully lower the disc holder (6) into the
guide(9).

9
⅝-11 60 (81) 90 (122) 120 (163)
¾-10 100 (136) 150 (203) 200 (271)
⅞-9 160 (217) 240 (325) 320 (434)
1-8 240 (325) 370 (502) 500 (6-78)
1⅛-8 350 (475) 525 (712) 700 (949)
FIGURE 7 - EFFECT OF NOZZLE RING
FIGURE 8 - EFFECT OF GUIDE RING
7 OPERATION
Crosby Style HC/HCA safety valves open with a
sharp pop at the set pressure and remain open,
relieving rated capacity at 3% overpressure.
As inlet pressure decays below the opening
pressure, the safety valve remains open until
a pressure about 4% below the set pressure
is reached. At that point, the safety valve
closessharply.
Nozzle ring
Guide ring
CROSBY®STYLES HC AND HCA ISOFLEX™ SAFETY VALVES
INSTALLATION, MAINTENANCE AND ADJUSTMENT INSTRUCTIONS
FIGURE 6 - TIGHTENING OF BONNET AND/OR
COOLING SPOOL STUD NUTS
Stud thread
Torque (ft·lb) (Nm) to produce stress in stud bolts
30.000psi (2.068bar) 45.000psi (3.203bar) 60.000psi (4.137bar)
Stress Stress Stress
ft·lb (Nm) ft·lb (Nm) ft·lb (Nm)
4 studs 6 studs
NOTES
1. Valve studs and nuts shall be clean and inspected
visually to ensure freedom from any objectionable
foreign matter, rust, burnsor physical damage.
2. With the bonnet in place, lubricate the bonnet
studs threads, the nut threads and nut face with
'Never-Seez' compound (which conforms to
Government specification MIL-A-907B, Federal
stock number 803-286-5453) or equivalent.
3. Install nuts on the studs finger-tight.
4. Tighten the nuts in the sequence shown in Figure
6 to approximately one-half the torque value
shown in the table. Repeat the same sequence
of tightening to the torque value shown. Then,
starting with the number 1 nut, tighten each nut in
order in a clockwise or counterclockwise direction
to the value shown in the table above.
5. Wipe off excess lubricant.
Complete the valve assembly with the cap assembly as described in Section 10 - paragraph 'Assembly of cap'
and seal wire the cap set screws.
The sharp opening is produced in two stages.
The initial lift is produced when the steam
pressure under the disc insert (5) exceeds
the spring pressure. To aid in starting the
popping action, steam escapes between the
safety valve seats and is deflected by an angle
on the nozzle ring (3) as shown in Figure 7.
This escaping steam acts on the face of the disc
holder (6) causing an unbalance and the safety
valve pops open. As the disc holder moves
vertically, steam begins to react against the
guide ring(10) and to push the disc holder up
to a high lift as shown in Figure 8. The reaction
of the deflected steam pushes against the
underside of the disc holder and lifts it still
higher on an accumulation of pressure.
As the boiler pressure drops, the safety valve
disc insert (5) settles to a moderate lift and
closes sharply.
The nozzle ring (3) is primarily for ensuring
sharp opening action. Raising the nozzle
ring, bringing it closer to the face of the disc
holder(6), eliminates 'simmer' or 'warn'.
The guide ring (10) is primarily for controlling
blowdown. Raising the guide ring reduces the
reactive pressures against the disc holder and
reduces blowdown. Lowering the guide ring
increases the reactive pressures against the
disc holder and increases the blowdown.

10
Install the gags as follows (refer to Figure 5):
• Remove the lever (27), forked lever (30),
cap(25) and spindle nut (23).
• Lubricate the threads and pointed end
ofthegag screw.
• Install the gag in place, being careful that the
legs fit uniformly. Contacts on both legs of the
gag should seat evenly on the underside of
the bonnet (13) top.
• Tighten the gag finger-tight.
Raise the system pressure until the safety
valvepops.
Record the popping and reseating
pressures(pressure at which the safety
valvecloses sharply).
CROSBY®STYLES HC AND HCA ISOFLEX™ SAFETY VALVES
INSTALLATION, MAINTENANCE AND ADJUSTMENT INSTRUCTIONS
CAUTION
All safety valves on the system except the
valve that is to be popped should be gagged.
System pressure should be 70% of valve set
pressure before gagging to prevent added loads
from being applied to the valve spindle due to
thermalexpansion.
Gagging must be done with care not to overload
the spindle since considerable damage may occur
to the spindle and other valve internals. However,
a minimum torque should be applied to the gag
byhand to ensure that the valve will not open.
8 TESTING
Set pressure testing and valve adjustments
The set pressure of a safety valve may be
checked without removing the valve from
the system by two methods described in the
following paragraphs:
• Set pressure lift assist device
The first method of set pressure testing is
with the use of a set pressure lift device.
This allows set pressure testing of the safety
valves on the system at pressures below
normal system operating pressures.
Two devices are available for use on
Crosby Style HC/HCA safety valves: the air
set pressure device and the hydraulic set
pressure device. Refer to test procedure
T-1652 for detailed instructions in the use of
the air set pressure device and instruction
I-11288 for detailed instructions in the use of
the hydraulic set pressure device.
• System pressure
The second method of set pressure testing is
by raising the system pressure and popping
the safety valve. Set pressure testing using
this method will determine the safety valve
set and closing pressure (blowdown).
Setting the safety valve with the set pressure
lift device is recommended before raising
the system pressure for popping pressure
testing. This allows the set point to be
established without raising and lowering
system pressure several times to determine
the safety valve set pressure.
Before set pressure testing and raising the
system pressure, the following items should
be checked:
- A pressure gauge with known accuracy
should be located on the system
beingtested.
- Outlet piping should be anchored sufficiently
to prevent any vibrations while the safety
valve is discharging. The outlet piping
should be direct and there should be no
obstructions to restrict the safety valve
discharging.
WARNING
Never strike a valve which is under pressure.
Premature actuation can result.
WARNING
Hearing and eye protection should be used when
working on a valve which is under pressure. Never
stand in front of the discharge of a safety valve
which is under pressure.
- Set screws should be tight and lock
wired. The tapped holes in the body for
drains should be connected to the drain
orplugged.
- Lifting gear should be fastened securely to
the safety valve to assist personnel testing
the valve. A rope may be attached through
the hole provided in the lever should
mechanical lifting be necessary.
• Communications should be set up between
the control room and personnel in the
testarea.