Emerson SAPAG 8400 Series Technical specifications

Sapag Safety Valves Series 8400/8500/8490/8590
Installation and Maintenance Instructions
without notice SAPDR-0060-EN-1308
Table of Contents
1. Introduction
2. Storage and Handling
3. Installation
Care in Handling
Inspection
Inlet Piping
Outlet Piping
4. Hydrostatic Pressure Tests
Hydrostatic Test of Vessel or System
Hydrostatic Test of Outlet System
5. Setting, Testing and Adjustments
New Valves
Reconditioned Valves
Valves Removed from Service
The Test Bench
Test Fluids
Valve Operation
Set Pressure Changes
Set Pressure Adjustment
Nozzle Ring Settings
• Style 8500/8590
Cold Differential Test Pressure Adjustments
• Temperature Correction
• Back Pressure Correction
Seat Leakage Tests
• Metal-to-Metal Seated Valves
• Soft Seated Valves
6. Valve Maintenance
Visual Inspection and Neutralizing
Disassembly
Cleaning
Inspection
Reconditioning of Valve Seats
Lapping Procedures
• Lapping Blocks
• Lapping Compounds
• Machining of Nozzle Seats
• Machining of Disc Insert Seats
Assembly
Assembly of Cap and Lifting Lever Devices
Soft Seat Construction
7. Style Variations
8. Service Records
9. Spare Parts
10. Trouble Shooting Pressure Relief Valves
Seat Leakage
• Seats Damaged by Foreign Matter
• Distortion From Piping Strains
• Operating Pressure too close to Set Pressure
• Chatter
• Incorrectly Adjusting Lifting Gear
• Other Causes of Seat Leakage
• Corrosion
11. Emerson Valves & Controls’ Field Services and Repair Programs
Ordering Information
Attention
The safety of lives and property often
depends on the proper operation of the
pressure relief valves. Consequently, the
valves should be kept clean and should be
periodically tested and reconditioned to
make sure they function properly.
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 pressure 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
Emerson products you should use only parts
manufactured by Emerson. Call your nearest
Emerson regional sales
office or representative for a Emerson service
engineer should you wish assistance with your
field needs.
SAPAG
Emerson.com/FinalControl © 2017 Emerson. All rights reserved.

Sapag Safety Valves Series 8400/8500/8490/8590
Installation and Maintenance Instructions
Emerson reserves the right to change the contents without notice page 2
1 Body
2 Nozzle
3 Nozzle Ring 3
4 Set screw 3, except P-T Orifice 8500/8590
4A Set Screw 3, (M-T Orifice)
4B Set Screw Rod 3, (M-T Orifice)
4C Set Screw Pin 3, (M-T Orifice)
5 Disc Holder 2
6A Bellows Tailpiece 2
6B Bellows 2
6C Bellows Flange 2
8 Disc Insert 1
9 Retention Clip 1
10 O-Ring 1
11 O-Ring Retainer 2
12 Retainer Screw(s) 2
13 Nozzle Ring Lockscrew P-T Orifice 8500/8590
14 Set Screw Plug P-T Orifice 8500/8590 (not shown)
15 Guide 3
16 Spindle 3
Parts list
No. Part Name Notes No. Part Name Notes
Figure 1
Style 8400 Style 8490 Soft Seat
8400/8500
only
Nozzle ring
Set Screw
(P-T Orifice
have lockscrews)
Style 8500
D-N Orifice
construction
17 Spindle Cotter Pin 1 (L-T orifice)
18 Spring 3
19 Spring Washers 3
20 Bonnet
21 Bonnet Stud
22 Bonnet Stud Nut
24 Adjusting Bolt
25 Adjusting Bolt Nut
26 Pipe Plug
27 Set Screw Gasket 1
28 Guide Gasket 2
29 Tailpiece Gasket 1
34 Seal & Wire
35 Seal Clip
36 Nameplate
40 Screwed Cap
41 Cap Gasket 1
Gasket Kit 1,4
42 Test Gag/Plug ( Plug only shown)
43 Test Gag plug gasket 1
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 Valves & Controls 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.
4. Contains complete set of gaskets for all style of valves
Note:
This vent must
remain open on
8490/8590
construction

Sapag Safety Valves Series 8400/8500/8490/8590
Installation and Maintenance Instructions
Emerson reserves the right to change the contents without notice page 3
Ordering Spare Parts
When ordering spare parts, the valve size, style and assembly number and/or serial number should
be given together with set pressure, part name and reference number from page 2. The valve
serial number is shown on the valve nameplate. Spare parts may be ordered from any Emerson
Valves & Controls Regional Sales Office or Representative.
Figure 2
Sample nameplate
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 strictly observed may
result in injury to personnel or loss of life.
CAUTION: An operating procedure or practice which if not strictly observed may
result in damage to or destruction of equipment.
These precautionary statements are by no means exhaustive.
Emerson Valves & Controls cannot be expected to know, evaluate, and advise customers
of all the possible applications and operating conditions for its products or of the possible
hazardous consequences which may result from the misapplication or misuse of such products.
Consequently, the improper handling, storage, installation, use or maintenance of any Emerson
Valves & Controls Product by a non Emerson Valves & Controls employee may void any Emerson
Valves & Controls guarantees or warranties with respect to such Product.
All personnel working with Emerson Valves & Controls products should be adequately trained and
thoroughly familiar with the contents of the appropriate instruction manual(s).
Emerson Valves & Controls cannot evaluate all conditions in which the products may be used.
However, Emerson Valves & Controls offers the following general safety suggestions:
• Never subject valves to sharp impact loads.
Rough handling (striking, bumping, dropping, etc.) may alter the pressure setting, deform valve
parts and adversely affect seat tightness and valve performance. Striking a valve which is under
pressure can cause premature actuation.
• Always lower the system pressure to the pressure level specified in the instruction before
making any adjustment to the valve. Furthermore, always install a proper test rod to gag an
installed valve before making any ring adjustments on the valve.
• Ear and eye protection should be used when working on a valve which has pressure.
• Never stand in front of the discharge outlet of a pressure relief valve which is under pressure.
• Always stand to the side of and at a safe distance from the valve discharge and use extreme
care when observing a valve for leakage.
The above precautions and suggestions are by no means exhaustive and the user should always
approach and use any pressure relief valve with great care.
Operation, Installation and Safety Instructions are available at www.valves.emerson.com or
from your local Emerson regional sales office or representative.

Sapag Safety Valves Series 8400/8500/8490/8590
Installation and Maintenance Instructions
Emerson reserves the right to change the contents without notice page 4
1. Introduction
Sapag Series 8000 pressure relief valves have been selected for installation because of their
performance features, reliability and ease of maintenance.
Adherence to the installation and maintenance procedures specified herein will provide the utmost
in safety, a minimum of maintenance, and a long service life. Sapag type 8400/8500/8490/8590
Valves are manufactured in accordance with the requirements of Section VIII Pressure Vessels,
ASME Boiler and Pressure Vessel Code. Type 8400 is a conventional closed bonnet valve. Type
8490 has a balanced bellows for minimizing the effect of back pressure.
Style 8500 is a high performance valve designed specifically for liquid service. The 8500 features
patented contoured liquid trim in a standard 8400/8490 envelope.
2. Storage and Handling
Valves are often on hand at the job site months before they are installed. Unless properly stored
and protected, valve performance may be adversely affected.
Rough handling and dirt may damage or cause misalignment of the valve parts. It is recommended
that the valves be left in their original shipping containers and that they be stored in a warehouse
or at a minimum on a dry surface with a protective covering until they are used.
3. Installation
Care in Handling
Pressure relief valves must be handled carefully and never subjected to sharp impact loads. They
should not be struck, bumped or dropped. Rough handling may alter the pressure setting, deform
valve parts and adversely affect seat tightness and valve performance.
When it is necessary to use a hoist, the chain or sling should be placed around the valve body and
bonnet in a manner that will ensure that the valve is in a vertical position to facilitate installation.
The valve should never be lifted or handled using the lifting lever.
Inlet and outlet protectors should remain in place until the valve is ready to be installed on the
system.
Inspection
Pressure relief valves should be visually inspected before they are installed to ensure that no
damage has occurred during shipment or while in storage.
All protective material, sealing plugs and any extraneous material inside the valve body or nozzle
must be removed.
The valve nameplate and other identifying tags should be checked to ensure that the particular
valve is being installed at the location for which it was intended.
The valve seals protecting the spring setting and ring adjustments should be intact. If seals are not
intact, the valve should be inspected, tested and seals properly installed before use.
Inlet Piping
Pressure relief valves should be mounted vertically in an upright position either directly on
a nozzle from the pressure vessel or on a short connecting fitting that provides direct and
unobstructed flow between the vessel and the valve. Installing a pressure relief valve in other
than this recommended position might adversely affect its operation. Where rounded or beveled
approaches cannot be provided ahead of the valve it is recommended that one size larger nozzle
or fitting be used. A valve should never be installed on a fitting having a smaller inside diameter
than the inlet connection of the valve.
Inlet piping (nozzles) must be designed to withstand the total resultant forces due to the
valve discharging at the maximum accumulated pressure and the expected piping loads. The
magnitudes of the bending moment exerted on the inlet piping will depend on the configuration
and method of supporting the outlet piping.
Many valves are damaged when first placed in service because of failure to clean the connections
properly when installed. Both the valve inlet and the vessel and/or line on which the valve is
mounted must be thoroughly cleaned of all foreign material. The inlet connection bolts or studs
should be drawn down evenly to avoid straining the valve body with possible distortion of the
nozzle flange or base.

Sapag Safety Valves Series 8400/8500/8490/8590
Installation and Maintenance Instructions
Emerson reserves the right to change the contents without notice page 5
Outlet Piping
Outlet piping should be simple and direct. Where possible, for non-hazardous fluids, a short
discharge pipe or vertical riser connected through a long radius elbow venting directly to
atmosphere is recommended. Such discharge piping should be at least the same size as the valve
outlet.
All discharge piping should be run as direct as is practicable to the point of final release for
disposal. Valve effluent must discharge to a safe disposal area.
Where discharge piping is long, due consideration shall be given to the use of long radius elbows,
and the reduction of excessive line strains through the use of expansion joints and proper means
of support to minimize line sway and vibration under operating conditions. Adequate drainage
is required to prevent corrosive media from collecting in the discharge side of the pressure relief
valve. When required, low point drains shall be provided in the discharge pipe. Particular care
must be observed to ensure that the drains are directed or piped to a safe disposal area.
In installations where the pressure relief valve discharges into a closed system, care must be taken
to ensure that built up and superimposed back pressure has been properly calculated, specified,
and accounted for when sizing and selecting the valve.
Where built up back pressure is expected to exceed 10% of set pressure or if superimposed back
pressure is variable, a bellows valve is required.
Discharge pipe
Low point
drain
Long radius
elbow
Free
support
Top of vessel
Rounded
approach
Short as
possible
Lid
Figure 3
Recommended installation-
discharging to atmosphere 4. Hydrostatic Pressure Tests
Hydrostatic Test of Vessel or System
When a pressure vessel or system is to be hydrostatically tested, it is recommended that the
pressure relief valve be removed and a blank flange be installed in its place. This practice
precludes the possibility of any damage to the pressure relief valve. Bent spindles and damaged
valve seats are problems that can be caused by improper hydrostatic test procedures.
Blank flanges must be removed and the pressure relief valve reinstalled before the vessel is placed
in service.
When the hydrostatic test must be performed with the valve in place, a test gag may be used.
Sapag Series 8000 are provided with test gags as standard. In the case of the Type C cap with
lifting lever, the lifting lever assembly must be replaced with a hydrostatic test cap and test
rod prior to hydrostatic testing. When test rods are used, care must be exercised to prevent
overtightening that could damage the valve spindle and valve seats. A test rod which is hand tight
will generally provide sufficient force to hold the valve closed.
After the hydrostatic test, the test rod (gag) must be removed and replaced by either a cap plug or
a cap not fitted with a test rod.
Hydrostatic Test of Outlet System
When a hydrostatic test must be conducted on the outlet piping system, with the valve in place,
special consideration must be given not to exceed the design pressure limits of the downstream
side of the pressure relief valve. The outlet side of a pressure relief valve is known as the
secondary pressure zone. This zone is normally designed to a lower pressure rating than the
inlet and frequently is designed to a lower pressure rating than the outlet flange. This is
particularly true in the case of balanced bellows designs and in the larger valve sizes.
Consult Sapag products specifications for the back pressure design limits of the Series 8000
valves.
5. Setting, Testing and Adjustments
New Valves
Each Sapag pressure relief valve is carefully set and tested at the factory prior to shipment.
However, it is good practice to inspect the valve prior to installation.
This inspection determines any damage which may have occurred due to rough handling in transit
or storage and initiates appropriate service records.
Reconditioned Valves
Valves which have not been in service for extended periods due to plant shutdown or long term
storage, or valves which have been repaired or reconditioned, should also be tested before being
put into operation.
Valves Removed From Service
Valves being removed from service should be tested on a shop test bench before being
disassembled to determine the set pressure and seat tightness. This is an important phase of
the maintenance routine and the test results should be recorded for review and determination of
necessary corrective action.
The “as received from service” condition of a pressure relief valve is a most useful tool in
establishing the proper time interval between inspections.
CAUTION: Improper testing may
cause valve damage and seat
leakage.

Sapag Safety Valves Series 8400/8500/8490/8590
Installation and Maintenance Instructions
Emerson reserves the right to change the contents without notice page 6
The Test Bench
The quality and condition of the shop test bench is paramount to obtaining proper test results. The
test bench must be free of leaks and the test fluid must be clean. Solids or other foreign material
in the test medium will damage the seating surfaces of the pressure relief valve being tested.
The test pressure gage must be calibrated and have a range proper to the pressure level of the
valve setting. Set pressure should fall within the middle third of the dial range of the test gage.
The test bench provides an accurate and convenient facility for determining valve set pressure
and seat tightness. It does not duplicate all of the field conditions to which a pressure relief valve
will be exposed while in service. It is not practical to attempt to measure relieving capacity or
blowdown using a test bench.
Test Fluids - Set Pressure Test
The Test Fluid should be air or nitrogen for valves used on gas and vapor service and water for
valves used on liquid service. Valves for steam service should be tested on steam. It may be
necessary to make a correction to the adjusted set pressure to compensate for the difference in
temperature of the test fluids(see appropriate instruction).
Valve Operation
Sapag Series 8000 valves intended for compressible fluid service and tested with air or steam will
open with a sharp clear popping action at the set point. Valves for liquid service tested with water
are considered open when there is a continuous unbroken stream of liquid flowing from the valve.
Set Pressure Changes
Set pressure changes beyond the Sapag specified spring range will necessitate a change in the
valve spring assembly consisting of the spring and two fitted spring washers. The new spring and
washers must be obtained from Sapag and the valve must be reset and the nameplate restamped
by an authorized valve repair facility.
Set Pressure Adjustment
Before making any adjustments reduce the pressure under the valve seat to at least 10% below
the stamped opening pressure. This will prevent seat damage due to turning of the disc on the
nozzle seat and minimize the chance of an inadvertent valve opening. A strong (high) ring position
is necessary to obtain a good clean popping action of the valve on air or gas with the limited
volume available on the test bench.
a. (Not required for testing on liquid.) Remove the nozzle ring set screw and raise the nozzle ring
until it touches the disc holder, then back it down two (2) notches. Exercise care in counting
the number of notches moved so that the ring can be returned to its proper position following
testing.
Moving the notches on the nozzle ring to the left will lower the nozzle ring.
Replace the nozzle ring set screw before each set pressure test. The set screw must engage one
of the ring notches, being careful that it does not bear on the top of a tooth.
b. Remove the cap or lifting lever following the instruction for valve disassembly. (See paragraph
6)
c. Loosen the adjusting bolt nut and turn the adjusting bolt clockwise to increase set pressure or
counterclockwise to reduce set pressure.
d. Retighten the adjusting bolt nut following each adjustment.
e. Two or three consecutive valve openings at the same pressure are necessary to accurately verify
the opening pressure.
f. Once the set pressure has been established, lower the nozzle ring to the installed ring position
as indicated in Table 1 and replace the nozzle ring set screw as described above. Seal wire the
adjusting bolt and adjusting ring set screw with identifying seals.
Nozzle Ring Settings
The nozzle ring adjustment is made at the factory and resetting in service is seldom necessary.
Should it be necessary to change blowdown or reduce valve simmer, the nozzle ring may be
adjusted as follows: (See the next paragraph for P, Q, R and T OrificeType 8500/8590)
a) Remove the nozzle ring set screw and insert a screwdriver to engage the ring notches.
b) Turning the ring to the right raises the ring, thereby increasing blowdown. Turning the ring to
the left lowers the ring, thereby decreasing the blowdown.
c) Do not lower the nozzle ring to the point where the valve begins to have excessive simmer.
Raising of the ring will reduce simmer.
d) The nozzle ring should not be moved more than two notches before retesting. When making
adjustments, always keep count of the number of notches and the direction in which the nozzle
ring is moved. This will permit returning to the original setting in case of error.
CAUTION: Should any adjustments
be made while the valve is
installed on a pressurized system,
the valve should be gagged while
ring adjustments are made.

D, E, F, G, H, J, K, L 1500 psig
M 1100 psig
N, P 1000 psig
Q 600 psig
R, T, T2300 psig
15-400 3%
401-1000 4%
1001-1500 5%
Sapag Safety Valves Series 8400/8500/8490/8590
Installation and Maintenance Instructions
Emerson reserves the right to change the contents without notice page 7
• Type 8500/8590
The Type 8500/8590 in the P, Q, R and T Orifice sizes is preset at the factory and cannot be
externally adjusted in the field, since the special contoured skirt on the disc holder prevents
engagement of the set screw with the nozzle ring. As a result the nozzle ring is not slotted and
is held in place by three set screws. The position of the nozzle ring must be set prior to valve
assembly as follows:
a. Screw the nozzle ring (3) on to the nozzle. The top of the nozzle ring should be below the nozzle
seating surface.
b. Install the disc insert retention clip (9) onto the disc insert. Assemble the disc insert (8) and disc
holder (5). The disc insert should snap into place using hand force only.
c. Lower the disc holder and disc insert carefully onto the nozzle.
d. Reach through the valve body outlet and turn the nozzle ring until it lightly touches the disc
holder. This is the highest lock position.
e. Carefully remove the disc holder and disc insert from the valve.
f. Lower the nozzle ring (turn to the left) the total number of revolutions shown in Table 2.
g. Carefully tighten each of the set screws on the nozzle ring to hold the ring in position.
Table 1
Service Orifice size Nozzle ring setting
(Below Highest Lock Position)
Styles 8400/8490 Pressure Relief Valve Recommended Nozzle Ring Settings
Vapor & Gases D through J -5
K through N -10
P through T -15
Liquids D through G -5
H through K -10
L through N -20
P through T -30
Styles 8500/8590 Pressure Relief Valve Recommended Nozzle Ring Settings
Liquids & Gases D, E, and F -3
G, H, and J -5
K and L -10
M and N -15
P and Q (See table 2)
R and T (See table 2)
Minus sign: indicates number of ring notches below starting position of nozzle ring which is the
highest position with the valve closed (contact with disc holder)
Table 2
8500/8590 Nozzle Ring Setting
Orifice Size Total revolutions below
highest lock position
P and Q 3/4 Revolution
R and T 1 Revolution
Cold Differential Test Pressure Adjustments
When a pressure relief valve is on a test bench at room temperature and atmospheric pressure,
and is to be installed on a system operating at a higher temperature and/or a higher back pressure,
a compensating adjustment is necessary. The test pressure required to have the valve open at the
desired set pressure under actual service conditions is known as the cold differential test pressure.
• Temperature Correction
When a Sapag Series 8000 valve is set on air or water at room temperature and then used at a
higher service temperature, the test pressure shall be corrected to exceed the set pressure using
the temperature correction shown in Table 3.
Note: this table is not applicable to steam service valves.
Table 3
Operating
Temperature % Excess Pressure
0-150°F None
151-600°F 1%
601-800°F 2%
801-1000°F 3%
• Back Pressure Correction
Conventional valves without balancing bellows set with atmospheric pressure at the outlet and
intended for use under elevated constant back pressure conditions shall be adjusted so that the
test pressure is equal to the set pressure minus the expected back pressure. See example below:
Set Pressure 100 PSI
Constant Back Pressure 10 PSI
Cold Differential Test Pressure 90 PSI
In all instances, the spring should be selected based on the cold differential test pressure; in the
example above, 90 PSI. See sample nameplate on page 3 which shows how temperature and back
pressure is indicated.
Saturated Steam Correction Factors
Sapag Style 8400 pressure relief valves that are used for saturated steam service and are within
the set pressure limits established in Table 4 may be set on air at ambient temperature, provided
the correction factors in Table 5 are applied to the valve set pressure.
Table 4 - (8400 Style Only)
Orifice Size Saturated Steam Set
Pressure (max)
Table 5 - Saturated Steam Service
Air Set Pressure Correction Factors at
Ambient Temperature
Set Pressure % Increase in Spring
(psig) Set Pressure

15-1000 (1.03-68.9) 40 0,6 0,017 20 0,3 0,0085
1500 (103.4) 60 0,9 0,026 30 0,45 0,013
2000 (137.9) 80 1,2 0,034 40 0,6 0,017
2500 (172.4) 100 1,5 0,043 50 0,75 0,021
3000 (206.8) 100 1,5 0,043 60 0,9 0,026
4000 (275.8) 100 1,5 0,043 80 1,2 0,034
5000 (344.8) 100 1,5 0,043 100 1,5 0,043
6000 (413.7) 100 1,5 0,043 100 1,5 0,043
Sapag Safety Valves Series 8400/8500/8490/8590
Installation and Maintenance Instructions
Emerson reserves the right to change the contents without notice page 8
Seat Leakage Tests
Ambiguous terms such as “bubble tight”, “drop tight”, “zero leakage” and “commercial tightness” are
sometimes used to describe seat tightness. These terms, however, lack uniform definition and true practical
meaning.
• Test Procedure
API Standard 527 provides a standard for “commercial” tightness and has been adopted by industry and
users in order to clarify testing methods and tightness criteria. This standard applies to flanged inlet nozzle
type pressure relief valves.
• Test Apparatus
A typical test arrangement for determining seat tightness for pressure relief valves per API Standard 527 is
shown in Figure 4. Leakage is measured using a 5/16 in. OD tube with 0.035 in. wall. The tube end is cut
square and smooth, is parallel to and 1/2 inch below the surface of the water. A snap-on type test clamp
shown in Figure 5 is available .
• Procedure
With the valve mounted vertically, the leakage rate in bubbles per minute shall be determined with pressure at the
pressure relief valve inlet raised up to and held at 90 percent of the set pressure (or cold differential test pressure -
CDTP) immediately after popping. This applies except for valves set at 50 psig or below, in which case the pressure
shall be held at 5 psig below the set pressure immediately after popping. The test pressure shall be applied for a
minimum of one minute for valves of inlet sizes through 2”; two minutes for sizes 21/2”, 3” and 4”; five minutes for
sizes 6” and 8”. Air (or nitrogen) at approximately ambient temperature shall be used as the pressure medium.
• Tightness Standard
a. Metal-to-Metal Seated Valves. The leakage rate in bubbles per minute shall be observed for at least one minute
and shall not exceed the values indicated in table 6 below.
b. Soft Seated Valves. For soft seated valves there shall be no leakage for one minute (zero bubbles for one minute).
Table 6 - Maximum seat leakage rate - Metal seated pressure relief valves
Set Effective Orifice Sizes 0.307 In2and Smaller Effective Orifice Sizes Larger than 0.307 In2
Pressure Max. Bubbles Approximate Leakage Rate Max. Bubbles Approximate Leakage Rate
PSIG per Minute Per 24 Hours per Minute Per 24 Hours
(BarG) Standard Standard Standard Standard
Cubic Feet Cubic Meters Cubic Feet Cubic Meters
• Sapag Seat Tightness Standard-Liquid Service Valves (Style 8500/8590)
Sapag liquid service pressure relief valves are checked for seat tightness by a quantitative seat
leakage test.
All of the test fluid passing through an assembled valve is collected and measured per the
following test procedure:
1. The inlet pressure is adjusted to a test pressure which is 90% of the Cold Differential Test
Pressure.
Valves set below 50 psig are tested at 5 psig below the cold differential test pressure.
2. The test pressure is maintained for a period of not less than ten minutes.
• Allowable Leak Rate
The maximum allowable leakage rate should not exceed 10 cubic centimeters per hour per inch of
diameter of nominal valve inlet size. For nominal valve sizes of 1 inch or less, the leakage rate shall
not exceed 10 cubic centimeters per hour. For soft seated valves there shall be no leakage for one
minute.
• Soft Seated Valves
For exceptional seat tightness, Sapag offers an O-ring soft seat design. Refer to Figure 13 on page
15.
The Sapag soft seat design will provide a valve that has no visible leakage at a test pressure of 90
percent of the set pressure or cold differential test pressure. Soft seated valves are tested using
the same test procedure used for metal-to-metal seated valves.
Figure 4 - Typical test arrangement
Figure 5 - Seat leak apparatus for 150
& 300 lb. outlets 1 inch through 10
inch sices
Note: the cover plate should be
fitted with a suitabble device to
releive body pressure in case of
accidental popping of valve
Note: the tube must
be bent so that reservoir runs
parallel to face of coverplate
Tube 5/16” O.D. x 0.0035” Wall
7.92 mm O.D. x .88 mm Wall
Cover plate
Air receiver

D & E # 10-24 UNC
F, G H 1/4 - 20 UNC
J, K, L 1/4 - 20 UNC
M, N, P, Q, R, T 3/8 - 16 UNC
Sapag Safety Valves Series 8400/8500/8490/8590
Installation and Maintenance Instructions
Emerson reserves the right to change the contents without notice page 9
6. Valve Maintenance
Visual Inspection and Neutralizing
A visual inspection shall be made when valves are first removed from service. The presence of
deposits or corrosion products in the valve and in the piping should be recorded and valves should
be cleaned to the extent possible prior to disassembly. Check the condition of external surfaces for
any indication of corrosive atmospheric attack or evidence of mechanical damage.
CAUTION: Valves in hazardous
fluid service and any other
materials classified as dangerous
must be neutralized immediately
after removal from service.
Disassembly
Sapag Series 8000 valves should be disassembled as described below. Parts identification may be
found in Figure 1 on page 2. The parts from each valve should be properly marked and segregated
to keep them separate from parts used in other valves.
a. Remove the cap (40) and cap gasket (41). If the valve has a lifting lever device follow the
instructions on pages 15.
b. Remove the nozzle ring set screw (4) and set screw gasket (27).
Record the position of the nozzle ring (3) with respect to the disc holder (5) by counting
the number of notches required to raise the ring until it just touches the disc holder. This
information will be needed again when reassembling the valve. (Measure the revolutions for P,
Q, R and T Orifice Style 8500/8590. See Table 2)
c. Loosen the adjusting bolt nut (25). Before releasing the spring load, make note of the depth of
the adjusting bolt in the bonnet and count the number of turns required to remove the spring
load. This information will help when reassembling the valve to its approximate original setting.
d. Release all of the spring load by rotating the adjusting bolt (24) in a counterclockwise direction.
e. Remove the bonnet stud nuts (22).
f. Lift the bonnet (20) straight up to clear the spindle (16) and valve spring (18). Exercise care when
lifting the bonnet as the spring and spindle will then be free to fall aside.
g. The spring and spring washers (19) can now be lifted off the spindle (16). The spring and spring
washers are fitted together and must be kept together as a subassembly. Spring washers are
not interchangeable between ends of the spring.
h. Remove the spindle, guide (15), disc holder and disc insert (8). For balanced bellows valves
(Style 8490/8590) special care must be taken not to damage the bellows subassembly (6).
If parts are difficult to remove, due to the presence of corrosive or foreign materials, soaking in
a suitable solvent may be required.
i. Remove the spindle from the disc holder.
j. Lift the guide off the disc holder.
k. Disc Insert Removal
Table 7 - Series 8000 disc insert
threaded hole sizes
Orifice Size Thread Size
• Orifice Sizes D through M (Metal Seats)
Screw a standard bolt into the tapped hole (see table 7) in the face of the disc insert. Using
hand force pull the bolt straight out. The disc insert with the retention clip (9) should come out
with moderate force.
If the valve has been in dirty service it may be necessary to use a suitable solvent to aid in
removal. If additional pullout force is required, a bolt with a T handle may be used. The method
described below for Orifice sizes N through T may be used if necessary.
• Orifice Sizes N through T (Metal Seats)
Safety precautions should be followed whenever heavy parts are being lifted or transported.
Dropping disc holder assembly may dislodge the insert.
The removal of the insert is accomplished by the use of a tool as shown in Figure 6. This tool
consists of a rectangular steel bar which spans the outside diameter of the disc holder with
a center hole through which the standard bolt can be inserted before screwing into the disc
insert. A nut and washer is also required as shown. Tightening the nut with a wrench will exert
a pulling force on the disc insert and cause it to be removed from the disc holder.
• Orifice Sizes D through K (O-Ring Seats)
The O-Ring seat design for Orifice sizes D through K has a retaining screw in the center of the
disc insert. A drilled and tapped hole (4-40 UNC) is provided in the center of the retaining screw
for removal of the disc insert (Figure 7). Screw a standard bolt into the hole in the retaining
screw. Using hand force pull the bolt straight out. The disc insert with the retention spring
should come out with moderate force.
• Orifice Sizes L through T (O-Ring Seats)
Safety precautions should be followed whenever heavy parts are being lifted or transported.
Dropping the disc holder may dislodge the insert.
Remove the three retaining screws from the insert. Remove the retainer and O-ring seat. A
tapped hole (refer to table 7) is provided in the disc insert for insertion of a removal bolt. Follow
instructions for metal seated insert removal.
Figure 6
Figure 7
Remove disc insert by pulling on bolt
Remove disc insert by pulling on bolt
Remove disc insert by turning nut
with wrench
Bolt
Washer
Nut
BoltRectangular bar
Bolt

Vise
jaws
Disc
holder
Bellows
Tailpiece
Tailpiece
gasket
Sapag Safety Valves Series 8400/8500/8490/8590
Installation and Maintenance Instructions
Emerson reserves the right to change the contents without notice page 10
l. For bellows valves only, place the disc holder in a vise (the larger sizes may require a 3-jaw
vise) as shown in Figure 8. Using a suitable wrench unscrew the tailpiece and bellows from the
disc holder.
m. Remove the nozzle ring (3) from the nozzle (2).
n. Remove the nozzle (2) from the valve body (1) if necessary. Unless the valve seat on the nozzle
has been mechanically damaged or shows signs of corrosive attack, it will not be necessary to
remove the nozzle. In most cases the nozzle can be reconditioned without removal from the
valve body.
To remove the nozzle, turn the valve body over taking care not to damage the bonnet studs
(21).
Turn the nozzle counterclockwise by using the wrench flats on the nozzle flange or a nozzle
wrench designed to clamp onto the nozzle flange.
Figure 8
Cleaning
External parts such as the valve body, bonnet and cap should be cleaned by immersion in a bath
such as hot Oakite solution or equivalent. These external parts may be cleaned by wire brushing,
provided the brushes used do not damage nor contaminate the base metals. Only clean stainless
steel brushes should be used on stainless steel components.
The internal parts such as the guide, disc holder, disc insert, nozzle ring and spindle should be
cleaned by immersion in a commercial high alkaline detergent.
Guiding surfaces on the disc holder and guide may be polished using a fine emery cloth. The
bellows and other metal parts may be cleaned using acetone or alcohol, then rinsed with clean tap
water and dried.
Inspection
Check all valve parts for wear and corrosion. The valve seats on both the nozzle and disc insert
must be examined to determine if they have been damaged. Most often, lapping the valve seats is
all that is necessary to restore them to their original condition.
If the inspection shows that the valve seats are badly damaged, remachining will be necessary
or it may be advisable to replace these parts. When the time element is a factor, it may be
advantageous to replace damaged parts from spare parts stock, thereby permitting the replaced
part to be checked and reworked at leisure. (See Figure 10 and Table 8 for critical dimensions.)
The valve spring (18) should be inspected for evidence of cracking, pitting or deformation.
The bellows (6B) in a Style 8490/8590 valve should be inspected for evidence of cracking, pitting
or deformation that might develop into a leak.
The bearing surfaces on the guide and disc holder should be checked for residual product build up
and any evidence of scoring. Inspection of valve components is important to ensure proper valve
performance. Damaged valve parts must be repaired or replaced.
Reconditioning of Valve Seats
The tightness of a valve and its proper operation depend directly on the condition of the seats.
Many pressure relief valve problems are due to eroded or damaged seats.
The standard Sapag Series 8000 valve is constructed with a flat metal-to-metal seat. It is important
that seating surfaces be properly refurbished by lapping with a flat cast iron lap coated with the
correct lapping compound.
• Lapping Procedures
Unless the seats have been badly damaged by dirt or scale, lapping the seating surfaces should
restore them to their original condition. Never lap the disc insert against the nozzle. Lap each
part separately against a cast-iron lapping block of the proper size. These blocks hold the lapping
compound in their surface pores and must be recharged frequently.
Lap the block against the seat. Never rotate the block continuously, but use an oscillating motion.
Extreme care should be taken throughout to make certain that the seats are kept perfectly flat.
If considerable lapping is required, spread a thin coat of medium coarse lapping compound on
the block. After lapping with the medium coarse compound, lap again with a medium-grade
compound. Unless much lapping is called for, the first step can be omitted. Next, lap again using
a fine grade compound. When all nicks and marks have disappeared remove all the compound
from the block and seat. Apply polish compound to another block and lap the seat.
As the lapping nears completion only the compound left in the pores of the block should be
present. This should give a very smooth finish. If scratches appear the cause is probably dirty
lapping compound. These scratches should be removed by using compound free from foreign
material.
Disc inserts should be lapped in the same way as nozzles. The disc insert must be removed from
the holder before lapping. Before the disc insert is placed back in the holder all foreign material
should be removed from both parts. The insert must be free when in the holder. If the disc insert
is damaged too badly to be reconditioned by lapping, it should be replaced.
Remachining the insert will change critical dimensions, affect the action of the valve and is not
recommended.
Top lapping
surface
Lapping block
to be squared
up
Bottom
rough surface
do not use
Motion shown
by dotted
lines
Lapping block resurfacing plate
Lapping block
Figure 9