SIST EN ISO 10434:2004

SLOVENSKI STANDARD
SIST EN ISO 10434:2004
01-november-2004
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SIST ISO 10434:2000
-HNOHQL]DVXQLVSULUREQLþQLP]JRUQMLPGHORP]DQDIWQRLQGXVWULMRSHWURNHPLMRLQ
SRGREQRLQGXVWULMR,62
Bolted bonnet steel gate valves for the petroleum, petrochemical and allied industries
(ISO 10434:2004)
Schieber aus Stahl mit geflanschtem Oberteil für die Erdöl- petrochemische und
verwandte Industrien (ISO 10434:2004)
Robinets-vannes en acier a chapeau boulonné pour les industries du pétrole, de la
pétrochimie et les industries connexes (ISO 10434:2004)
Ta slovenski standard je istoveten z: EN ISO 10434:2004
ICS:
23.060.30 Zapirni ventili (zasuni) Gate valves
75.180.01 Oprema za industrijo nafte in Equipment for petroleum and
zemeljskega plina na splošno natural gas industries in
general
SIST EN ISO 10434:2004 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 10434:2004

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SIST EN ISO 10434:2004

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SIST EN ISO 10434:2004

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SIST EN ISO 10434:2004


INTERNATIONAL ISO
STANDARD 10434
Second edition
2004-07-15


Bolted bonnet steel gate valves for the
petroleum, petrochemical and allied
industries
Robinets-vannes en acier à chapeau boulonné pour les industries du
pétrole, de la pétrochimie et les industries connexes




Reference number
ISO 10434:2004(E)
©
ISO 2004

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SIST EN ISO 10434:2004
ISO 10434:2004(E)
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©  ISO 2004
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ii © ISO 2004 – All rights reserved

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SIST EN ISO 10434:2004
ISO 10434:2004(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope. 1
2 Normative references . 1
3 Terms and definitions. 3
4 Pressure/temperature ratings. 3
5 Design . 3
6 Materials. 18
7 Testing, inspection and examination. 21
8 Marking. 24
9 Preparation for despatch. 25
Annex A (informative) Information to be specified by the purchaser . 27
Annex B (informative) Identification of valve terms. 28
Bibliography . 30

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SIST EN ISO 10434:2004
ISO 10434:2004(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 10434 was prepared by Technical Committee ISO/TC 153, Valves, Subcommittee SC 1, Design,
manufacture, marking and testing in collaboration with Technical Committee ISO/TC 67, Materials, equipment
and offshore structures for petroleum, petrochemical and natural gas industries, Subcommittee SC 6,
Processing equipment and systems.
This second edition cancels and replaces the first edition (ISO 10434:1998), which has been technically
revised.
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SIST EN ISO 10434:2004
ISO 10434:2004(E)
Introduction
The purpose of this International Standard is to establish the basic requirements and practices for flanged and
butt-welding end steel gate valves of bolted bonnet construction that parallel those given in American
Petroleum Institute API Standard 600, eleventh edition, 2001 (ISO 10434:1998). It is not the purpose of this
International Standard to replace ISO 6002 or any other International Standard that is not identified with
petroleum refinery, petrochemical or natural gas industry applications.

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SIST EN ISO 10434:2004

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SIST EN ISO 10434:2004
INTERNATIONAL STANDARD ISO 10434:2004(E)

Bolted bonnet steel gate valves for the petroleum,
petrochemical and allied industries
1 Scope
This International Standard specifies the requirements for a heavy-duty series of bolted bonnet steel gate
valves for petroleum refinery and related applications where corrosion, erosion and other service conditions
would indicate a need for full port openings, heavy wall sections and large stem diameters.
This International Standard sets forth the requirements for the following gate valve features:
 bolted bonnet;
 outside screw and yoke;
 rising stems;
 non-rising handwheels;
 single or double gate;
 wedge or parallel seating;
 metallic seating surfaces;
 flanged or butt-welding ends.
It covers valves of the nominal sizes DN:
 25; 32; 40; 50; 65; 80; 100; 150; 200; 250; 300; 350; 400; 450; 500; 600;
corresponding to nominal pipe sizes NPS:
 1; 11/4; 11/2; 2; 21/2; 3; 4; 6; 8; 10; 12; 14; 16; 18; 20; 24;
and applies for pressure Class designations:
 150; 300; 600; 900; 1500; 2500.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 7-1, Pipe threads where pressure-tight joints are made on the threads — Part 1: Dimensions, tolerances
and designation
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SIST EN ISO 10434:2004
ISO 10434:2004(E)
ISO 5208, Industrial valves — Pressure testing of valves
ISO 5209, General purpose industrial valves — Marking
ISO 5210, Industrial valves — Multi-turn valve actuator attachments
ISO 5752, Metal valves for use in flanged pipe systems — Face-to-face and centre-to-face dimensions
ISO 9606-1, Approval testing of welders — Fusion welding — Part 1: Steels
ISO 15607, Specification and qualification of welding procedures for metallic materials — Part 1: General
rules
ISO 15609-1, Specification and qualification of welding procedures for metallic materials — Welding
1)
procedure specification — Part 1: Arc welding
ISO 15610, Specification and qualification of welding procedures for metallic materials — Qualification based
on tested welding consumables
ISO 15614-1, Specification and qualification of welding procedures for metallic materials — Welding
procedure test — Part 1: Arc and gas welding of steels and arc welding of nickel and nickel alloys
ISO 15614-2, Specification and qualification of welding procedures for metallic materials — Welding
2)
procedure test — Part 2: Arc welding of aluminium and its alloys
ASME B1.1, Unified inch screw threads (UN and UNR thread form)
ASME B1.5, Acme screw threads
ASME B1.8, Stub acme screw threads
ASME B1.12, Class 5 interference-fit thread
ASME B1.20.1, Pipe threads, general purpose (inch)
ASME B16.5, Pipe flanges and flanged fittings
ASME B16.10, Face-to face and end-to-end dimensions of valves
ASME B16.11, Forged fittings, socket-welding and threaded
ASME B16.34:1996, Valves — Flanged, threaded and welding end
ASME B18.2.2, Square and hex nuts — Inch series
ASME BPVC-IX, BPVC Section IX — Welding and brazing qualifications
ASTM A193, Standard specification for alloy-steel and stainless steel bolting materials for high temperature
service
ASTM A194, Standard specification for carbon and alloy steel nuts for bolts for high pressure or high
temperature service, or both

1) To be published. (Replaces ISO 9956-2:1995)
2) To be published. (Replaces ISO 9956-4:1995)
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SIST EN ISO 10434:2004
ISO 10434:2004(E)
ASTM A307, Standard specification for carbon steel bolts and studs, 60 000 PSI tensile strength
MSS-SP-55, Quality standard for steel castings for valves, flanges and fittings and other piping
components — Visual method for evaluation of surface irregularities
3 Terms and definitions
For the purposes of this document, the definitions for pressure designation, Class, and nominal valve size
NPS given in ASME B16.34, and the following apply.
3.1
DN
alphanumeric designation of size for components of a pipework system, which is used for reference purposes,
comprising the letters DN followed by a dimensionless whole number which is indirectly related to the physical
size, in millimetres, of the bore or outside diameter of the end connections
[ISO 6708:1995, definition 2.1]
4 Pressure/temperature ratings
4.1 The pressure/temperature ratings applicable to valves specified in this International Standard shall be in
accordance with those specified in the tables of ASME B16.34 for Standard Class for the applicable material
specification and the applicable Class. Restrictions of temperature and pressure, for example, those imposed
by special soft seals or special trim materials, shall be marked on the valve identification plate, see 8.4.
4.2 The temperature for a corresponding pressure rating is the maximum temperature of the
pressure-containing shell of the valve. In general, this temperature is the same as that of the contained fluid.
The use of a pressure rating corresponding to a temperature other than that of the contained fluid is the
responsibility of the user.
4.3 For temperatures below the lowest temperature listed in the pressure/temperature tables (see 4.1), the
service pressure shall be no greater than the pressure for the lowest listed temperature. The use of valves at
lower temperatures is the responsibility of the user. Consideration should be given to the loss of ductility and
impact strength of many materials at low temperature.
4.4 Double seated valves, in some design configurations, may be capable of trapping liquid in the centre
cavity of the valve when in the closed position. If subjected to an increase in temperature, an excessive build-
up of pressure may occur leading to a pressure boundary failure. Where such condition is possible it is the
responsibility of the user to provide, or require to be provided, means in design, installation or operating
procedure to assure that the pressure in the valve does not exceed that allowed by this International Standard
for the resultant temperature.
5 Design
5.1 Body wall thickness
5.1.1 A valve body schematic is shown as Figure 1. The minimum body wall thickness, t at the time of
,
m
manufacture shall be as given in Table 1, except as indicated in 5.1.2 for butt-welding valve ends. Additional
metal thickness needed for assembly stresses, stress concentrations, and shapes other than circular shall be
determined by individual manufacturers, since these factors vary widely.
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SIST EN ISO 10434:2004
ISO 10434:2004(E)

Key
1 junction of body run and body neck 6 body neck
2 body end flange 7 axis of body run
3 body end port inside diameter 8 butt-welding end
4 axis of body neck 9 body run
5 body/bonnet flange
Figure 1 — Identification of terms
Table 1 — Minimum wall thickness for body and bonnet
Class designation
150 300 600 900 1500 2500
Nominal size Nominal size
Minimum wall thickness
DN NPS
t
m
mm
25 6,4 6,4 7,9 12,7 12,7 15,0 1
32 6,4 6,4 8,6 14,2 14,2 17,5 11/4
40 6,4 7,9 9,4 15,0 15,0 19,1 11/2
50 8,6 9,7 11,2 19,1 19,1 22,4 2
65 9,7 11,2 11,9 22,4 22,4 25,4 21/2
80 10,4 11,9 12,7 19,1 23,9 30,2 3
100 11,2 12,7 16,0 21,3 28,7 35,8 4
150 11,9 16,0 19,1 26,2 38,1 48,5 6
200 12,7 17,5 25,4 31,8 47,8 62,0 8
250 14,2 19,1 28,7 36,6 57,2 67,6 10
300 16,0 20,6 31,8 42,2 66,8 86,6 12
350 16,8 22,4 35,1 46,0 69,9 — 14
400 17,5 23,9 38,1 52,3 79,5 — 16
450 18,3 25,4 41,4 57,2 88,9 — 18
500 19,1 26,9 44,5 63,5 98,6 — 20
600 20,6 30,2 50,8 73,2 114,3 — 24
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SIST EN ISO 10434:2004
ISO 10434:2004(E)
5.1.2 The weld end preparation in butt-welding end valves (see 5.3.2) shall not reduce the body wall
thickness to less than the values specified in 5.1.1 within a region closer than t to the outside surface of the
m
body neck, measured along the run direction. The transition to the weld preparation shall be gradual and the
section shall be essentially circular through the entire length of the transition. Sharp discontinuities or abrupt
changes in section in areas that infringe into the transition shall be avoided, except that test collars or bands,
either welded or integral, are allowed. In no case shall the thickness be less than 0,77 t at a distance of
m
1,33 t from the weld end.
m
5.2 Bonnet wall thickness
The minimum bonnet wall thickness at the time of manufacture, except for the neck extension that contains
the packing, shall be t as given in Table 1. For the neck extension, the local minimum wall thickness shall be
m
based on the local diameter, e.g. the inside diameter of the stem bore or packing box bore, and shall be in
accordance with Table 2.
5.3 Body dimensions
5.3.1 Flanged ends
5.3.1.1 Body end flanges shall comply with the dimensional requirements of ASME B16.5. Unless
otherwise specified by the purchaser, gasket contact facing finish of the end flanges shall be in accordance
with ASME B16.5. Raised face end flanges shall be provided unless ring-joint or flat face flanges are specified
by the purchaser.
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SIST EN ISO 10434:2004
ISO 10434:2004(E)
Table 2 — Minimum wall thickness for bonnet neck extension
Class designation
Bonnet neck
extension inside
150 300 600 900 1500 2500
diameter
a
Minimum wall thickness
mm
mm
15 2,8 3,0 3,6 4,2 5,3 7,6
16 2,8 3,1 3,6 4,4 5,6 7,9
17 2,8 3,2 3,7 4,5 5,8 8,2
18 2,9 3,5 3,9 4,7 5,9 8,5
19 3,0 3,8 4,1 5,1 6,1 8,9
20 3,3 4,0 4,2 5,2 6,3 9,2
25 4,0 4,8 4,8 6,3 7,1 11,0
30 4,6 4,8 4,8 6,5 8,2 13,1
35 4,8 4,8 5,1 7,1 9,7 14,6
40 4,9 5,0 5,7 7,5 10,2 16,4
50 5,5 6,2 6,3 7,9 11,6 19,8
60 5,6 6,4 6,8 8,9 13,4 23,2
70 5,6 6,9 7,4 9,9 15,8 26,5
80 5,8 7,2 8,1 11,0 17,4 30,1
90 6,4 7,4 8,8 12,0 19,1 33,2
100 6,4 7,7 9,5 12,8 20,8 36,7
110 6,4 8,1 10,3 14,1 22,9 40,1
120 6,6 8,6 10,9 14,9 24,8 43,5
130 7,1 8,8 11,3 16,2 26,5 46,9
140 7,1 9,2 12,0 17,3 28,3 50,2
a
See 5.2.
5.3.1.2 Face-to-face dimensions for flanged end valves, Class 150, 300, and 600, shall be in accordance
with ASME B16.10 or ISO 5752, Basic Series 3, 4 and 5, except that the applicable tolerance shall be in
accordance with the tolerances specified in Table 4. For Class > 600, the face-to-face dimensions shall be the
same as the end-to-end dimensions given in Table 4.
5.3.1.3 Body end flanges and bonnet flanges shall be cast or forged integral with the body. However,
when specified by the purchaser, forged flanges may be attached by welding by a qualified welding operator
using a qualified welding procedure. It is required that when these flanges are attached by welding, a
butt-welded type joint shall be used. Heat treatment to ensure that the welded material is suitable for the full
range of service conditions shall be performed in accordance with the material specification.
5.3.2 Butt-welding ends
5.3.2.1 Butt-welding ends shall be in accordance with Figure 2 and Table 3 unless otherwise specified by
the purchaser.
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SIST EN ISO 10434:2004
ISO 10434:2004(E)

a)  Welding end for connection to pipe of wall thickness T uuuu 22 mm

b)  Welding end for connection to pipe of wall thickness T > 22 mm
Key
A nominal outside diameter of welding end
B nominal inside diameter of pipe
T nominal wall thickness of pipe
Figure 2 — Welding ends
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SIST EN ISO 10434:2004
ISO 10434:2004(E)
Table 3 — Butt-welding end diameters
Nominal size, DN 25 32 40 50 65 80 100 150 200 250 300 350 400 450 500 600
Nominal size, NPS 1 11/4 11/2 2 21/2 3 4 6 8 10 12 14 16 18 20 24
diameter 35 44 50 62 78 91 117 172 223 278 329 362 413 464 516 619
A mm
tolerance + 2,5 / − 1,0 + 4 / − 1
B mm tolerance + 1 / − 1 + 2 / − 2 + 3 / − 2
The inside and outside surfaces of valve welding ends are machine finished overall. The contour within the envelope is at
the option of the manufacturer unless specifically ordered otherwise.
Intersections should be slightly rounded.
Valves with minimum wall thickness equal to 3 mm or less may have ends cut square or slightly chamfered.
For nominal outside diameters and wall thickness of standard steel pipe, see ISO 4200.
5.3.2.2 End-to-end dimensions for butt-welding end valves shall be in accordance with Table 4, unless
otherwise specified by the purchaser.
Table 4 — End-to-end dimensions for butt-welding end valves
Class designation
Nominal Nominal
150 300 600 900 1500 2500
Size Size
End-to-end dimensions
DN NPS
mm
25 127 165 216 254 254 308 1
32 140 178 229 279 279 349 11/4
40 165 190 241 305 305 384 11/2
50 216 216 292 368 368 451 2
65 241 241 330 419 419 508 21/2
80 283 283 356 381 470 578 3
100 305 305 432 457 546 673 4
150 403 403 559 610 705 914 6
200 419 419 660 737 832 1 022 8
250 457 457 787 838 991 1 270 10
300 502 502 838 965 1 130 1 422 12
350 572 762 889 1 029 1 257 — 14
400 610 838 991 1 130 1 384 — 16
450 660 914 1 092 1 219 1 537 — 18
500 711 991 1 194 1 321 1 664 — 20
600 813 1 143 1 397 1 549 1 943 — 24
Tolerances applicable to the dimensions:
 For DN u 250: ± 2 mm;
 For DN > 250: ± 3 mm.

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SIST EN ISO 10434:2004
ISO 10434:2004(E)
5.3.3 Body seats
5.3.3.1 The inside diameter of the body seat, except for assembly drive lugs on threaded seat rings, shall
not be less than the applicable value specified in Table 5.
5.3.3.2 Integral body seats are permitted in austenitic stainless steel valves. When an austenitic stainless
steel or a hardfacing material is used for the body seat, this material may be weld-deposited directly on the
valve body. Otherwise, valve bodies shall have separate shoulder or bottom seated seat rings that are either
threaded or welded in place, except that for DN u 50, rolled or pressed-in seat rings may be used.
5.3.3.3 Body seating surfaces shall not have sharp corners at either the inner or outer seat circumference.
5.3.3.4 Sealing compounds or greases shall not be used when assembling seat rings; however, a light
lubricant having a viscosity no greater than kerosene may be used to prevent galling of mating threaded
surfaces.
Table 5 — Body seat inside diameter
Class designation
Nominal Nominal
150 300 600 900 1500 2500
Size Size
Minimum port diameter
DN NPS
mm
25 25 25 25 22 22 19 1
11/4
32 31 31 31 28 28 25
11/2
40 38 38 38 34 34 28
50 50 50 50 47 47 38 2
21/2
65 63 63 63 57 57 47
80 76 76 76 72 69 57 3
100 100 100 100 98 92 72 4
150 150 150 150 146 136 111 6
200 200 200 199 190 177 146 8
250 250 250 247 238 222 184 10
300 300 300 298 282 263 218 12
350 336 336 326 311 288 241 14
400 387 387 374 355 330 276 16
450 431 431 419 400 371 311 18
500 482 482 463 444 415 342 20
600 584 584 558 533 498 412 24
5.4 Bonnet dimensions
5.4.1 The bonnet stem hole shall be designed to have proper clearance for stem guiding and for the
prevention of packing extrusion.
5.4.2 The bonnet shall include a conical stem backseat in one of the following forms:
 a bushing positively secured against coming loose, i.e. not relying on friction;
 an integral surface in the case of an austenitic stainless steel valve;
 an austenitic stainless steel or hardfaced weld deposit that is a minimum of 1,6 mm thick.
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SIST EN ISO 10434:2004
ISO 10434:2004(E)
5.4.3 The restrictions of 5.12.3 on openings also apply to the bonnet.
5.4.4 Bonnets shall be one-piece castings or forgings subject to the same exceptions and requirements as
specified in 5.3.1.3.
5.4.5 The gland bolting shall not be anchored to the bonnet or yoke through a fillet welded attachment or
stud welded pins. The gland bolt design shall be such that during repacking the gland bolts are positively
retained.
5.5 Bonnet-to-body joint
5.5.1 The bonnet-to-body joint shall be a flange and gasket type.
5.5.2 For Class 150 valves, the bonnet-to-body joint shall be one of the following types illustrated in
ASME B16.5:
 flat face;
 raised face;
 tongue and groove;
 spigot and recess;
 ring joint.
5.5.3 For valves having pressure class designation greater than Class 150, the bonnet-to-body joint shall be
as in 5.5.2, except that the flat face joint is not permitted.
5.5.4 The bonnet flange gasket shall be suitable for the temperature range − 29 °C to 538 °C and be one of
the following:
 solid metal, corrugated or flat;
 filled metal jacketed, corrugated or flat;
 metal ring joint;
 spiral-wound metal gasket with filler and a centring/compression ring;
 spiral-wound metal gasket with filler, to be used only in a body-to-bonnet joint design that provides gasket
compression control.
For Class 150, the following may also be used:
 flexible graphite sheet, reinforced with a stainless steel tanged or corrugated insert.
5.5.5 Except for Class 150 valves and valves in sizes DN 65 and smaller, bonnet-to-body flanges shall be
circular.
5.5.6 Bonnet and body flange nut bearing surfaces shall be parallel to the flange face within ± 1°. Spot
facing or backfacing required to meet the parallelism requirement shall be in accordance with ASME B16.5.
5.5.7 The bonnet-to-body joint shall be secured by a minimum of four through type stud bolts. The minimum
stud bolt size for each valve size shall be as follows:
 either M10 or 3/8 when 25 u DN u 65;
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SIST EN ISO 10434:2004
ISO 10434:2004(E)
 either M12 or ½ when 80 u DN u 200;
 either M16 or 5/8 when 250 u DN.
5.5.8 The valve bonnet bolting cross-sectional area shall, as a minimum, meet the following requirement:
A
g
PS u 65,26 u 9 000
cb
A
b
where
P is the pressure class designation number, e.g. 150;
c
S is the allowable bolt stress at 38 °C, expressed in megapascals: when its value is > 138 MPa, use
b
138 MPa;
A is the area bounded by the effective outside periphery of the gasket — except that, in the case of a
g
ring joint, the bounded area is defined by the pitch diameter of the ring — expressed in square
millimetres;
A is the total effective bolt tensile stress area, expressed in square millimetres.
b
5.5.9 At assembly, all gasket contact surfaces shall be free of heavy oils, grease and sealing compounds. A
light coating of a lubricant, no heavier than kerosene, may be applied if needed to assist in proper gasket
assembly.
5.6 Gate
5.6.1 Gate configurations are categorized as illustrated in Annex B.
5.6.2 A one-piece wedge gate — as either a solid or flexible wedge design — shall be furnished, unless
otherwise specified.
5.6.3 A two-piece split wedge gate or parallel seat double disc gate may be furnished when specified. A
split wedge gate consists of two independent seating parts that conform to the body seats when closed. A
double disc gate has a spreading mechanism that forces the two parallel discs to the body seats when closed.
5.6.4 Except for a double disc gate, in the open position, the gate shall completely clear the valve seat
openings.
5.6.5 Gate and gate guides shall be designed so that all parts can function properly independent of installed
valve orientation.
5.6.6 Guides shall be provided in the gate and shell and these guides shall be designed so as to minimize
seat wear and maintain gate-to-stem alignment in all valve orientations. Gate-to-shell design shall consider
wear that may be caused by corrosion, erosion and abrasion.
5.6.7 Gate seating surfaces shall be integral or faced with weld metal. Unless specified, hardfaced seating
surfaces are not required. Finished thickness of any facing material shall be not less than 1,6 mm.
5.6.8 Wedge gates shall be designed to account for seat wear. The dimensions that fix the position of the
gate seats relative to the body seats shall be such that the gate, starting from the time of manufacture, can, as
a result of seat wear, move into the seats by a distance, h, defined as wear travel. Wear travel is in a direction
that is parallel with the valve stem. The required minimum wear travel varies with valve size in accordance
with Table 6.
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SIST EN ISO 10434:2004
ISO 10434:2004(E)
Table 6 — Minimum wear travel
Valve size range Wear travel, h
DN mm
25 u DN u 50 2,3
65 u DN u 150 3,3
200 u DN u 300 6,4
350 u DN u 450 9,7
500 u DN u 600 12,7
5.7 Yoke
5.7.1 The yoke may be either an integral part of the bonnet or a separate part. The yoke shall retain the
stem nut which links the handwheel to the stem.
5.7.2 Yokes shall be designed so that the stem nut can be removed when the valve is under pressure
without removing the bonnet from the valve body.
5.7.3 Yokes that are separate shall have the yoke-to-bonnet mating surfaces machined.
5.7.4 The yoke-to-stem nut bearing surfaces shall be machined flat and parallel. A lubricating fitting shall be
provided for the bearing surfaces.
5.8 Stem and
...