EN ISO 16812:2007

SLOVENSKI STANDARD
01-maj-2007
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SIST EN ISO 16812:2004
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Petroleum, petrochemical and natural gas industries - Shell-and-tube heat exchangers
(ISO 16812:2007)
Erdöl-, petrochemische und Erdgasindustrie - Rohrbüdelwärmetauscher (ISO
16812:2007)
Industries du pétrole, de la pétrochimie et du gaz naturel - Échangeurs de chaleur a
faisceaux (ISO 16812:2007)
Ta slovenski standard je istoveten z: EN ISO 16812:2007
ICS:
71.120.30 Prenosniki toplote Heat exchangers
75.180.20 Predelovalna oprema Processing equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 16812
NORME EUROPÉENNE
EUROPÄISCHE NORM
February 2007
ICS 75.180.20; 27.060.30 Supersedes EN ISO 16812:2003
English Version
Petroleum, petrochemical and natural gas industries - Shell-and-
tube heat exchangers (ISO 16812:2007)
Industries du pétrole, de la pétrochimie et du gaz naturel - Erdöl-, petrochemische und Erdgasindustrie -
Échangeurs de chaleur à faisceaux (ISO 16812:2007) Rohrbüdelwärmetauscher (ISO 16812:2007)
This European Standard was approved by CEN on 3 February 2007.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2007 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 16812:2007: E
worldwide for CEN national Members.

Foreword
This document (EN ISO 16812:2007) has been prepared by Technical Committee ISO/TC 67
"Materials, equipment and offshore structures for petroleum and natural gas industries" in
collaboration with Technical Committee CEN/TC 12 "Materials, equipment and offshore
structures for petroleum, petrochemical and natural gas industries", the secretariat of which is
held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of
an identical text or by endorsement, at the latest by August 2007, and conflicting national
standards shall be withdrawn at the latest by August 2007.

This document supersedes EN ISO 16812:2003.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United
Kingdom.
Endorsement notice
The text of ISO 16812:2007 has been approved by CEN as EN ISO 16812:2007 without any
modifications.
INTERNATIONAL ISO
STANDARD 16812
Second edition
2007-02-15
Petroleum, petrochemical and natural gas
industries — Shell-and-tube heat
exchangers
Industries du pétrole, de la pétrochimie et du gaz naturel — Échangeurs
de chaleur à faisceaux
Reference number
ISO 16812:2007(E)
©
ISO 2007
ISO 16812:2007(E)
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©  ISO 2007
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ii © ISO 2007 – All rights reserved

ISO 16812:2007(E)
Contents Page
Foreword. v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 General. 3
5 Proposals. 3
6 Drawings and other required data . 4
6.1 Outline drawings and other supporting data. 4
6.2 Information required after outline drawings are reviewed . 5
6.3 Reports and records. 6
7 Design . 7
7.1 Design temperature . 7
7.2 Cladding for corrosion allowance. 7
7.3 Shell supports . 7
7.4 Stationary head . 8
7.5 Floating head. 8
7.6 Tube bundle. 9
7.7 Nozzles and other connections. 12
7.8 Flanged external girth joints. 13
7.9 Expansion joints . 13
7.10 Gaskets . 14
7.11 Handling devices . 15
7.12 Hydrogen service. 15
8 Materials . 15
8.1 General. 15
8.2 Gaskets . 16
8.3 Tubes. 16
9 Fabrication. 16
9.1 Shells . 16
9.2 Pass-partition plates. 16
9.3 Connection junctions . 16
9.4 Tubes. 17
9.5 Welding . 17
9.6 Heat treatment. 17
9.7 Dimensional tolerances . 18
9.8 Gasket contact surfaces other than nozzle-flange facings. 18
9.9 Tube holes . 19
9.10 Tube-to-tubesheet joints. 19
9.11 Assembly . 19
10 Inspection and testing. 20
10.1 Quality assurance. 20
10.2 Quality control. 20
10.3 Pressure testing. 21
10.4 Nameplates and stampings . 22
ISO 16812:2007(E)
11 Preparation for shipment . 22
11.1 Protection. 22
11.2 Identification. 23
12 Supplemental requirements. 23
12.1 General . 23
12.2 Design . 23
12.3 Examination. 23
Annex A (informative) Recommended practices. 25
Annex B (informative) Shell-and-tube heat exchanger checklist . 27
Annex C (informative) Shell-and-tube heat exchanger data sheets . 28
Annex D (informative) Responsibility data sheet . 39
Bibliography . 41

iv © ISO 2007 – All rights reserved

ISO 16812:2007(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 16812 was prepared by 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 16812:2002), which has been technically
revised.
ISO 16812:2007(E)
Introduction
Users of this International Standard should be aware that further or differing requirements may be needed for
individual applications. This International Standard is not intended to inhibit a vendor from offering, or the
purchaser from accepting, alternative equipment or engineering solutions for the individual application. This
may be particularly applicable where there is innovative or developing technology. Where an alternative is
offered, the vendor should identify any variations from this International Standard and provide details.
Annex A provides some optional recommended practices.
A bullet (z) at the beginning of a clause or subclause indicates a requirement for the purchaser to make a
decision or provide information (see checklist in Annex B).
In this International Standard, where practical, US Customary (USC) units are included in parentheses for
information.
vi © ISO 2007 – All rights reserved

INTERNATIONAL STANDARD ISO 16812:2007(E)

Petroleum, petrochemical and natural gas industries —
Shell-and-tube heat exchangers
1 Scope
This International Standard specifies requirements and gives recommendations for the mechanical design,
material selection, fabrication, inspection, testing and preparation for shipment of shell-and-tube heat
exchangers for the petroleum, petrochemical and natural gas industries.
This International Standard is applicable to the following types of shell-and-tube heat exchangers: heaters,
condensers, coolers and reboilers.
This International Standard is not applicable to vacuum-operated steam surface condensers and feed-water
heaters.
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 15156 (all parts), Petroleum and natural gas industries — Materials for use in H S-containing
environments in oil and gas production
1)
ASME B 16.5 , Pipe Flanges and Flanged Fittings
ASME B 16.11, Forged Fittings, Socket-Welding and Threaded
ASME B 1.20.1, Pipe Threads, General Purpose (Inch)
2)
EJMA , Standards of the Expansion Joint Manufacturers Association
3)
NACE MR0103 , Materials Resistant to Sulfide Stress Cracking in Corrosive Petroleum Refining
Environments
4) th
TEMA Standards Set , 8 Edition, Standards of the Tubular Exchanger Manufacturers Association

1) ASME International, 3 Park Avenue, New York, NY 10016-5990, USA.
2) Expansion Joint Manufacturers Association, 25 North Broadway, Tarrytown, NY 10591, USA.
3) NACE International, P.O. Box 218340, Houston, TX 77218-8340, USA.
4) Tubular Exchanger Manufacturers Association, 25 North Broadway, Tarrytown, NY 10591, USA.
ISO 16812:2007(E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
annular distributor
additional chamber incorporated into a shell side nozzle to more evenly distribute shell side fluids entering or
exiting the tube bundle
3.2
category A welded joint
longitudinal welded joint within the main shell, communicating chambers, nozzles or transitions in diameter; or
any welded joint within a sphere or within a formed or flat head; or circumferential welded joint connecting
hemispherical heads to main shells, to transitions in diameters or to communicating chambers
3.3
category B welded joint
circumferential welded joint within the main shell, communicating chambers, nozzles or transitions in diameter,
including joints between the transitions and a cylinder at either the large or small end; or circumferential
welded joint connecting formed heads, other than hemispherical, to main shells, to transitions in diameter, to
nozzles or to communicating chambers
3.4
communicating chamber
heat-exchanger appurtenance that intersects the shell or heads of the heat exchanger and forms an integral
part of the pressure-containing envelope
EXAMPLES Sump, annular distributor.
3.5
effective surface
outside surface area of the tubes that contributes to heat transfer
3.6
full-penetration weld
welded joint that results in weld metal through the entire thickness of the components being joined
3.7
heat-exchanger unit
one or more heat exchangers for a specified service that may include alternative operating conditions
3.8
hydrogen service
service that contains hydrogen at a partial pressure exceeding 700 kPa (100 psi) absolute
3.9
item number
purchaser's identification number for a heat-exchanger unit
3.10
nubbin
projection on the flange gasket surface, positioned at the centre of the gasket, used to concentrate the bolt
load on the gasket
3.11
pressure design code
recognized pressure vessel standard specified or agreed by the purchaser
EXAMPLES ASME Section VIII, EN 13445.
2 © ISO 2007 – All rights reserved

ISO 16812:2007(E)
3.12
seal-welded
tube-to-tubesheet joint weld of unspecified strength applied between the tubes and tubesheets for the sole
purpose of reducing the potential for leakage
3.13
strength-welded
tube-to-tubesheet joint welded so that the design strength is equal to, or greater than, the axial tube strength
specified by the pressure design code
4 General
z 4.1 The pressure design code shall be specified or agreed by the purchaser. Pressure components shall
comply with the pressure design code and the supplemental requirements given in this International Standard.
th
4.2 Heat-exchanger construction shall conform to TEMA (8 edition), Class R, unless another TEMA class
is specified.
z 4.3 The vendor shall comply with the applicable local regulations specified by the purchaser.
4.4 Annex A includes some recommended mechanical and design details for information.
4.5 Annex B provides a checklist that can be used by the purchaser to ensure that bulletted items in this
International Standard are addressed.
4.6 Annex C provides examples of data sheets.
4.7 Annex D includes a recommended division of responsibility for completing the data sheet.
5 Proposals
5.1 The vendor's proposal shall include, for each heat exchanger unit, completed data sheets such as those
given in Annex C or, if a data sheet is included in the inquiry, a statement indicating complete compliance with
that data sheet.
th
5.2 Designs that are not fully defined by the nomenclature in TEMA (8 edition), Section 1, shall be
accompanied by sketches that are sufficient to describe the details of construction.
5.3 If an annular distributor is provided, the vendor shall define the type of construction proposed.
5.4 The vendor shall determine the need for, and if required, include expansion joints based on all
conditions supplied by the purchaser. The vendor shall state the type of construction proposed.
5.5 The proposal shall include a detailed description of all exceptions to the requirements of the purchaser's
inquiry.
5.6 For stacked heat exchangers, the vendor shall supply the following components unless otherwise
specified by the purchaser:
a) bolts, nuts and gaskets for interconnecting nozzles;
b) shims and bolting for interconnecting supports.
ISO 16812:2007(E)
5.7 The vendor shall provide a separate quotation for the following items unless otherwise specified by the
purchaser:
th
a) a test component consisting of a test ring and gland, in accordance with TEMA (8 edition),
Figure E-4.13-2 or equivalent, for each heat exchanger or group of similar heat exchangers with floating
heads;
b) one spare set of gaskets per heat-exchanger unit.
6 Drawings and other required data
6.1 Outline drawings and other supporting data
6.1.1 The vendor shall submit, for review by the purchaser, outline drawings for each heat exchanger unit.
The drawings shall include the following information:
a) service, item number, project name and location, purchaser's order number, vendor's shop order number
and other special identification numbers;
b) design pressure, test pressure, design temperature, minimum design metal temperature and any
restriction on testing or operation of the heat exchanger;
c) maximum allowable working pressure (MAWP) in the corroded condition and at the design temperature
for the shell side and tube side;
d) connection sizes, location, orientation, projection, direction of flow and, if flanged, the rating and facing;
e) coupling sizes, rating and orientation;
f) dimensions, orientation and location of supports, including bolt holes and slots, and the stacking
arrangement;
g) overall dimensions of the heat exchanger;
h) tube-bundle removal clearance;
i) mass of the heat exchanger, empty and full of water, and of removable components with a mass greater
than 25 kg (60 lb) (e.g. removable tube bundle, channel, channel cover and shell cover);
j) specified corrosion allowance for each side of the heat exchanger;
k) references to the applicable code and the purchaser's specification;
l) requirements for post-weld heat treatment;
m) requirements for radiographic examination;
n) requirements for material impact testing;
o) requirements for surface preparation and painting;
p) gasket materials;
q) insulation thickness;
r) location of expansion joints, annular distributors and any other special components or closures;
s) location and orientation of nameplates, lifting lugs, grounding clips or other attachments;
4 © ISO 2007 – All rights reserved

ISO 16812:2007(E)
t) location of the centre of gravity of the heat exchanger;
u) forces and moments on connections as specified by the purchaser.
z 6.1.2 The vendor shall submit flow-induced vibration analysis, if specified by the purchaser.
6.2 Information required after outline drawings are reviewed
6.2.1 Gasket details, including type and material, shall be shown on a separate drawing. This drawing shall
not be marked with any restrictions for use.
z 6.2.2 Qualified welding procedure specifications and procedure qualification records as required by the
pressure design code shall be submitted for review, if specified by the purchaser.
6.2.3 Upon receipt of the purchaser's review comments on the outline drawings, the vendor shall submit
copies of all detailed drawings. These shall fully describe the heat exchanger and shall include at least the
following information:
a) full views and cross-sectional views with all dimensions and materials sufficient for stress calculations for
each part;
b) bundle details, including the following:
⎯ tube layout,
⎯ tube description and number in each pass,
⎯ number of baffles, cross-baffle cut, layout and orientation in a view that shows the cuts,
⎯ details and locations of all sealing and sliding strips,
⎯ details and locations of tie-rods and spacers,
⎯ details and locations of support plates,
⎯ details of tubesheet and tube holes, including cladding or weld overlay if required,
⎯ gasket drawings,
⎯ details of pass-partition plates;
c) details of each pressure-retaining weld, including weld material, weld nominal thickness, weld location
and applicable non-destructive examination method;
d) details of each weld and weld nominal thickness for non-pressure attachments;
e) complete bills of materials, including the material specification;
f) expansion joint details;
g) details of cladding and weld overlay;
h) weld map for each heat exchanger showing the weld joints, including welding procedure number(s);
i) details of tube-to-tubesheet joints, including procedures for installation, welding, expansion, inspection
and testing;
j) flange-face finish;
k) special installation and maintenance instructions including lifting and handling.
ISO 16812:2007(E)
6.2.4 The vendor shall submit for the purchaser's review the following documentation.
a) Mechanical design calculations for all the heat exchanger pressure-retaining components. If calculations
are made on a computer, all input and output data shall be detailed so as to facilitate an understanding of
the calculation procedures. The formulas in the applicable sections of the pressure design code and
TEMA shall be referenced.
b) Design calculations based on seismic, wind, transportation and/or piping loads, if these loads are
provided by the purchaser.
c) Proposed procedures for assembly of flanged joints, if controlled bolt-tightening procedures (such as
hydraulic torque wrenches or hydraulic tensioning devices) are used. Any required lubricants shall be
stated.
d) Design calculations for thermal loads imposed on nozzles of stacked heat exchangers.
z 6.2.5 The vendor shall submit design calculations for supports or lifting and pulling devices, if specified by
the purchaser.
6.2.6 After final review, the vendor shall revise all the required drawings and welding procedures and
submit each with the following text marked on every sheet separately and dated: “CERTIFIED FOR
CONSTRUCTION”.
6.3 Reports and records
z After the heat exchanger is completed the vendor shall furnish the purchaser with the following documents in
the format and quantities specified by the purchaser:
a) “as-built” data sheet;
b) all outline and detail drawings, marked “CERTIFIED AS-BUILT”;
c) certified record of all impact tests performed;
d) certified mill test reports for all pressure parts, including tubes (each material test report shall be identified
by a part number);
e) complete certified bill of materials suitable for obtaining all replacement parts, including quantity,
description, material specification and identification of each part;
f) temperature charts of all post-weld heat treatments;
g) completed manufacturer's data report in accordance with the pressure design code;
h) nameplate rubbing or a facsimile;
i) all mechanical design calculations, marked “CERTIFIED AS-BUILT”;
j) non-destructive examination (NDE) map;
k) all associated NDE reports, including radiographic, magnetic-particle, liquid-penetrant, ultrasonic,
hardness, impact, positive material identification (PMI) and any other reports as applicable;
l) tube-to-tubesheet leak-test results;
m) hydrostatic test records in the form of a chart or certification.
6 © ISO 2007 – All rights reserved

ISO 16812:2007(E)
7 Design
7.1 Design temperature
z 7.1.1 All heat exchangers shall have two design temperatures for each side, a maximum design
temperature and a minimum design metal temperature (MDMT), as specified by the purchaser (e.g. in the
form shown in Annex C).
7.1.2 The design temperature of a component (including external bolting) influenced by both the shell side
and tube side fluids shall be the shell side or tube side design temperature, whichever is the more severe.
z 7.1.3 The input data needed to design an expansion joint shall be provided by the purchaser (e.g. in the
form shown in Annex C).
7.2 Cladding for corrosion allowance
7.2.1 If cladding (including weld overlay) is used, the full thickness of the cladding shall be used as
corrosion allowance unless specified otherwise or approved by the purchaser.
7.2.2 The minimum cladding thickness at the tube side face of a tubesheet shall not be less than 10 mm
(3/8 in) when tubes are expanded only, and 5 mm (3/16 in) when tubes are welded to the tubesheet. The
minimum cladding thickness on the shell side face shall not be less than 10 mm (3/8 in). Weld overlays shall
have sufficient thickness to provide the specified chemical composition to a depth of at least 1,5 mm (1/16 in).
7.3 Shell supports
7.3.1 The fixed shell support of removable-bundle heat exchangers shall be designed to withstand a
longitudinal force equal to 150 % of the bundle mass applied at the heat exchanger bundle centreline. The
shear stress for supports shall not exceed 40 % of the yield strength of the material.
7.3.2 Horizontal heat exchangers shall be provided with two or more saddles designed to support the heat
exchanger under all specified conditions. Design of the saddles shall be as follows.
a) Saddles shall be attached to saddle-bearing plates.
b) The bearing surface of the saddles shall be at least one-third of the circumference of the shell.
c) The saddle-bearing plates shall have the same nominal chemical composition as the shell and shall be
continuously welded directly to the heat exchanger shells.
d) The saddle-bearing plates shall be provided with vent holes 6 mm (1/4 in) in diameter, located at the
vertical centreline.
e) The saddle-bearing plates shall be at least 6 mm (1/4 in) thick and shall have all corners rounded to a
radius of at least 25 mm (1 in).
7.3.3 The lower shells of stacked removable-bundle heat exchangers shall be designed to carry the
superimposed loads without suffering distortion that can cause binding of the tube bundles.
7.3.4 The vendor’s design shall provide for a shim allowance of approximately 6 mm (1/4 in) between the
faces of stacked heat exchanger intermediate supports.
7.3.5 For horizontal heat exchangers, slotted holes shall be provided in the baseplate of all but one of the
saddles, to allow for longitudinal movement due to thermal expansion or contraction. The width of the slot
shall be equal to the anchor bolt diameter plus 8 mm (5/16 in). The length of the slot shall be equal to the
anchor bolt diameter, plus the allowance for longitudinal movement, plus 8 mm (5/16 in).
ISO 16812:2007(E)
7.4 Stationary head
7.4.1 Structural bracing shall not be used to retain pressure.
7.4.2 The pressure differential used to calculate the pass-partition plate thickness in accordance with
th
TEMA (8 edition), RCB-9.132, shall be the allowable tube-side pressure drop of the entire exchanger unit.
7.5 Floating head
th
7.5.1 Floating-head cover bolting shall comply with TEMA (8 edition), Section 5, Paragraph RCB-11. Bolt
spacings and clearances shall be not less than the minimum recommended by TEMA.
7.5.2 Floating-head cover bolting shall be readily accessible and shall have adequate spanner (wrench)
clearance between the floating-head bolts and the shell flange at the cover end when the shell cover is
removed.
7.5.3 Packed floating-head tailpipe and packed floating tubesheet designs (e.g. TEMA types P and W) shall
not be used.
7.5.4 Floating heads shall be designed for design pressure on either side, with atmospheric pressure or
vacuum (if specified) on the other side, unless otherwise specified by the purchaser. Examples of acceptable
floating-head designs are shown in Figure 1.

a)  Ring and dish construction b)  Flange and dish construction c)  Integral construction
Key
1 ring
2 gasket
3 dish
4 full-penetration weld
5 flange
6 integral machined cover
Figure 1 — Typical designs for floating-head covers
7.5.5 Internal floating-head covers shall have the specified corrosion allowance on all wetted surfaces
except gasket-seating surfaces. The specified corrosion allowance shall be included on the back side of the
floating-head backing device.
8 © ISO 2007 – All rights reserved

ISO 16812:2007(E)
7.6 Tube bundle
7.6.1 Tubes
7.6.1.1 The minimum outside diameter of the tubes shall be 19,05 mm (3/4 in) unless otherwise specified
or approved by the purchaser.
7.6.1.2 The tube-wall thickness shall be as listed in Table 1, or thicker if required by the design conditions,
unless otherwise specified or approved by the purchaser.
Table 1 — Minimum wall thickness of tubes
Dimensions in millimetres (inches)
a
Tube material
Minimum wall thickness
Carbon steel, low-alloy steel (max. 9 % chromium), aluminium and 2,11 (0,083)
aluminium alloy
Copper and copper alloys 1,65 (0,065)
High-alloy [austenitic, ferritic and austenitic/ferritic (duplex)] steel and 1,473 (0,058)
other non-ferrous materials
Titanium 1,067 (0,042)
a
For low-fin tubing, this shall be the minimum thickness at the root diameter.
7.6.1.3 The mean radius of U-bends shall be not less than 1,5 times the nominal outside diameter of the
tube.
7.6.2 Tubesheets
7.6.2.1 For a vertical heat exchanger where the stationary tubesheet is at the bottom, a suitable means of
holding the bundle in place shall be provided. If collar bolts or drilled-and-tapped holes are used, at least four
shall be provided and their location shall be identified on the drawings and by stamped markings on the OD of
the tubesheet.
7.6.2.2 The distance between the edge of the tube holes and the edge of all gasket grooves shall be not
less than 1,5 mm (1/16 in) for tubesheets with expanded tube-to-tubesheet joints and not less than 3 mm
(1/8 in) for tubesheets with seal-welded or strength-welded tube-to-tubesheet joints.
7.6.2.3 Tubesheets shall be designed for design pressure on either side, with atmospheric pressure or
vacuum, if specified, on the other side unless otherwise specified or approved by the purchaser.
7.6.2.4 A full-diameter stationary tubesheet shall be provided for removable bundle exchangers with
th
bonnets [see TEMA (8 edition), Figure N-1.2, Type B stationary head]. The tubesheet shall be designed to
maintain the gasket seal through the use of collar studs or tapped tubesheet holes and allow hydrotesting of
the shell side without the bonnet installed.
7.6.3 Baffles and support plates
7.6.3.1 The thickness of carbon steel or low-alloy steel (max. 9 % chromium) transverse baffles and
support plates shall be not less than twice the specified shell side corrosion allowance.
7.6.3.2 Transverse baffles and support plates shall have notches that are 10 mm (3/8 in) high to facilitate
drainage.
7.6.3.3 If shell-side longitudinal baffles are used, the minimum clearance between the longitudinal baffle
and the adjacent tubes shall be 3 mm (1/8 in).
ISO 16812:2007(E)
7.6.4 Impingement protection
th
7.6.4.1 If required by TEMA (8 edition), RCB-4.61, impingement protection shall be provided by a plate
baffle or rods on the tube bundle, an annular distributor or another means agreed upon by the purchaser and
the vendor.
7.6.4.2 If an impingement plate baffle is used, it shall extend at least 25 mm (1 in) beyond the projection
of the nozzle bore.
7.6.4.3 If an impingement plate baffle is used, the shell entrance and bundle entrance areas (as defined
by TEMA) shall be not less than the flow area of the inlet nozzle.
7.6.4.4 The nominal thickness of the impingement plate baffle shall be not less than 6 mm (1/4 in).
7.6.4.5 The impingement plate baffle shall be adequately supported (e.g. by welding to at least two
spacers) to avoid mechanical damage due to vibration.
7.6.4.6 Perforated impingement plate baffles shall not be used.
7.6.5 Bypass-sealing devices
7.6.5.1 Bypass-sealing devices (such as seal bars, dummy tubes or tie-rods as shown in Figure 2) shall
be used for non-isothermal service if bypass clearances exceed 16 mm (5/8 in) and shall be located as follows.
a) If the distance between baffle-cut edges is six tube pitches or less, a single seal, located approximately
halfway between the baffle cuts, shall be provided.
b) If the distance between baffle-cut edges exceeds six tube pitches, multiple seals shall be provided. A seal
shall be located every five to seven tube pitches between the baffle cuts, with the outermost seals not
more than 75 mm (3 in) from each baffle-cut edge.
7.6.5.2 Peripheral bypass seals shall extend from the peripheral edge of the transverse baffle into the
tube bundle so that the clearance to the nearest tube does not exceed the nominal clearance between tubes.
7.6.5.3 Internal bypass seals shall be installed so that the clearance to the nearest tube does not exceed
the nominal clearance between tubes.
7.6.5.4 Bypass sealing devices shall either be located to minimize obstruction of mechanical cleaning
lanes or shall be readily removable. Continuous cleaning lanes shall be maintained for square (90°) and
rotated-square (45°) pitch.
7.6.5.5 The nominal thickness of seal strips shall be the nominal thickness of the transverse baffles or
6 mm (1/4 in), whichever is less.
7.6.5.6 Bypass seal strips shall be attached to the transverse baffles by continuous welds on one side of
each baffle.
7.6.5.7 The leading and trailing edges of seal strips shall be provided with a radius or a bevel to prevent
damage to the shell when inserting or removing the bundle.
7.6.5.8 Peripheral bypass-seal strips shall not restrict the bundle inlet or outlet flows.
10 © ISO 2007 – All rights reserved

ISO 16812:2007(E)
Key
1 peripheral edge of baffle 9 single seal on centreline
2 tie rods, dummy tubes or flat bar 10 multiple seals, evenly spaced
3 edge of baffle cut 11 edge of baffle cut
4 plane of U-tube bend 12 plane of U-tube bend
5 detail of seals and tube clearance 13 U-tube bend
6 tubes 14 impingement plate
7 seal 15 peripheral bundle bypass lane
8 clearance: not to exceed nominal clearance between tubes 16 internal bundle bypass lane
Figure 2 — Typical cross-sections of tube bundle showing locations of bypass sealing devices
7.6.6 Bundle skid bars
7.6.6.1 For all removable bundles with a mass of more than 5 450 kg (12 000 lb), continuous sliding
surfaces shall be provided to facilitate bundle removal.
7.6.6.2 If skid bars are used, the following shall apply.
a) A minimum of two skid bars shall be provided.
b) They shall not be situated in the projected area of the nozzles.
c) They shall be welded to the transverse baffles and support plates.
ISO 16812:2007(E)
d) They shall protrude 0,8 mm (1/32 in) beyond the outside diameter of baffle and support plates.
e) Their leading and trailing edges shall be provided with a radius or a bevel to prevent damage to the shell
when inserting or removing the bundle.
7.6.7 Tube-to-tubesheet joint
The tube-to-tubesheet joint shall be expanded only, unless otherwise specified or approved by the purchaser.
If welded joints are specified, the joint shall be made by one of the following methods:
a) strength-welded only;
b) strength-welded and expanded;
c) seal-welded and expanded.
7.7 Nozzles and other connections
z 7.7.1 Connections DN 40 (NPS 1½) and larger shall be flanged. The purchaser shall specify the required
flange design code (e.g. ASME B16.5).
7.7.2 If welded connections are specified, they shall be bevelled.
7.7.3 Non-flanged connections smaller than DN 40 (NPS 1½) shall be forged couplings with an equivalent
rating to ASME B 16.11 class 6000 or shall be integrally reinforced welding fittings with tapered threads
equivalent to ASME B 1.20.1, and shall comply with the pressure design code. Threaded connections shall
not be used in hydrogen or sour service.
7.7.4 Flanged connectio
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