NB/T 47015-2023 English PDF (NB/T47015-2023)

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NB/T 47015-2023: Welding specification for pressure vessels
NB/T 47015-2023
NB
ENERGY INDUSTRY STANDARD OF
THE PEOPLE’S REPUBLIC OF CHINA
ICS 25.160.10
CCS J 33
Replacing NB/T 47015-2011
Welding specification for pressure vessels
ISSUED ON: DECEMBER 28, 2023
IMPLEMENTED ON: JUNE 28, 2024
Issued by: National Energy Administration
Table of Contents
Foreword ... 3
1 Scope ... 6
2 Normative references ... 6
3 Terms and definitions ... 7
4 General welding procedures ... 7
5 Welding procedures for steel pressure vessels ... 14
6 Welding procedures for aluminum pressure vessels ... 20
7 Welding procedure of titanium pressure vessel ... 22
8 Welding procedures for copper pressure vessels ... 25
9 Welding procedures for nickel pressure vessel ... 29
10 Welding procedures for zirconium pressure vessels ... 32
11 Welding procedures for composite metal pressure vessels ... 35
12 Corrosion-resistant layer strip electrode cladding procedures ... 39
Appendix A (Informative) Method and scope of weld position specification ... 43
Appendix B (Informative) Form and size of special material welding groove ... 46
Appendix C (Informative) Recommended welding procedure specification form .. 53
Appendix D (Informative) Recommended table for selection of common welding
materials ... 57
Welding specification for pressure vessels
1 Scope
This document specifies the basic requirements for welding of steel, aluminum,
titanium, copper, nickel, zirconium, composite metal pressure vessels.
This document applies to pressure vessels for gas welding, arc welding, submerged arc
welding, gas tungsten arc welding, metal arc welding, plasma arc welding, electron
beam welding, gas-electric vertical welding, stud welding, strip electrode cladding.
This document does not apply to welding procedures for gas cylinders.
2 Normative references
The contents of the following documents constitute essential clauses of this document
through normative references in the text. Among them, for dated references, only the
version corresponding to that date applies to this document; for undated references, the
latest version (including all amendments) applies to this document.
GB/T 985.3 Recommended joint preparation for gas-shield arc welding on
aluminium and its alloys
GB/T 3375 Welding terminology
GB/T 3670 Covered electrodes for manual metal arc welding of copper and copper
alloys
GB/T 9460 Solid wires and rods for fusion welding of copper and copper alloys
GB/T 13814 Nickel and nickel alloy covered welding electrodes
GB/T 15620 Nickel and Nickel alloy wires and rods
GB/T 30583 Specification for post weld heat treatment of pressure equipment
GB/T 39255 Shielding gas for welding and cutting
NB/T 47014 Welding procedure qualification for pressure equipments
NB/T 47016 Mechanical property tests of product welded test coupons for pressure
equipments
NB/T 47018 (all parts) Ordering technical conditions for welding consumables for
pressure equipment
JB/T 3223 Welding consumables quality management procedures
3 Terms and definitions
The terms and definitions as defined in GB/T 3375 and NB/T 47014 apply to this
document. If there is any inconsistency, the terms and definitions in NB/T 47014 shall
prevail.
4 General welding procedures
4.1 General provisions
4.1.1 In addition to complying with the provisions of this document, the welding of
pressure vessels shall also comply with the technical requirements of the design
documents.
4.1.2 In addition to the provisions of this document, any results that have been proven
effective through welding test research and practice, after being approved by the
relevant parties and included in the enterprise standard, can be used for pressure vessel
welding.
4.2 Welding materials
4.2.1 Welding materials include welding rods, welding wires, welding strips, flux, gases,
electrodes, gaskets.
4.2.2 The welding seams of pressure vessel's pressure components, the welds welded
to pressure components, the welding electrode, welding wire, welding strip, welding
flux for positioning welds melted into permanent welds, shall comply with the
provisions of NB/T 47018.
4.2.3 The gas used for gas shielded welding of pressure vessels shall comply with the
provisions of GB/T 39255.
4.2.4 Principles for selecting welding materials:
The mechanical properties of weld metal shall match those of the parent material. The
mechanical properties of weld metal, which is welded according to a reasonable
welding process, shall meet the requirements of NB/T 47016 and design documents.
When necessary, other properties shall not be lower than the corresponding
requirements of the parent material.
4.2.5 The manufacturing (installation) organization shall master the weldability of
welding materials; the welding materials used for pressure vessels shall have a welding
test or practice basis.
4.2.6 Welding materials shall have a product quality certificate; the user organization
shall accept or re-inspect according to the provisions of the quality management system
and relevant standards and design documents.
4.3 Weld position
The weld position is divided into four types: flat weld, vertical weld, lateral weld,
overhead weld. The specified methods and ranges are shown in Appendix A.
4.4 Welding procedure qualification and welders
For the following types of welds, the welding procedure shall be qualified according to
NB/T 47014; the welder shall be qualified according to TSG Z6002 "Examination rules
for welding operators of special equipment":
a) Pressure component welds;
b) Welds welded to pressure components;
c) Positioning welds of the above welds (referring to welding procedure), positioning
welds welded into the above permanent welds (referring to welders);
d) Overlay welding and repair welding on the surface of the parent material of the
pressure component.
4.5 Preparation before welding
4.5.1 Site
4.5.1.1 The site of high-alloy steel pressure vessels shall be separated from other types
of materials; anti-scratch pads shall be laid on the ground.
4.5.1.2 Non-ferrous metal pressure vessels shall be manufactured in a dedicated site or
dedicated space; corresponding protective measures shall be taken.
4.5.2 Welding groove
4.5.2.1 The welding groove shall be selected from standard grooves or designed by
itself according to the design drawings and process conditions. The groove form and
size shall consider the following factors:
a) Welding method;
b) Type and thickness of parent material;
4.5.5.5 Both ends of the tack weld melted into the permanent weld shall be easy to start
or connect the arc; otherwise, they shall be trimmed.
4.5.6 Preheating
4.5.6.1 The preheating and preheating temperature of the pressure vessel before welding
shall be determined based on comprehensive factors such as the delivery status,
chemical composition, mechanical properties, diffused hydrogen content of the
deposited metal, thickness, weldability of the base material.
4.5.6.2 The preheating temperature of the welded joint shall meet the requirements of
relevant standards; if necessary, it can be determined by welding cold crack test; when
the ambient temperature is low and the constraint of the welded joint is large, the
preheating temperature shall be appropriately increased.
4.5.6.3 When local preheating is adopted, in order to avoid excessive local stress, the
preheating range can be appropriately expanded.
4.5.6.4 The preheating range shall be larger than the range shown by the temperature
measuring point A (according to Figure 1); the temperature of any point in this range
must meet the specified requirements.
4.5.6.5 Measurement of preheating temperature
4.5.6.5.1 The temperature shall be measured on the back of the heating surface.
Alternatively, the heating source can be removed first, then the temperature can be
measured after the temperature in the thickness direction of the parent material is
uniform. The temperature uniformization time is determined by min (T is the
thickness of the parent material).
4.5.6.5.2 Location of temperature measuring point (as shown in Figure 1):
a) When the thickness of the parent material at the weld of the weldment is less than
or equal to 50 mm, A is equal to 4 times the thickness of the parent material and
does not exceed 50 mm;
b) When the thickness of the parent material at the weld of the weldment is greater
than 50 mm, A ≥ 75 mm.
the remaining thickness after grinding shall not be less than the minimum forming
thickness marked on the design drawing; otherwise, repair welding shall be performed.
For the cladding, overlay, lining layers of the composite plate, the grinding depth shall
not exceed 30% of its thickness and shall not exceed 1 mm; otherwise, repair welding
shall be performed.
4.6.8 For weldments with impact test requirements, the heat input shall be controlled;
the heat input of each weld pass shall not exceed the qualified limit.
4.6.9 For weldments with chromium content greater than or equal to 3% and total alloy
element content greater than 5%, when tungsten inert gas shielded welding or metal
inert gas shielded welding is used for root welding, argon or other protective gas shall
be filled on the back of the weld; or other measures shall be taken to prevent the back
weld metal from being oxidized; the back gas shielding shall be terminated only after
at least two layers are welded.
4.6.10 The root of the fillet weld shall be fully penetrated.
4.6.11 In multi-pass and multi-layer welding, the joints of different passes of welds shall
be staggered by about 50 mm in cross section as far as possible. For welds that are prone
to thermal cracks, the arc pit must be filled when the arc is closed. If arc pit cracks are
accidentally generated, they shall be polished and removed in time. Pay attention to the
cleaning between passes and layers; clean the slag and harmful oxides on the weld
surface before continuing welding.
4.6.12 For double-sided welding with full penetration, the weld root must be cleaned
and the metal of the tack weld must be removed (except for tack welds supported by
qualified welding procedure qualification). For mechanical welding and automatic
welding, if it is confirmed by test that the penetration and welding quality can be
guaranteed, root cleaning treatment may not be performed.
4.6.13 For double-sided welding of high-alloy materials (except duplex stainless steel)
with corrosion resistance requirements, the weld layer in contact with the corrosive
medium should be welded last.
4.6.14 During welding, the interpass temperature shall be controlled not to exceed the
specified range. When the weldment is required to be preheated, the interpass
temperature shall be controlled not lower than the preheating temperature, except for
the case where the preheating temperature is appropriately increased to prevent
cracking of the base weld.
4.6.15 Each weld should be welded in one go. When welding is interrupted, thermal
insulation, post-heating or slow cooling measures shall be taken in time for weldments
sensitive to cold cracks. When welding is resumed, preheating according to the original
requirements is still required.
4.6.16 For hammerable steel welded joints, hammering shall be used layer by layer to
reduce the residual stress of the joints; however, the base layer welds and cover layer
welds should not be hammered.
4.6.17 Arc starter plates, lead-out plates, product welded test coupons shall not be
removed by hammering.
4.7 Welding repair
4.7.1 The causes of defects that require welding repair shall be analyzed, improvement
measures shall be proposed, welding repair process documents shall be prepared
according to the qualified welding procedure.
4.7.2 Defects shall be cleaned before repair; non-destructive testing can be used for
confirmation if necessary.
4.7.3 The repaired parts shall be prepared with grooves; the shape and size of the
grooves shall prevent welding defects and be convenient for welders to operate.
4.7.4 If preheating is required, the preheating temperature shall be appropriately higher
than that of the original welded joint.
4.7.5 For pressure vessels or pressure-bearing components with corrosion resistance
requirements, the repaired parts still need to ensure that the corrosion resistance is not
lower than the original, meanwhile the performance of the repaired welded joints meets
the quality requirements.
4.8 Welding inspection and testing items
4.8.1 Before welding:
a) Base steel designation and welding material model and designation;
b) Welding equipment, instruments, process equipment;
c) Storage, preservation, drying, distribution of welding materials;
d) Assembly and cleaning of welding grooves and joints;
e) Welder qualifications;
f) Welding process documents.
4.8.2 During welding:
a) Welding methods, use of welding materials, etc.;
b) Inspection and record of welding specification parameters;
experience and test data. The welding materials recommended for commonly used steel
designations can refer to Table D.1 in Appendix D.
5.2.6 When welding steels of different steel designations, the principles for selecting
welding materials are as follows:
a) When welding between low-carbon steels, between low-carbon steels and low-
alloy steels, between low-alloy steels, the selected welding materials shall ensure
that the tensile strength of the weld metal is higher than or equal to the lower limit
of the tensile strength of the parent material on the lower strength side; meanwhile
it should not exceed the upper limit specified by the standard of the parent
material on the higher strength side.
b) When welding low-carbon steel, low-alloy steel and austenitic stainless steel,
when the design temperature is higher than 370 °C, nickel-based welding
materials shall be used.
c) When welding low-carbon steel, low-alloy steel and ferritic stainless steel or
duplex stainless steel, welding materials suitable for welding dissimilar steels can
be used....