NB/T 47015:2023 Welding specification for pressure vessels English Language
1 Scope
This document specifies the basic welding requirements for pressure vessels made of steel, aluminum, titanium, copper, nickel, zirconium and composite metal.
This document is applicable to the pressure vessels manufactured by the welding processes such as oxyfuel gas welding, shielded metal arc welding, submerged arc welding, gas tungsten arc welding, gas metal arc welding, plasma arc welding, electron beam welding, electrogas welding, stud welding and strip surfacing.
This document is not applicable to the welding specification for gas cylinders.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions 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.
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 Gases and gas mixtures for welding and cutting processes
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) Specification of welding materials for pressure equipment
JB/T 3223 Welding consumables quality management procedures
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 3375 and NB/T 47014 as well as the following apply. In case of any inconsistency, those given in NB/T 47014 shall prevail.
4 General welding specification
4.1 General requirements
4.1.1 In addition to the requirements of this document, the welding of pressure vessels shall also meet the technical requirements of design documents.
4.1.2 In addition to the requirements of this document, the results proved effective through welding test research and practice may be applicable to the welding of pressure vessels after being recognized by relevant parties and included in the enterprise standards.
4.2 Welding materials
4.2.1 Welding materials include covered electrodes, welding wires, welding strips, fluxes, gases, electrodes and backings.
4.2.2 As for the pressure vessels, the covered electrodes, welding wires, welding strips and fluxes used for the welds of pressure elements, welds welded with pressure elements, and tack welds fused into permanent welds shall meet the requirements of NB/T 47018.
4.2.3 Gases for gas shielded welding of pressure vessels shall meet the requirements of GB/T 39255.
4.2.4 Selection principle of welding materials:
The mechanical properties of weld metal shall match those of base metal. The mechanical properties of weld metal welded according to reasonable welding procedure shall meet the requirements of NB/T 47016 and design documents. Where necessary, other properties of the weld metal shall not be inferior to the corresponding requirements of the base metal.
4.2.5 The manufacturing (installation) unit shall master the weldability of welding materials. The welding materials used for pressure vessels shall have the basis of welding test or practice.
4.2.6 The welding materials shall be provided with product quality certificates. The using unit shall acceptance inspection or reinspection on the welding materials according to the requirements of quality management system as well as the relevant standards and design documents.
4.3 Weld position
Weld positions are classified into four types: flat position, vertical position, horizontal position and overhead position. Their specified process and scope are given in Annex A.
4.4 Welding procedure qualification and welders
When welding the following types of welds, the welding procedure adopted shall be qualified according to NB/T 47014, and the welders involved shall pass the examination according to TSG Z6002 Examination rules for welding operators of special equipment:
a) Welds of pressure elements;
b) Welds welded with pressure elements;
c) Tack welds of the above welds (for welding procedure), and tack welds fused into the above permanent welds (for welder);
d) Surfacing and repair welding on the surface of the base metal of pressure elements.
4.5 Preweld preparation
4.5.1 Site
4.5.1.1 The site of high-alloy steel pressure vessels shall be separated from that of other types of materials, where the ground shall be covered with anti-scratch pads.
4.5.1.2 Non-ferrous metal pressure vessels shall be manufactured in a dedicated site or space, and corresponding protection measures shall be taken.
4.5.2 Welding groove
4.5.2.1 The welding grooves shall be standard ones or self-designed based on the design drawings and process conditions. The groove type and size shall be determined with consideration of the following factors:
a) Welding process;
b) Type and thickness of base metal;
c) Using weld filler metal as little as possible;
d) Avoiding welding defects;
e) Reducing welding deformation and residual stress;
f) Being conducive to welding protection;
g) Convenience for welder to operate;
h) For groove of composite material, the dilution rate of weld metal in transition layer should be reduced; and it shall be easy to distinguish the interface between base layer and cladding layer when welding the corrosion-resistant layer.
4.5.2.2 See Annex B for the type and size of welding groove for special materials.
4.5.3 Groove preparation
4.5.3.1 Grooves may be prepared by cold working method or hot working method. To prepare the groove by hot working method, it is necessary to remove the oxide layer by cold working to expose the metallic luster.
4.5.3.2 The surface of the welding groove shall be smooth and free of cracks, delamination, inclusions and other defects.
4.5.4 Equipment and instruments
Welding equipment, heating equipment and auxiliary equipment shall be ensured to work normally, safely and reliably; the instruments to be used shall be within the validity period of calibration or verification.
4.5.5 Pairing and positioning
4.5.5.1 During pairing and positioning, it is necessary to prevent mechanical damage to the metal surface, especially to protect the surfaces of high-alloy steel and non-ferrous metals to prevent pollution from iron ions.
4.5.5.2 After pairing and positioning, the groove clearance, misalignment, angular value, etc. shall meet the requirements of drawings or standards.
4.5.5.3 Assembly shall not be forcibly done. The preheat temperature and range of tack welding shall be the same as those of main body welding. The length, throat and spacing of tack welds shall meet the requirements of welding procedure documents.
4.5.5.4 The tack welds shall be free from cracks, otherwise they shall be cleared and re-welded.
4.5.5.5 Both ends of the tack weld fused into a permanent weld shall be convenient for striking or arc connection, otherwise it shall be trimmed.
4.5.6 Preheating
4.5.6.1 The preheating of pressure vessels before welding and the preheat temperature shall be determined according to the comprehensive factors such as the delivery state, chemical composition and mechanical properties of base metal, and diffusible hydrogen content, thickness and weldability of deposited metal.
4.5.6.2 The preheat temperature of welded joints shall meet the requirements of relevant standards, and if necessary, it may be determined by welding cold crack test. When the ambient temperature is low and the restraint intensity of welded joints is high, the preheat temperature shall be appropriately increased.
4.5.6.3 In case of local preheating, in order to avoid excessive local stress, the preheat range may be appropriately expanded.
4.5.6.4 The preheat range shall be larger than the interval shown in temperature measuring point A (as shown in Figure 1), and the temperature at any point in this interval shall meet the specified requirements.
4.5.6.5 Measurement of preheat temperature
4.5.6.5.1 The temperature shall be measured on the back of the heating surface. Alternatively, the heating source may be removed first, and the temperature may be measured after the temperature is uniform in the thickness direction of the base metal. The time of temperature homogenization shall be determined according to min (T is the base metal thickness).
4.5.6.5.2 Position of temperature measuring point (as shown in Figure 1):
a) When the thickness of the base metal at the weld of weldment is less than or equal to 50mm, A shall be equal to 4 times the base metal thickness and not more than 50mm;
b) When the thickness of the base metal at the weld of weldment is greater than 50mm, A shall be ≥75mm.
a) Butt joint b) T-joint
Figure 1 Position of temperature measuring point A
4.6 Welding
4.6.1 Technicians shall prepare the welding procedure specification for each welded joint according to the standards, design documents, service requirements and site conditions, as well as the qualified welding procedure. See Annex C for the recommended form.
4.6.2 Welders shall operate in strict accordance with the welding procedure specification.
4.6.3 Effective protective measures shall be taken in any of the following situations in the welding environment, otherwise welding is prohibited:
a) The wind speed of gas shielded welding is greater than 2m/s, and that of other welding processes is greater than 10m/s;
b) The relative humidity is greater than 90%;
c) Rain and snow environment;
d) The temperature of weldment is lower than -20℃.
NB/T 47015-2023, NB 47015-2023, NBT 47015-2023, NB/T47015-2023, NB/T 47015, NB/T47015, NB47015-2023, NB 47015, NB47015, NBT47015-2023, NBT 47015, NBT47015
Introduction of NB/T 47015-2023
NB/T 47015:2023 Welding specification for pressure vessels English Language
1 Scope
This document specifies the basic welding requirements for pressure vessels made of steel, aluminum, titanium, copper, nickel, zirconium and composite metal.
This document is applicable to the pressure vessels manufactured by the welding processes such as oxyfuel gas welding, shielded metal arc welding, submerged arc welding, gas tungsten arc welding, gas metal arc welding, plasma arc welding, electron beam welding, electrogas welding, stud welding and strip surfacing.
This document is not applicable to the welding specification for gas cylinders.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions 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.
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 Gases and gas mixtures for welding and cutting processes
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) Specification of welding materials for pressure equipment
JB/T 3223 Welding consumables quality management procedures
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 3375 and NB/T 47014 as well as the following apply. In case of any inconsistency, those given in NB/T 47014 shall prevail.
4 General welding specification
4.1 General requirements
4.1.1 In addition to the requirements of this document, the welding of pressure vessels shall also meet the technical requirements of design documents.
4.1.2 In addition to the requirements of this document, the results proved effective through welding test research and practice may be applicable to the welding of pressure vessels after being recognized by relevant parties and included in the enterprise standards.
4.2 Welding materials
4.2.1 Welding materials include covered electrodes, welding wires, welding strips, fluxes, gases, electrodes and backings.
4.2.2 As for the pressure vessels, the covered electrodes, welding wires, welding strips and fluxes used for the welds of pressure elements, welds welded with pressure elements, and tack welds fused into permanent welds shall meet the requirements of NB/T 47018.
4.2.3 Gases for gas shielded welding of pressure vessels shall meet the requirements of GB/T 39255.
4.2.4 Selection principle of welding materials:
The mechanical properties of weld metal shall match those of base metal. The mechanical properties of weld metal welded according to reasonable welding procedure shall meet the requirements of NB/T 47016 and design documents. Where necessary, other properties of the weld metal shall not be inferior to the corresponding requirements of the base metal.
4.2.5 The manufacturing (installation) unit shall master the weldability of welding materials. The welding materials used for pressure vessels shall have the basis of welding test or practice.
4.2.6 The welding materials shall be provided with product quality certificates. The using unit shall acceptance inspection or reinspection on the welding materials according to the requirements of quality management system as well as the relevant standards and design documents.
4.3 Weld position
Weld positions are classified into four types: flat position, vertical position, horizontal position and overhead position. Their specified process and scope are given in Annex A.
4.4 Welding procedure qualification and welders
When welding the following types of welds, the welding procedure adopted shall be qualified according to NB/T 47014, and the welders involved shall pass the examination according to TSG Z6002 Examination rules for welding operators of special equipment:
a) Welds of pressure elements;
b) Welds welded with pressure elements;
c) Tack welds of the above welds (for welding procedure), and tack welds fused into the above permanent welds (for welder);
d) Surfacing and repair welding on the surface of the base metal of pressure elements.
4.5 Preweld preparation
4.5.1 Site
4.5.1.1 The site of high-alloy steel pressure vessels shall be separated from that of other types of materials, where the ground shall be covered with anti-scratch pads.
4.5.1.2 Non-ferrous metal pressure vessels shall be manufactured in a dedicated site or space, and corresponding protection measures shall be taken.
4.5.2 Welding groove
4.5.2.1 The welding grooves shall be standard ones or self-designed based on the design drawings and process conditions. The groove type and size shall be determined with consideration of the following factors:
a) Welding process;
b) Type and thickness of base metal;
c) Using weld filler metal as little as possible;
d) Avoiding welding defects;
e) Reducing welding deformation and residual stress;
f) Being conducive to welding protection;
g) Convenience for welder to operate;
h) For groove of composite material, the dilution rate of weld metal in transition layer should be reduced; and it shall be easy to distinguish the interface between base layer and cladding layer when welding the corrosion-resistant layer.
4.5.2.2 See Annex B for the type and size of welding groove for special materials.
4.5.3 Groove preparation
4.5.3.1 Grooves may be prepared by cold working method or hot working method. To prepare the groove by hot working method, it is necessary to remove the oxide layer by cold working to expose the metallic luster.
4.5.3.2 The surface of the welding groove shall be smooth and free of cracks, delamination, inclusions and other defects.
4.5.4 Equipment and instruments
Welding equipment, heating equipment and auxiliary equipment shall be ensured to work normally, safely and reliably; the instruments to be used shall be within the validity period of calibration or verification.
4.5.5 Pairing and positioning
4.5.5.1 During pairing and positioning, it is necessary to prevent mechanical damage to the metal surface, especially to protect the surfaces of high-alloy steel and non-ferrous metals to prevent pollution from iron ions.
4.5.5.2 After pairing and positioning, the groove clearance, misalignment, angular value, etc. shall meet the requirements of drawings or standards.
4.5.5.3 Assembly shall not be forcibly done. The preheat temperature and range of tack welding shall be the same as those of main body welding. The length, throat and spacing of tack welds shall meet the requirements of welding procedure documents.
4.5.5.4 The tack welds shall be free from cracks, otherwise they shall be cleared and re-welded.
4.5.5.5 Both ends of the tack weld fused into a permanent weld shall be convenient for striking or arc connection, otherwise it shall be trimmed.
4.5.6 Preheating
4.5.6.1 The preheating of pressure vessels before welding and the preheat temperature shall be determined according to the comprehensive factors such as the delivery state, chemical composition and mechanical properties of base metal, and diffusible hydrogen content, thickness and weldability of deposited metal.
4.5.6.2 The preheat temperature of welded joints shall meet the requirements of relevant standards, and if necessary, it may be determined by welding cold crack test. When the ambient temperature is low and the restraint intensity of welded joints is high, the preheat temperature shall be appropriately increased.
4.5.6.3 In case of local preheating, in order to avoid excessive local stress, the preheat range may be appropriately expanded.
4.5.6.4 The preheat range shall be larger than the interval shown in temperature measuring point A (as shown in Figure 1), and the temperature at any point in this interval shall meet the specified requirements.
4.5.6.5 Measurement of preheat temperature
4.5.6.5.1 The temperature shall be measured on the back of the heating surface. Alternatively, the heating source may be removed first, and the temperature may be measured after the temperature is uniform in the thickness direction of the base metal. The time of temperature homogenization shall be determined according to min (T is the base metal thickness).
4.5.6.5.2 Position of temperature measuring point (as shown in Figure 1):
a) When the thickness of the base metal at the weld of weldment is less than or equal to 50mm, A shall be equal to 4 times the base metal thickness and not more than 50mm;
b) When the thickness of the base metal at the weld of weldment is greater than 50mm, A shall be ≥75mm.
a) Butt joint b) T-joint
Figure 1 Position of temperature measuring point A
4.6 Welding
4.6.1 Technicians shall prepare the welding procedure specification for each welded joint according to the standards, design documents, service requirements and site conditions, as well as the qualified welding procedure. See Annex C for the recommended form.
4.6.2 Welders shall operate in strict accordance with the welding procedure specification.
4.6.3 Effective protective measures shall be taken in any of the following situations in the welding environment, otherwise welding is prohibited:
a) The wind speed of gas shielded welding is greater than 2m/s, and that of other welding processes is greater than 10m/s;
b) The relative humidity is greater than 90%;
c) Rain and snow environment;
d) The temperature of weldment is lower than -20℃.