1 Scope
This Part of GB/T 16508 specifies the requirements for fabrication, inspection and test, delivery information and nameplate of stationary shell boilers.
This Part is applicable to the shell boilers defined within the scope of GB/T 16508.1.
2 Normative References
The following referenced documents are indispensable for the application of this document. For dated reference, only the edition cited applies. For undated reference, the latest edition of the normative document (including any amendments) applies.
GB 146.1 Rolling Stock Gauge for Standard Gauge Railways
GB 191 Packaging - Pictorial Marking for Handling of Goods
GB/T 1804 General Tolerances - Tolerances for Linear and Angular Dimensions without Individual Tolerance Indications
GB/T 2652 Tensile Test Methods on Weld and Deposited Metal
GB/T 16507.5 Water-Tube Boilers - Part 5: Fabrication
GB/T 16508.1 Shell Boilers - Part 1: General Requirements
GB/T 16508.2 Shell Boilers - Part 2: Material
GB/T 16508.3 Shell Boilers - Part 3: Design and Strength Calculation
GB/T 19293 Method of X-Ray Radioscopy for Butt-Weld
GB/T 25198 Heads for Pressure Vessels
NB/T 47013.10 Nondestructive Testing of Pressure Equipments - Part 10: Ultrasonic Time of Flight Diffraction Technique
JB/T 4730.1~4730.6 Nondestructive Testing of Pressure Equipments
NB/T 47014 (JB/T 4708) Welding Procedure Qualification for Pressure Equipment
NB/T 47015 (JB/T 4709) Welding Specification for Pressure Vessels
NB/T 47016(JB/T 4744) Mechanical Property Tests of Product Welded Test Coupons for Pressure Equipment
TSG G0001 Boiler Safety Technical Supervision Administration Regulation
3 Terms and Definitions
For the purposes of this document, the following terms and definitions apply.
3.1
Cold forming
The plastic deformation processing conducted below the recrystallization temperature of workpiece material.
In engineering practice, the plastic deformation processing conducted below the ambient temperature are often referred to as cold forming; and the plastic deformation processing between cold forming and hot forming are referred to as warm forming.
3.2
Hot forming
The plastic deformation processing conducted above the recrystallization temperature of workpiece material.
4 Fabrication
4.1 Basic requirements
4.1.1 Qualifications of boiler fabrication organization and operation personnel shall meet those specified in GB/T 16508.1.
4.1.2 Materials for boiler fabrication the requirements of design document and GB/T 16508.2.
4.1.3 Fabrication, inspection and acceptance of boilers shall meet the requirements of TSG G0001 Boiler Safety Technical Supervision Administration Regulation, design documents and this Part.
4.1.4 Adoption of new process, new technology and new method for boiler fabrication and inspection unlisted in this Part shall be in accordance with relevant provisions of TSG G0001 Boiler Safety Technical Supervision Administration Regulation.
4.2 Mark and mark transplantation
4.2.1 Material marks for pressure parts and main loaded non-pressure parts (hanger/support and brace) shall have traceability. In the process of fabrication, if the original mark is cut off or the material is divided into several pieces, the fabrication organization shall specify the expression mode of the mark and complete mark transplantation prior to the material cutting.
4.2.2 Weld of pressure part, weld of product welding specimen and surrounding fillet weld between the pressure parts and the main loaded non-pressure parts shall be printed with steel seal of welder code, or the welder code shall be recorded in the welding record including weld map.
4.2.3 Non-destructive testing mark shall meet the requirements of NB/T 47013(JB/T 4730).
4.2.4 In the area of inner and outer arcs of tube bend, hard imprint mark is not allowed to be used.
4.3 Material cutting
4.3.1 Material cutting method is selected according to steel characteristics and specification. The adopted cutting method shall ensure machining precision.
4.3.2 During thermal cutting, the material may be pre-heated according to the type and thickness of the steels.
4.3.3 After the material is cut by thermal cutting method, surface slag surface layer affecting fabrication quality shall be removed.
4.4 Cold/hot forming and assembling
4.4.1 General requirements for cold/hot forming
4.4.1.1 Actual thickness of formed pressure parts not only shall not be less than the minimum forming thickness of the finished product as required by the design, but also shall meet the following requirements:
a) Thickness of the tube plate flange arc and foot ring as well as the thinnest corrugation of the corrugated furnace shall not be less than 85% of the design thickness;
b) Where the flange hole of the pressure part is not provided with reinforcing ring or is impossible to be reinforced, the thickness of the straight edge shall not be less than 70% of its design thickness.
4.4.1.2 For the pressure parts made of steels after being subjected to normalizing, normalizing and tempering or quenching and tempering, cold forming or warm forming should be adopted; where warm forming is adopted, temper brittleness temperature zone of steels shall be kept away from.
4.4.2 Surface polishing
4.4.2.1 The fabrication shall avoid any mechanical damage to the material surface.
4.4.2.2 Where the following requirements are met, the surfaces of the pressure parts shall be polished at a maximum inclination of 1: 3. Where the requirements are exceeded, repair welding and polishing shall be conducted according to the repair welding procedures that pass the qualification and the surface shall be subject to non-destructive testing according to JB/T 4730 and reach Grade I acceptance.
a) Dent depth of hot forming pressure part surfaces is greater than 0.5mm, but not greater than 10% of material thickness or 3mm;
b) Dent depth of cold forming pressure part surfaces is 0.5mm~1mm;
c) Raised height of pressure part surfaces exceeds 1mm.
4.4.2.3 The ruptures at the parts where the distance from the internal head manhole flange/boiler furnace hole flange on the tube plate to the starting point of the flange bending is greater than 5mm may be polished or soldered according to 4.4.2.2.
4.4.2.4 Any crack and rip due to unsatisfied steel plate quality and over-burning, shall not be subjected to repair welding.
4.4.3 Weld layout
4.4.3.1 The longitudinal welds of two adjacent shell sections at the shell (except that with unequal wall thickness), shell and boiler furnace as well as the butt welds at the head, tube plate, boiler furnace top or foot ring and the longitudinal weld at adjacent shell sections shall not be connected with each other. The distance between the centerlines of the welds (arc length of the excircle) is at least three times the thickness of the thicker steel plate and greater than or equal to 100mm.
4.4.3.2 The distance (L) between centerlines of the butt welds at the boiler heating surface tube (except the dissimilar steel joint) and the straight section of the tubing shall meet the following requirements:
a) The outside diameter is less than 159mm and L is greater than or equal to 2 times of the outside diameter;
b) The outside diameter is greater than or equal to 159mm and L is greater than or equal to 300mm.
Where the boiler structure is difficult to meet the requirements of this article, the heat-affected zone of butt welds shall not be overlapped and L shall be greater than or equal to 50mm.
4.4.3.3 Boiler heating surface tube and tubing butt weld position shall meet the following requirements:
a) The butt weld at the heating surface tube and tubing (except coil tube and molded tube fittings) shall be located at the straight section of the tube;
b) The distance between the centerline of the butt weld at the heating surface tube and the external wall of the shell and header, starting point of the tube bending and the edges of the tube supports and hangers is at least 50mm; for boilers with rated operating pressure of greater than or equal to 3.8MPa, the distance is at least 70mm and that for the tubing shall not be less than 100mm.
4.4.3.4 Main welds at the pressure parts and the neighboring areas shall be kept clear of the welded attachments. If impossible, the weld at the welded attachments may be penetrated through the main weld, but shall not be ended at the main weld and the neighboring areas.
4.4.3.5 Tube orifices in expansion connection shall not be arranged at the longitudinal weld of the shell and also shall avoid being arranged at the circumferential weld as much as possible.
4.4.3.6 The orifice of common downcomer shall not be made at the weld, and other welded tube orifices also shall avoid being made at the weld and its heat-affected zone.
4.4.3.7 For the shell with nominal inside diameter of greater than 1800mm, quantity of longitudinal butt welds at each section of the shell shall not be greater than 3 pieces; for the shell and boiler furnace with the nominal inside diameter of not greater than 1800mm; quantity of longitudinal butt welds at each section of the shell shall not be greater than 2. Arc length of the excircle between the longitudinal welds at each section of the shell shall not be less than 300mm.
4.4.3.8 During shell splicing, length of any shell section at the shell and the boiler furnace shall not be less than 300mm and that of any shell section at the header shell shall not be less than 500mm.
4.4.3.9 Quantity of butt welds at the tube sheet and head with the nominal inside diameter of greater than 2200mm shall not be greater than 2; that of the butt welds at the tube sheet and head with the nominal diameter of not greater than 2200mm shall not be greater than 1.
4.4.3.10 The distance from the butt weld of the head to the centerline of the head shall not be greater than 30% of the nominal bore of the end, furthermore, the weld shall not pass through the flange manhole or arranged on the circular arc of the plate edge of manhole.
4.4.3.11 The whole piece of the butt weld of the flat tube plate shall not be arranged at the flange arc, or penetrate through the flange hole.
4.4.3.12 Distance from the butt weld of the arched tube plate to the intersecting line of the straight part and the raised part shall not exceed of equivalent inside diameter (centerline is counted from that of edge flue row).
4.4.3.13 The butt weld of the foot ring shall be arranged in radial direction, the minimum excircle arc length between centerlines of two welds shall not be less than 300mm.
4.4.4 Groove preparation
4.4.4.1 The groove type, dimension and assembling gap of welding joints shall meet the requirements of the design document.
4.4.4.2 The groove surface shall be free from such defects as crack, delamination and inclusion.
4.4.4.3 The groove surfaces of low alloy steels with the lower limit of the standard tensile strength Rm of greater than or equal to 540MPa and Cr-Mo low alloy steels after thermal cutting shall be subject to magnetic particle testing according to JB/T 4730.4 and reach Grade I after completion of the preparation.
4.4.4.4 Before welding, the oxide skin, oil stain, slag and other harmful impurities within at least 20mm (calculated according to the distance from groove edge) of the groove and base material surface on its both sides shall be removed.
4.4.5 Head, tube plate and foot ring
4.4.5.1 Structure of the head shall be in accordance with those specified in GB/T 16508.3; fabrication and acceptance shall meet the requirements of those specified in this Part and GB/T 25198.
4.4.5.2 The actual edge deviation value of the steel plates on both sides of the butt welds at the head, tube plate and foot ring shall not be greater than 10% of the nominal plate thickness or 3mm; where the plate thickness is greater than 100mm, it shall not exceed 6mm.
4.4.5.3 For the head, the difference between the maximum inside diameter and the minimum inside diameter of the same section shall not be greater than 1% of its nominal inside diameter; for tube plate and foot ring, it shall not be greater than 0.5% of its nominal inside diameter.
4.4.5.4 Planeness of the tube plate shall be in accordance with those specified in Table 1.
Foreword I
1 Scope
2 Normative References
3 Terms and Definitions
4 Fabrication
5 Inspection and Test
6 Delivery Information and Nameplate
Appendix A (Normative) Welded Tube Orifice of Boiler
