GB/T 25198-2023 Heads for pressure vessels
1 Scope
This document specifies the types, type parameters and requirements for fabrication, inspection and acceptance of the heads for pressure vessels that are made of steel, non-ferrous metals (aluminium and aluminium alloys, copper and copper alloys, titanium and titanium alloys, nickel and nickel alloys, and zirconium and zirconium alloys) and clad plates.
This document is applicable to the hemispherical, ellipsoidal, dished, spherically dished, flat-bottomed and conical heads for pressure vessels that are formed by stamping, spinning and rolling or formed in flaps, with whole or spliced blank plates.
The fabrication, inspection and acceptance requirements of heads for atmospheric vessels and other pressure equipment may also refer to this document.
2 Normative references
The following documents contain requirements 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 150 (all parts) Pressure vessels
GB/T 9452 Testing method for working zone of heat treatment furnace
GB/T 12337 Steel spherical tanks
GB/T 26929 Terminology for pressure vessels
JB 4732 Steel pressure vessels - Design by analysis
JB/T 4734 Aluminium welded vessels
JB/T 4745 Titanium welded vessels
JB/T 4755 Copper pressure vessels
JB/T 4756 Nickel and nickel alloy pressure vessels
NB/T 10558 Coating and packing for pressure vessels transport
NB/T 47002 (all parts) Clad plate for pressure vessel
NB/T 47011 Zirconium pressure vessels
NB/T 47013.2 Nondestructive testing of pressure equipments - Part 2: Radiographic testing
NB/T 47013.3 Nondestructive testing of pressure equipments - Part 3: Ultrasonic testing
NB/T 47013.4 Nondestructive testing of pressure equipments - Part 4: Magnetic particle testing
NB/T 47013.5 Nondestructive testing of pressure equipments - Part 5: Penetrant testing
NB/T 47013.7 Nondestructive testing of pressure equipments - Part 7: Visual testing
NB/T 47013.10 Nondestructive testing of pressure equipments - Part 10: Ultrasonic time of flight diffraction technique
NB/T 47013.11 Nondestructive testing of pressure equipments - Part 11: Standard practice for X-ray digital radiography
TSG Z6002 Examination rules for welding operators of special equipment
TSG Z8001 Examination rules for nondestructive testing inspectors of special equipment
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 150 (all parts), GB/T 26929, JB 4732, JB/T 4734, JB/T 4745, JB/T 4755, JB/T 4756 and NB/T 47011 and the following apply.
3.1
heating temperature for forming
maximum temperature reached by the head blank or semi-finished product in the heating process
3.2
end forming temperature
temperature at which the plastic deformation of the head blank or semi-finished product ends
4 Symbols
For the purposes of this document, the following symbols apply.
A——the internal surface area of a head, m2;
C1——the negative deviation of material thickness, selected according to the corresponding material standard, mm;
D——the head diameter (inside or outside diameter of a head, as specified in Table 1 and Table 2), mm;
Di——the inside diameter of hemispherical, ellipsoidal, dished, spherically dished and flat-bottomed heads or the big-end inside diameter of conical heads, mm;
Dis——the small-end inside diameter of conical heads, mm;
Do——the outside diameter of ellipsoidal, dished and spherically dished heads, mm;
H——the total depth of a hemispherical, spherically dished or flat-bottomed head or a ellipsoidal or dished head based on inside diameter, mm;
Ho——the total height of a conical head or a ellipsoidal or dished head based on outside diameter, mm;
H′——the total height of a conical head up to the top of cone, mm;
h——the straight edge height of a hemispherical, ellipsoidal, dished, flat-bottomed or conical head, mm;
m——the mass of a head, kg;
Ri——the inside radius of a hemispherical head, or the inside radius of spherical portion of a spherically dished head or dished head, mm;
ri——the corner radius of transition section of a flat-bottomed head or dished head, or the corner radius of transition section at big end of a conical head, mm;
rs——the corner radius of transition section at small end of a conical head, mm;
V——the volume of a head, m3;
α——the half vertex angle of a conical head, °;
δn——the nominal thickness of a head, mm;
δs——the material thickness of a head, i.e., the feeding thickness when fabricating the head, which is also the specification thickness stated in material quality certificate, mm;
δmin——the minimum required fabrication thickness of a head, i.e., the minimum thickness of the finished head required by the design, mm;
δ′min——the minimum thickness of a finished head, i.e., the minimum measured thickness of the finished head, mm.
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5 Type parameters and designations
5.1 Type parameters of heads
5.1.1 See Tables 1 and 2 for the names, section shapes, type codes and type parameters of heads. The last letter A or B of the type code in Tables 1 and 2 represents "based on inside diameter" or "based on outside diameter" respectively. The numbers in parentheses in the type codes of conical heads shown in Table 2 are the half vertex angle values of conical heads. For the heads in Table 2, design details shall also be provided.
5.1.2 The straight edge height h of hemispherical, ellipsoidal, dished and flat-bottomed heads with straight edges and conical heads with folded edges shall be 25mm when the head diameter D≤2,000mm and shall be 40mm when the head diameter D>2,000mm. The straight edge height may be specified separately during design.
5.1.3 The calculation formulae for internal surface area, volume, mass and total height (total depth) of the types of heads listed in Tables 1 and 2 are given in Annex A.
5.1.4 The internal surface area, volume, mass and total height (total depth) of the types of heads listed in Table 1 are given in Annexes B to G respectively.
5.1.5 In addition to the types of dished heads listed in Table 1, there are also the following commonly used dished heads: Ri=0.8Di, ri=0.154Di; Ri=0.833Di, ri=0.154Di; Ri=1.0Di, ri=0.15Di; Ri=1.0Di, ri=0.06Di; Ri=0.9Di, ri=0.17Di, etc. The internal surface area, volume, mass and total depth of the above-mentioned dished heads may be calculated with reference to the methods provided in Annex A.
5.2 Head designation
Head designation shall be as follows:
①×③(④)-⑤-⑥⑦
where,
①——Type code of the head, see Table 1 and Table 2. For the conical head in Table 2, "α" in the type code shall be accompanied by a note specifying its value as a half vertex angle, in degrees;
②——Arabic numeral, which is the value of the diameter D of the head, in mm;
③——Arabic numeral, which is the value of the nominal thickness δn of the head, in mm;
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④——Arabic numeral, which is the value of the minimum required fabrication thickness δmin of the head specified in the design documents or the order technical documents, in mm;
⑤——Arabic numeral, which is the value of the feeding thickness δs (marked by the fabrication unit of heads, not necessarily by the design unit) of the head, in mm;
⑥——Material designation of the head;
⑦——Number of this document: GB/T 25198-2023.
Example 1:
An ellipsoidal head (the feeding thickness of the head at the time of fabrication is 12mm) made of Q345R based on outside diameter, with a diameter of 325mm, a nominal thickness of 12mm and a minimum required fabrication thickness of 10.4mm, shall be designated as follows:
Design designation: EHB 325×12 (10.4) - Q345R GB/T 25198-2023
Product designation: EHB 325×12 (10.4) - 12 - Q345R GB/T 25198-2023
Example 2:
A dished head (the feeding thickness of the head at the time of fabrication is 22mm) made of Q345R based on inside diameter, with a diameter of 2,400mm, a nominal thickness of 20mm, a minimum required fabrication thickness of 18.2mm, Ri=1.0Di, ri=0.10Di, shall be designated as follows:
Design designation: THA 2400×20 (18.2) - Q345R GB/T 25198-2023
Product designation: THA 2400×20 (18.2) - 22 - Q345R GB/T 25198-2023
Example 3:
A conical head (type CDA) (the feeding thickness of the head at the time of fabrication is 14mm) made of 09MnNiDR, with a diameter at big end of 2,400mm, a diameter at small end of 1,000mm, a half vertex angle of 60°, a nominal thickness of 14mm and a minimum required fabrication thickness of 11.6mm, shall be designated as follows (with design details provided):
Foreword I
1 Scope
2 Normative references
3 Terms and definitions
4 Symbols
5 Type parameters and designations
6 Fabrication, inspection and acceptance
7 End-of-manufacturing data
8 Product marking
9 Coating and transport packing
Annex A (Informative) Calculation formulae for internal surface area, volume, mass and total height (total depth) of heads
Annex B (Informative) Type parameters of HHA hemispherical heads
Annex C (Informative) Type parameters of EHA ellipsoidal heads
Annex D (Informative) Type parameters of EHB ellipsoidal heads
Annex E (Informative) Type parameters of THA dished heads
Annex F (Informative) Type parameters of THB dished heads
Annex G (Informative) Type parameters of SDH spherically dished heads
Annex H (Informative) Ordering specification for heads
Annex I (Informative) Reduction ratios for fabrication thickness of heads
Annex J (Informative) Groove types and codes of heads
Annex K (Informative) Certificate of conformity and data report of head products
Annex L (Informative) Densities of common materials
