NB/T 47003.2-2022Atmospheric pressure vessels - Part 2: Silos for solid materials (English PDF)

Foreword

This document was issued on 4 November 2022 by the National Energy Administration of the PRC and takes effect on 4 May 2023.

It is a NB/T standard: recommended rather than compulsory, but it is the text a Chinese reviewer applies when assessing a submission.

It is classified under ICS 23.020.10, Chinese classification J 74.

It replaces NB/T 47003.2-2009, which is superseded.

This document has been drafted in accordance with the rules given in GB/T 1.1-2020, Directives for standardization - Part 1: Rules for the structure and drafting of standardizing documents.

NB/T 47003, Atmospheric pressure vessels, is divided into two parts: Part 1, Steel welded atmospheric pressure vessels; Part 2, Silos for solid materials.

This document constitutes Part 2 of NB/T 47003, Atmospheric pressure vessels.

This document replaces NB/T 47003.2-2009, Silos for solid materials. In addition to structural adjustments and editorial changes, the following main technical changes have been made with respect to NB/T 47003.2-2009:

a) the range of application of the design pressure of silos for solid materials has been changed (see 1.2; 1.2 of the 2009 edition);

b) the responsibilities of the user or of the party commissioning the design have been added (see 4.2.1);

c) the safety factors for carbon steel, low alloy steel and high alloy steel have been changed: the safety factor applied to the lower limit of the standard tensile strength of the steel has been adjusted from 2.4 to 2.3 (see 4.6; 4.8 of the 2009 edition);

d) the pressure test has been deleted (see 4.8 of the 2009 edition) and the tightness test and the water filling test have been added (see 4.10);

e) the steel grades of steel materials and the allowable stresses of section steel have been added (see Clause 5; Clause 5 of the 2009 edition);

f) aluminium plate (see 5.7), aluminium tube (see 5.8), aluminium extruded bar (see 5.9), aluminium hot extruded profile (see 5.10) and aluminium alloy forgings (see 5.11) have been added;

g) the overpressure coefficient of the material load has been added (see 6.1);

h) the use coefficient I for seismic calculation has been deleted (see 6.4 of the 2009 edition);

i) the calculation method for the wind load has been changed (see 6.5; 6.5 of the 2009 edition);

j) the calculation of the material load on the conical part of the silo shell has been changed (see 6.11; 6.10 of the 2009 edition);

k) the stability check of the cylindrical part of the silo shell has been added (see 6.15);

l) Annex B, Calculation of the horizontal pressure on the cylindrical shell of an eccentrically discharged silo, has been added (see Annex B).

This document was proposed by and is under the jurisdiction of the National Technical Committee on Boilers and Pressure Vessels of Standardization Administration of China (SAC/TC 262).

The drafting organizations of this document are: Gansu Lanke Petrochemical High-tech Equipment Co., Ltd.; China Kunlun Contracting and Engineering Corporation; SINOPEC Engineering Incorporation; SINOPEC Shanghai Engineering Company Limited; China Special Equipment Inspection and Research Institute; Hefei Municipal Administration for Market Regulation; Ningbo Special Equipment Inspection and Research Institute; Shanghai Lanbin Petrochemical Equipment Co., Ltd.; Lanzhou Petroleum and Chemical Equipment Inspection Institute of the Machinery Industry Co., Ltd.; China Huanqiu Contracting and Engineering Co., Ltd. Beijing Branch; Beijing Yanhua Engineering Construction Co., Ltd.

The main drafters of this document are: Liu Fulu, Wan Hesheng, Li Mengqiang, Yuan Shaoyun, Dang Zhanwei, Chen Chao, Chen Zhiwei, Chen Qiang, Zhang Yong, Huang Huandong, Zhang Peng, Zhang Bing, Gao Zhongwen, Zhu Baoguo, Yin Changchuang, Zhang Yicheng, Su Houde, Li Yanming, Yue Guoyin and Liu Pengfei.

The successive editions of this document and of the documents it replaces are: JB 2880-1981; JB/T 4735-1997; NB/T 47003.2-2009.

1 Scope

NB/T 47003.2-2022 is Part 2 of the Chinese standard for atmospheric pressure vessels and covers silos for solid materials, replacing the 2009 edition. A silo is not a tank with powder in it: stored solids arch and rathole, they exert pressures that depend on whether the contents are filling or discharging, and the switch to flow can load the transition of a hopper far beyond anything the static head would suggest. The standard is built on that. It sets the scope and the defined terms, then the material properties that govern design - bulk density, angle of internal friction, wall friction angle and flow function - and how they are determined. Loads follow: the filling and discharge pressures on the vertical wall and on the hopper, the patch loads from eccentric discharge, and the combination with wind, snow, seismic and thermal actions. Design rules then cover the cylindrical shell and its buckling under axial compression, the conical and pyramidal hoppers and the transition ring or skirt where the hoop tension concentrates, the roof and its openings, the supporting structure and the skirt or leg arrangement, and the discharge outlet with its gate and flow-promoting devices. Materials, wall thickness and corrosion and abrasion allowances are specified, followed by fabrication and welding, dimensional tolerances, inspection and testing, marking and the documentation supplied on delivery. It applies to welded steel silos for the Chinese energy and process industries.

1.1 This document specifies the requirements for the design, fabrication, inspection and acceptance of silos for solid materials (hereinafter referred to as silos).

1.2 This document applies to steel and aluminium welded vertical cylindrical silos used to store granular or powdery loose solid materials, within the following range of application:

a) the inside diameter of the silo shell is not greater than 20 m;

b) the volume is not less than 15 cubic metres;

c) the design positive pressure is not greater than 20 kPa and the design negative pressure is not lower than -5 kPa;

d) the design temperature range is in accordance with the service temperature range permitted for the metallic material of the silo shell;

e) the ratio of the height H to the inside diameter Di is not greater than 5.

1.3 This document does not apply to the following silos:

a) silos directly buried underground;

b) silos containing materials whose degree of toxic hazard is extreme or high;

c) hoppers that are frequently moved;

d) groups of silos connected in a row by an operating platform.

1.4 Boundary of the silo. The scope defined in this document covers the silo shell and the parts connected with it to form an integral whole, delimited within the following boundaries.

a) For the connection between the silo and external piping: 1) the end face of the groove of the first circumferential joint of a welded connection; 2) the end face of the first threaded joint of a threaded connection; 3) the sealing face of the first flange of a flanged connection; 4) the first sealing face of a special connector or of a pipe fitting connection.

b) The closure elements of the openings of the silo, such as nozzles, manholes and handholes, the formed heads, the flat covers and their connecting fasteners.

c) The support elements of the silo, the reinforcing elements of the openings, the pads and other attachments, together with their welds to the shell.

d) The safety accessories and instruments directly mounted on the silo.

2 Normative references

The following documents contain provisions which, through normative reference in this text, constitute indispensable provisions of this document. For dated references, only the edition corresponding to that date applies to this document; for undated references, the latest edition (including all amendments) applies to this document.

GB/T 150.1 Pressure vessels - Part 1: General requirements

GB/T 150.2 Pressure vessels - Part 2: Materials

GB/T 150.3 Pressure vessels - Part 3: Design

GB/T 150.4 Pressure vessels - Part 4: Fabrication, inspection and testing, and acceptance

GB/T 699 Quality carbon structural steels

GB/T 700-2006 Carbon structural steels

GB/T 713 Steel plates for boilers and pressure vessels

GB/T 983 Stainless steel covered electrodes

GB/T 985.1 Recommended joint preparation for gas welding, manual metal arc welding, gas shielded arc welding and beam welding

GB/T 985.2 Recommended joint preparation for submerged arc welding

GB/T 985.3 Recommended joint preparation for gas shielded arc welding of aluminium and aluminium alloys

GB/T 985.4 Recommended joint preparation for clad steel

GB/T 1220 Stainless steel bars

GB/T 1591-2018 High strength low alloy structural steels

GB/T 3077 Alloy structural steels

GB/T 3091 Welded steel pipes for low pressure liquid delivery

GB/T 3190 Chemical composition of wrought aluminium and aluminium alloys

GB/T 3191 Aluminium and aluminium alloy extruded bars

GB/T 3274 Hot rolled plates and strips of carbon structural steels and high strength low alloy structural steels

GB/T 3880 (all parts) Wrought aluminium and aluminium alloy plates, sheets and strips for general engineering

GB/T 4237 Hot rolled stainless steel plates and strips

GB/T 4437.1-2015 Aluminium and aluminium alloy hot extruded tubes - Part 1: Seamless round tubes

GB/T 4842 Argon

GB/T 5117 Covered electrodes for manual metal arc welding of non-alloy and fine grain steels

GB/T 5118 Covered electrodes for manual metal arc welding of creep-resisting steels

GB/T 5293 Classification requirements for solid wire electrodes, tubular cored electrodes and electrode-flux combinations for submerged arc welding of non-alloy and fine grain steels

GB/T 6479 Seamless steel tubes for high pressure chemical fertilizer equipment

GB/T 6892 Wrought aluminium and aluminium alloy extruded profiles for general engineering

GB/T 6893 Aluminium and aluminium alloy drawn (rolled) seamless tubes

GB/T 8162 Seamless steel tubes for structural purposes

GB/T 8163 Seamless steel tubes for liquid service

GB/T 10858 Aluminium and aluminium alloy welding wires

GB/T 12470 Classification requirements for solid wire electrodes, tubular cored electrodes and electrode-flux combinations for submerged arc welding of creep-resisting steels

GB/T 13296 Seamless stainless steel tubes for boilers and heat exchangers

GB/T 14957 Steel wires for fusion welding

GB/T 14976 Seamless stainless steel pipes for fluid transport

GB/T 24511 Stainless steel and heat-resisting steel plates and strips for pressure equipment

GB/T 26929 Terminology for pressure vessels

GB 50009 Load code for the design of building structures

GB 50341-2014 Code for design of vertical cylindrical welded steel oil tanks

GB 50813 Code for design of anti-static ignition and explosion protection of powder material silos in the petrochemical industry

JB/T 4734-2002 Aluminium welded vessels

NB/T 10558 Coating, transport and packaging of pressure vessels

NB/T 47002.1-2019 Clad steel plates for pressure vessels - Part 1: Stainless steel-steel clad plates

NB/T 47003.1 Atmospheric pressure vessels - Part 1: Steel welded atmospheric pressure vessels

NB/T 47008 Carbon and alloy steel forgings for pressure equipment

NB/T 47010 Stainless and heat-resisting steel forgings for pressure equipment

NB/T 47013 (all parts) Nondestructive testing of pressure equipment

NB/T 47014 Welding procedure qualification for pressure equipment

NB/T 47015 Welding specification for pressure vessels

NB/T 47018 (all parts) Technical specifications for the ordering of welding consumables for pressure equipment

NB/T 47029 Aluminium and aluminium alloy forgings for pressure vessels

YB/T 5092 Stainless steel wires for welding

3 Terms and definitions

For the purposes of this document, the terms and definitions given in GB/T 150.1 and GB/T 26929 and the following apply.

3.1 pressure - The force acting perpendicularly on unit surface area of the silo. In this document, unless otherwise specified, pressure means gauge pressure.

3.2 operating pressure - The highest pressure that can be reached at the top of the silo under normal operating conditions.

3.3 design pressure - The maximum pressure set at the top of the silo which, together with the corresponding design temperature, constitutes the basic design loading condition of the silo.

3.4 calculation pressure - The pressure used, at the corresponding design temperature, to determine the thickness of each part or element of the silo.

3.5 test pressure - The pressure at the top of the silo during the tightness test.

3.6 metal temperature - The average value of the temperature across the metal section of an element of the silo. In no case shall the surface temperature of the metal of the element exceed the service temperature permitted for the metallic material.

3.7 design temperature - The metal temperature of the element set under normal operating conditions. The design temperature, together with the design pressure, constitutes the design loading condition. Note: for silos having several operating conditions, the design pressure and the design temperature corresponding to each of the most severe conditions shall be indicated on the drawings or in the corresponding technical documents.

3.8 test temperature - The metal temperature of the silo shell during the tightness test.

3.9 required thickness - The thickness obtained by calculation with the formulae; where necessary, the thickness required by other loads shall also be included (see 4.3).

3.10 design thickness - The sum of the greater of the required thickness and the minimum thickness plus the corrosion (wear) allowance.

3.11 nominal thickness - The nominal thickness is the design thickness increased by the negative deviation of the material thickness and rounded up to the thickness of a standard material size, that is, the thickness marked on the drawing.

3.12 effective thickness - The effective thickness is the nominal thickness less the corrosion (wear) allowance and less the negative deviation of the material thickness.

3.13 minimum required fabrication thickness - The minimum thickness which, after forming of the silo shell, ensures that the design requirements are satisfied.

4 General requirements

4.1 General

4.1.1 The design, fabrication, inspection and acceptance of silos shall comply with the provisions of this document; for matters not specified in this document, the provisions of NB/T 47003.1 shall apply, and the relevant national laws, regulations and safety technical codes shall also be observed.

4.1.2 The design unit and the fabrication unit of the silo shall establish a sound quality management system and operate it effectively.

4.2 Responsibilities

4.2.1 Responsibilities of the user or of the party commissioning the design. The user or the party commissioning the design of the silo shall formally submit to the design unit, in written form, the design conditions of the silo (UDS - User's Design Specification), which shall contain at least the following contents:

a) the main standards and codes on which the design of the silo is based;

b) the operating parameters (including the operating pressure, the operating temperature range, the height of the material, the loads on the nozzles, etc.);

c) the place of use of the silo and its natural conditions (including the ambient temperature, the seismic fortification intensity, the wind load and the snow load, etc.);

d) the composition and the characteristics of the material stored;

e) the intended service life;

f) the geometrical parameters and the orientation of the nozzles;

g) any other necessary conditions required for the design.

4.2.2 Responsibilities of the design unit: a) the design unit shall be responsible for the correctness and the completeness of the design documents; b) the design unit shall keep the complete set of design documents of the silo throughout its design service life.

4.2.3 Responsibilities of the fabrication unit:

a) the fabrication unit shall carry out the fabrication in accordance with the requirements of the design documents; if it is necessary to modify the original design, a written document from the original design unit agreeing to the modification shall be obtained, and the modified parts shall be recorded in detail on the as-built drawings;

b) before the fabrication of the silo, the fabrication unit shall draw up a complete quality plan, whose contents shall include at least the fabrication process control points, the inspection items and the acceptance criteria of the silo or of its elements;

c) during the fabrication process and after completion of the silo, the inspection department of the fabrication unit shall carry out the various inspections and tests on the silo in accordance with this document, with the design documents and with the quality plan, shall issue the corresponding reports, and shall be responsible for the correctness and the completeness of those reports;

d) after the inspection has been passed, the fabrication unit shall issue a product certificate of conformity;

e) for each unit it fabricates, the fabrication unit shall keep the following technical documents on file for inspection for at least the design service life of the silo: 1) the quality plan; 2) the records of the inspection and test items whose choice is left to the fabrication unit by the standard; 3) the original design drawings and the as-built drawings of the silo.

4.3 Loads. The following loads shall be taken into account in the design:

a) pressure (internal pressure, external pressure);

b) the gravity load of the silo itself (including the internals, etc.) as well as of the material contained under operating conditions or of the test liquid in the water filling test condition;

c) the horizontal pressure, the vertical pressure and the friction force produced by the loose solid material;

d) the dead weight loads of the equipment, piping, ladders, platforms and other attachments on the top of the silo;

e) the wind load, the seismic load, the snow load and the additional loads of the attachments;

f) where necessary, the effect of the following loads shall also be taken into account: 1) the forces arising from the supports, the connected piping and other components; 2) impact loads, including the forces caused by the inlet or outlet of the loose material or by collapse of the material; 3) the forces caused by differences of thermal expansion; 4) the variation of the material load caused by the internals; 5) the forces to which the silo is subjected during transport, erection and maintenance.

4.4 Determination of the design pressure

4.4.1 The design pressure of the silo shall not be lower than its operating pressure.

4.4.2 When a breather valve is fitted at the top of the silo, the design positive pressure shall not be less than the opening pressure of the breather valve; the design negative pressure shall be taken as 1.25 times the suction pressure of the breather valve and shall not be lower than -5 kPa.

4.5 Determination of the design temperature

4.5.1 The design temperature shall not be lower than the maximum metal temperature that the element can reach under operating conditions. For metal temperatures below 0 degrees C, the design temperature shall not be higher than the minimum temperature that the metal of the element can reach.

4.5.2 When the metal temperatures of the various parts of the silo under operating conditions are different, the design temperature of each part may be set separately.

4.5.3 The metal temperature of an element shall be determined by one of the following methods: a) by heat transfer calculation; b) by measurement on a silo of the same type already in service; c) on the basis of the temperature of the material inside, combined with the external conditions.

4.5.4 For silos erected in the open in cold regions, or placed in unheated workshops and affected by low ambient temperature, the minimum design temperature shall be taken as the lowest value of the monthly mean minimum air temperatures over the years.

4.5.5 When the influence of the atmospheric ambient temperature is taken into account, the design temperature of the skirt shell (excluding the transition section) and of the anchor bolts should be taken as the lowest value of the monthly mean minimum air temperatures over the years for the place of use, increased by 20 degrees C.

4.6 Thickness additions. The thickness addition shall be determined by formula (1): C = C1 + C2, where C is the thickness addition, in mm; C1 is the negative deviation of the thickness of the material, to be selected according to the corresponding material standard, in mm; C2 is the corrosion (wear) allowance, in mm, which shall be considered in order to prevent the thickness of the silo from being reduced and thinned by corrosion or mechanical wear.

For carbon steel and low alloy steel, the corrosion (wear) allowance C2 of the silo shell shall generally be not less than 1.5 mm.

For stainless steel, the corrosion (wear) allowance C2 of the silo shell shall generally be not less than 0.5 mm.

For aluminium materials, the corrosion (wear) allowance C2 of the silo shell shall generally be not less than 1 mm.

For carbon steel and low alloy steel, the corrosion allowance C2 of the skirt shell shall generally be not less than 2 mm.

For carbon steel and low alloy steel, the corrosion allowance C2 of the anchor bolts shall generally be not less than 3 mm.

4.7 Minimum thickness. The minimum nominal thickness of the wall plate of the silo shell (excluding the corrosion or wear allowance) shall comply with the provisions of Table 1. In Table 1, for an inside diameter Di of the silo shell not greater than 10 000 mm, the minimum nominal thickness is 5 mm for carbon steel and low alloy steel and 4 mm for aluminium and high alloy steel; for an inside diameter Di greater than 10 000 mm and not greater than 20 000 mm, it is 6 mm for carbon steel and low alloy steel and 5 mm for aluminium and high alloy steel.

4.8 Allowable stress

4.8.1 The allowable stresses of the materials used in this document shall be selected in accordance with Clause 5 and with the related standards. The basis for determining the allowable stress is: for metallic materials other than bolting materials, see Table 2; for bolting materials, see Table 3. According to Table 2, for carbon steel, low alloy steel and ferritic high alloy steel the allowable stress is the minimum of Rm/2.3, ReL(Rp0.2)/1.5 and ReL at design temperature (Rp0.2 at design temperature)/1.5; for austenitic high alloy steel it is the minimum of ReL(Rp0.2)/1.5 and ReL at design temperature (Rp0.2 at design temperature)/1.5; for aluminium and aluminium alloys it is the minimum of Rm/3.5, Rp0.2/1.5 and Rp0.2 at design temperature/1.5. In these expressions Rm is the lower limit of the standard tensile strength of the steel, in MPa; ReL(Rp0.2) is the standard yield strength at room temperature (or the 0.2% non-proportional extension strength) of the steel (or aluminium), in MPa; ReL (Rp0.2) at design temperature is the yield strength (or the 0.2% non-proportional extension strength) of the steel (or aluminium) at the design temperature, in MPa. Footnote a of Table 2: where a slight permanent deformation of the element is admissible, the allowable stress may be suitably increased, but it shall not exceed 0.9 times Rp0.2 at design temperature; this provision does not apply to flanges or to other cases in which a slight permanent deformation would cause leakage or failure.

For steel bolting materials, Table 3 gives the following values: for carbon steel, hot rolled or normalized, ReL at design temperature divided by 2.7 for bolt diameters not greater than M22 and divided by 2.5 for M24 to M48; for low alloy steel, quenched and tempered, ReL at design temperature divided by 3.5 for diameters not greater than M22, divided by 3.0 for M24 to M48 and divided by 2.7 for diameters of M52 and above; for austenitic high alloy steel, solution treated, ReL (Rp0.2) at design temperature divided by 1.6 for diameters not greater than M22 and divided by 1.5 for M24 to M48. ReL (Rp0.2) at design temperature is the yield strength (or the 0.2% non-proportional extension strength) of the steel at the design temperature, in MPa.

4.8.2 When the design temperature is lower than 20 degrees C, the allowable stress at 20 degrees C shall be taken.

4.8.3 Allowable stress of clad steel plate. For clad steel plate whose bond ratio between the cladding layer and the base layer reaches grade 2 or above in NB/T 47002.1-2019, when it is necessary to take the strength of the cladding material into account in the design calculation, the allowable stress at the design temperature shall be determined by formula (2): the allowable stress at design temperature of the clad plate equals the sum of the allowable stress at design temperature of the base plate multiplied by delta 1 and the allowable stress at design temperature of the cladding plate multiplied by delta 2, divided by the sum of delta 1 and delta 2; where delta 1 is the nominal thickness of the base steel plate, in mm, and delta 2 is the thickness of the cladding material, excluding the corrosion (wear) allowance, in mm.

4.8.4 When the seismic load and the wind load are combined with the other loads of 4.3, the design stress of the element is allowed not to exceed 1.2 times the allowable stress; the combination requirements shall follow the provisions of the corresponding standards.

4.8.5 Allowable axial compressive stress. The allowable axial compressive stress of a cylinder or of a tube shall be taken as the smaller of the following two values: a) the allowable stress of the material at the design temperature (see Clause 5); b) the allowable axial compressive stress obtained by the following steps: 1) calculate the value A by formula (3), A equals 0.094 times delta e divided by Ro, where A is the external pressure strain coefficient, delta e is the effective thickness of the cylinder or tube, in mm, and Ro is the outside radius of the cylinder or tube, in mm; 2) according to the material selected, the design temperature and the value of A, determine the value B from the calculation charts for cylinders under external pressure given in GB/T 150.3 or in JB/T 4734 (using interpolation for intermediate temperatures). If the value of A falls to the left of the material line at the design temperature, the value of B shall be calculated by formula (4), B equals two thirds of A multiplied by the modulus of elasticity at design temperature, where B is the external pressure stress coefficient, in MPa, and the modulus of elasticity at design temperature is that of the material, in MPa.

4.9 Weld joint coefficients

4.9.1 The weld joint coefficients listed in this subclause apply to the corresponding calculations of the various elements of this document; their values shall be selected according to the type of butt joint between the pressure-retaining elements of the silo and according to the nondestructive testing requirements.

4.9.2 The weld joint coefficients of steel silos are given in Table 4: for a fully penetrated butt joint, the coefficient phi is 1.0 with 100% nondestructive testing, 0.85 with partial nondestructive testing and 0.70 with no nondestructive testing; for a single-side welded butt joint with backing strip, phi is 0.9, 0.80 and 0.65 respectively; for a single-side welded butt joint without backing strip, no value is given for 100% nondestructive testing, while phi is 0.70 with partial nondestructive testing and 0.60 with no nondestructive testing. Note: this document does not generally require 100% nondestructive testing, but when the design requires 100% nondestructive testing and the corresponding value of phi is taken, the testing shall be carried out to the acceptance level of nondestructive testing required by GB/T 150.4.

4.9.3 The weld joint coefficients of aluminium silos are given in Table 5: for a fully penetrated butt joint, phi is 0.95 with 100% nondestructive testing, 0.85 with partial nondestructive testing and 0.70 with no nondestructive testing; for a single-side welded butt joint with backing strip, phi is 0.90 with 100% nondestructive testing and 0.80 with partial nondestructive testing, while no value is given when no nondestructive testing is carried out. Note: this document does not generally require 100% nondestructive testing, but when the design requires 100% nondestructive testing and the corresponding value of phi is taken, the testing shall be carried out to the acceptance level of nondestructive testing required by JB/T 4734.

4.10 Tests

4.10.1 After fabrication of the silo, a tightness test shall be carried out; the tightness test may be a pneumatic tightness test or a leak test. When required by the design documents, a water filling test may be carried out.

4.10.2 Before the water filling test, the hydrostatic pressure of the liquid column at each calculation section shall be calculated, and the strength and stability of each element of the silo shell and of the connections between elements shall be checked in accordance with NB/T 47003.1. The stress during the water filling test shall not be greater than 0.9 times ReL (Rp0.2) of the material of each element.

4.10.3 The test method, the test medium and the inspection requirements shall be indicated in the design documents.

5 Materials

Clause 5, Materials, begins on page 127 of the printed volume and is not contained in the pages examined for this record. It covers the steel grades and the allowable stresses of plates, tubes, bars, section steel, forgings and bolting materials, as well as aluminium plate (5.7), aluminium tube (5.8), aluminium extruded bar (5.9), aluminium hot extruded profile (5.10) and aluminium alloy forgings (5.11), which were added with respect to the 2009 edition.

6 Design calculation

Clause 6, Design calculation, begins on page 140 of the printed volume and is not contained in the pages examined for this record. With respect to the 2009 edition it adds the overpressure coefficient of the material load (6.1), changes the calculation method for the wind load (6.5), changes the calculation of the material load on the conical part of the silo shell (6.11) and adds the stability check of the cylindrical part of the silo shell (6.15).

7 Fabrication, inspection and acceptance of steel silos

Clause 7, Fabrication, inspection and acceptance of steel silos, begins on page 168 of the printed volume and is not contained in the pages examined for this record.

8 Fabrication, inspection and acceptance of aluminium silos

Clause 8, Fabrication, inspection and acceptance of aluminium silos, begins on page 176 of the printed volume and is not contained in the pages examined for this record.

A Annex A (Informative) Structure of silos for solid materials

Annex A is informative and begins on page 178 of the printed volume; it illustrates the structure of silos for solid materials.

B Annex B (Informative) Calculation of the horizontal pressure on the cylindrical shell of an eccentrically discharged silo

Annex B is informative and begins on page 182 of the printed volume; it was newly added in the 2022 edition and gives the calculation of the horizontal pressure on the cylindrical shell of a silo with eccentric discharge.