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GB/T 16508.3-2013 English PDF (GBT16508.3-2013)

GB/T 16508.3-2013 English PDF (GBT16508.3-2013)

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GB/T 16508.3-2013: Shell boilers -- Part 3: Design and strength calculation

This Part of GB/T 16508 specifies the design and structural requirements for basic pressure parts of shell boilers, and provides the basic design requirements for castiron boiler (Appendix A), rectangular header (Appendix B) and water tube plate (Appendix C). This Part is applicable to the design calculation for cylindrical parts subject to internal and external pressures, heads, tube plates, tension braces and foot rings as well as opening and reinforcement.
GB/T 16508.3-2013
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 27.060.30
J 98
Replacing GB/T 16508-1996
Shell Boilers -- Part 3: Design and strength calculation
ISSUED ON: DECEMBER 31, 2013
IMPLEMENTED ON: JULY 1, 2014
Issued by: General Administration of Quality Supervision, Inspection and Quarantine of the PRC;
Standardization Administration of the PRC.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative References ... 5
3 Terms and Definitions ... 6
4 Symbols and Units ... 6
5 Basic Requirements for Design ... 7
6 Cylindrical Parts Subject to Internal Pressure ... 13
7 Cylindrical Boiler Furnace, Circular Flue, Smoke Tube and Other Part
Subject to External Pressure ... 30
8 Convex Head, Boiler Furnace Top, Hemispherical Boiler Furnace and
Convex Tube Plate ... 46
9 Flat Plates and Tube Plates with Tension Brace (Support and Reinforcement) ... 55
10 Tension Braces and Reinforcing Parts ... 66
11 Flat Cover and Cover Plate ... 76
12 Foot Ring ... 81
13 Opening and Opening Reinforcement ... 84
14 Welded Tee Junction ... 96
15 Verification Method for Determining Maximum Permissible Operating
Pressure of Part ... 101
Appendix A (Informative) Design Calculation of Pressure Part on Cast-iron Boiler ... 108
Appendix B (Informative) Design Calculation of Rectangular Header ... 110 Appendix C (Informative) Design Calculation of Water Tube Plate ... 116 Shell Boilers -- Part 3: Design and strength calculation
1 Scope
This Part of GB/T 16508 specifies the design and structural requirements for basic pressure parts of shell boilers, and provides the basic design requirements for cast- iron boiler (Appendix A), rectangular header (Appendix B) and water tube plate (Appendix C).
This Part is applicable to the design calculation for cylindrical parts subject to internal and external pressures, heads, tube plates, tension braces and foot rings as well as opening and reinforcement.
2 Normative References
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the normative document (including any amendments) applies. GB/T 1576 Water Quality for Industrial Boilers
GB/T 2900.48 Electrotechnical Terminology of Boilers
GB/T 9252 Method for Cycling Test of Gas Cylinders
GB/T 12145 Quality Criterion of Water and Steam for Generating Unit and Steam Power Equipment
GB 13271 Emission Standard of Air Pollutants for Boiler
GB/T 16508.1-2013 Shell Boilers - Part 1: General Requirements
GB/T 16508.2 Shell Boilers - Part 2: Material
GB/T 16508.4 Shell Boilers - Part 4: Fabrication, Inspection and
Acceptance
NB/T 47013
(JB/T 4730)
Nondestructive Testing of Pressure Equipment
TSG G0001 Boiler Safety Technical Supervision Administration
Regulation
TSG G0002 Supervision Administration Regulation on Energy
Conservation Technology for Boiler
3 Terms and Definitions
For the purposes of this document, the terms and definitions established in GB/T 16508.1 and GB/T 2900.48 apply.
4 Symbols and Units
Meanings and units of the symbols used in chapters and sections of this Part are as follows:
Et - the elasticity modulus of material upon temperature calculation, MPa; p - the calculating pressure, MPa;
[p] - the maximum permissible operating pressure upon verifying calculation, MPa; pr - the rated pressure of boiler, MPa;
p0 - the operating pressure, MPa;
ts - the saturation temperature of medium corresponding to the calculating pressure (the rated outlet temperature of hot water boiler), ??C;
tc - the calculating temperature, ??C;
tmave - the rated average temperature of medium, ??C;
??pa - the design additional pressure (the set pressure of relief valve), MPa; ??ph - the liquid column static pressure borne by pressure part, MPa;
??pf - the additional pressure of dynamic resistance of medium flow, MPa; ?? - the correction coefficient;
shall not exceed 2000mm; where butt connection is adopted for boiler furnace ends and tube plate flange, the calculating length of the plain boiler furnace may be increased to 3000mm.
5.1.4 The lowest safe water level of the steam boiler shall be 100mm higher than the highest fire line; however, for the horizontal shell boiler with the inside diameter not greater than 1500mm, the lowest safe water level shall be 75mm higher than the highest fire line. The minimum and maximum safe water level of the boiler shall be indicated in the drawing.
5.1.5 The structural type of pressure component (part) as well as the arrangement of openings and welds shall avoid or reduce the combined stress and stress concentration as possible. The adopted weld type shall comply with the design document and GB/T 16508.4. The weld subject to non-destructive testing shall be designed as the type for which the required non-destructive testing may be carried out. 5.1.6 Full-penetration butt joint shall be adopted for main weld of the main pressure part for the boiler (e.g. longitudinal and circumferential welds of shell, boiler furnace, reversal chamber and header, as well as butt welds of head, tube plate, boiler furnace top and foot ring); overlapped structure shall not be adopted for the weld of boiler pressure part; splicing shall not be adopted for tension brace.
5.1.7 Where the inside diameter of shell is greater than 1000mm, man-hole shall be arranged on the shell or head (tube plate); where personnel cannot enter into the boiler due to structural constraint, only inspection hole may be arranged; for the boiler with smoke tube arranged in shell, the arrangement of man-hole and inspection hole shall give consideration to the overhaul demand of both upper and lower parts of shell; for the shell boiler with inside diameter of shell as 800~1000mm, at least one inspection hole shall be arranged on shell or head (tube plate); the quantity of hand-holes arranged at the lower part of vertical shell boiler shall meet the requirements of cleaning and inspection and shall not be less than 3.
5.1.8 For the boiler with furnace, the combustion shall be completed in furnace. Water entering into the boiler shall not directly scour the boiler furnace. For the boiler with inside diameter of furnace greater than 1400mm or heat input greater than 12MW, at least 3 measuring points shall be arranged in boiler for temperature measurement. 5.1.9 The hydraulic test pressure shall meet the requirements of GB/T 16508.1. 5.1.10 Corrosion allowance
The corrosion allowance shall meet the following requirements:
a) For the pressure parts with nominal thickness ??>20mm and all plain
5.4 Discharge requirements
5.4.1 The excess air coefficient at smoke discharge point shall meet the following requirements:
a) For the combustion boiler in coal combustion chamber and the layered coal- burning boiler with membrane wall, the excess air coefficient at smoke
discharge point shall not exceed 1.4;
b) For other layered coal-burning boiler, the excess air coefficient at smoke discharge point shall not exceed 1.65;
c) For the pressure combustion oil-fired (gas-fired) boiler, the excess air coefficient at smoke discharge point shall not exceed 1.15;
d) For the negative pressure combustion oil-fired (gas-fired) boiler, the excess air coefficient at smoke discharge point shall not exceed 1.25.
5.4.2 During system design of boiler, the drive motor of matched auxiliary machine of boiler should be equipped with frequency converter.
5.4.3 The design smoke discharge temperature of boiler shall meet the following requirements:
a) Not higher than 230??C for steam boiler with rated evaporation less than 1t/h; b) Not higher than 180??C for hot-water boiler with rated thermal power less than 0.7MW;
c) Not higher than 170??C for steam boiler with rated evaporation greater than or equal to 1t/h and hot-water boiler with rated thermal power greater than or equal to 0.7MW.
5.4.4 The boiler shall be equipped with necessary desulfurization and dedusting equipment and should be equipped with de-nitration equipment; the discharge of boiler air pollutants shall meet the requirements of GB 13271.
5.5 Permissible stress
5.5.1 The permissible stress [??]J of common materials in this Part is selected according to GB/T 16508.2; sometimes structural characteristics and operating conditions of parts shall also be considered while used for design calculation; multiply the correction coefficient according to Formula (1):
cylindrical parts subject to internal pressure, including shell, header, internal pressure tube, large horizontal water tube, etc.
6.2 Symbols and units
a - the arc length between two openings along the mean-diameter peripheral direction of the shell upon calculating the slant ligament efficiency, mm; a1 - the technological coefficient of bent tube;
b1 - the thickness reduction ratio of actual manufacturing process of outer thickness of bent tube;
C - the additional thickness, mm;
C1 - the corrosion allowance of pressure part, mm;
C2 - the manufacturing thickness reduction of pressure part, mm;
C3 - the thickness tolerance of steels for pressure part, mm;
Di - the inside diameter of shell, mm;
Do - the outside diameter of header shell, mm;
d - the pitch length of opening diameter, the dimension of elliptical opening in the direction of corresponding pitch length, mm;
de - the equivalent diameter of opening, mm;
dm - the mean diameter of two adjacent openings, mm;
do - the outside diameter of tube, mm;
K - the conversion coefficient of slant bridge;
K1 - the shape coefficient of bent tube;
m - the absolute percentage of the lower thickness deviation (negative) to the nominal thickness of tube, %;
n - the ratio of the distance (b) between two openings along the axial direction of shell to the arc length (a) between two openings along the mean-diameter peripheral direction of the shell;
n1 - the ratio of the radius R of bent tube centerline to the outside diameter of tube; [p]w - the maximum permissible calculating pressure upon verifying calculation of bent tube, MPa;
R - the radius of bent tube centerline or the arc header centerline, mm; s0 - the minimum pitch length between two adjacent openings for which the inter- opening effect may not be considered, mm;
s - the pitch length between two adjacent openings in longitudinal (axial) direction or the interval between inner walls of firebox tube plate, mm;
s?€? - the pitch length between two adjacent openings in the horizontal (circumferential) direction, mm;
s?€? - the pitch length between two adjacent openings in inclined direction, mm; a - the angle of opening axis deviating from the radial direction of shell, ??; ?? - the nominal thickness of pressure part, mm;
???€? - the thickness deviation of abutting edge, mm;
??c - the required thickness of pressure part, mm;
??min - the minimum thickness of finished pressure part, mm;
??bc - the theoretical required thickness at the outer side of bent tube made of steel tube, mm;
??be - the effective wall thickness at the outer side of bent tube, mm;
??bmin - the minimum thickness at the outer side of finished bent tube, mm; ??e - the effective thickness of pressure part, mm;
?? - the attenuation coefficient of longitudinal bridge;
???€? - the attenuation coefficient of horizontal bridge;
???€? - the attenuation coefficient of slant bridge;
??d - the equivalent attenuation coefficient of slant bridge;
??d=1.00) (among which, the minimum value shall prevail). Where the bridge is located in weld, it shall be treated according to the relevant requirements in 6.9.3. 6.6.2 For weld passing the inspection for technical requirements for fabrication, the welded joint coefficient ??w is selected according to GB/T 16508.1. Where the circumferential weld is opening-free, the circumferential welded joint coefficient may not be considered.
6.6.3 Where the pitch length (longitudinal, horizontal or slant) between two adjacent openings in opening row is not less than the value calculated according to Formula (23), the attenuation coefficient of bridge may not be calculated.
0 2 ( )m iS d D ??? ????€? ?€? ?€? (23)
Where, dm is determined according to Formula (29).
6.6.4 Where the pitch length between two adjacent openings is less than the s0 value calculated according to Formula (23), and the diameter of either opening is not greater than the maximum permissible diameter of the un-reinforced opening determined according to 13.3.6, the attenuation coefficient of bridge shall be calculated according to the requirements of 6.6.6~6.6.12.
Where one of the two adjacent openings in opening row is greater than the maximum permissible diameter of the un-reinforced opening specified in 13.3.6, reinforcement shall be carried out based on single opening according to the requirements of 13.3.7~13.3.9 under the conditions specified in 13.7.2. Opening-free treatment shall be carried out after reinforcement.
Where both adjacent openings shall be reinforced, their pitch length shall not be less than 1.5 times of their mean diameter.
Where both openings shall be reinforced, reinforcement calculation shall not only meet the requirements of 13.3.7~13.3.9, but also meet the following requirements: a) The height of thickened tube joint shall be 2.5 times the thickness; b) The weld leg dimension of thickened tube joint shall be equal to the thickness of thickened tube joint;
c) Where the pitch length of two openings is less than the diameter sum of two openings, thus resulting in overlap of their effective reinforcement scope, reinforcement shall be carried out according to the method that the total reinforcement area of two openings is not less than the sum of reinforcement Formula (40):
1 3
1 12 (4 1)
C C
n n
??? ?€? ?€??€? ?€? (40)
Where, n1 is the ratio of radius of bent tube centerline to the outside diameter of tube. 6.7.3 Additional thickness of tube subject to internal pressure
6.7.3.1 Upon design calculation, the additional thickness of tube is calculated according to Formula (38).
For straight water tube, C1 is treated according to the principle in 6.7.1; for heat exchange tube, C1 and C2 are taken as 0 while C3 is calculated according to Formula (41):
3 1( )100 c
mC C
????€? ?€??€? (41)
For bent tube made of steel tube, C1 is treated according to the principle in 6.7.1; for heat exchange tube, C1 is taken as 0 while C2 and C3 are respectively calculated according to Formulas (42) and (44):
2 1
( )100 bcC C
??? ???????€? ?€??€? (42)
Where, the technological coefficient ??1 of bent tube is calculated according to Formula (43):
25 od
??? ?€? (43)
Where the actual fabrication process reduction ratio b1 for the thickness at the outer side of bent tube is greater than the calculated a1 value, a1 shall be taken as the actual fabrication process reduction ratio for the thickness at the outer side of bent tube. 3 1 2( )100 bc
mC C C
????€? ?€? ?€??€? (44)
6.7.3.2 Upon verifying calculation, the additional thickness C of tube is calculated according to Formula (38).
For straight tube, C1 is treated according to the principle in 6.7.1; for heat exchange tube, C1 and C2 are taken as 0 while C3 is calculated according to Formula (39). 6.9.1 For expansion tube orifice, the bridge attenuation coefficient ??, ???€? and ???€? shall not be less than 0.3; the distance from the expansion tube orifice center to the weld edge shall not be less than 0.8d, and shall not be less than 0.5d+12mm; the longitudinal weld shall be free from any expansion tube orifice; the expansion tube orifice, where necessary at circumferential weld, shall meet the requirements of "Boiler Safety Technical Supervision Administration Regulation" (TSG G0001).
6.9.2 The thickness of shell of expansion tube shall not be less than 12mm. The clear distance between expansion tube orifices shall not be less than 19mm. Expansion connection should not be adopted for the tube with outside diameter greater than 63.5mm.
6.9.3 The welded tube orifice shall be kept away from main weld as possible, and the clear interval between tube orifice weld edge and adjacent main weld edge less than 10mm shall be avoided. Where it is inevitable, the welded tube orifice shall meet the following requirements:
a) The main weld within the range of 1.5 times of the tube opening diameter (the tube opening diameter, where less than 60mm, is 0.5d+60mm) to the tube
orifice center passes the radiographic testing or ultrasonic testing, and the opening surrounding shall be free from slag inclusion defect;
b) Residual stress of the tube or tube joint after welding is eliminated through heat treatment or local heat treatment.
In this case, the attenuation coefficient of this position is taken as the product of bridge attenuation coefficient and welded joint coefficient.
The clear interval of weld edges of adjacent welded tube orifices should not be less than 6mm, where heat treatment or local heat treatment is carried out after welding, this limit ceases to be effective.
6.9.4 See Figure 7 for the connection type of flat tube plate or convex head of shell and flange.
6.9.5 The groove fillet welding, where adopted for shell and flat tube plate, shall meet the following requirements:
a) The rated pressure of boiler shall not be greater than 2.5MPa;
b) The position with smoke temperature not greater than 600??C (the position free of smoke erosion and equipped with reliable heat insulation may not limited by the above-mentioned condition);
I?€?, I?€? and I?€??€? - the required inertia moment, mm4;
l - the length of straight section of flanged part, mm;
L - the calculating length of boiler furnace, mm;
n1 - the strength security coefficient;
n2 - the stability security coefficient;
Ro - the outside radius of corrugation of corrugated furnace, mm;
R - the medium radius of corrugation of corrugated furnace, mm;
r - the inside radius of corrugation of corrugated furnace, mm;
s - the corrugation pitch length of corrugated furnace, mm;
u - the roundness percentage of horizontal plain boiler furnace;
W - the corrugation depth of corrugated furnace, mm;
X - the increment of calculating length of plain furnace;
?? - the distance between neutral axis x-x and circle-center-penetrating axis x0-x0, mm;
???€? - the half included angle, rad (radian);
?? - the nominal thickness of pressure part, mm;
??c - the theoretical required thickness of pressure part, mm;
??min - the minimum thickness of finished pressure part, mm;
??s - the design thickness of pressure part, mm;
??e - the effective thickness of pressure part, mm;
??min - the minimum attenuation coefficient.
7.3 Cylindrical boiler furnace
7.3.1 Plain boiler furnace
C=C1+C2+C3 (73)
Generally, 0.5mm is taken as the additional thickness C1 of corrosion thickness reduction; if the thickness is larger than 20mm, 0mm may be taken as the corrosion allowance; if the corrosion thickness reduction exceeds 0.5mm, then the actually possible value of corrosion thickness reduction is taken. The additional thickness C3, which considers the lower thickness tolerance (where is negative value) of material, is determined according to relevant material standards. The additional thickness C2, which considers the technology thickness reduction, shall be determined accordin...

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