Design, Stress Analysis and DetailingDesign, Stress Analysis and Detailing

CODES & STANDARDSCODES & STANDARDS

PIPING

• Codes, Standards & Regulations– ASME– DIN– TRD– BS– IBR

• Codes and Standards:• Several groups have written codes and standards

for materials, inspection, design, stress analysis, fabrication, heat treatment, welding and construction of pipes and piping components. Regulations, practices, rules and laws are also available for use of piping. Certain aspects are mandatory and certain aspects are recommendatory. The commonly used American Codes and Standards on piping are given below:

• 1. ASME B31.1 - Power Piping

• 2.          ASME B31.2 - Fuel Gas Piping

• 3.          ASME B31.3 - Process Piping

• 4.          ASME B31.4 - Pipeline Transportation Systems for Liquid

• Hydrocarbons and other Liquids.

• 5.          ASME B31.5 - Refrigeration Piping

• 6.          ASME B31.8 - Gas Transmission and Distribution Piping

• Systems

• 7.          ASME B31.9 - Building Services Piping

• 8.          ASME B31.11 - Slurry Transportation Piping Systems.

• Through the use of codes and standards, safety and uniform economy are obtained. The codes and standards primarily cover the following aspects:

• 1.      Factors safety• 2.      Material property• 3.      Thickness calculation• 4.      Loads• 5.      Load combinations• 6.      Stress limits• 7.      Stress intensification factors• 8.      Flexibility factors• 9.      Supports• 10.   Flexibility analysis.

• Even though the use of codes and standards is not a legal requirement the same becomes a legal requirement in a contractual situation. Certain regulations are legally binding. The Indian Boiler Regulations, 1950 (IBR) is binding on the Indian Boiler-makers and Boiler-users, of certain kind of boilers. The codes and standards do not cover all aspects of the piping. The codes and standards are not textbooks. They do not cover the theory. They provide answers to the following aspects:

• 1.      Know what• 2.      Know how

• The “Know why” is not covered by the codes and standards. The “Know why” is learned by study, experimentation, application and experience. In most of the situations, a knowledge of “Know what” and “Know how” is sufficient to solve the problems. A knowledge of “Know why” will help in handling the following situations:

• 1.      Material selection• 2.      Applicable code and standards• 3.      Evaluation of the deviations• 4.      Use of new fabrication and inspection methods.

• Codes and Standards:

• The following codes and standards are referred:

• 1.ASME-I : Rules for Construction of Power Boilers

• 2.ASME B31.1-1998 : Power Piping

• 3.ASME B16.5-1996 :Pipe Flanges and Flanged Fittings – NPS ½ through 24.

• 4.IS 1239 (Part-I)-1990 :Mild Steel Tubes, Tubular and other

• Wrought Steel Fittings - Mild Steel Tubes

• 5.IS 1239 (Part-II)-1992 :Mild Steel Tubes, Tubular and other

• Wrought Steel Fittings – Steel Pipe Fittings

• Nominal Pipe Size (NPS):

•  The Nominal Pipe Size (NPS) in an ASME method of indicating the approximate outside diameter of the connected pipe in inches. Note that the unit (inch) is not followed after the designation.

• Class of Fittings:

• The class of fittings is an ASME method of indicating the pressure carrying capacity of the fittings.

• Schedule of Pipes:

• The schedule of pipes is an ASME method of indicating the pressure carrying capacity of the fittings.

• Types of Flanges:

• The following types of flanges are used:

• 1.                   Threaded

• 2.                   Socket welding

• 3.                   Blind

• 4.                   Slip-on welding

• 5.                   Lapped

• 6.                   Welding neck.

• Pressure – Temperature Rating:• Ratings are maximum allowable working gauge

pressure at a given temperature. These values are given in ASME B16.5.

• Selection of Flanges:• The flanges are selected based on the application,

pressure, temperature and size.

 ASME Section-I PG 9 – Materials Specifications List. ASME Section-II Part-A – Material Specifications.

- SA106, 192, 299, 210, 213, 234, 515. ASME Section-II Part-D – Table IA – Maximum Allowable Stress

- Table Y, U ASME Section-II Part-A Tubes - SA450 - Specification for General Requirements for tubes. Pipes - SA530 - Specification for General Requirements for Pipes. Fittings - SA234 - Specification for Piping Fittings. Drum combined bending Stress – BS 1113, ANNEX-B. 

REFERENCES

Boiler Codes have been written by various nations in the past century to ensure safety of personnel and to avoid loss of property. Boiler codes cover the whole gamut of activities including Design, Fabrication, Testing, Construction and Operation. Although these codes are framed on a common intent, there are variations on the degree of conservation on different aspects. One such area where variations do exist between Boiler Codes is the criteria stipulated for calculating the allowable stresses. In the present day context of evolving competitive design without sacrificing the safety needs laid down in the boiler codes, an attempt has been made by comparing the various aspects in the design like allowable stress, Design temperature criteria, the various formulae used to determine the thicknesses for drums / shells, headers, tubes, dished / flat ends, etc, other aspects like minimum design requirements for drums/headers & tubes and presented in annexures. The various aspects of IBR Regulations are called out and consolidated against major items like drum, headers, lines & links, etc. The following codes have been considered for the study:-

 1.IBR 19502.ASME Section-I3.BS 11134.DIN TRD 300. 

COMPARISON OF BOILER CODES 

The observations made between various boiler codes in respect of design are given below:-

 1) Yield strength at room temperature is not considered in BS1113

and IBR whereas factor of safety at room temperature in ASME Section-I is 1.5 and the same in TRD is 2.4.

 For tensile strength at room temperature, both IBR and BS1113 considers a factor of safety of 2.7 whereas in ASME Section-I indicates 3.5 and not considered in TRD. In the case of rupture strength, all codes consider factor of safety as 1.5 except BS1113 which shows 1.3.

2) In the case of Design Pressure of the boiler IBR alone considers pressure drop for various components inline with erstwhile ISO R831 whereas the rest of the codes indicate the boiler to be designed for drum design pressure.

 3) In respect of Design Temperatures, all codes apply some fixed

temperature allowances over the medium temperature except ASME Section-I which states that parts to be designed for actual metal temperatures.

4) Comparison material grades among various codes indicate specification as common for most of the material compositions. DIN (GERMAN) indicates a specification 12 Cr, 1 Mo, ¼ V composition (X20) which is not finding a place in both ASME & BS1113. Also, when there is a specification indication for austenitic steels like 18 Cr 8 Ni, 18 Cr 10 Ni Cb in both ASME & BS1113, there is no such grade under TRD 300.

 It is concluded that ASME Section-I gives the most stringent criteria on design for deciding the allowable stresses (Tensile / 3.5) compared to other international codes below creep region. BS1113 & IBR are same in respect of design criteria for allowable stresses (Tensile / 2.7). TRD 300 is in between ASME & IBR / BS1113 since the allowable stress values of DIN falls in between them. Above creep region, BS1113 gives more liberal criteria (Creep rupture / 1.3) compared to other international codes. Weight savings arising out of adopting BS1113 compared to ASME Section-I is also illustrated in an annexure.

Sl.No. Item Description

01. Applicability of Code Regulations

02. Maximum Allowable Working Pressure

03. Design Pressures & Design Temperatures

04. Comparison of Codes

05. Design Stresses - Factors of Safety

06. Comparison of Material Grades

07. Temperature Limits for various Steel Grades

08. Design - Calculation of Thickness Required

09. Openings in Shell

10. Ligament Efficiency

11. Drum / Headers comparison - 2 sheets

12. Tubes comparison

13. Relationship between Allowable Stress, Weight Savings

14. IBR Regulations - Clauses - 2 sheets

15. IBR Regulation Numbers - Ascending Order - 8 sheets

16. Requirements as per ASME Section-I - 3 sheets

17. Salient Clauses of BS1113 - 3 sheets

COMPARISON OF BOILER CODES

APPLICABILITY OF CODE REGULATIONS IBR

 Applicable to boiler that is a closed vessel exceeding 22.75 litres in capacity which is used to generate steam under pressure.

 ASME Sec. I

 Applicable to boilers in which the steam or any other vapour is generated at a pressure more than 15 PSI (g).

 BS 1113

 The rules specify the requirements for the water tube steam generating plant subject to internal pressure.

 TRD 300

 The rules apply to steam boilers and to feed water preheaters, SH with shut off devices, RH, DESH, steam and hot water lines and fittings which are regarded as part of the steam boiler installation.

   

MAXIMUM ALLOWABLE WORKING PRESSURE

 IBR

 It is the working pressure of any component of the boiler.

 ASME Sec. I

 It is the maximum pressure to which any part of the boiler is subjected to except when SV or SRV or Valves are discharging at which time the MAWP shall not be exceeded by more than 6%.

 BS 1113

 It is the highest set pressure on any SV mounted on the steam drum.

 TRD 300

 For steam generators, the design pressure shall be the allowable pressure. 

 

AREA 

IBR 

ASME SEC.I

 

BS 1113

 

DIN TRD 300

 DESIGN PRESSURE Drum design pressure with pressure drop

Drum design pressure

Drum design pressure

Drum design pressure

 

RADIATION 

 50C

 50C

 50C

 

CONVECTION 

 39C

 35C

 35C

 

ECONOMISER 

 11C

 25C

 15+2xAct. wall thick)

CMax. 50C

 

WATER WALLS / SH WALLS 

 28C

 50C

 50C

 GAS TOUCHED DRUMS/HEADERS 

 28C

 25C

 20C

AC

TU

AL M

ETA

L T

EM

PER

ATU

RE

371C

(M

IN)

FO

R G

AS

TO

UC

HED

PO

RTIO

N

DESIGN PRESSURES & DESIGN TEMPERATURES - ALLOWANCES USED IN

VARIOUS CODES

  IBR 1950 ASME SEC.I BS 1113 DIN TRD 300 REMARKS

DESIGN PRESSURE

DESIGN PRESSURE

WITH PRESSURE DROP

DRUM DESIGN

PRESSURE

DRUM DESIGN

PERSSURE

DRUM DESIGN

PRESSURE

 

DESIGN TEMPERATUE ALLOWANCE RADIATION

50C

ACTUAL METAL TEMPERATURE

371C (MIN)

50C

50C

 

CONVECTION

39C

35C

35C

 

ECONOMISER

11C

25C

(15 + 2 Se) C

Max. 50C

Se - ACTUAL WALL THICKNESS in mm.

WATER WALL

28C

50C

50C

 

TUBE THICKNESS

FORMULA tmin

PD--------- + *C2f + P 

PD--------- + 0.005D2f + P 

PD--------- 2f + P 

PD--------- 2f + P 

P=DESIGN PR.D=OUTSIDE DIAf=ALLOWABLE STRESS CORR. TO DESIGN METAL TEMP.

FACTOR OF SAFETY

Et R 1.5 , 2.7 SR SC 1.5

Et R 1.5 , 3.5 SR SC 1.5

Et R 1.5 , 2.7 SR 1.3

Et R 1.5 , 2.4 SR 1.0

Et = YIELD STRENGTHR = TENSILE STRENGTHSR = RUPTURE STRENGTHSC = CREEP STRENGTH

 FOR ASME MATERIALS ALLOWABLE STRESS CAN BE TAKEN DIRECTLY FROM ASME SEC.II PART-D

COMPARISON OF CODES

*C = CORROSION ALLOWANCE = 0.75mm FOR P ≤ 70 bar; 0 mm FOR P > 70 bar

 PROPERTIES

 IBR

 ASME SEC.I

 BS 1113

 DIN TRD

300 

 Min. yield strength at Room Temperature

 ---

 1.5

 

 ---

 ---

 Min. yield strength at Design Temperature

 ---

 ---

 1.5

 1.5

 

 Average yield strength at Design Temperature

 1.5

 1.5

 ---

 ---

 

 Min. ultimate tensile strength at Room Temperature

 2.7

 3.5

 2.7

 2.4

 

 Average creep rupture strength for 100,000 hours life at Design Temperature

 1.5

 1.49

 1.3

 1.0

 Average creep strength for 1% creep in 100,000 hours at Design Temperature

 1.0

 1.0

 ---

 ---

For Austenitic steels, FS = 1.35 To be used at temperature below 1500F For components without an acceptance test certificate to DIN 50049, FS shall be increased by 20%.

DESIGN STRESSES – FACTORS OF SAFETY IN VARIOUS CODES

Max. Service Temperature

475C885F

500C930F

550C1020F

560C1040F

575C1065F

600C1110F

625C1155F

Gr.AA192

Gr.B Gr.A1

Gr.C Gr.C

    T1P1

  T2 / P2

T12/P 12

  T11/P11

T22/P22

    T9/P9

BS3059-3602-3604

360

410

440-460

490Nb

243

      620

  621

622

660

  629

DIN (GERMANY)17175VdTUV.B1(Werkstoff-Nr.)

St.35.8 1.0305

St.45.8 1.0405

17 Mn4 1.0481

19 Mn5 1.0482

15 Mo3 1.5415

16 Mo51.5423

15NiCuMoNb51.6368

 

13CrMo441.7335

 

 

10Cr Mo9 101.7380

(14MoV63)1.7715

  (X12Cr MO 91)1.7386

GOST (RUSSIAN)TY 14-3-460-75

 

20

            15 XM

12X1MF

      (15XIMI F)

 

JIS (JAPAN)G3456 G3458G3461 G3462

STPT38STB 35

STPT 42STB 42

STPT 49

    STPA12STBA12

  STPA20STBA20

STPA22STBA22

  STPA23STBA23

STPA24STBA24

    STPA26STBA26

NF A 49-213 (FRENCH)

TU37-C

TU42-C

TU48-C

TU52-C

TU15 D3

    TU15CD2.05

TU13CD4.04

  TU10CD5.05

TU10CD 9.10

    TU Z10CD9

ASMESA 106SA 192SA 209 - SA 210SA 213 - SA 335

This is indicative only. However, the actual maximum service temperature for various steels shall be limited as prescribed in the relevant codes.

COMPARISON OF MATERIALS GRADES

Sl. Nominal MATERIAL SPECIFICATION Temp.

No. Composition ASME Section-I DIN – TRD 300 BS 1113 Limit C

 01.

 Carbon Steel

 SA178 Gr.C, Gr.D,SA192, SA210 Gr.A1& Gr.CSA106 Gr.B, Gr.C

 St 35.8St 45.8

 BS3059 P2 S2 360, 440BS3602 P1 360, 430, 500 Nb

 427 

 02.

 ½ Mo

 SA209 T1

 15 Mo3

 ----

 482

 03.

 1 Cr ½ Mo

 SA335 P12SA213 T12

 13 Cr Mo 44

 BS3059 P2 S2 620BS3604 P1 620 – 440

 535

 04.

 1¼ Cr ½ Mo

 SA213 T11SA335 P11

 ----

 BS3604 P1, 621

 552

 05.

 2¼ Cr 1 Mo

 SA213 T22SA335 P22

 10 Cr Mo 910

 BS3059 P2 S2 622-490BS3604 P1, 622

 577

 06.

 9 Cr 1 Mo ¼ V

 SA213 T91SA335 P91

 X 10 Cr Mo V Nb91

 -----

 635

 07.

 12 Cr 1 Mo ¼ V

 -----

 X 20 Cr Mo V 121

 BS3059 P2 S2 762BS3604 P1 762

 700

 08.

 18 Cr 8 Ni

 SA213 TP304 H

 -----

 BS3059 P2 304 S51BS3605 – 304 S59 E

 704

 09.

 18 Cr 10 Ni Cb

 SA213 TP347 H

 -----

 BS3059 P2 347 S51BS3605 347 S59 E

 704

TEMPERATURE LIMITS FOR VARIOUS STEEL GRADES OF TUBES / PIPES

 AREA

 IBR

 ASME SEC.I

 BS 1113

 DIN TRD 300

 

 Tube thickness

  PD + C 2f + P

  PD +0.005D 2f + P

  PD

2f + P

  PD

2f + P 

 Shell thickness 

  PR + 0.75fE 0.5 P

  PR

fE (1 Y) P

  PR

fE 0.5 P

  PR

fE 0.5 PE 

 Dished end thickness 

  PDK + 0.75 2f

PR

2f 0.2 P

  PDK

2f

2PR 1+ 1 2f P 

 Flat end thickness

CPd + C f

  CPd f

PCd f

PCd f

DESIGN - CALCULATION OF THICKNESS REQUIRED IN VARIOUS CODES

 

 IBR

PD8.08 [Dt (1 K)]1/3 K = 1.82 St

 ASME Sec. I

PD8.08 [Dt (1 K)]1/3 K = 1.82 St

 BS 1113

PD8.08 [Dt (1 K)]1/3 K = 1.82 St

   TRD 300

t branch

For dia of Opg. 50 mm, 2 t shell

  For dia of Opg > 50 mm,

opg dia t branch

if 0.2, then 2. shell ID t shell opg dia t branch

if > 0.2, then ≠ 2. shell ID t shell

OPENINGS IN SHELL

 EFFICIENCY

 ASME

 IBR

 BS 1113

 Longitudional

P d

P

  P d

P

  P d

P

 Circumferential 

  PC d

PC

  PC d

PC

  PC d

PC

 Diagonal 

J + 0.25 (1 0.01 Elong) 0.75 +J

0.00375 + 0.005 J

  

   2

A + B+ (A B)2 + 4C2

2

A + B+ (A B)2 + 4C2

TRD 300 gives lengthy equations for calculating the ligament efficiency factors. For a single opening, ’all di A + A’

all

VA = and for multiple openings, ’

all SV 2 AP+ A’ A’

all

   ’all ”all di A0 + A1 + A2

all all

VL = ’

all ”all SV AP0 (1+cos2)+2AP1+2AP2+A1+A2 A1 A2

all all 

LIGAMENT EFFICIENCY

 DESCRIPTION

 IBR

 ASME SEC.I

 BS 1113

 DIN TRD 300

 

Min. Plate thickness for shell

6 mm

6 mm

6 mm

3 mm

Type of weld joint

Single or double ‘U’ or ‘V’ type.

Double welded butt type. The shape shall be such as to permit complete fusion and complete joint penetration.

Double ‘V’ Type or ‘U’ type.

Double ‘V’ type.

Position of tube holes 

Allowed through welded seams, if they are radiographed and stress relieved. The ligament efficiency shall be multiplied by a factor 0.95.

Any type of opening that meets the requirements for compensation may be located in a welded joint.

Machining of holes through the centre of main seam welds is permitted provided the seam welds have been subjected to NDE.

-----

Circularity of Drum 

Difference between internal diameter of drum shall not exceed 1%.

The drum shall be circular within a limit of 1% of mean diameter based on the differences between maximum and minimum mean diameters.

Maximum internal diameter of drum shall not exceed the nominal internal diameter by more than 2%.

The average bore shall not deviate by more than 1% from the nominal diameter.

Percentage deviation from circularity 

2 (d max. d min.) X 100 d max. + d min.

D max. D min. X 100 DS

D max. D min. X 100 DS

2 (d max. d min.) X 100 d max. + d min.

Hand hole size in Headers

89 x 63.5

89 x 70

-----

------

 

DRUM / HEADERS - COMPARISON WITH VARIOUS CODES

 DESCRIPTION

 IBR

 ASME SEC.I

 BS 1113

 DIN TRD 300

 

Hydraulic test point - Shop & test pressure.

Drums & Headers greater than 1000 mm shall be hydraulic tested at shop to 1.5 times the Design Pressure.

-----

Drums & Headers greater than 600 mm shall be hydraulic tested at shop to 1.5 times the max. permissible working pressure.

-----

Wall thickness tolerance for pipes / headers.

+ 15% 5%

12.5%

+ 10% 10%

+ 12.5% 10.0%

Hydraulic test pressure at site.

1.5 times the Drum Design Pressure.

1.5 times the maximum allowable Working Pressure.

1.5 times the maximum permissible Working Pressure.

1.3 times the maximum allowable Working Pressure.

Requirement of Safety Valves.

Two safety valves - the bore not less than 19mm. 

Two or more safety valves.

Two safety valves. Minimum bore 20 mm.

Two or more safety valves.

Water level indication.

Two means of indicating water leve.

Two numbers of gauge glass. Two independent remote level indicators instead of one gauge glass.

Two independent means of water level indication.

Two means of indicating water level.

 

 DESCRIPTION

 IBR

 ASME SEC.I

 BS 1113

 DIN TRD 300

 

 TYPE

 Cold drawn or hot finished seamless or ERW

 Cold drawn or hot finished seamless or ERW

 Cold drawn or hot finished seamless or ERW

 Cold drawn or hot finished seamless or Longitudinally welded

 Minimum thickness allowed for various tube Diameters - Seamless.

 Up to D32 - 2.03Up to D51 - 2.34D51 to D76 - 2.64D76 to D89 - 3.25D89 to D114 - 3.66

 Up to D32 - 2.41Up to D51 - 2.67D51 to D76 - 3.05D76 to D102 - 3.43D102 to D127 - 3.81

 Up to D38 - 1.7D38 to D51 - 2.2D51 to D70 - 2.4D70 to D76 - 2.6D76 to D95 - 3.0D95 to D102 - 3.3D102 to D127 - 3.5

 Min. - 3 mmMax. - 6.3 mmfor Water wall tubes

 Ovality (Deviation from circularity)

 D Max. D Min. x 100 Dshall not exceed 20D R

 D D Min. x 100 D shall not be more than 50D % R

 2(DMax.DMin.) x100 DMax + DMin 

 Provides calculation for wall thickness for inside & outside of bend as per TRD301 Annex-2.

 Wall thickness tolerance

 + 10% 5%

 + 22% 0%

 + 10% 10%

 + 15% 10%

TUBES - COMPARISON WITH VARIOUS CODES

 Sl.No

   Materia

lSpecn.

 DesignTemp.

C

Allowable Stress Kg/mm2

% increase

in allowable

Stress

Correspond-ingin

allowableStress

ASME BS 1113

 01.

 Water Walls

 SA210 Gr.C

 385

 11.038

 13.228 19.8

 11.4

 02.

 Downcomers

 SA106 Gr.C

 357

 11.993

 13.570 13.0

 9.8

 03

 Riser Pipes

 SA106 Gr.B

 357

 10.339

 11.859 14.7

 9.8

 04.

 Economiser

 SA210

A1

 311

 10.546

 12.896 22.3

 16.0

 05.

 Low temp. SH

 SA210

A1

 373

 10.087

 12.442 23.7

 17.6

Item

RELATIONSHIP BETWEEN ALLOWABLE STRESS, WEIGHT AND SAVINGS IN WEIGHT

 (TYPICAL 250 MW)

a) Circularity of drum 243 (a)256 (b)b) Drawing preparation 249c) Type of weld joint 253d) Long seam intersection 254E )Position of tube holes 255f) Hydro Test 268g) Maximum working pressure for shell 270h) Stress factors 271I )Ligament efficiency 272 (215)j) Longitudinal stress 273K Shape of Dished end plate 275l) Dished end with openings 277M) Dished end maximum working pressure 278n) Reinforcement calculation 279o) Attachment of Branch pipes 280p) Mountings on the drum 281q) Attachment (SV) to dru 296r) Water gauges 320s) Uncompensated hole 187

I) DRUM

IBR REGULATIONS

a) Header shapes and Process 154 (a)

b) Hand holes 164 (a)

c) Uncompensated hole 187

d) Maximum working pressure 270

e) Stress factors 271

f) Ligament efficiency 272 (215)

g) Shape of Dished end 275

h) Dished end opening 277

i) Dished end maximum working pressure 278

j) Reinforcement calculation 279

k) Attachment of Branch pipes 280

l) Flat ends maximum working pressure 340 (f)

m) Headers for boiler & SH 342

II) HEADERS

a) Process 151 (a), (b), (c)b) Tubes 244 (a)c) Maximum working pressure 338 (a)d) Percentage ovality 338 (b), (c)

a) Integral boiler piping 244 (b)b) Process 343 (1)c) Material, permissible stress 343 (2)d) Hydraulic Test 343 (3)e) Temperature limits for Pipes, Tees, Branches 349f) Maximum working pressure 350g) Steam pipe bending thinning 361 (a)h) Butt welding fittings 361 (A)i) Branch welded to pipes 249 to 253j) External Reinforcement 362 (b)k) Hydraulic Test 374

III) TUBES

IV) LINES & LINKS (BOILER INTEGRAL PIPING)

a) Discharge capacity 293b) Over pressure of safety valve 294c) Pressure drop 295d) Attachment to boiler 296

1) Procedure of Hydro test of boiler 3792) Registration Fee 3853) Submission of plans of boilers 3934) Submission of plans of steam pipes 395

a) Requirements 320 a, b.

V) BOILER MOUNTINGS

A. SAFETY VALVES

B. WATER GUAGES

VI) GENERAL

 BOILER & SH TUBES Regn. 151: Tubes Cold drawn or hot finished  a)           Seamless or ERW tubes b)            Tubes < 5” dia - can be used inside the boiler

> 5” dia - can be used outside the boiler c)             Flash welding allowed.  HEADERS MUD BOXES, ETC. OF WATER TUBE BOILERS

Regn. 154: a) Headers Seamless or Welded steel or cast steel. i)            Where welded, the welding shall be stress relieved, radiographed or

UT. ii) Headers may be closed by forging, bolting, screening or welding.

IBR

MAIN HOLES Regn. 164 (a): Hole size not less than 3½ x 2½ in. PDRegn. 187: Uncompensated hole - Maximum 203 mm =

1.82 fe

 FUSION WELDED DRUMS Regn. 244 (a): Tubes Regn.244 (b): Pipes of boiler shall comply with Chapter VIII. Regn.243 (a): Circularity of drum 1%.

2 (d max. d min.)

Regn. 243 (b): Percentage deviation = x 100from circularity (d max. + d

min.) 

d = internal dia Regn. 249: Fully dimensioned sectional drawing showing in full

detail the construction of drum - Fully dimensioned drawings of the proposed weld preparation of the main seams to a scale - attachment, seatings, etc. to be furnished.

Regn. 253: Drum - type of welded joint - Single or double ‘U’ or ‘V’ type.

 Regn. 254: Longitudinal seams in successive rigs shall not fall

in line except where the rigs of drum are in two halves of unequal thickness.

 Regn. 255: Position of tube holes:- 

Tube holes through welded seams, if they are radiographed and stress relieved - The efficiency and ligament multiplied by a factor 0.95 except the distance from edge hole to edge of weld > 13mm (½”).

 Regn. 256: Circularity of drum:-

The difference between internal diameter of drum shall not exceed 1%.

Regn. 268: Hydro test - 1½ times the maximum permissible working pressure after completion of welding and heat treatment of drum (internal dia > 1000 mm).

2 f E (T 0.03)Regn.270: The working pressure - WP =

D + T 0.03Weld factor 0.95.

 Regn. 271: For temperature at or below 454C

E t R (or)

1.5                   2.7  For temperature above 454C

E t SR (or) (or) SC

1.5 1.5In case SC valves are not available, the allowable stress may be

E t SR lower of (or) 1.5 1.5 Regn. 272: The ligament efficiency as per Regn. 215.  P d P nd P P1

Diagonal and Curve P P d P  Circumferential ligament.

PD2

Regn. 273: Longitudinal Stress = fd = 1.273A

PD2

M = 1.273

MRYThe stress due to bending f b =

Ia

 Regn. 275: Shape of Dished end plate a)            Hemispherical b) Elliptical heads -H 0.2D c)           Partial spherical heads - H 0.18D. 

Figures 23A, B, C.

Regn. 276: Gradual thinning up to a maximum of 10% of thickness where the corner radius joins the dishing radius.

 Regn. 277: Dished end with opening (inline with ISO). 

d A d1 = d DT T

 Regn. 278: Dished end plate maximum working pressure 2f (T C)

WP = DK (Shape factor)

Minimum head thickness - 5 mm. Regn. 279: Reinforcement calculation.

Regn. 280: Attachments of Branch Pipes by welding. 

Figures 24A to D, 26A to E, 27A to D.

VALVES, GAUGES AND AUXILIARIES Regn. 281: Every boiler shall be provided. 

Two safety valves - one of which may be a high steam and low water type, the bore not less than 19mm.

 Two means of indicating water level.

 a steam pressure gauge.

 a steam stop valve.

 a feed check valve.

 one feed apparatus.

 A blow down cock valve.

 A manhole - A safety valve at the end

of SH outlet.

New Regn.281A: Water level and or firing control. SAFETY VALVES Regn. 293: Discharge capacity. 

Saturated steam E = CAP  E

Superheat steam ES =

1 + 2.7 TS

1000

  Regn. 294: Over pressure of safety valves: 

Where discharge area < 80% - Over pressure shall not exceed10% of set pressure.

 Where discharge area > 80% - Over pressure shall not exceed

5%.

Regn. 295: Pressure drop: 

Reset at a pressure at least 2.5 below but not more than 5% below safety valve set pressure. The 5% limit increased to 10% for valves having seat bore less than 32 mm and or having a set pressure of 2 bar gauge or less.

 Regn. 296: Attachment to Boiler: 

The axis valve shall be vertical. Branches shall be as short as possible.

 Regn. 320: Water Gauges: 

Every boiler shall have two means of indicating the water in it of which one shall be conventional gauge glass. Minimum length of visible portion of gauge glass 200 mm.

 b) For boilers > 10,000 lb/hr., one of water gauges may be of

remote water level indicator type.

BOILER AND SH TUBES, HEADERS Regn. 338(a): 2f (T C) C = 0.75 for P 70 Kg/m2

WP =

(D T + C) = 0 for P > 70 Kg/m2

 The working metal temperature.

 ECO = The maximum water temperature + 11C.

 Furnace & boiler tubes = Sat. temperature + 28C.

 Convection SH =Maximum steam temperature + 39C.

 Radiant SH = Maximum steam temperature + 50C.

  

For temperature at or below 454C. 

TS Et (or)

2.7 1.5  

For temperature above 454C 

SR or SC

1.5

If SC not available

 E t SR

(or)1.5                 1.5

  b) % Ovality = D max. D min.

x 100 D

Regn. 340 (f): Flat ends for headers - 

f (t C)2

WP =

d2 K

 Regn. 342: Cylindrical headers - As per Regn. 270. 

End attachments - As per Regn. 340(f).

 

STEAM PIPES AND FITTINGS

 Regn.343(1): Carbon steel, Cast steel, Alloy steel, cold or hot

finished, butt welded or ERW.  Regn. 343(2): Material used, the permissible stress figures

specified in the code may be accepted.

Regn. 343(3): The hydraulic test may be dispensed with if id 600 mm.

 Regn. 349: The temperature limits for pipes, Tees, branches,

etc. shall be as per Table-2. Regn. 350: Working Pressure.  2fe (t C)

WP = C = 0.75.

D t + C

STEAM PIPE FITTINGS Regn. 361(a): Pipe bends thinning 12.5%. Regn. 361(A): Butt welding fittings. Regn. 362(a): Branch welded to pipe Regn. 249 to 253. Angle not

less than 60. Regn. 362(b): External Reinforcement : 

Multiple radial plates of horse shoe form or the form of collars applied to or around the junction between branch and main.

Regn. 374: Hydro test pressure in the piping system - 1.5 times the design pressure.

 REGULATIONS FOR THE REGISTRATION AND INSPECTION OF BOILERS

Regn. 379: Procedure of Hydro test. 

Test pressure 1.5 times the maximum working pressure.  Temperature of water > 20 < 50C.  Not exceeding 6% of the required pressure. Regn. 385: Registration Fee: Regn. 393: Submission of plans of boilers: a)           Drawing Approval. b) & c) Boilers made outside India, Technical

Advisor (Boilers) and then CIB user state. 

d) Scrutiny fees as per Regn. 385 subject to a maximum of Rs. 20,000.

 Alteration fee at 10% of the fee of the first scrutiny fee.

Regn. 395: Submission of plans of steam pipes: 

Rs. 30 for 30 meters minimum of Rs. 50. 

Fittings like DESH, Separators, etc. Rs. 150 each.

Sl.No.

DESCRIPTION CLAUSE REQUIREMENT AS PER ASME SEC.I 2001 REMARKS

1. Service Limitations

PG-2 a)Boilers in which steam/vapour is generated at a pr. more than 15 PSIG b)High temp. water boilers > 160 PSIG or 250 Deg.F

 

2. Plate material PG-6 Shall be of pressure vessel quality SA202; SA204; SA240(Type 405 only) SA302; 387(A.S) SA285; SA299; SA515; SA516 (C.S), SA / EN - 10028 - 2

 

3. Pipes, Tubes materials

PG-9 PG 9.1 for boiler parts materials PG 9.1 & 9.2 for superheater matrials

 

4. Boiler plate min.thick

PG-16.3 The min. thickness of any boiler plate under pressure shall be 1/4 in (6 mm)

 

5. Tubing calculation PG-27.2.1 "Upto and including 5 inches outside dia" (127mm) t(inch)=PD/2S+P +0.005D+e e = 0 for tubes strength welded to headers P = Max. allowable working pressure(psi) D = Outside dia(in) S = Max. allowable stress (psi)

 

Sl.No.

DESCRIPTION CLAUSE REQUIREMENT AS PER ASME SEC.I 2001

REMARKS

6. Piping, Drums and headers calculation

PG-27.2.2

t =PD / 2SE+2YP + C (or) t = PR / SE - (1-y)P+ C E = efficiency of liagament of weld joints Y = temperature co-efficient C = Min. allowance for threading and structural stability (0) R = Inside radius in

 

7. Hemispherical head

PG-29.11 t = PL / 1.6S L = radius to which formed head measured on concave side

 

8. 2:1 Semi-ellipsoidal

PG-29.7 & PG-27.2.2

t = PR / SE - (1-y)P + C R = Inside radius of end cover

 

9. Max. Dia of opening in shell

PG-32.1.2 & PG-32.1.3.2

K Factor = PD / 1.82 St Max. dia of opening without compensation as per Fig PG 32

 

10. Compensation Calulation

PG - 37 & PW - 15

Limits of reinforcement X = greater of 2d or 2(t + tn) but not greater than pitch Y = the smaller of 2 1/2t or 2 1/2 tn

 

Sl.No. DESCRIPTION CLAUSE REQUIREMENT AS PER ASME SEC.I 2001 REMARKS

11. Max. allowable stress for drum (Bending and Longi stress)

PG - 22 & Sec.3.3.4 of BS-1113

Total stress = fb + fd fb = stress due to bending fd = Direct longitudinal stress

 

12. Hydraulic test pr. PG 99.1 1.5 times the max. allowable working pr. Calculate stress at hydraulic test by substituting in thick formula.Stress at hydro to be leser than 90% yield stress at 100 deg. F.

 

13. Min. weld size PW - 16.1 Check as per Fig. PW 16.1  

14. Min. weld size PG - 37 PW - 15

Combined strength of each path >min. weld strength required

 

15. Feed water connection

PG - 59.2 Boiler pr. 400 PSI or over the feed water inlet shall be fitted with sleeves.

 

16. Blow - off PG - 59.3.3

Boiler shall have a bottom blow off outlet in the lowest water space.

 

17. Water level indicator

PG - 60.1.1

a) Two nos. gauge glass over a boiler pr. Of 400 PSI b) Two independent remote level indicators instead of one gauge glass in case of pr. above 900 PSI c) The lowest visible part of gauge shall be at least 2 in. above lowest water level

 

Sl.No.

DESCRIPTION CLAUSE REQUIREMENT AS PER ASME SEC.I 2001

REMARKS

18. Water level indicator

PG - 60.1.6

a) Connection to the gauge glass shall not be less than 1/2" pipe size b) Water gauge glass drain not less than 1/4 in. Above 100 PSI pr. Drain connects to safe discharge point

 

19. Pressure gauges PG - 60.6.1

Pr. Gauge connection to the boiler shall not be less than 1/2 in. Inside dia. for steel pipe.

 

20. Test pr. Gauges PG-60.6.3

Connection to the test pr. gauge shall be at least 1/4 in. pipe size

 

21. Feed water supply

PG-61 a)Boiler having more than 500 sq. ft. of water heating surface shall have two means of feeding water b) The feed connection shall not be less than 3/4" pipe size for water heating surface more than 100 sq. ft.

 

Sl.No.

DESCRIPTION CLAUSE REQUIREMENT AS PER ASME SEC.I 2001

REMARKS

22. Boiler safety valve reqts

PG-67.1 Boiler with water heating surface exceeding 500 sq. ft. and steam generating capacity exceeding 4000 lb/hr two or more safety valves are required.

 

    PG-67.3 a) one or more safety valves shall be set at or below max. allowable working pr. B)The highest pr. Setting shall not exceed 3% of the max. allowable working pressure

 

    PG - 67.2 c) The safety valve will discharge all the steam generated by the boiler without allowing the pr. to rise more than 6% above max. allowable working pressure.

 

    PG-68.2 The discharge capacity of the safety valve on the boiler is at least 75% of the aggregate value capacity required

 

23. Drain, vents provisions

PG - 58.3.7

Piping connections for items such as drains, vents for a high temp. Boiler.

 

2..1.2 MATERIALS FOR PP. 

BS MATERIALS OR AGREED BETWEEN MANUFACTURER AND PURCHASER

  2.2 DESIGN STRESSES 2.2.3 FOR C, C-Mn AND LOW ALLOY STEELS 

FE = Re (T)/1.5 OR Rm /2.7 WHICHEVER GIVES A LOWER VALUE.

 2.2.4 FOR AUSTENTIC STEEL 

FE = Re (T)/1.35 OR Rm /2.7 WHICHEVER GIVES A LOWER VALUE.

SALIENT CLAUSES OF BS-1113-1990  SECTION –2 MATERIALS AND DESIGN STRESSES

2.2.7 DESIGN TEMPERATURE  2.2.7.1 DRUMS AND HEADERS 

NOT HEATED BY GAS - EQUALS FLUID TEMP.HEATED BY GAS - ADD 25 C.

 2.2.7.2 BOILER TUBES  

SUBJECT TO RADIANT HEAT -- SAT TEMP. + 50 C. 

NOT SUBJECT TO RADIANT HEAT -- SAT TEMP. + 25 C.  2.2.7.3 SH & RH TUBES 

SUBJECT TO RADIANT HEAT -- SAT TEMP. + 50 C. 

NOT SUBJECT TO RADIANT HEAT -- SAT TEMP. + 35 C.  2.2.7.4 ECONOMIZER TUBES 

MAX FLUID TEMP + 25 C.

SECTION –3 DESIGN  3.3.4 COMBINED STRESSES IN DRUMS AND HEADERS. 

TO BE BROUGHT IN PLACE OF REG.73 OF IBR 3.3.1 MINIMUM 9.5 mm THICK FOR HEADERS OF OD 300 mm AND

ABOVE. 3.3.2 MINIMUM 6 mm THICK FOR HEADERS UPTO OD 300 mm

t = PDi / 2 f n - P

 3.3.3.1. MAX DIA OF UNREINFORCED OPENING 200 mm.  3.6.1 DISHED ENDS 

TORI AND SEMI ELLIPSOIDAL DISHED ENDS.  3.6.1.2 t= PDOK/2f

 MINIMUM THICKNESS OF DISHED ENDS TO BE 9.5 mm.

3.6.1.3.1 UNREINFORCED OPENINGS 

OPENINGS NOT TO BE GIVEN IN D/10 AREA. 3.7.2 TUBES AND PIPES 3.7.2.1 t = P do/2f + P.

 MINIMUM THICKNESS TO AS UNDER

 

UPTO 38 MM OD 1.7

38 TO 51 MM OD 2.2

51 TO 70 MM OD 2.4

70 TO 76 MM OD 2.6

76 TO 95 MM OD 3.0

95 TO 102 MM OD 3.3

102 TO 127 MM OD 3.5

SECTION 4 MANUFACTURE AND WORKMANSHIP  4.2.2.5.1 PLATES CAN BE BUTT WELDED

PRIOR TO FORMING PROVIDED WELD IS NDT EXAMINED.

  4.2.2.5.2 OUT OF ROUNDNESS NOT TO

EXCEED 1 % OF NOM INTERNAL DIA.   4.3.1.1.6 LONGITUDINAL DRUM SEAMS TO

BE WELDED BEFORE CIRCUMFERENTIAL SEAMS AND WHRE PRACTICABLE THE LONGITUDINAL SEAMS OF ADJACENT COURSES SHALL BE STAGGERED.

  4.3.1.1.7 HOLES CAN BE MACHINED

THROUGH THE SEAMS AFTER SEAM HAS BEEN NDT EXAMINE PRIOR TO PWHT.

SECTION 5 INSPECTION AND TESTING  5.10.1.1         HYDROSTATIC TEST PRESSURE  5.10.2.1 HYDRO TEST PRESSURE OF BOILER 1.5 TIMES

THE MAX WORKING PRESSURE. 

DRUMS AND CYLINDRICAL HEADERS GREATER THAN 600 MM SHALL BE HYDROSTATICALLY TESTED AT SHOP.

 5.10.3.1 ALL COMPONENTS NOT REASONABLY

ACESSIBLE TO INSPECTION AFTER ASSEMBLY TO BE HYDROTESTED AT SHOP.

SECTION 7 VALVES, GUAGES AND FITTINGS 7.2 SAFETY VALVES  7.2.1.1 MINIMUM BORE 20 mm 7.2.1.2 FOR EVAPOTATION UPTO

3700 KG/H ONE SAFETY VALVE FOR GREATER EVAPORATION TWO SAFETY VALVES

  7.2 WATER LEVEL GUAGE  

EACH BOILER TO HAVE TWO INDEPENDENT MEANS OF WATER LEVEL INDICATION.

 Sl.No

.

 Description

 BHEL

 MBEL

 

01.

BOILER DRUM - Shell Material

Thickness in mm Internals

CARBON STEEL to SA299

195 / 165Turbo Separators (92 Nos)

ALLOY STEEL to Specification BS EN 10028-2 1993 Grade NC 271

111/111 Cyclone Separators (168 Nos) 

02.

DOWNCOMERS

6 Nos. of D368 SA106 Gr.C

4 Nos. of D508 BS 3602 500Nb - Supply pipes - 48 Nos. of D139.7 

03. WATERWALLS D51 at 63.5 Centres Rifled - SA210 Gr.C Tangential firing.

D66.7 at 92 Centres Rifled - BS 3059 243 S2 Calls for optimisation with headers.Front / Rear wall firing. 

04.

RISERS

68 Nos. of D159 - SA106 Gr.C Risers are connected to the top of drum. 

48 Nos. of D168.3 - BS 3602 500 Nb The rear and bottom of drum.

05.

PRIMARY SUPERHEATER

Strap type support with hanger tubes.SA240 Type 310/304.

Armchair support with hanger tubes.BS 1563 - 620 - 440. 

BOILER PRESSURE PARTS  COMPARISON BETWEEN BHEL & MBEL (500 MW) Page 01 of 02

Page 02 of 02

Sl.No.

Description

BHEL

MBEL

06. PLATEN SH / FINAL SH Flex connectors for spacing between tubes.Tangent Flex tie at close spacings.

Common Header for inlet & outlet of all assemblies.

Wraparounds for spacing between tubes.

Only 2 DAGS of Material BS 3059 622 S2 & T91 - Half the horizontal bottom portion of platen membraned.

Individual headers for both inlet & outlet of each Coil Assembly (Calls for optimisation).

07.

REHEATER

Front RH - Flex connectors for spacing. Rear RH - Alignment band for spacing.

Tube strap support for both Front & Rear Reheater.

08.

ECONOMISER

Two loop D51 - SA210 Gr.A1

Not covered in the scope.

09.

ATTEMPERATOR

Liner is positioned with shell support screws.

Liner is positioned with shell by support bar welded to liner out side and support ring.

10.

STEAM COOLED WALLS

D63.5 / D51 at 152.4 Centres - SA210 Gr.C

D44.5 at 115 Centres - BS 3059 243 S2.

COST SAVINGS DUE TO NEW MATERIALS

 Sl.No.

 Pipe / Tube

Specification

 UsageArea

Annual Quantum

(2003-04)

Tons

 Cost/Ton

 Total Cost

Increase

 Substitute

dMaterial

Cost Savings

(%)

Total Savings

(in Crores)

 01.

 

 SA106 Gr.B /

Gr.C

 Water wall Headers,

Downcomers, Risers

 

 2000

 70,000

 14

 WB361

 25%

 3.5

 02.

 SA213 T22

 SH / RH

coils

 1060

 60,000

 6.36

 SA213 T232

 23%

 1.46

 

 03.

 

 SA213 T91

 SH / RH

coils

 257

 1,30,00

0

 3.34

 SA213 T922

 21%

 0.7

 04.

 

 SA213 TP347

H

 SH / RH

coils

 173

 2,10,00

0

 3.63

 SA213 T922

 21%

 0.76

 TOTAL SAVINGS / YEAR

 6.42

 

Cost Savings projected by M/s. V&M.

1 = Code case but covered in DIN.  2 = Published in ASME.