Piping Design Criteria

8/11/2019 Piping Design Criteria

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LARSENT & TOUBRO LTD.

RAJASTHAN RAJYA VIDYUT UTPADAN

NIGAM LTD.

2 660 MW CHHABRA SUPERCRITICAL

TPS, STAGE II, UNIT 5 & 6 L&T S&L LIMITED

EPC TENDER PACKAGEDESIGN CRITERIA FOR

PIPING SYSTEM

Rev:A

Date:01 MAY 2013

L&T - S&L Job No.:L764000 Document No.: L764000-CV03-00-ZEN-130001 Page 3 of 20

TABLE OF CONTENTS

1.0 INTRODUCTION .................................................................................................................... 4

2.0 APPLICABLE DESIGN CODES & STANDARDS .................. ............... ............... ............... .. 5

3.0 PRE-REQUISITE FOR PIPE COMPONENT STANDARD DESIGN ................ ............... ........ 7

4.0 PRESSURE & TEMPERATURE RATING OF PIPE ............................................................ 11

5.0 PIPING HANGER AND SUPPORT ...................................................................................... 11

6.0 PIPING INSULATION .......................................................................................................... 14

7.0 PIPING SPECIALTIES......................................................................................................... 14

8.0 PIPING MATERIAL ............................................................................................................. 14

9.0 PIPE ARRANGEMENT DESIGN PLAN ............................................................................... 15

10.0 PIPE SUPPORT DESIGN STANDARD ............................................................................... 18

11.0 GENERAL REQUIREMENTS FOR STRESS & FLEXIBILITY ANALYSIS .......................... 19

12.0 REFERENCES ..................................................................................................................... 20


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1.0 INTRODUCTION

This document describes the design criteria of Piping System for 2 660 MW

CHHABRA SUPERCRITICAL TPS,STAGEII,UNIT5&6. This document needs to

be used in conjunction with the relevant standards as mentioned in the Piping

Material Specification, Valve list, relevant P&IDs and relevant system design criteria

documents.

The plant consists of two Supercritical Boilers with two set of steam turbines and the

associated equipment and auxiliaries. The entire plant mechanical system and its

associated equipment and auxiliaries are subdivided in the systems listed below:

Main, Reheat Steam System & HP/LP Bypass system

Feed water System

Heater Drain & Vent Systems

Extraction Steam System

Aux Steam System

Condensate System & Condensate polishing plant

Condensate Storage & Transfer System

Condenser Air Removal System

Main Cooling Water System

Aux. Cooling Water System

Closed cooling water System

Fuel Oil System

Instrument & Service Air System

DM Water System

Sampling System

Compressed Gas System

Service & Potable Water System

Raw Water System

Chemical Dosing System

Plant Waste water collection & treatment system

Electro chlorination system


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Fire protection system & HVAC

The detail design criteria of these respective systems are mentioned in separate

documents.

2.0 APPLICABLE DESIGN CODES & STANDARDS

The primary and principal piping design code shall be Power Piping ASME B31.1.

Piping for the package facilities may be designed in accordance with the

manufacturers standard. All Piping covered under this specification shall comply withall currently applicable statutes, regulations and safety codes in the locality where the

piping will be installed. The piping shall also conform to the latest applicable

standards specified. All codes and standards referred to in the specification shall be

understood to be the latest version on the date of offer made by the Bidder unless

otherwise indicated. Nothing in this specification shall be construed to relieve the

Bidder of this responsibility.

Publications of the following nationally recognized organization are applicable to the

design, manufacture, and testing of the piping & fittings included in the specification to

the extent specified therein.

American Society of Mechanical Engineers (ASME)

ASME B31.1 Power Piping Code

Indian Boiler Regulations(IBR)

ASME Section I Power Boiler

ASME Section IX Welding Qualification

American Society of Testing and Material (ASTM)

American Institute of Steel Construction (AISC)

National Fire Protection Association (NFPA)

American Welding Society (AWS)

American Water Works Association (AWWA)

American Petroleum Institute (API)

Pipe Fabrication Institute (PFI)

Bid specification

requirements andapplicable codes &standards.


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Steel Structure Painting Council (SSPC)

Manufacturers Standardization Society of the valve and fittings Industry Inc.

(MSS)

British Standards Institute (BSI)

Indian Standard(IS)

International Organization for Standardization (ISO)

Pipe Fabrication Institute (PFI), USA Standards

Some of the relevant standards and references are as follows:-

ASME B31.1 Power Piping

ANSI B1 20.1 Pipe Thread.

ANSI B 16.5 Steel pipe flanges and flanged fittings.

ANSI B 16.9 Wrought steel butt-welding fittings.

ANSI B 16.11 Forged steel socket welding and screwed fittings.

ANSI B 16.25 Butt welding ends.

ANSI 36.10 Welded & seamless wrought steel pipe.

ANSI B 36.19 Stainless steel pipe.

ASTM A-105 Forging, carbon steel, for piping components.ASTM A-335 Alloy steel pipe

ASME-Sec.-8, Div-1 Boiler & Pressure Vessel Code

ASME B16.20 Metallic Gasket for Pipe Flanges

ASME B16.21 Nonmetallic Flat Gaskets for Pipe Flanges

ASTM A 182

Forged or Rolled Alloy & Stainless Steel Pipe

Flanges, Fittings and Valves and parts for High

Temperature Service

ASTM A 193/ 194Alloy & Stainless Steel Bolting Material/ Nuts for

High Temperature Service

IBR With latest amendments where applicableAPI-5L Specification for Line Pipe

IS-554Dimensions of pipe threads where pressure tight

joints are required on the threads.

IS-816Code of practice for use of metal arc welding for

general construction in mild steel.

IS-817Code of practice for training and testing of metal arc

welder.

IS-823 Code of procedure for manual metal arc welding of


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mild steel.

IS-1239

(Part-I & II)

Mild steel tubes, tubular and other wrought steel

fittings.

IS-1363Black hexagon bolts, nut lock nuts (dia. 6 to 36 mm)

and black hexagon screws (dia 6 to 24mm).

IS-1367Technical supply conditions for threaded steel

fasteners.

IS-2016 Plain washers.

IS-3589 Steel Pipes for Water and Sewage

IS-2062 Structural steel (fusion welding quality)

IS-3138 Hexagonal bolts and nuts (M-42 to M-150)

IS-9404Color code for identification of pipelines used in

thermal power plants.

IS 1364Hexagonal Bolts, Screw and Nuts Grade A &

Grade B

API-1104 Standard for Welding Pipeline and Facilities

PFI ES 3 Fabricating Tolerances

PFI ES 5 Cleaning of Fabricated piping

PFI ES - 16Access holes and plugs for radiographic inspection

of pipe welds

PFI ES - 20Wall thickness measurement by Ultrasonic

examination

PFI ES - 24Pipe bending methods, Tolerance. Process and

Material requirement

PFI ES - 29Internal Abrasive Blast Cleaning of Ferrite pipe

material

The codes and standards specified above are indicative but not exhaustive.

3.0 PRE-REQUISITE FOR PIPE COMPONENT STANDARD DESIGN

3.1. Pipe:

3.1.1. The representation of pipes will be in any of the following methods

DN 250 x Sch.40 or DN250 x STD or OD 273 x 22 AWT or ID 340 x 60 MWT

3.1.2. For piping material refer clause no.8.0.

3.1.3. Unless otherwise specified in the system design criteria, in any case a minimum

corrosion allowance of 0.75 mm shall be considered while selecting thickness.

1.0mm


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3.1.4. Unless otherwise specified or approved or unsuitable due to corrosion or other

considerations, all pipes are to be seamless drawn steels and follow ASME

B36.10. Accordingly Stainless Steel Pipe will follow ASME B36.19.

3.1.5. The following standard pipe sizes will be used for different systems:

Diameters DN 15, 20, 25, 40, 50, 80, 100, 150, 200, 250, 300, 350, 400 etc.

3.1.5.1. Piping systems larger than DN 600 for water service may be designed as per

AWWA standard. (Applicable in case of BOP lines only)

3.1.5.2. Pipes with diameter size smaller than DN25 may be used only for Control Air,

Chemical Dosing, Sealing Water, Instrument connections, Cooling Water

connections to equipment, sampling pipes, etc.

3.1.6. The maximum allowable velocity of flow in pipes will be as per relevant system

design criteria.

3.1.7. Pipe Thickness

3.1.7.1. Straight Pipe receiving Internal Pressure: Thickness of Straight Pipe receiving

internal pressure will be calculated based on thickness table given under ASME

B31.1 of Power Piping Code 104.1.2 & also stipulated in IBR.

3.1.7.2. Statutory requirements as laid down in Indian Boiler Regulations (latest edition)

will also be taken care in pipe system designs. Pipe wall thickness as calculated

by ASME Code formula will also be checked for IBR requirements for piping

systems falling under IBR purview. The higher thickness of the two (ASME & IBR)

shall be adopted.

3.1.7.3. Straight Pipe Receiving External Pressure Thickness of Straight Pipe receiving

external pressure will be calculated based on ASME Boiler and Pressure Vessel

Code Division 1, Section VIII UG-28, UG-29 and UG-30.

3.1.7.4. For carbon and alloy steel piping, Pipe size DN50 and smaller shall have

minimum thickness of schedule 80 and piping DN80 & larger shall have a

minimum thickness of schedule STD.

3.1.7.5. For Stainless steel, piping DN50 and smaller shall have a minimum thickness of

Sch. 40S. Piping DN80 & larger shall have a minimum thickness of Sch.10S.

3.1.8. Hydro Field Test:

Unless otherwise indicated in system design criteria for relevant systems, all

piping systems shall be hydro tested at 1.5 times the design pressure.


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3.1.9. All piping threads shall confirm to ASME B 1.20.1 except where otherwise

specified.

3.1.10. Unless otherwise stated, the design of steam trap discharge piping shall be

based on clause 122.11.2 of ASME B31.1.Steam drain pipe will be designed for

same conditions as the main piping up to the last drain valve in each drain line.

3.1.11. Wherever possible, steam trap discharges will run individually to the receiver.

Condenser or Flash Tank shall serve the purpose of receiver as per the system

requirements.

3.1.12. Steam trap discharges are to be ganged to a condensate return header in

accordance to the following:

Arrange steam trap discharges of varying pressures to enter the header in

descending order of pressure, with the highest discharge pressure farthest from

the receiver.

3.2. Pipe Fittings:

All branch connections shall be realized through the use of tees, crosses and laterals

to the extent such standard fittings are available as per ASME standards. When

intersection welds are employed due to non-availability of standard fittings, they shallbe of suitable structural adequacy by virtue of intrinsic weld connection, reinforcing

plates or rings or material inherent in the branch.Etc.

3.2.1. Generally, butt welding will be employed for joining pipes DN80 & above and

Socket welding will be employed for pipes DN50 and below, where weld

connections are required. Pipe joints shall be designed in accordance with ASME

B31.1.

3.2.2. Threaded joints shall conform to that specified in clause 114 of ASME B31.1, in

which specific consideration shall not be limited only to the pipe type and size.

Screwed (Threaded) coupling shall be used for galvanized pipes of DN50 and

below. Below 25mm bore connections, compression type (union) couplings may

be used in positions where leakage will not introduce any hazard. The threads

shall be entirely covered by the seal weld and only qualified welders shall carry out

such seal welding.

3.2.3. All welded branches shall be reinforced where needed as per the applicable

codes/regulations.


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3.2.4. Temperature connection stubs shall be prepared as per approved drawing for the

temperature connection.

3.2.5. Flanges may be used for coupling of pipes where welding is not possible and / or

frequent maintenance is predicted or when piping has lining / coating or when the

piping is not critical in terms of operating pressure, temperature and fluid

properties. Flange joints including flange type, bolting & gasket shall conform to

that specified in Table 112 of ASME B31.1.

3.2.6. All flanges and contact surfaces shall be concentric with the axis of the piping. All

flanges and fittings shall be accurately machined and drilled true to the template.

3.2.7. Flanges will also comply with the requirements of code to which the piping is

designed i.e. ASME 16.5 for flanges up to 24 NPS, ASME 16.47 / AWWA C207

for greater than 24 NPS.

3.2.8. Dimensions of steel BW fittings for sizes not covered in ASME B16.9 shall confirm

to MSS SP-48, MSS SP-44.

3.2.9. Bolts, Studs, nuts and washers for flanges shall be galvanized for Carbon Steel &

Plastic flanges and stainless steel for stainless steel flanges.

3.2.10. Elbow, Bend, Return, Miter can be used for changing the direction of flow in the

pipe.

3.2.10.1. Long radius elbows will be used where elbows are required. However for high

pressure steam pipes like MS and HRH lines, bends will be used. Unless

otherwise stated, pipe bends for critical piping such as main steam pipe, hot

reheat pipe shall conform to that specified in clause 104.2.1 of ASME B31.1.

3.2.10.2. Bends used, will be of pulled type or forged. Hot bending with packing may be

used for larger sizes according to facilities available, but hot bends in alloy or

stainless steel may only be made after prior approval.

3.2.10.3. Bend thinning allowance shall be provided for all bends as per the

recommendations of ASME B31.1.

3.2.10.4. All pipe bends shall be made true to angle. Plane with no negative tolerance and

shall have a smooth surface free of flat spots, Crease and corrugations. A cross

section through any bend portion of the pipe shall be true in diameter. Thinning

allowance shall be considered as per ASME B31.1. The ends of pipe bends shall

be beveled according to ASME B 16.25. After bending, the bent portion shall have

the minimum calculated thickness as per ASME B31.1. Necessary ultrasonic test


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is to be carried out to ensure the minimum thickness at the bent (elongated)

portion. Measurements shall be taken in accordance with PFI standard ES-20

using the "Pulse Echo" method.

3.2.10.5. Bending on Pipes shall only be done where indicated on the isometric drawings or

when allowed by the applicable piping class, otherwise formed elbows shall be

used. No wrinkling, excessive thinning or flattening is allowed. Excessive

scratches, gauge or die marks will be the grounds for rejection. Bending tolerance

and minimum tangents of bends shall be in accordance with PFI standard ES-24.

3.2.10.6. All piping bends are subjected to heat treatment as required by clause 129.3 of

ASME B 31.1.

3.2.11. For change of diameter of the pipe, Reducer or Swage (MSS SP-95) will be used.

Eccentric reducers will be used on pipe rack or pump suction lines for maintaining

the elevation of pipe and to avoid cavitation respectively. Concentric reducers will

be used for change in diameter of pipe with that of nozzle of equipment etc.

3.2.12. Tee is generally used to branch off from the main line. Refer piping material

specification for branch connection details.

3.2.13. Lateral is used, where the branch off from the main line is at an angle of less

than 90.

3.2.14. Other fittings like Full Coupling, Half Coupling, Reducer Insert, plugs, caps; Union,

Olets, etc are also used, where required.

3.3. Valve:

Valves for all the piping systems shall be in line with the HP valve specification, LP

valve specification and Butterfly valve specification.

4.0 PRESSURE & TEMPERATURE RATING OF PIPE

ForPressureandTemperature rating of pipes, the preferredstandardClassesof

150,300,600, 800, 900, 1500, 2500,4500orspecial ratingofASME B16.5and

ASME B16.34, will be used as the basis, and accordingly Pipe Material

specification and Valve List will be prepared. Pipe Material specification will be

uniformlyappliedtoeach& everysystem.

5.0 PIPING HANGER AND SUPPORT


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5.1. All piping supports will be designed in accordance with the provisions of ASME

B31.1 or the standard to which the pipe work is designed. Pipe Hanger and

Support design shall be as per MSSSP-58.

5.2. All supports will be provided with means of adjusting the tension of springs,

height of supports and the length of rods or straps. All such adjusting devices will

be capable of being securely locked.

5.3. Parts of supporting elements for high working temperature piping will be made of

suitable alloy steel or will be protected so that the temperature of the

supporting member will be maintained within the appropriate temperature limits ofthe material.

5.4. Load variation of Variable spring hanger should be less than 20% (Not more than

10% for critical piping systems) and load variation in constant spring hanger must

be restricted to 6%.

5.5. The supporting arrangements of all piping systems will be designed with due

regard to any additional loads imposed during hydro testing & cleaning and steam

blowing operations.

5.6. Support shall be so designed and fabricated that, in the event of spring failure;

they do not release the pipe.

5.7. Helical compression type spring will be provided with the means to prevent

misalignment, buckling, eccentric loading or excessive travel, with a working

stress not exceeding 10N/mm2 at the most favorable loading conditions.

5.8. The supports shall be designed to meet all static and operational conditions to

which the piping system and connected equipment shall be subjected. These

conditions shall include Hydrostatic Test loadings, thermal expansion and

contraction, occasional loadings, impact loadings etc. The piping system shall be

adequately supported such that the system is sufficiently flexible to allow for thethermal expansion and contraction as well as be rigid enough to take the

occasional (seismic and wind) and impact loadings.

5.9. All pipe supports shall be designed so they do not disengage due to thermal

movements of the supported pipe. All spring supports must be locked during In-

service Hydro Test. For systems where thermal growth or contraction shall occur,

sufficient clearance shall be provided to prevent interference between supports

and surrounding equipment during this growth.


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5.10. Clevises, turnbuckles and other such accessories connecting to rods shall be

forged steel and compatible with the rod material. Welding of extension pieces to

support rods shall not be done.

5.11. All Constant Support and Variable Support units shall be provided with

Hydrostatic Test and erection locks, installed and preset in the cold position on

the units before they are shipped. The locks will be removable and replaceable in

a cold position and will be provided with permanent means of attaching them to

the support unit when not in use.

5.12. Attempts shall be made to use variable spring and rigid hangers as much aspossible. Rigid hangers shall preferably be used where vertical movement of the

pipe is negligible.

5.12.1. Variable spring supports/hangers may be used provided the following conditions

are met.

The variation in supporting effort between hot and cold condition does not

exceed 20% of the load, which is higher of the operating condition, and cold

setting load.

The resulting effect of load take-up/release by a group of hangers in a span

does not overstress the piping span or cause overloading at equipment

terminals.

5.12.2. Otherwise, constant load type support/hangers must be used. On the other hand

rigid hangers can be used where possible without exceeding the stipulated limits

of terminal forces and moments and the stress.

5.13. Snubbers will be used to absorb the shocks during occasional loads, i.e., thrust

due to safety valve discharge, steam hammer, etc. where required.

5.14. All large pipes and all long pipes shall have at least two supports each arranged

so that any length of pipe or valve may be removed without any additionalsupports being required.

5.15. Variable springs shall be furnished with travel stops. The travel stops shall be

factory installed at the "cold" position.

5.16. Spring hangers should not be loaded more than 80% of the spring travel range.

5.17. Hanger rods (except rigid hangers where both tension and compression may

occur) shall be subjected to tensile loading only. At hanger locations where lateral


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movement is anticipated, suitable linkage and rocking washers shall be provided

to permit swing.

5.18. Tie rods/struts shall preferably be used for restraints to achieve low friction

restraining. The Tie-rods/struts shall have proper arrangement and adequate

length, so that, thermal movements in other directions, which are intended to be

free are not constrained and there is no appreciable shift in centerline of pipe or

the elevation of the supporting point on pipe due to sway. The design shall have

provisions for adjusting the length to take up any slack and securely locking in

position permanently once adjustment is done.5.19. All relevant hangers shall be designed to take the dynamic movements for

dynamic loading in addition to the thermal movements.

6.0 PIPING INSULATION

Thermal Insulation for all the piping systems shall be in line with the design

requirements specified in DESIGN CRITERIA DOCUMENT FOR THERMAL

INSULATION (Reference-13.3).

7.0 PIPING SPECIALTIES

7.1. Traps: Traps are used to eliminate the condensate formed in the steam or gas /

airlines and form a water hammer free line. Traps are to be so designed that the

discharge the condensate water automatically.

7.2. Strainers: Unwanted substance in the fluid system is removed through strainer. It

is used to protect components like Pump, Control Valve, Steam Trap, etc. Inside

the entity of strainer is installed structure, either perforated or of wire mesh.

Screen/screening elements plays an important part in filtering out unwanted

substance. Generally it has 40 meshes at the inlet of pump, and during trial runs60 mesh is used and the same will be replaced after the trial runs are completed

and the supply fluid is ensured of free from impurities. However respective pump

supplier recommendations will be sought for mesh size.

7.3. Expansion Joints: These are used to increase the flexibility in the pipelines and to

protect equipment.

8.0 PIPING MATERIAL

INCLUDE AIR VALVESALSO


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8.1. Carbon Steel is used for most of the piping in the Power plant but is restricted to

Pipe design temperature of 410 C. For any temperature above 410 C Alloy

Steel will be provided. However Stainless steel is used, where corrosion effect is

severe or as a special requirement.

8.2. The design of main & branch piping for CW will be in accordance with AWWA

M11.

8.3. Buried (Underground) piping will be coated and wrapped and also confirming to

IS: 10221 & AWWA C203-93.

8.4. Selection of Piping Materials will be as per Piping Material Specification.

9.0 PIPE ARRANGEMENT DESIGN PLAN

9.1. General Guidelines:

9.1.1. All piping will be routed to provide a neat and economical layout requiring a

minimum number of fittings.

9.1.2. Overhead piping, inclusive of fittings, insulation & support steelwork, will have a

minimum vertical clearance of 2.3M above access platform & walkways, and 6.0

M minimum above roadways.

9.1.3. Drains and vents are to be provided at lowest and highest points of every system

to drain out/remove the non-condensable gases from the system during hydro

test, startup conditions etc.

9.1.4. Only steam pipes will have a minimum drainage slope of 1:100 and slope will

preferably be in the direction of flow. However at hot condition, minimum slope of

1:200 shall be maintained.

9.1.5. Exhaust line from turbine driven feed water pump, will be routed as directly as

possible to the condenser.

9.1.6. Valve stem will be installed vertically, but for handling purpose it can be installedand turned horizontal up to 90 Deg., if required.

9.1.7. As far as possible all process pipes will run above ground on pipe supports.

Wherever the pipes have to cross roads or other facility, this will be through

proper pipe trench or pipe rack.

9.1.8. No Valves or any components will be installed on the pipe stretch running in the

trench, until and unless it is unavoidable. Under such unavoidable circumstances,

the valve if placed will have the hand wheel projected out of the trench for easy

INDICATE

DOC.NO

IT SHOULD BE 7.5 M. Refer clause 5.4.6 of bid

specification.

It is Turbine exhaust not the feed pump exhaust.


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operation / maintenance and all such components will be indicated in the

respective drawing.

9.1.9. All the fuel oil lines in the plant battery limit will be routed above ground

/trench/culvert.

9.1.10. In case of having a requirement of Flange & Flanged valve in the two adjacent

lines, the location of flanges / valves will be so selected that the operation &

maintenance of the same can be easily taken up.

9.1.11. Pressure Gauge installed in Pump suction/discharge lines and other similar

piping systems will be as close to the equipment as possible.9.1.12. Temperature gauge, which is installed after the Intersection of two branch lines,

has to be placed at an appropriate distance where exact reading of thoroughly

mixed fluid can be recorded.

9.1.13. Long radius elbows will be used wherever change in the direction of pipe routing

is required. However bends will be used for Main Steam & Hot Reheat piping

systems in general.

9.1.14. Pipe wall penetration sleeves will be suitable selected beyond insulation with due

consideration to insulation thickness clearances and maximum pipe movement.

9.1.15. Straight length of pipe, for flow measuring devices will satisfy ASME

recommendations and/ or manufacturer recommendations.

9.1.16. All motor operated valves, control valves and frequently operated manual valves

will be accessible from or near a floor, above or below or from a platform. Manual

valves, if required will be facilitated with extended stem.

9.1.17. All valves operators like positioners, limit switches etc. will be accessible for

maintenance, calibration etc.

9.1.18. Steam & Feed Water Lines with conditions listed below fall in the scope of IBR.

9.1.18.1. Lines having design pressure (max. working pressure) above 3.5 Kg/cm2 (g).9.1.18.2. Line sizes above 10" inside diameter having design pressure 1.0 Kg/cm2 (g) &

above.

9.1.18.3. Lines with design pressure less than 1.0 Kg/cm2 (g) are excluded.

9.1.18.4. Users of steam like steam tracing lines, jacket of the steam jacketed lines and

Steam heating coil within the equipment are excluded from IBR scope.

9.1.18.5. Boiler feed water lines to steam generator, flash drum shall be under purview of

IBR.

ALL THE LINES GOT CONNECTED TBOILER ARE UNDER IBR PERVIEW.


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9.1.18.6. For Alloy Steel and carbon steel pipes and fittings conforming to ASTM A335

Gr.P11,P22 and P91, A106 Gr.B & C respectively, the manufacturer shall certify

the following values in tabulated form as required at various working metal

temperature in IBR, Form III A.

Et = 0.2 % Proof Stress

Sc = 0.01 Creep Rate in 100,000 hours - average values (Min values 20% lower)

Sr = Stress to rupture in 100,000 hours- average values (Min values 20% lower)

These certified values shall be furnished along with the offer.

For A106 Gr. B & C pipes, only Etvalues need to be furnished.

a) Ladle analysis: Carbon less than / equal to 0.25% and sulphur less than / equal

to 0.05% for all pipes under IBR.

9.1.19. Drip legs shall be provided at the lowest point in the steam system to remove

condensate.

9.1.20. All stubs welded to the pipe including welded Thermo-wells & instrument source

tapings shall be installed on the pipe prior to stress relieving.

9.1.21. Installation of Control Valve

9.1.21.1. Control valves will be placed on the horizontal run of pipe with suitable access.

9.1.21.2. Valve stem will be vertically upright in general.

9.1.21.3. Enough space will be provided between the valve and the ground/platform for

supporting and maintenance.

9.1.21.4. While installing control valve on pipe passing overhead/ceiling, the pipe routing will

be turned down to a lower elevation, and the control valve will be installed just

above the ground / floor level. Valve Stem will be vertically upright and there will

be enough space between valve & ground level for maintenance purpose.

9.1.21.5. If reducers are to be installed in the upstream and downstream of Control valve

under such circumstances the reducers will be welded to the control valve so as to

minimize the spool, unless valve operators interfere with one another.

9.1.21.6. Control valves which supply water to the Condensate Makeup System and

Condenser Hot Well, will be installed as close to the Condenser as possible, so as

to avoid / minimize the effect of water hammering and flashing in the downstream

pipeline.

9.1.22. Installing of Isolation valve and Check Valve


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Rev:A

Date:01 MAY 2013


9.1.22.1. Remote manually operated valves in the pipe system, if required will be oriented,

taking into account location and support of the operator. Chain wheel operation

will be the last option for the maintenance of valve i.e. a valve which is normally

open at all times. If a chain wheel operator is necessary, the valve will be located

so that the chain may be fastened against the building column and avoiding the

obstruction to passage.

9.1.22.2. Stem of all manual valves should be in vertically upright position, unless other

orientations eliminate the need for remote operating devices or platforms, without

degrading the performance of valve.

9.1.22.3. Swing and either spring loaded or non-spring loaded lift check valves will be used

for general service.

9.1.22.4. Swing or non-spring loaded lift check valve will be located in the horizontal

position and non slam and spring loaded lift check valves in either horizontal or

vertical position. Non-slam check valves will be located in the riser originating at

the pump discharge.

9.1.23. Installing Position of Safety & Relief Valve

9.1.23.1. Unless otherwise stated the safety relief valves shall be installed as per

Manufacturers recommendation

9.1.23.2. Safety valves will be located as close as possible to the equipment.

9.1.23.3. Safety valve will be located at a minimum of 10D (ID) downstream from tangent

point of any bend or elbow or extension nozzle of main run.

9.1.23.4. When two or more SRVs are to be located adjacent to one another along the

steam header pipe, the distance between centerlines of any two valves shall be

greater than or equal to 1.5 times the sum of the inlet internal diameters of the two

adjacent valves Spacing between three or more SRVs should be unequal.

9.1.23.5. Safety valve vents will run straight, separately and as short as possible.

9.1.23.6. Keep the distance between the centre line of the safety valve and the vertical

centerline of the discharge elbow to a minimum.

9.1.23.7. Each valve discharge piping will be oriented parallel to the axial centerline of the

pipe it is protecting.

9.1.23.8. Slip joint in the outlet of SRVs shall be used as & when required.

10.0 PIPE SUPPORT DESIGN STANDARD

ec a ves o greater or equa to s ahave dash pot arrangement.


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NIGAM LTD.




PIPING SYSTEM

Rev:A

Date:01 MAY 2013


10.1. Piping will be supported & anchored in an appropriate manner in accordance with

the provisions of ASME B31.1 or the standard to which the piping is designed.

10.2. Supporting straps around flanges or welded joints will not be accepted.

10.3. Particular attention will be paid to sliding surfaces in guides and sliding supports

and to springs employed in variable & constant load supports. Stainless Steel and

low friction plastic may be provided for important sliding surfaces.

10.4. Pipe support material should not interfere / obstruct the equipment or with any

structures and should have adequate space for maintenance.

10.5. Support material has to be appropriately selected for the particular type of pipe.10.6. Special attention has to be given while designing supports for pipes operating at

high temperatures

10.7. The maximum distance between two consecutive supports will generally be as

per ASME B31.1, Table 121.5.

10.8. The sum of the longitudinal stresses, SL due to pressure, weight & other

sustained loads shall not exceed the basic material allowable stress in the hot

condition.

10.9. If at any locations, the supports are to be taken from concrete structure / slab, the

location of the insert plates are to be defined to civil for incorporation of same in

their drawings.

10.10. In case of vertically hanging type support, hanger rod vertical swing angle should

not exceed 4.

10.11. For pipes having design temperature above 150 Deg.C, bottom supports shall be

avoided as far as possible and hanger type supports shall only be used.

However, where bottom support cannot be avoided, the same shall be provided

with suitable shoes along with balls/rollers/rockers to minimize frictional

resistance against thermal movements. The material of shoe as well as theball/rockers/rollers shall be suitable for the design temperature of the supported

pipe and shall be of sufficient hardness so as to permit a reasonably long life

keeping its roundness and maintaining a low friction factor. Where a constant

load type support is required, the bottom support shall also be of constant load

type.

11.0 GENERAL REQUIREMENTS FOR STRESS & FLEXIBILITY ANALYSIS

hall bemerged with

ection 5.0


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NIGAM LTD.




PIPING SYSTEM

Rev:A

Date:01 MAY 2013


General requirements for stress & flexibility analysis for all the piping systems shall

be inline with the design requirements specified in Design Criteria Document for

DESIGN CRITERIA DOCUMENT FOR PIPING STRESS ANALYSIS

12.0 REFERENCES

12.1. ASME B31.1 Power Piping.

12.2. Design Criteria Document for Thermal Insulation- L764000-CV03-00-ZEN-130004

12.3. Design Criteria Document for Piping Stress Analysis-L764000-CV03-00-ZEN-

130003.

Documents

Piping Design Criteria