Codes & standards of practice for thermal power plant equipments

Sl No.	Particular	Code/standards of practice
A	Boilers
1	Code of practice for Constructions in steel	IS 800
2	Rules for construction of power boilers	ASME Section I
3	IBR materials	ASME BPVC SEC-II
4	Construction of heating boilers	ASME BPVC SEC-IV
5	Non-destructive testing	ASME BPVC SEC-V
6	Code of practice for design loads for buildings structures.	IS 875
7	Criteria for Earthquake Resistant – Design of Structures	IS 1893
8	Code for unfired pressure vessels	IS 2825
9	Indian Boiler Regulation	IBR 1950
10	Welding and Brazing Qualifications	ASME Section IX
11	Power piping	ASME B 31.1
12	Construction of pressure vessels	ASME BPVC SEC-VIII
13	Acceptance test for steam generator	DIN 1942
14	APH performance test code	ASME PTC 4.3
15	Boiler performance test	ASME PTC 4.1
16	Deaerator performance test code	ASMEPTC 12.3
17	Specification for wrought aluminium and aluminium alloys sheet and strip (For General Engineering Purpose)	IS 737
18	Design & construction of RCC chimney	IS 4998-1992
B	REFRACTORY & INSULATION
1	Moderate heat duty fire clay refractories Group-A	IS:6
2	High heat duty fire clay refractories	IS:8
3	Insulating bricks	IS : 2042
4	Method of determination of thermal conductivity of thermal insulation material	IS3346
5	Code of practice for storage and handling of insulating materials	IS10556
6	Industrial application and finishing of thermal insulting materials at temperatures above 80 deg C and up to 700 Deg. C	IS14164
7	Specification for Bonded Mineral Wool	IS: 8183
8	Hexagonal wire netting for general purpose	IS 2150
9	Methods of test for mineral Wool Thermal Insulation Material	IS3144
C	STEAM TURBINE & AUXILARIES
1	Duplex oil coolers design	ASME SEC-VIII, TEMA “C”
2	Steam ejector design	ASME SEC-VIII, DIV-1,TEMA “C”
3	Steam condenser design	HEI-IX EDITION
4	Thermal acceptance test for steam turbine	DIN 1943
5	Steam turbine performance test	ASME PTC 6
6	Surface condenser performance test codes	ASME PTC 12.2
7	Overall plant performance	ASMEPTC 46
D	WTP
1	Chemical dosing tanks design	BS 4994 1987
2	DM water storage  tank	IS 803
3	WTP vessels design	IS 2825
E	PUMPS ,COMPRESORS & FANS
1	Centrifugal pumps performance test code	ASME PTC 8.2
2	Design of Pumping Systems that use Centrifugal Pumps	PIP RECP001
3	Design of ASME B73.1 and General Purpose pump Base plates	PIP RESP002
4	Seal Flush and Lubrication Guidelines for Centrifugal Pumps	PIP REEP001
5	Compressors  performance test codes	ASMEPTC 10
6	Guide for selection installation and maintenance of air Compressor up to 10 bars.	IS 6206
7	Code of practice for testing of positive air displacement type Compressors and exhausters	IS 5456
8	Air receivers for compressed air installation	IS: 7938
9	Fans  performance test codes	ASMEPTC 11
F	BELT CONVEYORS
1	Specification for troughed belt conveyors	IS: 1891
2	Code of practice for conveyor safety	IS: 4776
3	Specification for pulleys for belt conveyors	IS: 7403
4	Specification for idlers for belt conveyors	IS8598
G	MAINTENANCE
1	Bars and Keyways for Flexible couplings	AGMA 9002
2	Pipe Threads, General Purpose	ASME B1.20.1
3	Cast Iron Pipe Flanges and Flanged Fittings	ASME B16.1
4	Pipe flanges and flanged fittings	ASME B 16.5
5	Roller Bearings –Dynamic Load Ratings and Rating Life – Part 1 : Calculation Methods.	ASME STD 9
6	Specification  for  Forgings,  Carbon  steel,  for  Piping Components	ASTM  A105
7	Specification for Seamless Carbon Steel Pipe for High Temperature Service.	ASTM A106
H	ELECTRICAL & INSTRUMENTATION
1	Design of Power transformer	IS 2026
2	Code of practice for earthing.	IS: 3043 - 1987
3	Guide for safety procedures and practices in electrical work: General.	IS: 5216(Part-1)-1982
4	General requirements for switchgear and control gear for voltages not exceeding 1000 V AC or 1200 V DC	IS:4237 - 1983
5	Air break switches, air break dis-connectors, air-break switch disconnectors and fuse-combination units for voltages not exceeding 1000 V AC or 1200 DC : General requirements	IS:4064(Part-1)-1978
6	Miniature air break circuit breakers for voltages not exceeding 1000 volt	IS: 8828 - 1978
7	Residua current operated circuit breakers.	IS:12640 - 1988
8	Contactors for voltages not exceeding 1000 V AC or 1200 V DC.	IS:2959 - 1985
9	PVC Insulated cables for working voltages up to and including 1100 V.	IS:694 - 1990

 

Interview questions & answers on Boiler Alkali Boilout

 

1-Why do you carry out an Alkali boil out of a Boiler?

Alkali Boil out is done for

• To remove oil & grease
• To remove rust, scale  

2-When you will carry out alkali boil out on Boilers?

Alkali boil out is carried out for new boilers or Boiler where maintenance works like Bank tubes replacement, SH coils replacement are done.

3-List down the chemicals required for Alkali boil out of a Boiler

• Hydrous Tri-Sodium Phosphate (Na3PO4.12 H2O)
• Anhydrous Di-Sodium Phosphate (Na2HPO4)
• Wetting agent (Surfactant / Detergent)

4-What is the ratio of selection of Disodium phosphate & detergents for alkali boil out

Quantity of Anhydrous Di-Sodium Phosphate (Na2HPO4) = Hydrous Tri-Sodium Phosphate X 20-25%

Quantity of Wetting agent (Surfactant / Detergent) = Hydrous Tri-Sodium Phosphate X 5-6%

 5-What are the two conditions for newly erected boilers for carrying out Alkali Boil out?

Boiler’s Hydraulic test should be completed

Boilers’ refractory dry out procedure should be completed

6-What are the pre-checks to be carried out before carrying out Alkali Boil out?

Pre-checks:

1-Ensure Boiler erection work is completed & its all auxiliaries trials taken & found okay

2-Ensure Fuel handling & fuel feeding system is okay & trial is being taken with respect to Mechanical, Electrical & instrumentation

3-Ensure Deaerator & related pumps are ready & can be taken into line readily

4-Ensure DM water is available

5-Ensure sufficient quantity of fuel is available at yard or at bunker

6-Ensure all equipment are hooked up to DCS

7-Ensure sufficient local PG & TG are avail be at Boilers

8-Ensure competent team is available

9-Ensure chemicals required for boil out & testing are available

10-Ensure all sample points are identified & competent person/team is there to collect the sample as per per decided frequency.

11-Ensure chemical dosing system is available

12-Ensure drain lines/flushing lines sample/sample lines are extended to safe location

7-Write down the procedure of Alkali Boil out in detail?

Procedure:

1. Maintain the drum level just 6” -8”below the drum man hole door
2. Initially, collect the required chemicals at drum platform as per dosage quantity decided
3. Dissolve all the chemicals into water & then pour the chemical mixture into the drum from man hole
4. After pouring, close the manhole door & raise the drum level up to normal operating level or just 2” below the normal operating level.
5. Light up the boiler as per Boiler start-up & light up SOP
6. Raise the Boiler pressure & temperature as per Boiler pressurizing curve
7. Ensure thermal expansion of Boiler is happening & is uniform at all the headers
8. Give IBD when drum pressure reaches 5 to 6 kg/cm2
9. Raise the boiler pressure slowly & bring it to 50% of normal operating pressure or 40 kg/cm2, whichever is lower.
10. Boil the chemical at same pressure for 10-12 hours.
11. During boil out keep crack open CBD valve to avoid line & valve chocking
12. During boil out period, operate the IBD for 15-20 second at every one hour & ensure water is replenished every time you give blow down.
13. Note: Do not take drum level gauge glass into line during alkali boil out, keep one set of drum level transmitter on line
14. At the end of the boiling period, collect the sample of IBD sample & test for oil traces. If the oil level is not in the allowable limit, then again add the chemicals & start boiling until the sample oil parameter meets the desired value.
15. In order to decide the boil out is completed, the oil traces of 3 samples collected at 15 minute span should be < 5 ppm (Ensure consistency in results)
16. After boil out, stop the boil out procedure & Box up the boiler & allow to cool the Boiler.
17. During cooling period operate the blow down valves of drum & water wall panel bottom headers at least 2-3 times throughout the cooling period. And ensure normal water level in drum every time.
18. Open the drum & super heater vents at pressure 2 kg/cm2
19. Start rinsing the boiler, until the drain water pH equals to feed water pH
20. After rinsing, drain the boiler completely & at the same time start to make up the boiler with DM water until the drain water pH becomes equal to feed water pH
21. For flushing the super heater coils, raise the boiler pressure up to 40 kg/cm2 by Boiler feed pump (Hydraulic test of boiler at 40 kg/cm2 pressure) & then flush the water with from drain valve present before MSSV.This rinsing procedure is continued until the drain water pH becomes the makeup feed water
22. Open the drum manhole doors & clean the internal surfaces with wire brushes
23. Cut the stub ends/inspection caps of bottom headers & put wooden block in cut caps tightly.
24. Again fill the boiler with feed water up to normal operating level & remove the wooden blocks one by one to remove the debris, scale or any other foreign materials from headers.
25. Repeat above procedure for all bottom headers, then inspect all bottom headers for any debris, scale & foreign materials.
26. After ensuring, everything is okay, then inspection caps should be welded subsequently radiography & hydraulic test should be done.

Read Boiler refractory dry out procedure

Questions & Answers on steam blowing

Boiler feed pumps start up & shutdown procedure

                    

                 Start-up Pre-check lists

• Ensure Boiler feed pump is not in permit for maintenance works
• Ensure all the maintenance activities on pumps are completed
• Ensure equipment are normalized from electrical & mechanical side
• Ensure Boiler feed pump is free from obstacles
• Ensure enough lighting or illumination is available there
• Ensure pump coupling is well guarded by robust coupling guard
• Ensure Pumps local field instruments like pressure gauges, switches, vibration sensors, DP gauges are healthy
• Ensure coupling is free to rotate

Starting procedure:

Start permissive (interlocks)

• Ensure deaerator level is normal
• Ensure feed pumps suction valves is open
• Ensure cooling water line & outlet valves to bearings & mechanical seals are open and also water is circulating through the lines.
• Ensure bearing temperatures are normal
• Ensure bearing vibration showing DCS is zero
• Ensure there is no alarm exists for strainer DP (differential pressure)
• Ensure suction pressure is normal
• Ensure discharge valve of the pump is closed
• Ensure minimum recirculation valve or ARC valve is in open condition
• Ensure balance leak off line valve to deaerator is open (In some valves are not provided to balance leak off line)

Start-up sequence

• Take clearance from electrical & field person to start the pump
• After getting the clearance from both the team, start the pump by giving minimum set point 80% if it is VFD driven.
• Once the pump started, ensure pump will attain minimum 40% RPM in just 10 seconds (in case of journal bearing pumps).For non-journal bearing pumps speed ramp up time is not recommended specifically.
• During speed ramp up check bearing vibrations & temperatures are normal.
• Ensure pressure in the discharge pressure gauge is increasing slowly & has reached rated pressure at rated speed.
• Then check the vibration, bearing temperatures & sound from pump.
• Check & ensure the correctness of balance leak off line pressure
• Wait for stabilization of the pump, once the pump attained rated parameters, check the motor current, temperature & vibrations & ensure they are within permissive limit.

Also recheck pump bearings vibration, temperatures & any abnormal sound from pump.

Pump normal shutdown procedure

• For VFD driven pumps reduce the pump speed to 80% (for start delta driven pumps speed cannot be reduced)
• Close the pump’s discharge valve
• Then stop the pump

Do not’s for Boiler feed pumps

• Do not rotate the pump in reverse direction, reverse direction leads the seize of pump
• Don not run the pump if its suction water temperature is more than design/required
• Do not operate the pump at less than 80<% load for long time to avoid damage to the bearings
• Do not close the auto recirculation line valve
• Do not close the balance leak off line valve (if provided)
• Do not stop the pump with discharge valve open
• Do not throttle the suction valve of the pump at lower load, can throttle discharge valve

 

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powerplant & calculations