Boiler Hydro Test

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HYDROSTATIC TEST

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1.0 GENERAL

After installation of all pressure parts, the unit is subjected to the required initial Hydrostatic Pressure tests. The exact Hydrostatic test procedure to be followed depends on local job site conditions. The procedure outlined below is general in nature.

2.0 LIMITS OF HYDROSTATIC TEST

2.1 Main boiler with water circulation system (from feed check valve inlet to drum) with SH saturated connection tubes blanked). Ref. Fig. 1.

2.2 SH SYSTEM

From drum (with SH saturated connection tubes blanked) to MS stop valve. (Ref. Fig. 2)

2.3 RH SYSTEM

RH inlet header to RH -Outlet header. (Suitably blanking the RH inlet and outlet headers with the isolating devices if provided or by means of blank langes) Ref. Fig.3.

3.0 TEST PROCEDURE

The Unit shall be hydro-tested for conformation to IBR Code requirement in two areas (i) Primary Circuitary, Drums, Economisers, Waterwalls, Superheaters at one and half times the design pressure and (ii) Reheaters at one and half times the design pressure or a t minimum 70 kg/sq.cm.(g)

NOTE:

It is preferable to do the hydro test at one stroke at the stipulated hydro test pressure indicated in the pressure part arrangement drawing. If it is not possible to accomplish this the hydro test may be conducted twice, once for drainable portion and another including non drainable portion at the stipulated hydro test pressure (official test 1 1/2times the design pressure). In case site would prefer to conduct a hydro test at a lower pressure prior to official hydro test the same may be done once at the design pressure. For the site hydrostatic pressure respective BOILER pressure part arrangement drawing has to be referred.

4.0 PRESSURE GAUGES

During testing, atleast three properly calibrated pressure gauges are to be located one at drum level, one at operating floor level and one near pressure raising pump.

The indicator of the pressure gauges selected should have atleast 6" dial with dials graduated over a range of double the intended maximum test procedure, but in no case the range be less than 11/2

times that pressure. The pressure gauges should be calibrated as per FQAF-1 5 of FQA systems manual.

For typical “Test Pressure Gauge Range” Refer Table 1 - “TYPICAL HYD. TEST PROCEDURE AND TEST PRESSURE GAUGE RANGES”.

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5.0 PREPARATIONS FOR THE TEST

Prior to Hydrostatic testing, the following items should be inspected.

i. All necessary welds completed, x-rayed and stress relieved.

ii. All necessary valves including drain valves installed and closed.

iii. All safety valves installed and hydrostatic plugs, should be assembled before commencing the test.

iv. All debris shall be removed manually from all pressure parts including headers and drums.

v. The drain valve and test valve in the official calibrated pressure gauge sensing line must be open.

vi. All manhole closure plates (except drum manhole) and header handhole caps should be closed and bolted or welded tight.

vii. The isolating valves provided in all the other branching systems like SB System tapping, SH spray connections, Pr.gauges etc.,have to be closed tightly.

viii. All vents necess ary to prevent air entrapment during filling operation such as superheater link Vents, economiser link vents, drum vents etc., shall be kept open.

ix. When valves are in TANDEM (Double valved) both valves must be closed during the hydrotest.

x. In 500 MW Units, if the boiler circulating pumps are of the sub-merged motor or canned motor type, installation of the rotating elements should be defered until the hydrostatic test of the unit has been completed. The pump casings must be blanked off during the test.

xi. Joint Inspection protocol prior to Hydrostatic Testing of Boiler prepared by FQA also to be duly filled up. (FQA-01-00-00-L-17 (a))

6.0 WATER QUALITY

6.1 It is the responsibility of the customer to provide properly treated water, as specified below at ambient temperature but in no case less than 70oF(21oC)

NOTE: The temperature limitation for hydrostatic testing is 70oF or 21oC. The important point is that the hydrostatic pressure should not be applied when the water is less than this limit.It does not make any difference if the water is heated externally or once it has been pumped in to the boiler.

The easiest way to achieve and maintain proper hydrostatic temperature in cold weather is with an externa l steam supply. The full water is heated with a direct contact heater and the temperature is maintained by using the steam coil air heater. For a new project where no steam is available. It is advised to consider electric heaters or fuel fired space heaters.

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The best method of maintaining non-drainable portion above freezing temperature is by use of steam air heater. M/s.CE too had good success with fuel fired space heaters. For this the unit should be completely insulated and lagged.

During testing, the temperature of water should in no case exceed 490o C.

6.2 It is recommended to use demineralised or cop ensate quality water of specified purity for both drainable and non-drainable portions (REFER NOTE BELOW).

6.3 For Quality of Treated water, Boiler water and Feed water, Refer Table -2.

6.4 During initial hydraulic test, one may expect some leaks requiring draining, repairing and refilling. So it will be in order to use, initially filtered water free from chlorine for drainable portions only.

It is necessary that the filtered water is clear, free from suspended and colloidal impurities with a restriction of the total dissolved contents to 100 ppm. However, filtered water should not be used for Lay Up work even for drainable portions.

6.5 For non-drainable portions only demineralised or condensate quality water should be used.

6.6 For superheater and reheater (drainable and non-drainable sections) treated condensate or demineralised water can also be used. The treatment shall include 10 ppm arnmonia and 200 ppm hydrazine. This treated water will have a pH value of approximately 10.

6.7 The use of fill water treated with solid chemicals should be avoided. Deposits of solid materials in superheaters and reheaters are detrimental from heat transfer and corrosion point of view. Super-heaters and reheaters containing stainless steel tubing are particularly vulnerable to stress corrosion cracking in the presence of chemicals as caustics and chlorides.

In the case of 500 MW. Unit sets, the boiler water circulation pumps are to be filled with condensate or demineralised water before putting water into the boiler for testing boiler with boiler circulating water pumps.

NOTE:

Demineralised or condensate quality water is defined as containing no more than ppm identifiable solids and essentially a zero concentration (or lowest detectable level) of organic materials.

6.8 After chemical cleaning, steam blowing and lay up of the units, if situation warrants to do hydraulic testing of the pressure parts usage of treated DMwater or treated condensate is only recommended. For quality of treated DM water REFER TABLE-2.

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7.0 AIR TESTING THE PRESSURE PARTS

7.1 Before filling the boiler with water an air tightness test is to be performed to detect leakages due to valve left in open position, x-ray plug forgotten, any cuts or gauges etc., not observed by visual inspection. This will reduce the DM water consumption, as well as time.

7.2 The air should be filtered and free from oil and dust prior to entering the unit.

7.3 The boiler is to be pressurised not more than 2 kg/sq.cm.(g).

7.4 Before admitting air, close all the manhole doors including drum manhole,handhole plates, isolating valves in drain lines, branching lines and vent lines including the vent valves in SH link, eco. link and drum link, Drain and Test Valves in official pressure gauge etc.,

7.5 After completing the air tightness testing keep the drum man hole, vent valves in SH links, etc., link and drum link and drain and test valves in official pressure gauge in open position.

8.0 FILLING PUMP AND PRESSURISING PUMP

WITH

TEMPORARY CONNECTED PIPELINES

8.1 i. Check for correct direction of rotation.

ii. Open air vent of the pump during start-up.

iii. Check motor current at no load as well as at full load conditions. Check whether a correct fuse is introduced in the circuit to avoid damages to the motor.

iv. Before starting the filling pump, the delivery valve to be closed and the suction valve kept opened. Then open delivery valve gradually for filling. Before stopping the pump,delivery valve should be closed.

v. Before starting the pressurising pump it should be ensured that the delivery valve is kept open.

8.2 Connected pipe lines (temporary)

i. Should all be welded.

ii. Delivery line of pressurising pump should be of high pressure seamless pipe to withstand the required test pressure.

iii. Mixing tank should be of required capacity.

iv. Flow regulating valves, drain valves, overflow lines should be provided with the mixing tank.

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9.0 FILLING THE SYSTEMS

9.1 i. The boiler water circulation system is filled through filling lines connected to the boiler drain head or and eco. filling lines (in higher capacity boilers). If the unit is filled through the economiser recirculating line valve should be in the vide open position.

ii. As the water raises upto the drum manholes, the later shall be tightly closed and boiler filling shall be completed.

iii. Then checking of the filling shall be done through the vents.

iv. Close and open the vent valves several times in order to allow the entrapped air to vent out.

v. Stop the fill pump and let water lay for some hours.

9.2 In no case water entry into superheater should be permitted through the drum. This is to prevent carry over of suspended impurities into the superheater.

9.3 Fill the superheater and reheater with the quality of water indicated under point 6.5 per SH drain header and R1 + drain header respectively until all the elements are filled and the water overflows through the vent valves.

CAUTION : 1. If it is decided to do the hydraulic pretest of boiler water circulating system and superheaters at the same time, treated DM water / condensate only should be used. The SH connection tubes in the drum need not be plugged in this case. Take care of point No. 9.2. Also refer Fig. 4.

2. The water temperature during hydrostatic test should be ambient temperature but in no case less than 21oC.

10.0 PRESSURISING THE SYSTEMS

10.1 The pressure shall be raised up by means of test pumps.

10.2 The pressure shall be increased at a rate of not more than 10 kg/sq.cm.(g) per minute upto approximately 80% of the test procedure and by 1 to 2 kg/sq.cm.(g) per minute beyond that value.

10.3 Raise the pressure to the hydrostatic test pressure. The pressure shall be under proper control at all times. The pump operator and the responsible person watching the official test gauge must have radio-telephonic contact. When the test pressure is reached the responsible person watching the test gauge shall give orders to stop the test pumps immediately and to cut off the electric connections.

10.4 The test pressure is held for about half an hour. During the holding time the test gauge pressure reading shall not drop noticeably.

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11.0 HYDROSTATIC TESTING

11.1 The hydraulic test pressure reading will be taken from the official pressure gauge located at the highest point in the presence of the Inspector.

11.2 After the hydraulic test pressure has been noted and agreed by the Inspector, the hydrostatic test pressure is then reduced to not less than the maximum allowable working pressure and the whole pressure parts checks will be carried out.

11.3 If leaks are found, it will be necessary to release the pressure and drain these portions. Make the repairs and refill the unit as mentioned above and repeat hydrostatic test.

11.4 Details of the leaks noticed during Hydraulic Tests are to be furnished as given below for better understanding:

a. Exact location of leak(s) component circuit, Elevation, materials etc.,

b. Description of leak(s) such as straight tube elbow, shop or field weld, torchcut, where alugwas removed and attachment weld etc.,

c. Magnitude of leaks-weeping/sweating, leaks, burn through, longitudinal crack.

12.0 DEPRESSURISATION OF THE PRESSURE PARTS

12.1 The pressure parts shall be depressurised at a depressurisation rate of 1 kg/cm. sq/ minute.

12.2 While releasing the pressure, the vents should be opened when the system pressure reaches 1 kg/sq.cm to prevent creation of vacuum in the system.

13.0 INSPECTION OF THE BOILER PRESSURE PARTS

AFTER TESTING

13.1 After completion of the hydraulic test, the inspector shall carefully examinethe boiler inside and outside and satisfy himself that it has satisfactory with-stood the test.

13.2 To enable the inside inspection of the boiler the interior has to be equipped with suitable scaf folding for inspecting the elements, walls, tubes and welds.

14.0 PROCEEDINGS TO PREVENT ACCIDENTS AND

ENDANGERING OF PERSONS DURING PRESSURE TEST

14.1 Due to the fact that during the pressure test the boiler and boiler house area are under an increased risk of danger, special safety precautions have to be taken to prevent accidents. These arrangements are made by the erection and commissioning services according to the instructions of the site management.

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14.2 During the period of raising, holding and releasing the test pressure, the entry to the boiler house is prohibited for all persons not participating in the pressure test, Works at the pressure parts or in the direct neighbourhood are not permitted.

14.3 All companies working on the site must be notified of the pressure test in writing. No claim based on the restriction or stopping of work will be accepted.

15.0 HYDROSTATIC TEST REPORT

After completion of the hydrostatic test a written report as per the IBR format shall be issued and signed by the Inspection Authority.

16.0 PRESERVATION OF BOILER AFTER HYDROSTATIC TEST

16.1 There is generally sometime delay between hydrostatic test and further initial boiling out and chemical cleaning of the unit. Hence, the unit should be kept under preservation for protecting the internal surfaces from oxidation.

16.2 Remove all the hydrostatic gags from the safety valves and hyd. test pump with temporary pipes connections prior to filling the unit.

16.3 Fill the unit with hydrazine and Ammonia treated DM water containing 300 ppm hydrazine and 10 ppm Ammonia with a pH value of 10.0 to 10.5 till it overflows at vents.

16.4 The unit should be kept Under nitrogen cover with a pressure of 0.5 kg/sq.cm. In the absence of nitrogen capping facility the unit should be pressurised with the aid of a fill pump to 5 kg/sq.cm.

16.5 Samples can be collected pe riodically say once a week or fortnight, depending on the pressure holding worthiness of the system, tested for pH and hydrazine content.

16.6 In case the sample-water does not meet the criteria for lay up water, the conditioning system shall be operated as to restore the required composition.

16.7 No welding shall be carried out on pressure parts when the system is under preservation or the system is filled with water.

16.8 If there is a chance of freezing, the water in the drainable circuits can be displaced by nitrogen and the unit can be laid up under nitrogen pressure. Temporary heating equipment should be provided to keep the non-drainable superheater (reheater) elements above freezing temperature.

16.9 The reheater should be laid up under nitrogen pressure with the reheater isolating devices closed or with the blank flanges.

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TABLE - 1

TYPICAL HYD. TEST PRESSURE AND TEST PRESSURE

GAUGE RANGE

2. PR. OF AIR FOR TESTING PR. PARTS 2 KG/SQ.CM. (G) PR.AFTER

REGULATOR

RANGE OF PR. GAUGE 0-4 KG/SQ.CM.

TABLE - 2

QUALITY OF WATER

1. DEMINERALISED WATER (SPECIFICATION)

1. pH at 25o C : 7 ± 0.2

2. Electrical Conductivity at 25o C : Less than 0.2 Michromhd/cm

3. Total Hardness

(Ca + Mg) PPM CaCO ₃ : Nil

4. Total Silica : Less than 0.02

5. SiO₂PPM : Less than 0.01 IS preferable

6. Chloride PPM as NaCl : Nil

7. Sodium PPM as Na : Less than 0.003

8. Organic Matter : Should be free in any cast it should Mgm KMnO4 /Litre not exceed 0.2 PPM on an average.

9. General Appearance : Clear: Free from odour, colour and Haziness. No Glittering to tyndal effect.

2. QUALITY OF TREATED DM WATER OR TREATED CONDENSATE

The DM water or Condensate treated with 10 PPM ammonia and 200 PPM hydrazine to have a pH value of approximately 10.

BOILERS ASSOCIATED WITH THE MACHINES BOILERS & SH HYD. TEST PR KG/SQ.CM (G) TEST PR. GAUGE RANGE KG/SQ.CM RH HYD TEST PRESSURE KG/SQ.CM. (G) TEST PR. GAUGE RANGE KG/SQ.CM. 120 MW 237.0 0-400 70.0 0-150 210 MW (LP) 237.3 0-400 70.0 0-150 210 MW (HP) 263.7 0-400 70.0 0-150 500 MW 306.0 0-600 76.5 0-150

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3. QUALITY OF BOILER WATER

Drum operating pressure 126-165 166-180 181-205 kg/sq.cm.(g)

Total Dissolved Solids - max (ppm) 50 25 15

Specific Electrical Conductivity

at 25oC (s/cm) 100 50 30

Phosphate Residual (ppm) 5-10 5-10 2-6

pH at 25o C 9.1-9.8 9.1-9.8 9.1-9.6

Silica (max.) (ppm) To be controlled on the basis of silica inboiler water and drum pressure relationship (Fig.1) to maintain less than 0.02 ppm in the steam leaving the drum 0.1

4. QUALITY OF FEED WATER

( Drum operating pressure 101 kg/cm.sq.(g) and above )

Hardness Nil

pH at 25oC (copper alloy pre boiler system) 8.8 to 9.2

pH at 25oC (copper free pre boiler system) 9. 0 to 9.4

Oxygen maximum ppm 0.007

Total Iron (Tax) ppm 0.01

Total Copper (max) ppm 0.005

Total CO2 Nil

Total Silica (max) ppm 0.02

Specific electrical conductivity at 25o C measured after cation exchanger in the + from

and after CO2 removal (max) m s/cm 0.3

Hydrazine - residual ppm 0.01 to 0.02

Permanganate Consumption Nil

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TABLE - 3

WATER VOLUME (TYPICAL FOR VARIOUS CAPACITY OF UNITS)

SYSTEM 120 MW M3 200/21O MW (LP Unit) M3 21OMW (HP Unit)M3 500MW M3 Generating Surfaces 70.4 126.5 130.0 160.0 Drum 21.1(Full) 37.0(Full) 35.0(Full) 60.0(Full) Economiser 30.0 30.0 25.0 135.0 Superheater

(Drum to SHO Header)

47.0 95.0 95.0 145.0

Reheater 15.0 48.0 50.0 220.0

Total 183.5 336.5 335.0 720.0

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FIGURE-2 HYD. TEST LIMIT SUPERHEATER SYSTEM

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FIG-4 HYDROSTATIC TEST LIMIT-BOILER WATER CIRCULATION

SYSTEM

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FIG-5 SILICA IN BOILER WATER RELATIONSHIP WITH DRUM

PRESSURE

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Sl. Equipment Frquency Qty

No. Description 10C HP BP BP Of Change per BIr

1 Bearings-Guillotin Servogem. Lithan3 Bharat 3 Years 10 Kg

Gates HTxx MP

Grease 3

2 Filter cum LubricatoServospin 12 Shell 1 Year 5 Litrs

Tellus 15 HP

3 Actuators Castrol 2 Years 1.25

Alpha SP 68 - Litrs

of lndrol -Servomesh SP 68

Recommended Lubricants DUCTS, GATES AND DAMPERS

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Boiler Hydro Test

RECOMMENDED

HYDROSTATIC TEST

CONTENTS

1.0 GENERAL

2.0 LIMITS OF HYDROSTATIC TEST

3.0 TEST PROCEDURE

4.0 PRESSURE GAUGES

5.0 PREPARATIONS FOR THE TEST

6.0 WATER QUALITY

7.0

AIR TESTING THE PRESSURE PARTS

8.0

FILLING PUMP AND PRESSURISING PUMP

WITH

TEMPORARY CONNECTED PIPELINES

9.0

FILLING THE SYSTEMS

10.0

PRESSURISING THE SYSTEMS

11.0

HYDROSTATIC TESTING

12.0

DEPRESSURISATION OF THE PRESSURE PARTS

13.0

INSPECTION OF THE BOILER PRESSURE PARTS