HP SECTION WEEP HOLE

MONITORINGPresented By

Prem BabooSr. Manager(Prod)

National Fertilizers Ltd. India

LEAKAGE DETECTION SYSTEM

MICRO GENIE – SCAN

WEEP HOLE MONITOR

PURPOSE

WEEPHOLE MONITORING SYSTEM FOR REACTOR AND STRIPPER

IN UREA PLANT WAS INSTALLED TO DETECT THE LEAKAGE

FROM VESSELS.

EVERY WEEPHOLE HAS CORRESPONDING WEEPHOLE

CONNECTED TO IT INTERNALLY THROUGH 2 mm DEEP GROOVE.

THE SYSTEM INSTALLED IN SUCH A WAY THAT ONE WEEPHOLE

OUT OF ALL THE CONNECTED PAIRS IS CONNECTED TO

INCOMMING N2 HEADER ON ONE SIDE WHILE THE

CORRESPONDING OPPOSITE WEEPHOLES ARE GROUPED TO

MAKE 4 OR 5 HEADERS.CONNECTED TO THE BUBBLERS FOR

CONTINOUS MONITORING. THIS WILL ENSURE N2 FLOW

THROUGH ALL THE PAIRS OF CONNECTED WEEPHOLES.

Principle of working

10 K OHM

Resistance is CONNECTED TO END POINT

0 - 20 K

Resistance

measurement

ALARM

< 3 K (LEAK)

>20K (OPEN)

WEEP HOLE MONITOR

MAKE : LECTROTEK SYSTEMS (PUNE)

GENERAL DESCRIPTION : THE MICROGENIE-SCAN

IS A MICROPROCESSOR-BASED SCANNER WHICH

HAS BEEN SPECIALLY DESIGNED FOR RESISTANCE

INPUT TO MONITOR REACTOR LEAKAGE.

EASY AND VERY SIMPLE IN INSTALLATION.

LOW PRICING EQUIPMENT.

EASY IN MAINTENANCE.

OUTSTANDING FEATURES OF

MICROGENIE-SCAN

1.SOFT-TOUCH MEMBRANE KEYS FOR PROGRAMMING.

• 2. PROGRAMMING METHOD IS USER-FRIENDLY.

• 3. NON-VOLATILE MEMORY FOR SETUP DATA ( SET POINTS, PRINT INTERVAL

ETC.).

• 4. DUAL, 4-DIGIT DISPLAYS AND LED BARS FOR INFORMATION.

• 5. PROGRAM INHIBIT FACILITY PROVIDED.

• 6. RS-232-C SERIAL PORT.

• 7. MODULAR CONSTRUCTION OFFERS EASE OF MAINTENANCE.

• 8. EXCLUSIVE FEATURE – SOFTWARE CALIBRATION.

• 9. EXCLUSIVE FEATURE – UNWANTED CHANNELS CAN BE SKIPPED.

WEEP HOLE PROBE DRAWING

4mm SS316 ROD

0.5mmPTFE sleeve

CERAMIC BLOCK (spring loaded)

CONNECTION SCREW

4mm HEX nut for connection on

Cable gland

ProbeHeadss316plate below

Ceramic block

Teflon sheet below

ceramic block

1/4"NPT (F)Thread

25mm

265mm

Line-I

In line-II

310mm(10)

280mm(10)

190mm(70)

170 mm(45)

4mm

Head Cover

CONSTRUCTION

• THE INSTRUMENT IS HOUSED IN A ½ DIN EXTRUDED ALUMINIUM RACK SUITABLE FOR CONTROL ROOM MOUNTING. A SMALL BUT HIGHLY FUNCTIONAL KEYBOARD CONSISTING OF 4 MEMBRANE KEYS IS PROVIDED AS THE INSTRMENT OPERATOR INTERFACE. ELECTRICAL AND I/O TERMINATIONS ARE TO INSTRUMENT’S REAR VIA SCREW TYPE TERMINALS

• THE ELECTRONICS IS LOCATED ON MODULARLY DESIGNED BOARDS FOR EASY FIELD TROUBLE SHOOTING AND MAINTENANCE.

• ALL CARDS ARE PLUG-IN TYPE AND SEGREGATED BY THEIR FUNCTIONS VIZ.: INCLUDING

• POWER SUPPLY,CPU,A/D,DISPLAY.

SPECIFICATIONS :

• 1.PROCESS INPUT :0-20 K OHMS

• 2.DISPLAY : 2* 4-DIGIT,7 –SEGMENT LEDS,

• 3.POWER SUPPLY: 90V-270V AC,50 HZ

• 4. OVER RANGE : “OPEN” INDICATION

• 5.SET POINTS: HIGH AND LOW

• 6.RELAY OUTPUTS : ALARM RELAYS CHANGEOVER TYPE,DPDT,POTENTIAL FREE,RATING 5A,240V AC,RESISTIVE LOADS, 2 COMMON RELAY OUTPUTS.

• 7.COMMUNICATIONS : RS-232-C SERIAL PORT.

• 8.SCANNING : AUTO-MANUAL FACILITY.

• 9.DISPLAY TIME: 1-99 SEC/CHANNEL PROGRAMMABLE.

• 10.ACCURACY: (+/-) 2% FS, (+/-) 1 DIGIT.

• 11.AMBIENT TEMP.: 10-50 DEGREE CENTIGRADE .

• 12.EFFECTS OF TEMPERATURE: 0.015% PER DEGREE CENTIGRADE CHANGE, REFERRED TO 25 DEGREE CENTIGRADE.

SPECIFICATIONS

• MAINS PWR.SPL: 90-270V AC 50HZ ( 0.25 AMP FUSE )

• RS232C SERIAL PORT

• PROCESS INPUT : 0 – 20 K OHMS

• NUMBER OF CHANNELS : 96

• CONTROL O/P : HIGH / LOW ALARMS INDICATIONS

• CHANNEL SPECIFICATIONS:

CHANNEL NO. TAG NO. RANGE RELAY OUTPUTS

1- 96 0-20Kohms COMMON HIGH- LOW ALARMS FOR

ALL CHANNELS.

IDENTIFICATIONWEEP HOLES HAVING SUFFIX “ a ” AND “d ” HAVE

TOBE PROVIDED WITH CONDUCTIVITY PROBES

WHERE AS WEEP HOLES HAVING SUFFIX “ b ”

AND “ c ” HAVE TO BE LEFT OPEN TO

ATMOSPHERE.

ALL THE WEEP HOLES HAVE TO BE CHECKED BY

PASSING AIR/N2 EVERY WEEK/FORTNIGHT FOR

ANY LEAKAGE AND BLOCKAGE & THE PRESSURE

OF THE TESTING MEDIUM SHOULD NOT BE MORE

THAN 0.5 Kg/Cm2.

WEEPHOLE MONITORING POINTS

73

a

73b

72c 72a 72b72d

72f72e

71a71d 71b71c

70b70a

70d69a 69b 70c

69d 69c 68b 68a

51a 52b 52d 51d 51b 51c

61d

61b61

a61c

60b 60a60e60f

60c60d

Ch no

73

72

71

70

69

61

605959a 59b

52a 52c53c53a

53d

53b

51

52

53

68c68d68

11-SEC UREA - I

WEEP HOLE PROBES LOCATION DRAWING

38 a,b,c

F-7 FLOOR

39a

37a

37b 22c 22b

F-6

36a

36b

34a

34b

F-5

F-4

15a

15b

13a

13b

11a

11b

14a

14b

12a

12b

10a

10b

8a

8b

F-7

F-6

F-5

F-4

F-3

1b

HV-2

3a

3b

F-1

5a

5b

9a

9b

7a

7b

F-2

4a

4b

6b

6a

1 - 16 and 33 - 39 channels

39bCPP SIDE 21 SIDE

10a,b,c

38c 38b

Three probes

Three Probes

16a

16b

38a

35a

35b

33a

33b

PV-7 floor

11-R-1

PV-9 floor

LV-2 floor

2a

2b1a

10c

21- SEC UREA - I

WEEP HOLE PROBES LOCATION DRAWING

F-7 FLOOR

73b

71a

71b 22c 22b

72a

F-6

70a

70b

68a

68b

66a

66b

F-5

F-4

65a

65b

63a

63b

61a

61b

64a

64b

62a

62b

60a

60b

58a

58b

F-7

F-6

F-5

F-4

F-3

51b

HV-2

53a

53b

F-1

55a

55b

59a

59b

57a

57b

F-2

54a

54b

56b

56a

73a11 SIDE EXPN. SIDE

60a,b,c

72c 72b

Three probes

Three Probes

60c

52a

52b51a

69a

69b

67a

67b

72 a , b , c

LV-2 floor

PV-9 floor

PV-7 floor

21 -R-1

51 to 73 channels

CHECKING OF WEEP HOLES

THE WEEPHOLES CAN ALSO BE CHECKED INDIVIDUALLY

BY DISCONNECTING THE OUTCOMMING TUBES AT A

SUITABLE FREQUENCY TO BE DECIDED BASED

ON ACTUAL EXPERIENCE.

SINCE TWO WEEPHOLES ARE CONNECTED INTERNALLY,

PAIR OF SUCH WEEPHOLES ARE TO BE IDENTIFIED

(TIME TO TIME ) IN SUCH A WAY THAT OUT OF THE

TWO , ONE IS TO BE CONNECTED TO HEADER L2

( THE N2 FEEDING HEADER TO WEEPHOLES )AND THE

SECOND ONE TO HEADER L3 FOR CONNECTING RETURN

TO THE BUBBLER.

TO CHECK AND REMOVE THE CHOKING OF EXISTING WEEPHOLES

N2

L1 L2

L3

V1V2

V4

V3

1

2

3

4

A

B

C

D

ACKNOWLEDGEMENT OF LEAKAGE

NORMALLY WHEN THE LEAKAGE STARTS, IT COMES OUT IN THE

FORM OF LIQUID AND GASES AS THEY ARE HOT. THE LEAKY

MAY SOLIDIFY AT PLACES IN THE N2 HEADER WHERE THE

TEMPERATURE IS LOW. THAT IS WHY WEEP HOLE

NOZZLES ARE KEPT SHORT AND OPENED TO ATMOSPHERE FOR

EASY VISIBILITY.

SINCE THE N2 IS ALLOWED TO PASS INBETWEEN THE LINER

AND SHELL , THE PRESSURE OF N2 MUST NOT EXCEED MORE

THAN 0.5 Kg/Cm2. EXCESS PRESSURE MAY DAMAGE THE

LINER WHEN THE EQUIPMENT IS IN DEPRESSURISED

CONDITION.

WHY AND WHERE THIS SYSTEM IS

NEEDEDHIGH PRESSURE

CORROSIVE ENVIORENMENT

LINER USED SURFACE

LINER USED IN UREA – 1 :

V-1 : SS-316L IS USED

E-5 : SS-316L IS USED

E-1 : 2-RE-69 IS USED

IN REACTOR SS-316L MODIFIED IS USEDNOW WE WILL SEE DIFFERENT MATERIAL COMPOSITIONS

TYPE OF MATERIAL Cr Ni Mo C Mn N P S Si Cu Fe Ti

UREA GRADE ALLOY 24-26 21-23.5 2 - 3 < 0.02 1.5-2 0.1-0.15 < 0.02 <0.015 < 0.4

2RE-69 24-26 21-23.5 2-2.6 < 0.020 1.5-2 0.1-0.15 < 0.02 <0.015 <0.40 BALANCE

HVD-1 @ 24-28 7.5-10 2 - 3 < 0.10 < 2 < 1 1 - 2 BALANCE

FERRALIUM ALLOY $ 24-27 4.5-6.5 2 - 4 < 0.04 < 1.5 0.1-0.25 < 0.04 < 0.03 < 1 1.5-2.5 BALANCE

SS-316L # 16-18 10-14 2 - 3 < 0.03 < 2 < 0.045 < 0.03 < 1

SS-316Ti 16-18 10-14 2 - 4 < 0.08 < 2 < 0.1 < 0.045 < 0.01 < 1 Max0.7

@ 25 10 2.5 <0.05 1.25 <0.02 <0.03

# MODIFIED SS-316 L 16 12 < 0.03 2

$ 24 4.5 2 < 0.04 1.5 1

STELLITE 28

UREA GRADE MATERIALS & THEIR COMPOSITION

PREVENTS STRESS CORSN.

(WITH HUEY TEST )

MAX. HARDNESS

Max.Corsn.Resistance

Ni - IMPARTS DUCTILITY/ WELDABILITY/TOUGHNESS

MO- PREVENTS PITTING CORROSION/CREVICE CORROSION

Cr- INCREASE CORROSION RESISTANCE

MICROGENIE-SCAN

THE MICROGENIE –SCAN IS A MICROPROCESSOR BASED

SCANNER WHICH SCANS THE PROCESS VALUE AT

VARIOUS CHANNELS.THE CHANNELS CAN BE SCANNED

IN AUTO MODE OR A DESIRED CHANNEL CAN BE

PERMANENTLY VIEWED IN THE MANUAL MODE.THE

PHILOSOPHY OF THE DESIGN HAS BEEN TO MAKE

PROGRAMMING A VERY SIMPLE TASK EVEN FOR THE

SHOP-FLOOR PERSONNEL.THIS HAS BEEN ACHIEVED BY

USING A USER-FRIENDLY SCROLLING FUNCTION WHICH

PROMPTS AN OPERATOR TO GO THROUGH A SEQUENCE

OF PROGRAMMING STEPS.

INPUT CONNECTIONS

INPUT CONNECTIONS ARE MADE VIA A TERMI

QUICK ARRANGEMENT. THE TERMI-QUICK

ARRANGEMENT IS A FLATE –CABLE WITH

LOCKING TYPE CONNECTORS AT EITHER END

AND A SENSOR TERMINATION BOARD.

THE INSTRUMENT CAN BE REMOVED FROM THE

PANEL BY JUST DISCONNECTING ITS FLAT CABLE

CONNECTOR.YOU NEED NOT DISCONNECT THE

SENSOR CABLING.

EDIT MODE PARAMETERS

• LOWER DISPLAY : UPPER DISPLAY

• HOURS (REAL TIME CLOCK) 00.00 TO 23.59

• Hrs : Mts

• YEAR (REAL TIME CLOCK) 1990 TO 3000

• nn.dd (REAL TIME CLOCK) 01.01 TO 12.31

• Month : Day

• Pint (Print interval) 00.01 TO 99.59

• Hrs : Mts

• dint Display Interval/Scan Time PER CHANNEL 0001 TO 0099 SEC.

• Sr Ln(serial no. of a unit) 0000 to 0072 only last two digits functional

LIMIT MODE PARAMETERS

• LOWER DISPLAY UPPER DISPLAY

• AH / AL For High / Low setpoint

• gH / gL on/off relay diffreential gap

• Calibration mode parameters

• Z Calibration at zero side/Lower value of Specified range

• S Calibration at Span side / upper value of specified range

• IH /OH SKIP / UNSKIP A CHANNEL

Today still too many accidents (ruptures, explosions)

of high-pressure equipment items in the urea industry

do occur…

Safety Risks of Urea High Pressure

Equipment

1. High pressures

2. High Temperatures

3. Various kinds of corrosion phenomena (inside and outside)

4. Crystallization risks.

5. Large volumes

6. Release of toxic ammonia in case of a leak

Integrity of carbon steel pressure

bearing wall can be threatened by:

1. Carbamate corrosion due to damage of protective layer with

(corrosion rate 1000 mm/year):

2. An early and reliable detection is a must.

3. Stress corrosion cracking behind loose liner when water and

contaminants are present.

4. Stress corrosion cracking from outside when water and

contaminants are present

Cracks in carbon steel

behind liner !

Do realise

Typical lifetime of the 316L Urea Grade protective

layer of a urea reactor is 20-30 years

While

Typical lifetime of a urea plant is 40-50 years.

Thus

Every urea reactor will finally operate close to the

end of lifetime conditions of the protective layer

Meaning that at a certain moment a leak in the

protective layer is nearly unavoidable

Gas phase leak

CO2 and NH3 gases flashing forming carbamate solids

below 60oC

Liquid phase leak without urea

1. Carbamate flashes forming CO2 and NH3 gases

2. No carbamate solids above 60oC

Liquid phase leak with urea

1. Carbamate flashes forming CO2 and NH3 gases

2. No carbamate solids above 60oC

3. BUT urea solids are present below 133oC and also above

133oC urea partly decomposes into NH3 and HNCO but

also forms biuret, triuret etc. with even higher melting

points

Passive systems

1. Checking for vapors

2. Checking the smell of NH3

3. NH3 Reagent (color change)

4. Checking of bubbles in a dipped vessel

filled with oil

5. Conductivity

6. Infrared

All systems wait for leak to show up at the

detector, while clogging can already occur…

Weep hole monitoring by vacuum system

Advantages(Developed by Ureaknowhow.com

By Mr. Mark Brouwer)

1. It detects the maximum liner area (also around clips and other

failure modes like condensation corrosion, fatigue cracks, clogged

groove etc.)

2. It can be applied in every design reactor, also in case

3. no grooves are present

4. one hole is present in the liner compartment

5. clogged situations

6. It avoids risks of liner bulging and damage

7. A vacuum system allows larger distances between high-pressure

equipment items (for example with twin urea lines)

Fixed weld connections of liner to carbon steel

are assumed to be most critical…

…But clip welds, cold spots (condensation

corrosion), etc. can also lead to leaks in

liner

Grooves in an austenitic buffer layer do not avoid contact carbamate – carbon

steel

Liner compartment with only

one hole

A vacuum system is best solution for liner

compartments with only one leak detection hole

Requirements for a State-of-the-Art leak

detection system

1. Active vacuum based leak detection system

2. Reliable and accurate ammonia detector

3. DCS alarm in case of not proper

functioning

4. Probability of Failure of demand max 0.01

to reach E-5 risk factor

Further requirements for quick and easy locating of

leak

1. The possibility to check for open circuits (avoid clogging

risks)

2. The possibility to identify the leaking liner circuit in

order to minimize downtime to locate and repair the leak

3. To have information about the leak size (in order to be

able to select and prepare the right and most suitable

method to pinpoint the leak to minimize the downtime to

locate and repair the leak)

4. To be able to introduce a leak detection tracer for

pinpointing the leak .

5. To distinguish false air leaks from real liner leak

1. An active, vacuum based leak detection system

2. With an accurate and reliable ammonia detector

3. Meeting the Probability of Failure on Demand

requirement of maximum 0.01.

4. The DCS operator will be warned in case there is

5. A lack of vacuum pressure

6. Clogging

7. Malfunctioning of the ammonia detector

8. And of course a liner leak is present

Features of “UreaKnowHow.com “Leak

Detection System

Benefits Boreal Laser Ammonia Detector

1. Safe

2. Very accurate

3. NH3 specific

4. Self calibrating

5. No maintenance

6. No consumables

7. No memory effect

8. No saturation effect

9. Provides alarm when not functioning

HELIUM LEAK DETECTION

A Helium Leak detector, also known as a Mass

Spectrometer Leak Detector (MSLD), is used to locate

and measure the size ofleaks into or out of a system or

containing device. The tracer gas, helium, is

introduced to a test part that is connected to the leak

detector. Helium is the best choice of tracer gas to find

leaks for a number of reasons. It is non-toxic, inert,

non-condensable, non-flammable and not normally

present in the atmosphere at more than trace amounts

(5 ppm). Due to its small atomic size, helium passes

easily through leaks. The only molecule smaller than

Helium is Hydrogen which is not inert. It is also

relatively inexpensive and is available in various size

cylinders.

Helium Leak Detection

A Helium Leak detector, also known as a Mass

Spectrometer Leak Detector (MSLD), is used to locate and

measure the size of leaks into or out of a system or

containing device. The tracer gas, helium, is introduced to

a test part that is connected to the leak detector. The

helium leaking through the test part enters through the

system and this partial pressure is measured and the

results are displayed on a meter.

Helium leak detectors consists of the following

components:

A spectrometer to detect the mass of helium

A vacuum system to maintain the pressure in the

spectrometer A mechanical pump to evacuate the

part to be tested Valves which enable the various

stages of detection: evacuation, test & venting

An amplifier and readout instrumentation to

monitor the output signal

Power supplies and controls

Fixturing that attaches the part to be tested to the

detector

Methods of Leak Testing Parts

There are two main methods to leak test parts using

helium: Vacuum Testing (outside-in) and Pressure

Testing (Inside-out). The detection method should be

selected based on the working conditions of the part to

be tested. It is important to maintain the same

pressure conditions during the test as will exist during

the actual use of the part. Vacuum systems should be

tested with a vacuum inside the chamber. A

compressed air cylinder should be tested with high

pressure inside the cylinder.

Vacuum Testing (Outside-in)

In Vacuum testing, the part is evacuated with a separate pumping

system for larger volumes, or within the detector itself for smaller

volumes. To Locate a leak, helium is administered to the suspected

leak sites of the part using a spray probe with an adjustable flow.

Methods of Leak Testing Parts

There are two main methods to leak test parts using helium: Vacuum

Testing (outside-in) and Pressure Testing (Inside-out). The

detection method should be selected based on the working

conditions of the part to be tested. It is important to maintain the

same pressure conditions during the test as will exist during the

actual use of the part. Vacuum systems should be tested with a

vacuum inside the chamber. A compressed air cylinder should be

tested with high pressure inside the cylinder.

Vacuum Testing (Outside-in)

In Vacuum testing, the part is evacuated with a separate

pumping system for larger volumes, or within the detector

itself for smaller volumes. To Locate a leak, helium is

administered to the suspected leak sites of the part using a

spray probe with an adjustable flow.

Pressure Testing (Inside-out)

In Pressure Testing, the part is pressurized with helium or

a mixture of helium and air. To Locate a Leak, the

potential leak sites of the part are scanned using a Sniffer

Probe connected to the inlet of the leak detector.

Leak Testing Vacuum Systems & Pressure

Systems

Vacuum systems and pressure systems should be

leak tested under the same conditions as their

operational conditions. Vacuum systems are tested

with a portable leak detector. The leak detector is

connected to the line of the vacuum pump. Helium

is applied to the potential leak site using a spary

prove. If a leak exists, helium enters the system and

quickly diffuses through it. The leak detector

should respond within seconds. Pressure

systems can be charged with helium or a mixture

of helium and nitrogen. The leak testing is

performed by using a Sniffer probe.

Helium Leak Detection Applications

Quality control of production parts and

assemblies using helium leak detectors can

help assure the integrity of your production

process. Typical examples include:

hermetically sealed packages, valves, Mani

folding, seals, vacuum vessels and systems,

medical devices, high purity piping, brake

lines, fuel lines, hydraulic lines, refrigeration

assemblies, radiators, heat exchangers,

condensers, storage tanks.

Maintenance of Systems

Industrial process tools that use vacuum systems or

pressure systems must be tested to check for

occasional leaks. This can be part of preventative

maintenance or in the event of an unexpected

failure. Typical examples of vacuum systems

include: Vacuum furnaces, vacuum coaters, electron

microscopes, glove boxes, linear accelerators,

electron beam and ion beam process equipment,

semiconductor process equipment, laser process

equipment. Typical examples of pressurized

systems include: power plants, gas handling

systems, bioreactors, liquid gas facilities,

underground tanks, underground cables and pipes.