76530132 process design manual lurgi

Process Design Manual Process Engineering Design Basis (Rev 0, October 2000)

PROCESS DESIGN MANUAL

FOR

PROCESS ENGINEERING DESIGN BASIS

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Responsible Issuer: Head of Department – Process Engineering

Table of Contents

Section

1.0 P&ID Engineering and Philosophy

2.0 Utility Battery Limit and Utility Header & Block Valves

3.0 Connection for Instruments

4.0 Equipment Sparing Philosophy

5.0 Equipment Duty Margin

6.0 Pressure Relief Philosophy

7.0 Insulation and Tracing Philosophy

8.0 Process Block Valves Philosophy

9.0 Utility Station Location Philosophy

10.0 Isolation Blinds / Spading Philosophy

11.0 Tank Fittings and Accessories Philosophy

12.0 Equipment Design Philosophy

13.0 Minimum Liquid Surge Requirement

14.0 Utility Conditions

15.0 Noise Control

16.0 Aromatics Handling

17.0 Corrosion Allowance

18.0 IBR requirements

Anoop Sharma, Approval: Name, Date, Signature

Copying of this document, and giving it to others and the use or communicationof the contents thereof, are forbidden without express authority by Lurgi.

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Dated : December 04, 2000

Foreword

We are pleased to note that Process Engineering Department is releasing the “Process Engineering Design Basis” for use by its engineers.

In the past, it was seen that the engineers had to resort to repetitive use of uncompiled information required by them in their day to day work. The need was therefore felt to compile all the design guidelines/data in one place. The exercise carried out by the process engineers was therefore a fruitful one in the generation of this manual.

We are sure the manual will serve as a useful tool for the process engineers in their day to day work.

Dr. Sudhir Kapoor Onkar GuptaManaging Director and CEO Director Operations

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1.0 P&ID Engineering and Philosophies

1.1 General

Pressure drop and velocity criteria for the sizing of lines are outlined below. For revamped units higher line velocities may be considered for existing lines.

1.2 Standard Line Sizes

The following non-standard line sizes will not be used unless approved by customer.

¼”, 2 ½”, 3 ½”, 5”, 7”, 9”.

1.3 Minimum Line Sizes

The following guidelines should be applied:

2” NB Minimum nozzle size for vessels, tanks and heat exchangers.2” NB Minimum process (hydrocarbon) line size.1½” NB Minimum utility line size.¾” NB Minimum bridle drain or pump casing vent / drain.½” NB Minimum chemical injection. Tubing size to be 10 mm.1½” NB Minimum on pipe rack.4” NB Minimum for underground lines (wrapped and coated)

1.4 Roughness Coefficient

The following roughness coefficients are to be used, unless stated otherwise:

Material Roughness (Inches)

Carbon steel pipe

Flare/vent headers (heavily corroded)

Stainless steel pipe

Glass reinforced epoxy pipe

0.0018

0.018

0.001

0.0001

1.5 Pressure Drop Calculations

Design margins for two phase flow pressure drop calculations normally are 50% of the pressure drop calculated at normal flow to allow for inherent inaccuracy in the calculation methodology, manufacturing tolerances, deterioration of the new pipe with scale, etc.It is important not to oversize pipe with vertical upward two-phase flow. The flow regime shall be calculated for design, normal, and turndown. Every effort shall be made to avoid slug flow regime.

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1.6 Pressure Drop Calculations for Vapour and Liquids

These margins are based on experience and range from 0% to 20% plus on the pressure drop at normal flow, depending on the configuration of the system being designed. For most systems, 20 % pressure drop margin is applied. However for very low pressure systems, margins are individually assessed, for example in a tank to vent pipework.

1.7 Equivalent Lengths

Pipe fitting, contractions and enlargements are taken into account by utilising “equivalent lengths” as per normal engineering practices.

1.8 Limiting Velocities and Pressure Drops

ft/s m/s Press. Drop, bar/100 m

Liquids

Pump Suction- boilingPump Suction- sub-cooledPump DischargeSidestream Draw-offAmine, Carbonate, Sour WaterSodium HydroxideSalt WaterErosion Limits

Gases

GeneralLess than 1.03 bara Upto 6.9 baraUpto 69 baraOver 69 bara

Compressor Suction - Reciprocating- Centrifugal

Steam General

High Velocity Flow (pressure let down)

45.210474 to 610API-RP-14E

250200150100

20 to 4040 to 80

50 √ d *

0.9 Mach

1.221.63.051.222.141.22 to 1.833.05API-RP-14E

75604530

6 to 1212 to 25

15 √ d *

0.9 Mach

0.1 to 0.060.05 to 0.22

0.2 to 0.50.06 to 0.1

----

0.1 to 0.060.06 to 0.130.13 to 0.5

0.2% of Pressure

0.10.1

0.02 to 0.6**

* d is in inches** Depends if short or long line and steam pressure level

1.9 Net positive Suction Head (NPSH)

A margin of at least 0.9 m between calculated NPSH and available NPSH has to be applied.For positive displacement pumps, effect of acceleration head on NPSH will be taken into account.

1.10 Differential Head Calculations

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Besides discharge piping loss, other losses taken into account are:

Orifice pressure drops : 0.2 kg/cm2 assumed

Equipment drops; e.g. heat exchangers : fouled pressure drop

Control valve pressure drop : The greater of the following :(for pump head calculations)

- 50 – 60% of the total frictional loss excluding the control valve - 0.7 kg/cm2

- 15% of the pump differential head

For valves installed in extremely long or high pressure drop lines, the percentage drop cross the valve may be somewhat lower, but at least 15% up to 25%, where possible, of the system friction drop should be taken.

Head Loss : Based on low liquid level in suctionvessel and high liquid level in the discharge vessel or discharge nozzle elevation of discharge vessel, which ever is higher.

1.11 Boiler Feed Water Pumps

BFW pumps will meet the requirements of ASME code section 1; i.e. be capable of supplying water to boiler at a pressure of 3% higher than the highest setting of any safety valve on the boiler.

1.12 Vents, Drains and Steam out/Purge connections for Equipment:

a. Process Vessels

Process vessels (tower and drums) shall have vents, drains and steam-out or purge connections as shown below:

Equipment Volume m³

Vent Size in

Drain Size in

Steam out or Purge Size, in

Upto 17 (600 ft3)

17 to 141.5 (600 – 5000 ft3)

141.5 to 283 (5000 – 10,000 ft3)

283 to 708 (10,000 – 25,000 ft3)

over 708 (over 25,000 ft3)

2

2

3

4

6

2

3

4

4

6

2

2

3

3

Two 3 ** To be located on opposite sides

b. Exchangers (Shell and tube)

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Provide 1” NB x 300 # (min.) flanged vents and drains at high and low points on Heat Exchangers. All vents and drains are to be valved and blanked off.Exchangers in total condensing service require a 2” vent connection at the opposite end of the shell inlet.

Sizes of Multi purpose connections and pressure gauge connections on exchanger nozzle shall be 1” NB x 300 # (min.) for below 12 “ nozzles and 2” NB x 300 # (min) for 12” and over nozzles.

Multi purpose nozzles can be used for thermometer connections if required.

1.13 Piping

Pipe Size, in Vent Size, in Drain Size, in

4 and below

6 to 10

12 and over

¾

¾

1

¾

1

1½

1.14 Air Coolers

On Air Coolers one 2” vent shall be placed at the highest point on the inlet header and one 2” drain at the lowest point in the outlet header. The exact locations of these vents and drains are dependent on the actual cooler design. Connections are to be valved and blanked off.

1.15 Pump Casings

For non-volatile services, casing vents and pumps drains shall be piped into a sewer or closed drain system.

For volatile services, casing vents and drains are to be piped to the relief header and sewers.

1.16 Additional Notes

1. Valved and blanked off vent and drain connection shall be furnished on all equipment that is not self-venting or self-draining. Connection shall be located on equipment, if practical, but may be located on connected piping when there are no valves or blocks between the vent or drain connections and the equipment.

2. Hydrostatic vents and drains for piping are to be provided and will not be shown on P&ID.3. When soda ash neutralisation is required in shell and tube exchangers, standardise on 2” flange

connection.4. At relief valves, a ¾” valve blanked off bleed shall be shown upstream of safety valve. 5. Vents from vessels that may chill and freeze during depressurising shall have double block valves

separated by at least 900 mm.6. Steam out connections shall be located at minimum distance above the bottom head seam of

vertical vessels and the side or head of horizontal drums.

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7. Steam-out connections shall be located at minimum distance above the bottom head seam of vertical vessels and the side or head of horizontal drums.

8. Blanked off vents shall be located on the top head of towers and vertical vessels. They shall be located on the top of horizontal drums at the same end as the drain and the end opposite from the steam out or purge connection.

9. A vessel drain shall be located in the bottom outlet line when the outlet line is located where it can be used to drain the vessel. Consider adding downstream orifice for vessel drains under pressure to limit drain velocity.

10. Minimum size vents for vessels having only one personnel access way shall be 4” for horizontal vessels and 2” for vertical vessels.

11. Minimum manhole size shall be 20” internal diameter.12. Large size manholes will be specified if required to accommodate internals. For underground

vessels the minimum manhole size is 30” internal diameter.13. In trayed columns, manholes will be provided above top tray, below the bottom tray, at the feed

tray, at any other tray as identified on process data sheets. Maximum spacing of manholes does not exceed 10 m. The minimum spacing of trays between manholes shall be 760 mm.

14. In horizontal vessels, equal or longer than 6 m, if an internal baffle is installed, two manholes will be required, one manhole in every compartment.

2.0 Unit Battery Limit and Utility Header & Block Valve

2.1 General

For new units and / or new storage, two block valves, blind and ¾” bleed or vent will be provided at battery limits. When a second valve is located within the process unit, only one block valve is required.

2.2 Utility Header

At unit battery limit, provide isolation valves as below:

• For steam, fuel gas, steam condensate, boiler feed water & hydrogen, provide double block valves, blind & ¾” bleed. For HP steam, also provide a 1” warm-up bypass.

• For instrument/plant air, service water, nitrogen, cooling water etc., provide a single valve, blind and ¾” bleed.

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3.0 Connection for Instruments

3.1 Instrument Connection Size (for guidance only)

S. No. Instrument First Isolation Connection(Piping / Vessels)

Instrument Connection

1 Thermowell 2” Flanged * 2” Flanged Temperature Element Connection to Thermowel ½”.

2 Pressure Instrument/Differential Pressure (Direct Type, Pipe Mounted)

¾” Welded ½” NPT

3 Pressure Instrument/Differential Pressure (Direct Type, Equipment Mounted)

2” Flanged * ½” NPT

4 Pressure Instrument• Diaphragm Seal, Pipe• Diaphragm Seal, Vessel

2” Flanged **2” Flanged *

2” Flanged **2” Flanged *

5 Differential Pressure (Diaphragm Seal)

3” Flanged 3” Flanged

6 Standpipe• Upto 330# Ratings• 600# and above ratings

3”4”

7 Level Gauge (On Vessel) 2” Flanged * ¾” Flanged8 Level Gauge (On Standpipe) ¾” Flanged * ¾” Flanged9 Displacer Level TX (Vessel/Stand

Pipe External)2” Flanged * 2” Flanged *

10 Displacer Level TX (Top, Internal) 4” Flanged * 4” Flanged *11 Level Switch (Vessel, S/P)

External2” Flanged * 2” Flanged *

12 Annubar 2” Flanged * ½” NPT (Pressure Tap)13 O2 Analyser (On Stack) 4” Flanged **14 Analysers (Others Except ‘B’) 3” Flanged **15 Sample Probe 2” Flanged **

* Flange rating shall be min 300#** Flange rating as per Pipe Specification

4.0 Equipment Sparing Philosophy

The Following equipments shall be provided with a spare:

• Main Process Pumps viz. Feed Pumps, Product pumps, reflux pumps and transfer pumps• Reciprocating Compressors• All Control Valves shall be provided with manual bypass globe valve unless provided with

handwheel• Filters where duplex is specified or where additional Filter is required owing to process reasons.

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5.0 Equipment Duty Margins

Equipment duty margins (between normal and design duties) are specified on the process data sheet.In case of new equipment, duty margins are allowed as follows as minimum requirement.

5.1 Heat Exchanger (Shell and Tube)

A nominal over surface, based on either 10% on flow and / or duty will be used depending on if the services is critical or non critical, in consultation with the Customer.

5.2 Air cooler

Use similar approach as above.

5.3 Fired Heaters

Use similar approach as above.

Notes:• For fuel fired heaters a maximum of 25% excess air is allowed.• For gas fired furnaces the excess air is 15%.

5.4 Pumps

Centrifugal Pumps : For small process pumps and reflux pumps use 20% margin on normal flow. For large pumps, use 10% of normal flow.

Reciprocating Pumps : Use 10% of normal flow for both small and large pumps.

5.5 Compressor

For both centrifugal and reciprocating compressors, use 10% margin of normal flow.For air blower use 10% margin on normal flow.

6.0 Pressure Relief Philosophy

All relief valves load and size shall be calculated according to the following mentioned codes:

• API 520• API 521• API 526• API 527• API 2000

The size of relief valves are based on either over-pressure condition, fire exposure or vacuum situation for a particular system.

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6.1 Typical over pressure conditions is:

Blocked Discharge Inadvertent Valve Opening Utility Failure Cooling Water Failure Electrical / Mechanical Failure Loss of Air Cooler Fans Loss of Heat in Fractionation Loss of Instrument Air or Electric Power Instrument Failure or Blow-by Reflux Failure Abnormal Heat Input From Reboilers Heat Exchanger Tube Failure Trapped Liquid Expansion

6.2 Typical vacuum considered would be:

In-breathing due to pumps out and temperature variation Steam condensation (Vacuum arising from steam out under maintenance conditions

not be considered for vacuum relief protection) Equipment normally operating under vacuum Equipment operating under vacuum conditions during start-up, shutdown, regeneration, or

evacuation Liquid full vessels that can be blocked in, and cooled Distillation columns and associated equipment that can be subjected to vacuum due to loss to heat

input. Pressure vessels containing liquid having vapour pressure at minimum ambient temperature less

than atmospheric pressure.

6.3 Relief Valve Selection Type

Balanced bellow will be used for the cases where the built-up backpressure and the variable superimposed backpressure exceeds 10%, but is below 50% of the set pressure.Pilot operated relief valves may be used for systems when maximum set point accuracy is required. They will be installed in equipment, which operate very close to set pressure. All above valves are also limited by process considerations (i.e. H2S service etc.) and material.

Notes:1. Valve selection will be based on maximum operating temperature and relief valve set pressure.

2. Where H2S is present, process data sheet will contain a note to indicate its presence.

3. Safety valves on column circuits are preferred to be located at the highest point in the overhead vapors lines. Alternatively, these safety valves can be located as per below provided that the pressure drop in the inlet line is within 3% of set pressure.

4. PSV discharge to be free draining to flare header, and join at 45o angle for 2” and larger size and 90o and free draining towards flare header for 1 ½” and higher size.

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5. Inlet and outlet valve to be full port.

6. Relief valves on highly viscous fluid lines to be steam jacketed.

7. Relief valves, which are susceptible to plugging, shall be steam traced and have a rupture disc installed under them.

8. Staggered pressure setting may be specified to minimise losses.

9. For atmospheric relief, the open end of discharge will be located 30m from any source of ignition. Discharge is usually 3m higher than any equipment or manholes (Ladder, platform etc.) within 15m radius

7.0 Insulation and Tracing Philosophy

To reduce heat loss, piping, vessels, tanks and the equipment will be insulated where operating temperature exceeds 70oC.

The table showing insulation thickness with temperature is below:

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COLUMN CONDENSER

REFLUX DRUM

FREE DRAINING

FREE DRAINING

FLARE HEADER

NO POCKETS

SUFFICIENTLY HIGH TO AVOID LIQUID ACCUMULATION. ALSO ENSURE SAFETY VALVES ACCESSIBILITY FOR MAINTENANCE


Table - 1Insulation Thickness for Personal Protection

Insulation thickness in mmSurface temperature of insulation less than 60°C

Nom Dia. (in)

Operating Temperatures in ° CUpto 125

126 - 150

151 - 200

201 - 250

251 – 300

301 - 350

351 - 400

401 - 450

451 - 500

501 - 550

0.5 25 25 25 25 25 25 40 50 50 650.75 25 25 25 25 25 25 40 50 50 65

1 25 25 25 25 25 40 40 50 65 651.5 25 25 25 25 25 40 50 50 65 752 25 25 25 25 25 40 50 65 75 803 25 25 25 25 40 50 50 65 75 904 25 25 25 25 40 50 65 75 80 1056 25 25 25 25 50 50 65 75 90 1058 25 25 25 40 50 50 75 80 100 115

10 25 25 25 40 50 50 75 80 105 12512 25 25 25 40 50 65 75 90 115 12514 25 25 25 40 50 65 75 90 115 13016 25 25 25 40 50 65 80 90 115 13018 25 25 25 40 50 65 80 90 115 14020 25 25 25 40 50 65 80 90 115 140

Flat Surface

25 25 25 40 50 65 80 90 115 140

Types of Insulation MaterialsBonded Mineral Wool pipe sections (MW)Bonded Mineral Wool mattress (MW)Cal. Silicate Pipe Sections (Cal. Sil)Cal. Silicate Lags (Cal. Sil)

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Table - 2Insulation Thickness for Heat Conservation

Insulation thickness in mmHeat Loss = 150 Kcal/hr-m2 (max)

Nom Dia. (in)

Operating Temperatures in ° CUpto 125

126 - 150

151 - 200

201 - 250

251 – 300

301 - 350

351 - 400

401 - 450

451 - 500

501 - 550

0.5 25 25 35 50 60 70 85 95 110 1150.75 25 30 40 50 65 75 90 100 115 125

1 25 30 40 55 65 80 95 105 125 1251.5 25 30 45 60 70 85 100 115 130 1402 25 30 45 60 75 90 105 120 140 1503 25 35 50 65 80 100 115 135 150 1504 25 35 50 70 85 105 120 140 150 1506 25 35 55 75 90 110 130 155 160 1658 25 40 55 75 95 115 140 160 175 180

10 25 40 55 80 100 120 145 170 185 19012 25 40 60 80 100 125 150 175 195 20014 25 40 60 80 105 125 150 175 200 21016 25 40 60 85 105 130 155 180 205 21018 25 40 60 85 105 130 155 185 210 22020 25 40 60 85 105 130 155 185 215 220

Flat Surface

25 40 60 85 105 130 155 185 215 220

Types of Insulation MaterialsBonded Mineral Wool pipe sections (MW)Bonded Mineral Wool mattress (MW)Cal. Silicate Pipe Sections (Cal. Sil)Foam Glass pipe sections (upto 125 °C only) (FG)

Notes:

1. Applicability for thermal insulation Temp. range 60 to 550 °C For Pipes, Ductwork and Equipment. NOT applicable for Embedded/Buried lines, buildings and structures.

2. For operating temperatures above 550°C, decide material and thickness on case to case basis.

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Table - 3Insulation Thickness for Cold Insulation

Nom Dia. (in)

Operating Temperatures in ° CUpto + 5

+4 to -7

-8 to -18

-19 to -32

-33 to -45

-46 to –60

-61 to -75

-76 to -90

-91 to -100

-101 to

-120

-121 to

-130

-131 to

-145

-146 to

-1550.5 35 50 60 80 90 110 125 145 155 165 170 180 1800.75 40 50 65 80 95 120 135 155 165 175 180 185 190

1 40 55 70 85 105 125 140 160 170 185 190 195 2001.5 45 60 75 95 115 135 155 175 190 200 210 215 2202 45 65 80 100 120 145 165 185 200 215 220 225 2303 50 70 90 110 130 160 180 205 220 235 240 250 2554 55 75 95 115 140 170 190 220 230 250 255 265 2706 60 80 100 130 150 185 210 240 255 275 280 290 2958 60 85 110 135 160 195 225 255 270 290 300 305 310

10 65 90 115 140 170 205 235 265 280 305 310 320 32512 65 90 115 145 175 215 240 275 290 315 325 335 34014 65 90 120 150 180 220 245 280 300 315 330 340 34516 65 95 120 155 185 225 255 290 305 320 340 350 35518 70 95 125 155 185 230 260 295 315 330 350 360 36520 70 95 125 160 190 230 265 300 320 340 355 365 370Flat

Surface70 95 125 160 190 230 265 300 320 345 355 365 370

Types of Insulation Materials Rigid Polyeurethene Foam

Tracing

In case of tracing, steam or electrical tracing shall be used.

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8.0 Process Block Valves Philosophy

8.1 Single Block Valves

Single block valves shall be installed for the following conditions:

In piping at all vessels and tanks nozzles, where the nozzle is below liquid level of the vessels and tanks.

In exchanger inlet and outlet, only if exchanger requires frequent inspection or cleaning. In suction and discharge piping of pumps, turbines and compressors. At equipment in auxiliary piping for gland oil, flushing oil, cooling water and for removal of

equipment. At equipment in steam piping for steam driven equipment. At fuel oil and fuel gas piping to furnaces or fired heaters. Valve shall be located 15m from the

equipment and accessible for rapid operation in emergency. For drains to closed drain header. Install a check valve, one pair of flanges and a bleed valve

upstream of block valve. (Note: Flanges and bleed to be provided between check and block valves.)

In product lines to slop header. Install a check valve and block valves. For gas stream <100 barg pressure or liquid system of <60 barg pressure. If the operations will be

more frequent than twice per annum, or the system contains gases or liquids, which are potentially toxic, then a double block and the bleed system will be used.

In lines to flare header

8.2 Double Block Valves

Double block valves shall be installed for the following conditions:

For cases where cross contamination cannot be tolerated. For vents and drains in ANSI Class 600 rating and over. For drains containing C5 (plus lighter hydrocarbons) or lighter hydrocarbons. In this case the double

block valves must be minimum of 100cm straight pipe apart. A check valve will be installed upstream of the first block valve. A pair of flanges shall be provided between the check and first block valve.

Where high pressure (above ANSI CI 300 rating) is likely to be removed on the run; e.g. spared machinery or equipment.

For gas stream >100 barg or liquid systems > 60barg or gas/liquids which are potentially toxic. For the equipment which may be opened for maintenance “ on the run” (e.g. filters).

9.0 Utility Station Location Philosophy

Utility steam, air and service water outlets shall be furnished with hose connection of minimum size 1” nominal. As a general rule provide first block valve (ideally at header) followed by a ¾” bleeder, check valve and block valve adjacent to equipment or piping. All utilities are to terminate with a hose connection (Assuming a maximum hose length of 25m, utility stations for LP steam, service water and plant air shall be provided at following locations:

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In Process Units

At grade to serve equipment within a maximum 25m radius. At top platforms of drums located at the grade. At first level platforms of structures and towers. At second level platforms of structures and towers.

In Off-Sites

Utility stations will be provided near pump stations and chemical injection systems. (Direct connections from utility header to process vessels must be avoided to stop process fluid entering into utility system.

10.0 Isolation Blinds / Spading Philosophy

Isolation blinds will be provided as follows:

On all spared pumps, turbines and compressors on the equipment side of the block valve, where applicable.

At unit limits either between double blocks or on unit side. (refer Section 2.0). At equipment, which can be physically entered, provision for temporary blinds. For vents and drains- provision for temporary blinds.

Nominal Line Size (Inches) Blind Type12” and under Spectacle BlindOver 12” inches Circular with spacer

11.0 Tank Fittings and Accessories Philosophy

The following guidelines will be used (as a minimum) during detail engineering to specify fittings and accessories for all types of atmospheric tanks.

11.1 Manholes – Number and Sizes

Shell Roof Roof Internal Floating Roof

Nominal Tank Dia.(Meters)

All Tanks Types Fixed Roof TanksFloating Roof Tank

Fixed RoofInternal Floating Roof

NumberSize (inch)

NumberSize (inch)

NumberSize (inch)

NumberSize (inch)

NumberSize (inch)

3 to 6 1 24 1 24 1 24 1 24 1 24

> 6 to 12 2 24 2 24 1 24 2 24 1 24

>12 to 18 2 24 2 24 1 24 2 24 1 24

>18 to 45 2 24 2 24 2 24 2 24 2 24

>45 3 24 2 24 2 24 3 24 2 24

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11.2 Filling and Suction Nozzles – Minimum Sizes

Nominal Tank Diameter (meters) Nozzle Diameter(Inch)

<14.9 315.2 to 30.1 430.4 to 60.5 6>61 8

11.3 Roof Drains

Nominal Tank Diameter (meters) Drain Diameter(Inch)

< 6 36 to 18 4> 18 6

11.4 Sample / Gauge Hatch

Provide one 8” gauge hatch for level measurement per tank.

11.5 Water Draw-off/Drain – Number and Sizes

All draw-off connection shall be furnished complete with the following:

4” nozzle, 1200mm diameter by 610mm deep-water draw-off sump, internal pipe terminating 100mm above bottom of sump and drain valve.

Nominal Tank Diameter (meters) Number Required<12 112.1 to 45 246 to 61 3>61 4

Water draw-off nozzles shall be located near shell manholes to facilitate cleaning of sumps.

12.0 Equipment Design Philosophy

12.1 Pressure Vessels Design

Design Pressure

The design pressure for pressure vessels shall be as per the following criteria:

a. For operating pressures upto 70 kg/cm2g, the highest of the following to be considered :

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• Maximum Operating Pressure + 2.0 kg/cm2

• Maximum Operating Pressure x 1.1• 3.5 kg/cm2 (g)

b. For operating pressures above 70 kg/cm2g :

• For operating pressures between 70 and 140 kg/cm2g : Operating Pressure + 7.0 kg/cm2

• For operating pressures greater than 140 kg/cm2g : Operating Pressure x 1.05

c. For vessels operating under vacuum, design pressure to be 1.0 kg/cm2g and full vacuum.

Notes:1. For equipment connected to flare (e.g, flare knockout drum), design pressure of equipment to be

same as flare design pressure.2. Equipment in circuits that can be evacuated by an ejector and suction drum on reciprocating

compressor will be designed for full vacuum conditions in addition to operating conditions. Strippers using steam will be designed to full vacuum conditions.

3. Mal-operation during the steam out of vessels is not to be considered.4. The vessels open to atmosphere shall be designed for full of water condition.5. Design pressure mentioned above does not include the liquid head.

Design Temperature

The equipment design temperature shall be as follows:

For temperature below 0o C : Lowest possible operating temperature For temperature above 0oC : Operating Temperature + 30oC Boiling water service : Saturation temperature at design pressure.

Note: For exchangers, pumps, compressors, filters, etc., use as above pressure vessel design temperature

12.2 Pump Shut Off

Equipment in a pump discharge circuit with a down stream block valve shall have a design pressure which should be the higher of the two :

- suction vessel operating pressure + normal liquid static head + pump differential shut-off pressure

- suction vessel design pressure + maximum liquid static head + pump differential pressure (at normal flow)

For estimates of pump shut off head on motor driven centrifugal pumps at normal operating suction pressure, use the suction pressure plus 1.25 times the rated differential pressure of pump. The suction pressure shall be the vessel normal operating pressure plus the normal liquid static head.

For constant speed turbine driven pumps, use the suction pressure 1.35 times rated differential pump pressure. For variable speed turbine pumps, uses the suction pressure plus 1.5 times rated differential pump pressure.

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For a full liquid system at the discharge of a positive displacement pump, the mechanical design pressure shall be higher of these two:

• P (rated) discharge + 2 kg.cm2• P (rated) discharge * 1.1

The shut off pressure will be confirmed based on equipment purchased.

12.3 Tank Design

The minimum design pressure and design temperature requirements of tanks shall be as below:

Design Pressure

Cone Roof Tank : +20 mbarg / -6 mbargDome Roof Tank : 0.04 to 1.04 barg

Tank design pressure does not include liquid head. Design pressure is for the top of the tank. Mal-operation during steam out is not to be considered. A vacuum breaker shall be provided.

Blanketed storage tanks shall have a blanketing pressure of 150 mmwc unless specified by client.

Design Temperature

The tanks design temperature shall be as follows:

For temperature below 0o C : Lowest possible operating temperature For temperature above 0oC : Operating Temperature + 30oC Boiling water service : Saturation temperature at design

pressure.

The minimum design temperature shall be the lowest temperature expected in service.

12.4 Tower Overhead System

For equipment in a tower overhead system with a relief valve, the design pressure shall be arrived as follows:

a) In front of a train of equipment, design pressure to be compatible with the relief valve set pressure plus liquid static head.

b) In rear of a train of equipment, design pressure to reflect relief valve set pressure, liquid static together with line and equipment pressure losses, including fouled equipment.

12.5 Compressor Systems

For centrifugal or axial compressor, the design pressure of upstream equipment should be set at a safe margin above the settle-out pressure. The safe margin is normally at least 10%.

Downstream equipment will be set at blocked in conditions.

For reciprocating compressors, each stage is fitted with safety valve at a margin above the normal discharge pressure by the vendor. The piping and equipment downstream will be set at blocked-in

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condition. The upstream equipment will be set at in the usual way, above the normal operating pressure or the settle out pressure and protected by relief valve.

12.6 Piping Systems

Design pressure for the piping will normally be at least equal to theoretical maximum expected operating pressure and similar to the connected equipment.

Design temperature for the piping will take into consideration flowing conditions, shut conditions and solar radiation and will be similar to the connected equipment.

For relief valve inlet pipe, design temperature and pressure will be same that of the connecting equipment. For discharge pipe, design temperature must be determined separately.

12.7 2/3rd Rule for Heat Exchangers

For shell and tube heat exchangers the low-pressure side shall be specified for a mechanical design pressure at least equal to 2/3rd of high-pressure side mechanical design pressure. If this is not possible, a relief valve of adequate size must protect the low-pressure side. 2/3rd rule shall necessarily be adhered to when:• LP fluid is on tube side• Relief discharge cannot be connected to flare header owing to nature of fluid• Relief discharge is two phase and cannot be connected conveniently to a low-pressure destination

with free-draining piping.• Liquid relief cannot be connected to CBD system• When the 2/3rd criteria calls for an increase by less than a factor of 1.5 of the mechanical design

pressure of the LP side as would be calculated from normal estimation procedures.

13.0 Minimum Liquid Surge Requirement

The “liquid surge volume” within a vessel is determined by the following factors: The control range The manual intervention range The required residence time for separation, degassing, etc. The possibility of liquid slugs in the feedline.

The surge time shall not be confused with residence time as surge time is hold up time between two level, usually HLL and LLL, while residence time is hold up time from NLL to empty vessel.The guidelines for Surge time is given below:

Service Surge time (minutes )LLL to HLL

Feed to unit 15 – 20Product to storage 2Feed to tower 5 – 7Feed to furnace 4 – 10Compressor suction 5Manual control and manual intervention 20

Level transmitters and level gauges shall cover the cut-off point (low-low / high-high) also

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14.0 Utility Conditions

The plant utility conditions are project specific. However, The Typical utility conditions for the plant is given below for guidelines only:

S. No. Parameter Minimum Normal Maximum Mechanical Design

1 High Pressure Steam (HP) *Pressure, kg/cm2 38 40 42 46Temperature, oC 380 390 400 420

2 Medium Pressure Steam (MP) *Pressure, kg/cm2 12 14 15 18Temperature, oC 210 290 305 350

3 Low Pressure Steam (LP) *Pressure, kg/cm2 3 4 4 7Temperature, oC 143 175 190 240

4 Condensate Return (Suspect / Pure) *Pressure, kg/cm2 8.5 / 6Temperature, oC 40 / 90 100 / 100 150

5 Service WaterPressure, kg/cm2 3 5 6 10Temperature, oC Ambient 65

6 Cooling Water*Supply Pressure, kg/cm2

4 4.5 5 7

Return Pressure, kg/cm2

2.2 2.5 2.8 7

Supply Temperature, oC

28 33 65

Return Temperature, oC 45 45 657 Demineralised Water *

Pressure, kg/cm2 4 7.5 8 12Temperature, oC 30 40 45 65

8 Boiler Feed Water (HP / MP) *Pressure, kg/cm2 47/25 50/28 -/35 - /40Temperature, oC 100 100-110 150

9 Plant Air (Oil and water free) *Pressure, kg/cm2 4 5 8 10Temperature, oC 40 50 65

10 Instrument Air * Pressure, kg/cm2 5 6 7 10Temperature, oC Dew Point = (-) 40 65

11 Fuel GasPressure, kg/cm2 2 3 4.5 6.5Temperature, oC 35 45 55 65

12 Fuel Oil (@ BL / @ burner) *Supply Pressure, kg/cm2

8 /6.4 10/8.4 12/10.4 18

Return Pressure, kg/cm2

-/2.5 -/3.5 -/3.5 18

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Temperature, oC 140 210 240 26013 Nitrogen *

Pressure, kg/cm2 4 6 7 10.5Temperature, oC 40 Dew Point = (-) 100 oC at

atmospheric pressure

* The operating and design conditions are typical and tentative and shall not be used for design purposes. For actual utility conditions please refer project design basis of the specified project.

15.0 Noise Control

Sound Level Limits for Personnel

All process units should conform to a work area limit of 90 dBA. The maximum eight-hour exposure level for personnel exposure shall not exceed a continuous sound pressure level of 87dBA. This limit does neither apply to locations where excessive noise exposure is infrequent, or to non-recurring operating conditions such as venting.At no time shall personnel be exposed to sound- levels in excess of 115 dBA. Hearing protection does not alter this requirement.

Area Sound Level Limits

The following limits shall apply to all plant areas and buildings.Executive office, conference rooms 35 dBASemi-private offices, small conference rooms 45 dBAGeneral offices, laboratories 50 dBAControl rooms 55 dBAWorkshop offices 65 dBAPersonnel shelters 70 dBAWorkshops, machine rooms 75 dBAOperating areas within 15m of permanent operator's station 85 dBAor maintenance station

Noise reduction

The following methods will be considered for noise reduction.Heaters : Intake / outlet silencers, Acoustic lining / laggingMotors : Low noise motors or enclosuresAir Cooled Heat Exchangers : Decrease tip speed, Hub seals, Acoustic

shrouds on gear or belt drives, Low noise motors

Compressors : In line silencers Lagging Acoustic Enclosures Valves : Low noises trim Acoustic lagging SilencersVents : SilencersFlares : Acoustically baffled multi-port nozzles

Plant Fence Line Noise Levels

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Plant fence line noise levels shall not exceed the following:

Leq 72dBALIO 75dBA

Where Leq is the equivalent continuous equal energy level. LIO is the 10% excess sound level.During the detailed engineering phase of the project noise shall be further controlled by placing limitations on the suppliers of new equipment and for the refurbishment of existing equipment where applicable.

Meteorological Conditions

The pertinent data shall be referred from Project Design Basis, to be provided by the client.

16.0 Aromatics Handling

Special precaution shall be given when handling the process streams containing Aromatics (Carcinogen) with following specifications:

• Benzene content greater than 1% by weight• C6 through C9 aromatics greater than 25% weight• Butadine content greater than 5% by weightIn handling these streams following precautions shall be taken:

• Pumps shall be dual mechanical seals• The followings shall be connected to closed blowdown system

1. Vessel drains2. Pump drains3. Control valve, level gauge and level instrument drains.

17.0 Corrosion Allowance

The minimum corrosion allowance shall be as per the following table:

Sl. No. Service Corrosion Allowance (mm)1 Carbon Steel Pressure Vessels 32 Carbon steel atmospheric vessels 33 Alloy steel vessels 1.54 Stainless steel vessel Nil5 Clad / lined vessels 3 mm clad thk6 Carbon steel / LAS exchangers 37 SS / HAS / Non ferrous exchangers Nil

18.0 IBR Requirements

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The IBR requirements are as below:

Vessels: Any closed vessel exceeding 22.75 litres in capacity which is used

exclusively for generating steam under pressure and include any mounting or other fittings attached to such vessels, which is wholly or partially under pressure when steam is shut-off comes under IBR.

Piping : Any pipe through which steam passes and if : Steam system mechanical design pressure exceeds 3.5 kg.cm2g or Pipe size exceeds 254 mm internal diameter.

Then the pipe is under IBR.

The following Items are not under IBR Steam tracing Heating Coils Tubes of Tanks Steam Jackets

All steam users (Heat Exchangers, vessels, condensate pots etc.) where condensate is flashed to atmospheric pressure i.e. downstream is not connected to IBR system are not under IBR and IBR specification is done at last isolation valve upstream of equipment.

All steam users where downstream piping is connected to IBR i.e. condensate is flashed to generate IBR steam are covered under IBR.

Deaerator, BFW pumps are not under IBR and IBR starts from BFW pump discharge.

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76530132 process design manual lurgi

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